Pasteurellosis of cows. Symptoms and course in different forms. Forms and symptoms

Pasteurellosis(Latin, English - Pasteurellosis; hemorrhagic septicemia) is a contagious infectious disease of animals of many species, characterized by acute course septic phenomena, lobar pneumonia, pleurisy, edema in various areas of the body, and in subacute and chronic cases, purulent-necrotizing pneumonia, damage to the eyes, joints, mammary glands and hemorrhagic enteritis (see color insert).

Historical background, distribution, degree of danger T and and damage. The disease has been known for a long time, but its infectious nature was established in 1878 by E. M. Zemmer, Pirronchito and Rivogliata. The pathogen was first isolated by L. Pasteur in 1880. In the same year, L. Pasteur conducted the first experiments to weaken bacterial cultures isolated from dead chickens and immunized birds. In honor of his merits, this pathogen was named pasterella, and the disease it caused was named pasteurellosis.

The disease is widespread in all countries of the world. In our country, pasteurellosis is registered in all regions, but the highest incidence is observed in the central zone of the Russian Federation. The economic damage from pasteurellosis consists of losses from mortality, forced slaughter of sick animals and the costs of carrying out preventive and health measures.

The causative agent of the disease. The causative agent of pasteurellosis - Pasteurella multocida - is a polymorphic, often short, gram-negative, immobile ellipsoidal rods, located separately, in pairs or, less often, in chains; they do not form spores; aerobes and facultative anaerobes. Smears from blood and organs are characterized by bipolar coloring, often with a pronounced capsule. On ordinary nutrient media they give good typical growth.

Antigenically, P. multocida is heterogeneous; it has 4 capsular serotypes (A, B, D, E) and 12 somatic types. Determination of the antigenic structure of P. multocida strains plays an important role in the selection of vaccine strains, in particular for the preparation of a vaccine against large pasteurellosis cattle- serotype B, birds - A and D and pigs - A, B, D.

The pathogenic and virulent properties of various serotypes of the pathogen to different animal species vary widely.

In the occurrence of pasteurellosis among animals, especially in small and large livestock, hemolytic pasteurella (P. haemolytica), which has two biotypes: A and T, which is currently taxonomically included in the genus Actinobacillus, plays a certain role. To differentiate P. multocida from P. haemolytica, growth on MacConkey agar, white mouse resistance test and hemolysis on blood agar (positive for the latter) are used.

Pasteurella is stable in manure, blood, cold water for 2...3 weeks, in corpses for up to 4 months, in frozen meat for 1 year. Direct Sun rays kill them within a few minutes, at a temperature of 70...90 "C they die within 5...10 minutes. Treatment with a 5% solution of carbolic acid neutralizes pasteurella after 1 minute, with a 3% solution - after 2 minutes , 5% solution of lime milk (calcium hydroxide) - after 4...5 minutes, 3% hot solution (50 ° C) of sodium bicarbonate and 1% solution of bleach - after 3 minutes.

Epizootology. All species of domestic mammals and birds are susceptible to pasteurellosis. Buffaloes, cattle, rabbits and chickens are most susceptible. Horses and carnivores have relatively high resistance to pasteurellosis. Pasteurellosis appears in the form of sporadic cases, but under conditions conducive to its spread, it can acquire the character of an epizootic.

The main source of the infectious agent is sick and recovered animals, as well as clinically healthy animals that were in close contact with patients with pasteurellosis. Pasteurellosis carriage is of great importance in the epizootology of the disease, which in disadvantaged farms reaches 70% among cattle, 50% in sheep, 45% in pigs, more than 50% in rabbits, and from 35 to 50% among chickens.

Factors contributing to the epizootic spread of pasteurellosis include mass movements of animals without due consideration of the degree of welfare of farms due to pasteurellosis, the lack of proper organization of economic and veterinary-sanitary measures in livestock and poultry farms, wide use There is not enough neutralized slaughterhouse waste as feed.

The ways of excretion of pathogens from an infected body are different: with feces, urine, especially with discharge from the nose during coughing, snorting, with blood during bleeding. Sick cows can also excrete pasteurella in their milk.

The pathogen is transmitted through direct contact (keeping healthy and sick animals together), as well as through infected feed, water, soil, care items, milk, waste from the meat processing industry, mouse-like rodents, insects, wild birds and humans.

Infection of animals is possible through the respiratory system (aerogenous route), injured skin and mucous membranes.

Morbidity and mortality from pasteurellosis can vary greatly depending on the virulence of the pathogen, the immunological structure of the herd, housing and feeding conditions, the presence of concomitant infections and the timeliness of health measures. In modern conditions of keeping animals, pasteurellosis can occur simultaneously with other diseases: parainfluenza, infectious rhinotracheitis, adenovirus infection, salmonellosis, streptococcosis, diplococcosis; in pigs - with erysipelas, plague, salmonellosis; in chickens - with colibacillosis and staphshucoccosis. Mixed infections usually take a longer and more malignant course.

Animal pasteurellosis is observed at any time of the year, in pigs more often in March - April and September - November, in cattle in July - August and September - November.

Pathogenesis. Development and severity pathological process for pasteurellosis depend on the state of the animal’s body and the virulence of the pathogen. At the sites of penetration, Pasteurella multiply, penetrate into the lymph and blood, causing septicemia and death of the animal in most cases after 12..36 hours. Toxic products of Pasteurella play an important role in the development of pathological processes - endotoxins and especially aggressins, produced by the pathogen and suppressing the body's resistance . The generalization of the process is facilitated by the inhibition of phagocytosis by Pasteurella (incomplete phagocytosis) and massive damage to the capillaries. As a result, extensive swelling develops in the subcutaneous and intermuscular tissue.

Course and clinical manifestation. IN Depending on the virulent properties and routes of penetration of the pathogen, the incubation period for pasteurellosis lasts from several hours to 3 days. The disease can occur hyperacutely, acutely, subacutely and chronically.

In cattle hyperacute course a sudden increase in body temperature to 41 °C, severe cardiac disorders, and sometimes bloody diarrhea are observed. The death of the animal occurs after a few hours with symptoms of rapidly increasing cardiac weakness and pulmonary edema.

Spicy Pasteurellosis, as a rule, occurs with primary damage to either the intestines (intestinal form), or the respiratory system (thoracic form), or with the appearance of edema in various parts of the body (edematous form). Body temperature is elevated in all forms of acute pasteurellosis.

Intestinal form It often manifests itself in young animals and is characterized by progressive diarrhea and weakness of animals. There are frequent cases of blood appearing in stool. Animals experience thirst, anemic mucous membranes and increasing depression.

At chest form They note signs of acute fibrinous pleuropneumonia: accelerated and labored breathing, cough, discharge from the nasal openings, first serous and then serous-purulent, rapid pulse. Auscultation of the chest reveals areas of dullness, increased bronchial breathing, and sometimes friction sounds. Towards the end of the disease, diarrhea mixed with blood often develops. The illness lasts for several days. Many sick animals die, or the disease takes a subacute or chronic course.

Edema form characterized by the formation of rapidly spreading inflammatory edema of the subcutaneous tissue and intermuscular connective tissue in the head, neck, dewlap, labia, and sometimes extremities. The mucous membrane of the oral cavity, the frenulum of the tongue and the tongue are swollen and bluish in color. Breathing is difficult, wheezing. Sticky saliva is released from the corner of the mouth. Animals die due to symptoms of increasing heart failure and asphyxia.

In buffaloes, pasteurellosis occurs hyperacutely or acutely with the same clinical signs as in cattle.

In sheep, acute pasteurellosis with its inherent general clinical signs of septicemia is rarely observed. Fever and severe depression of the general condition are accompanied by the development of edema of the subcutaneous tissue of the anterior part of the body and fibrinous pleuropneumonia. Patients die on the 2...5th day. The subacute and chronic course of the disease is characterized by symptoms of prolonged fibrinous pleuropneumonia, keratitis, mucopurulent rhinitis, arthritis and progressive exhaustion.

Sheep pasteurellosis, caused by hemolytic pasteurella, most often manifests itself as pneumonia and, less often, mastitis.

Porcine pasteurellosis most often occurs as a secondary infection, complicating plague, influenza, erysipelas and other diseases. Much less often, the disease occurs acutely, as an independent infection, characterized by the phenomena of hemorrhagic septicemia and damage to the lungs and pleura. In the case of a hyperacute course of the disease, the animal’s body temperature suddenly rises (up to 41...42 °C). Sick pigs lie down and refuse to feed. The skin of the ears and abdominal wall becomes bluish-purple - a sign of heart weakness. Pharyngitis often develops, and the subcutaneous tissue in the neck area swells greatly. Animals die due to asphyxia within 1...2 days. If the disease drags on, signs of fibrinous pneumonia come to the fore. A severe cough, shortness of breath and mucopurulent rhinitis appear. The disease usually ends in death on the 5th...8th day. In the chronic course of pasteurellosis in sick pigs, the body temperature remains within normal limits, the cough decreases, but weakness and emaciation progress, eczema may appear, and joints may swell. Some animals survive, but most die within a few weeks.

Pasteurellosis in rabbits often manifests itself acutely; subacute and chronic courses are less common. In an acute case, the animal’s body temperature suddenly rises (up to 41 “C and above) and signs of catarrh of the upper respiratory tract- runny nose, sneezing. Breathing becomes difficult. The rabbit is not eating well and is noticeably weakening. Diarrhea appears. Death can occur within 24...48 hours. It is characteristic that shortly before the death of the animal, the body temperature drops sharply. The subacute course of the disease in rabbits in most cases is the result of an exacerbation of a chronic disease. In this case, clinical signs characteristic of bronchopneumonia, lobar pneumonia, and fibrinous pleurisy are observed. Diarrhea is common. Chronic manifestations of pasteurellosis occur in permanently unfavorable rabbit farms. In this case, the characteristic signs of pasteurellosis are rhinitis, conjunctivitis and keratoconjunctivitis. Breathing becomes difficult. IN subcutaneous tissue abscesses can be detected.

In birds, pasteurellosis can occur in different ways. Sometimes a completely healthy-looking bird dies. Only just before death is a depression in the general condition and a blue discoloration of the crest noted. Instant, overnight death of birds that looked completely healthy the day before, especially if waterfowl are also dying, is an important diagnostic sign of pasteurellosis. In the acute course of the disease, the bird becomes lethargic, keeps itself apart, sits in one place, and a lot of foamy mucus flows from the mouth and nasal openings. Body temperature rises to 43.5 °C, feathers are ruffled and dull. Faeces that are grey, yellow or greenish in color, sometimes mixed with blood, are passed very frequently. Cyanosis of the comb and catkins is clearly expressed. Breathing is accelerated and difficult due to the presence of thick mucus in the respiratory tract. There is no appetite, thirst increases, general weakness progresses, the bird has difficulty getting up and most often dies after 3 days.

Pathological signs. In cattle with hyperacute and acute pasteurellosis, pathological changes are characterized by multiple hemorrhages on the serous membranes, enlargement and swelling of the lymph nodes, acute gastroenteritis, often hemorrhagic in nature, but the spleen is not enlarged. In addition, a typical symptom is swelling in the subcutaneous tissue and intermuscular tissue in the head (pharynx and intermaxillary space), neck, dewlap, genitals and anus. Celebrate dystrophic changes in the liver, kidneys and heart.

At chest form diseases, especially pronounced changes are found in the lung area: lobar or necrotizing pneumonia and pleuropneumonia. The process affects individual sections of the lungs, and sometimes entire lobes. With pasteurellosis, lobar pneumonia is somewhat different from classical pneumonia - it usually spreads quickly, as a result of which marbling appears indistinctly, the exudate contains many red blood cells, necrotic foci quickly appear - dull, dirty grayish or dark brown in color, the size of a pea to a fist. Regional The lymph nodes enlarged, juicy, with pinpoint hemorrhages.

When opening sheep, hemorrhages are most often found in the subcutaneous tissue, muscles, serous membranes, lymph nodes, intestines and heart. The lungs are usually enlarged, cyanotic, and foamy fluid accumulates in the trachea.

In pigs, the necropsy picture depends on the severity of the disease. If the disease is acute, then numerous hemorrhages are found on the skin, serous and mucous membranes, gelatinous-serous swelling of the subcutaneous tissue in the larynx and neck, pulmonary edema, enlargement and hyperemia of the lymph nodes.

With a prolonged course, changes in the lungs are pronounced. Pleurisy, severe compaction of lung tissue, is diagnosed. On section they have a variegated appearance due to hepatization of various stages. In addition, airless dense areas of varying sizes are found in the lungs.

In rabbits, in case of death during the acute course of the disease, numerous hemorrhages are found on the mucous membrane of the upper respiratory tract, in the lymph nodes, on the mucous and serous membranes of the intestines. Striped hemorrhages between the tracheal rings are considered especially characteristic. The lungs are hyperemic, edematous, dotted with pinpoint hemorrhages. At subacute course diseases establish fibrinous or purulent pleurisy, lobar hemorrhagic pneumonia. Chronic pasteurellosis in rabbits is characterized by changes in the mucous membrane of the upper respiratory tract and lungs, the presence of abscesses under the skin, in the lymph nodes, in the mammary gland, and in internal organs. In many cases, the mucous membrane of the stomach and intestines is inflamed. There may be small necrotic lesions in the lungs and liver.

In birds with hyperacute pasteurellosis, changes in corpses are usually absent. In some cases, exudate is noted in the cardiac sac, and pinpoint hemorrhages under the epicardium. In cases of acute disease, hemorrhages are found in the deep layers of the skin and subcutaneous tissue, almost always hemorrhages of varying sizes on the serous membranes and fat in the abdomen, sternum, and gonads (ovary). The heart sac is filled with exudate. The heart (pericardium and epicardium) is almost always covered with numerous hemorrhages and appears as if splashed with blood. Signs of enteritis are observed, with inflammation of the duodenum being the most pronounced. Exudate is often found in the abdominal cavity. The liver is in a state of parenchymal degeneration, yellowish in color, dense in consistency, covered with pinpoint grayish necrotic lesions. The spleen is usually not changed.

In a disease that progresses more slowly, the following changes are observed: the comb and earrings are blue, the pectoral muscles are dark-colored, hemorrhages on the epicardium, on the intestinal mucosa, the liver is enlarged, with multiple small foci of a necrotic nature. With arthritis, a curd-like purulent exudate accumulates in swollen joints.

Diagnosis and differential diagnosis. The diagnosis of pasteurellosis is established on the basis of a complex of epizootic, clinical, pathological and laboratory studies.

Laboratory diagnosis of pasteurellosis involves: 1) microscopy of blood smears and fingerprint smears from affected organs; 2) isolation of pure culture on nutrient media with identification by biochemical properties; 3) isolation of pasteurella by infecting laboratory animals (white mice or rabbits) with a suspension from pathological material and a culture from a nutrient medium; 4) determination of the virulence of isolated cultures for white mice and rabbits. To determine the virulence of hemolytic pasteurella, 7-day chicken embryos are used; 5) determination of serovariant affiliation of Pasteurella.

As test material, blood from the superficial vessels and nasal mucus are taken from sick animals, and after death or forced slaughter - blood from the heart, lymph nodes (mesenteric, retropharyngeal, mediastinal, suprauterine, etc.), pieces of lungs, liver, spleen, heart , kidney, tubular bone. IN summer time during long-term transportation, pathological material is preserved with a 30% sterile glycerin solution.

The diagnosis of pasteurellosis caused by P. multocida is considered established: 1) when virulent pasteurella are isolated from the blood or simultaneously from several parenchymal organs; 2) when isolating a culture only from the lungs of cattle or pigs; 3) in sheep, simultaneous isolation of P. haemolytica from the lungs, blood and parenchymal organs serves as the basis for the diagnosis of hemolytic pasteurellosis.

Isolation from the lungs of both weakly virulent P. multocida and P. haemolytica indicates a mixed disease of pasteurellosis caused by Pasteurella of both species. Such pasteurellosis is diagnosed as pasteurellosis pneumonia.

When diagnosing pasteurellosis, it is necessary to differentiate from febrile diseases of a septic nature, which are also accompanied by the appearance of inflammatory edema under the skin: anthrax, emphysematous carbuncle and malignant edema.

Immunity and specific prevention. Animals that have recovered from pasteurellosis acquire immunity for 6...12 months. For specific prevention diseases in Russia, more than 15 vaccines are recommended, mostly inactivated: polyvalent emulsified against pasteurellosis of pigs; lyophilized against pasteurellosis in cattle and buffaloes; sorbed against avian pasteurellosis; against salmonellosis, pasteurellosis and streptococcosis in piglets; associated against salmonellosis, pasteurellosis and enterococcal infection of piglets and a live vaccine against pasteurellosis of waterfowl from strains AB and K of the Krasnodar NIVS. Vaccines are used for preventive purposes and involuntarily in case of stationary problems on farms. Intense immunity is formed on the 7...10th day after revaccination and lasts up to 6 months.

For passive immunization, hyperimmune sera are used against pasteurellosis in cattle, buffaloes, sheep and pigs.

Prevention. To prevent the disease, managers and specialists of farms and animal owners must ensure that the following measures are taken: all animals entering the farm are kept in quarantine for 30 days under veterinary control and, if indicated, vaccinated against pasteurellosis; stock herds with animals only from farms that are free from pasteurellosis; do not allow contact between farm animals and animals in personal use; have sanitary checkpoints on farms and provide service personnel with a change of clothes and shoes; protect animals from various stressful influences; in areas unfavorable for pasteurellosis, systematically vaccinate animals; farms in which pasteurellosis has been registered must be equipped with only vaccinated livestock throughout the year.

Treatment. Sick animals are injected with hyperimmune serum against pasteurellosis. therapeutic dose and one of the antibiotics (terramycin, oxytetracycline, biomycin, chlortetracycline, tetracycline, streptomycin, chloramphenicol), long-acting drugs (dibiomycin, ditetracycline, disreptomidazole, bicillin-3) or more modern drugs - enrofloxacin, etc. Can be used for therapeutic purposes pathogenetic and symptomatic agents.

Control measures. When an animal disease with pasteurellosis is established, the farm (farm, brigade, department, etc.) is declared unaffected by pasteurellosis; by decision of the territorial administration, restrictions are introduced and a plan of organizational, economic, veterinary and sanitary measures to eliminate the disease is approved.

In a farm unaffected by pasteurellosis, it is prohibited to: 1) import (export) animals outside the farm for breeding and consumer purposes, with the exception of exporting clinically healthy animals to a meat processing plant; import (export) animals susceptible to pasteurellosis; 2) regroup, mark (with violation of the integrity of the skin) animals, as well as carry out surgical operations and vaccinations against other diseases; 3) graze animals from disadvantaged groups and give them water from open water bodies; 4) sell milk from animals sick or suspected of having pasteurellosis. Milk must be pasteurized for 5 minutes at 90 °C and used as animal feed. Milk from healthy cows is used without restrictions; 5) remove (remove) feed, implements, equipment and other items from the premises of dysfunctional farms; 6) transport manure and liquid fraction to the fields in an undisinfected form.

Animal slaughter products are subjected to veterinary inspection at the slaughter site. If there are degenerative or other pathological (abscesses, etc.) changes in the muscles, the carcass with internal organs is sent for disposal. In the absence of pathological changes in the carcass and internal organs, slaughter products are sent to a meat processing plant in compliance with current veterinary regulations. sanitary rules for the transportation of meat products.

In order to localize the epizootic focus and eliminate the disease, farm managers and veterinary specialists must ensure the following activities: 1) clinical examination and thermometry of all animals of the disadvantaged group; 2) isolation in a separate room of sick and suspected animals and assigning them special equipment and sanitary and hygienic means, as well as service personnel, including a veterinary specialist; 3) clinically healthy animals, regardless of their location, be immunized against pasteurellosis with one of the vaccines in accordance with the instructions for use.

Routine disinfection in the premises where animals are kept is carried out immediately when the first cases of disease or death appear, and then daily during the morning cleaning of premises where sick and suspected of disease animals are located. Premises, walking yards, cages (and the soil under them) where animals suspected of being infected (conditionally healthy) are kept must be disinfected after each case of isolation of a sick animal and subsequently every 10 days until restrictions are lifted, in accordance with the current instructions “Carrying out veterinary disinfection of livestock facilities."

Before the restrictions are lifted, the following measures are carried out in a troubled point: 1) repairs to the premises where sick and suspected animals were kept; 2) disinfection and cleaning of the entire farm area from manure and debris, then repeated disinfection and plowing; 3) disinsection, deratization and final disinfection of premises.

The restriction on farms (farm, team, yard) is lifted 14 days after the general vaccination of animals and the last case of recovery or death from pasteurellosis, as well as a set of organizational, economic, veterinary and sanitary measures with final disinfection.

Test questions and assignments. 1. What are the clinical and epizootological features of the manifestation of animal pasteurellosis depending on the serotype of the pathogen? 2. What factors determine the stationarity and seasonality of the disease? 3. What biomaterial should be sent to the laboratory for research and when is the final diagnosis of the disease considered established? 4. What set of measures should be carried out on a dysfunctional farm? 5. Name the means and methods of treating sick and suspected animals with pasteurellosis. 6. How is specific immunoprophylaxis of pasteurellosis carried out in animals of different species?

1.7. NECROBACK T ERIOSIS

Necrobacteriosis(lat. - Necrobacteriosis; Necrobacillosis; necrobacillosis) - an infectious disease of animals of many species and humans, characterized by purulent-necrotic lesions of the skin, mucous membranes, internal organs and limbs (see color insert).

Is T orical information, distribution, economic damage. The disease has been known under various names since the mid-19th century. first in sheep and later in other species. The pathogen was first isolated by R. Koch (1881) and described in detail by F. Leffler (1884).

The disease is widespread on all continents. In Russia, the disease in the hoof form has become widespread in cattle since the 1970s during the process of widespread Holsteinization and the purchase of breeding stock; it has existed in reindeer for a long time.

Economic damage is great in dairy and beef cattle breeding (due to damage to the limbs) and reindeer husbandry (deaths of up to 80% of young animals and up to 30% of adult reindeer are noted).

The causative agent of the disease. The causative agent of necrobacteriosis - Fusobacterum necrophorum - is a strict anaerobe. This is a non-spore-forming, gram-negative, very polymorphic microorganism. The typical location in the affected tissues is in the form of filaments, sometimes reaching a length of 100...300 microns. The thickness of bacteria is 0.7... 1 microns. Along with the threads, you can find individual rods 3...4 microns long and even short forms in the form of cocci. Unevenly stained bacteria have the appearance of a rosary, often swollen in places, with thickenings. There are four serotypes: A, AB, B, C, of ​​which the most pathogenic is A And AB.

The pathogen grows under anaerobic conditions in liquid media (MPPB, etc.) with turbidity of the medium, gas formation or without it, and the formation of sediment. On blood agar it forms small (2...3 mm in diameter) matte convex colonies with a smooth or rough edge and a greenish zone of alpha or beta hemolysis. Decomposes a number of Sugars with the formation of acid and gas, but not constantly (depending on the strains). Forms indole, hydrogen sulfide, milk does not constantly curdle, gelatin does not liquefy constantly. Cultures of the pathogen are pathogenic for mice and rabbits.

The pathogen produces several strong pathogenicity factors: exo- and endotoxins - leukocidin, necrotoxin, hemolysin, cytoplasmic toxin, and a number of enzymes - lecithinase, hyaluronidase, etc.

In the external environment, the microorganism is weakly resistant and, under the influence of sunlight, is inactivated within 8...12 hours. It persists in the soil for up to 60 days in winter and up to 30 days in summer; manure - up to 30...60 days; water and urine - up to 10... 15 days. The causative agent of necrobacteriosis is also weakly resistant to physicochemical factors and disinfectants and dies at 60...80 °C in 5...30 minutes, at 100 °C - in 1 minute; under the influence of 70% alcohol - in 10 minutes; 1.5% phenol solution - in 5... 10 minutes; 1% sodium hydroxide solution - in 20 minutes; bleach - in 30...60 minutes; 2.5% formaldehyde solution - in 10...15 minutes.

Epizootology. All types of domestic animals are susceptible, many wild animals, birds, humans, but the degree of susceptibility varies. Cattle and reindeer are most susceptible to the disease. The disease manifests itself in different animals in different clinical forms. Young animals are generally more sensitive.

The source of the infectious agent is sick bacteria-carrying animals, which release a highly virulent pathogen, infecting pastures, livestock buildings and other objects. Transmission factors are infected pastures, floors, litter, care items.

The pathogen is released into the external environment through feces, urine, saliva, excreta, purulent contents of foci of necrosis of the skin, hooves, discharge from the uterus, etc. Animals become infected from infected environmental objects through injured skin of the extremities, mucous membranes of the gastrointestinal tract, during pathological childbirth , perhaps during mating through microtrauma of the genital tract. The autogenous route of infection is not of great importance. As a rule, the initial introduction of infection into a farm occurs with sick or infected animals. Contagiousness is low. Then the infection on the farm becomes stationary with a tendency to increase the severity of the pathological process due to repeated passage of the pathogen through naturally susceptible animals. Seasonality (spring-summer) is observed only in reindeer.

The disease occurs sporadically, in the form of small epizootic outbreaks or epizootics (in cattle, reindeer).

Pathogenesis. After penetration through the gates of infection, the pathogen of increased virulence begins to multiply in damaged (dead) tissues, produce toxins, in particular leukocidin, which destroys leukocytes and macrophages, inhibiting phagocytosis, which promotes further proliferation of microorganisms and blocks the formation of immunity. Tissue necrosis develops with the formation of purulent-necrotic foci. The pathogen spreads through the bloodstream, forming secondary necrotic foci (metastases) in organs. With the participation of toxins and enzymes, a favorable environment is created for further lesions - bronchopneumonia, pleurisy, peritonitis, abscesses, phlegmon, etc. The pathological process can be complicated by secondary pyogenic microflora, and the disease becomes malignant. With necrobacteriosis of the extremities, this process is usually local in nature.

Course and clinical manifestation. The incubation period for necrobacteriosis is several days. Clinical signs depend on the type and age of the animal, the course and form of manifestation of the disease. The course of the disease can be acute (mainly in young animals), acute and chronic, benign or malignant.

There are three main forms of the disease (Table 1.4).

Cattle pasteurellosis is a dangerous infectious disease that literally leads to the death of a cow in just a few days. In addition, this disease also extends to most other domestic animals, birds and humans. Therefore, it is extremely important to know the main manifestations of this disease and take timely measures to neutralize it.

What is the disease?

Cattle pasteurellosis is a consequence of the development of pathogenic bacteria in the body. As this disease progresses, the affected animal develops blood poisoning, pneumonia (including purulent pneumonia), endometritis, conjunctivitis and a number of other secondary diseases and complications.

The most susceptible to infection are cows, rabbits and Domestic bird. The disease is also transmitted to many species of wild animals. It is widespread in almost all countries of the world. In Russia greatest number cases of infection are registered in the central regions of the country.

Causes and causative agent

Pasteurellosis is caused by bacteria of the genus Pasteurella. There are several types of such bacteria. Two of them are dangerous for cattle:

1. Pasteurella multicida.
2. Pasteurella hemolytica.

Both types of pathogens are characterized by fairly low resistance to external negative impacts. When exposed to sunlight, the bacterium dies within 10 minutes. The pathogen can live in manure or moist soil for 2 weeks. When exposed to temperatures of 80 degrees or higher, pasteurella dies within 5 minutes. From disinfectants solutions of creolin, slaked lime, and caustic soda are destructive for infection.

When ingested by a cow, the bacteria become established in the animal's respiratory tract and intestines. In this case, the spreaders of the disease are most often sick cattle and those individuals that have already been cured. In addition, the pathogen is also long time able to live in the body of healthy animals.

The bacterium enters the external environment along with fecal matter, blood, milk, saliva and urine of animals. Transfer can occur in the following ways:

• with food and water;
• through care items;
• through the common litter;
• by air;
• along with mucus when sneezing or coughing;
• through the ground;
• in contact with wild animals or humans.

The infection can also be transmitted to healthy individuals through the bites of blood-sucking insects and rodents that have previously been in contact with sick livestock.

Most often, pasteurellosis develops in cows from mid-summer to late autumn. At this time they are observed optimal conditions for the development of infection. Young animals are more susceptible to infection.

Symptoms and course for different forms

Once it enters the body, the bacterium begins to develop extremely quickly. Damaging tissue, pasteurella spreads along with blood and lymph. At the same time, their waste products cause septicemia. The pathogen is also capable of damaging tissue capillaries, which leads to swelling throughout the body. After blood poisoning, death occurs within the next 3 days.

The incubation period for pasteurella in the body ranges from 5-6 hours to 3 days. After this, the disease manifests itself in acute, hyperacute, chronic and subacute forms. Each of them suggests its own clinical signs.

Acute

The acute course of pasteurellosis is accompanied by the following main manifestations:

• general depression, accompanied by loss of appetite;
• increased heart rate and breathing;
• the temperature rises above 40 degrees;
• cessation of milk production.

With the further development of the acute course of the disease, it can manifest itself in various forms: thoracic, intestinal and edematous. In the chest form, the underlying disease is supplemented by pleuropneumonia. In this case, in addition to the main symptoms, the following clinical signs also appear:

• purulent exudate is released from the nasal cavity;
• breathing is very difficult;
• severe diarrhea, in which after a certain time the amount of blood increases;
• when listening to the lungs, friction sounds are heard from them;
• may be accompanied by a strong dry cough.

In the intestinal form of pasteurellosis, the following clinical signs are observed:

• refusal of food;
• excessive thirst;
• weakness and depression;
• rapid weight loss;
• blue discoloration of mucous membranes.

Most often, this manifestation of the disease is observed in young animals.

With edematous pasteurellosis, inflammation of the subcutaneous layer of tissue develops. This leads to severe swelling in the area of ​​the udder, genitals, neck and other parts of the body. If this form of the disease develops, death occurs within 1-2 days. The edematous form is accompanied by the following symptoms:

• cessation of milk production;
• rapid breathing, while it is extremely difficult for the cow to breathe;
• on different areas swelling occurs in the body;
• Asphyxia may gradually develop, which leads to the death of livestock.

Subacute

In the case of a subacute course, the disease develops more slowly. It can last up to two weeks. At the same time, on initial stage symptoms are poorly developed and gradually become more pronounced. The main signs of this form of the disease include:

• increased body temperature;
• severe dry cough;
• oppression and refusal of food;
• increased thirst;
• mucous discharge from the nasal cavity, which in a short time turns purulent;
• the appearance of swelling in the neck and head;
• conjunctivitis.

Reference. Based on subacute pasteurellosis, secondary diseases often develop, for example, enteritis.

Super acute

The hyperacute form of the disease is the most dangerous. From the end of the incubation period of the pathogen to the death of the cow, no more than 12 hours pass. Often no clinical signs appear at all. Therefore, it is extremely difficult to diagnose and treat this course of the disease.

If clinical signs are present, they manifest themselves as follows:

• a sharp increase in the cow’s body temperature to 42 degrees;
• severe swelling;
• diarrhea with a large amount of blood in the stool.

Death occurs as a result of pulmonary edema or disruption of the cardiovascular system.

Chronic

The chronic form of the disease differs less severe symptoms and a longer period of development (up to 4-5 weeks). But despite this, it also often ends in death. The symptoms in this case are as follows:

• difficulty breathing;
• rapid weight loss;
• refusal of food;
• swelling of the joints of the limbs;
• severe diarrhea is possible.

Diagnostics

Since the disease is infectious and often fatal, it timely diagnosis is a top priority. Detection of pasteurellosis in the body of cattle is carried out on the basis of clinical signs, laboratory and pathological studies.

For laboratory studies, samples from dead or intentionally killed animals are used. Particles of the liver, lung, spleen, and lymph nodes are suitable for this purpose. Materials are taken no later than 5 hours from the moment of death of the livestock. The culture isolated from the resulting sample is placed in a nutrient medium and its membership in the Pasteurella genus is determined.

In pathoanatomical studies, a positive analysis result is established if the following changes are detected in organs and systems:

• numerous hemorrhages in the lungs, intestines, respiratory tract, as well as on the pericardium and epicardium of the heart;
• large accumulations of blood and lymph that form in the tissue under the skin;
• enlarged lymph nodes;
• separate departments digestive tract and intestines are significantly inflamed and swollen.

Attention! It is extremely important to carry out a comprehensive analysis in order to distinguish pasteurellosis from piroplasmosis, anthrax and other diseases with similar clinical manifestations. Correct diagnosis of such a disease is the basis for its successful treatment.

Treatment

If characteristic signs of the disease are detected, the animal is immediately isolated from the rest of the herd. A warm, dry room with well-equipped ventilation is used as quarantine. At the same time, the cow is transferred to a special diet, carefully balanced in terms of vitamins, mineral composition and nutrients.

The entire further course involves exclusively drug treatment. It assumes a symptomatic and specific focus. In the first case, it is assumed that the functioning of the organs and systems of the body affected by the disease will improve. For this purpose, use:

• painkillers;
• antipyretics;
• diuretics;
• medicines that restore normal function digestive tract.

In parallel with the treatment of symptoms, the fight against developing infection is also carried out. For this purpose, serum against pasteurellosis can be used. But it is worth noting that it is used only in the first stages of development. acute form diseases. At further progression disease it becomes useless. The vaccine against bovine pasteurellosis is administered intravenously or intramuscularly in dosages determined by the veterinarian.

In addition to the main treatment, a number of antibiotics are also prescribed to help cope with inflammation and eliminate developing pasteurella. The main drugs of this type include:

• levomecithin;
• biomycin;
• streptomycin.

Various products give a good effect sulfa drugs. To support the body, livestock may be prescribed intravenous injections glucose. The general course of treatment lasts until the animal recovers completely and is determined individually in each specific case.

Prevention

A more effective measure to combat pasteurellosis is high-quality preventive activities:

• ensuring proper sanitary conditions for keeping livestock on large farms and subsidiary plots;
• proper balance of animal feeding. This also includes constant monitoring of feed quality;
• acquisition of new heads for the herd exclusively from those that have been tested and are successful in various respects infectious diseases farms;
• quarantine of newly acquired animals for a period of at least 30 days for examination and vaccination;
• providing personnel working on the farm with a set of work clothes, which they will use exclusively within their workplace;
• periodic disinfection of livestock buildings, feeders and equipment with solutions of caustic soda, slaked lime or creolin.

To prevent mass infection of the entire herd, if an animal is suspected of having pasteurellosis, it is immediately isolated in a separate room. In this case, the breeder is obliged to contact a qualified veterinarian as soon as possible.

Attention! If cases of the disease have been registered on a farm, its herd is replenished exclusively with animals that have been vaccinated.

Conclusion

Pasteurellosis is a fairly common disease of livestock. It can lead to serious consequences and in as soon as possible reduce the farm's population. That's why preventive measures Breeders should pay special attention to its prevention. In addition, if symptoms of the disease are detected, you should immediately seek professional help. Trying to solve the problem on your own can make the situation significantly worse.

Pasteurellosis- hemorrhagic septicemia is an infectious disease of many species of mammals and birds, characterized in acute cases by symptoms of septicemia, in subacute and chronic cases - predominant damage to the lungs.

Pasteurellosis is widespread in all countries of the world. It is usually observed sporadically and occurs chronically, but under conditions conducive to its spread, it manifests itself as an epizootic.

In the USSR, the study of the disease and the development specific means P. V. Sizov, V. P. Shamatava, M. K. Ganiev, N. M. Nikiforova, A. V. Lukyanchenko and others made a great contribution to the defense.

The causative agent of the disease— Pasteurella multocida is a small, gram-negative, non-motile and non-spore-forming bacterium, found isolated, in pairs, and less commonly in chains.

The size and shape of the microbe varies depending on the origin of the strain; Can be painted with all aniline dyes. Bacteria found in the tissues of sick animals are small, have an ovoid shape (0.3 - 1.25 x 0.25 - 0.5 µm), they stain well bipolarly methylene blue or according to Romanovsky - Giemsa. In fresh cultures, the cells have a clearly visible capsule.

Pasteurella are facultative aerobes that grow well on ordinary nutrient media at 37 °C. When reseeding freshly isolated cultures, it is necessary to use media with the addition of blood serum or media obtained by enzymatic hydrolysis of meat. The growth of bacteria in the broth causes uniform turbidity of the medium; 3 forms of colonies are formed on MP A: smooth (s), rough (R) and mucoid (M). Enzymatic properties are weak. The most characteristic is the formation of indole in the broth with tryptophan and the reduction of nitrates to nitrites.

P. multocida is antigenically heterogeneous. Based on the results of the seroprotection reaction, 4 immunological types are distinguished - I, II, III and IV (Robert, 1947), which allows the RIGA to distinguish 4 serological groups of Pasteurella - A, B, D and E (Carter, 1961) based on the capsular antigen. The serotyping of Pasteurella has not been fully resolved.

The pathogenic and virulent properties of various serogroups of the pathogen vary widely. They are most pronounced in relation to the species of animal from which they are isolated. Pasteurella type A most often causes disease in birds, less often in pigs, cattle and buffalo; strains B and E - mainly in cattle; group D - found in all animal species. In Pasteurella it is noted certain dependence between virulence, capsule formation and toxin formation (lipopolysaccharide endotoxin). Epizootic strains of Pasteurella are highly virulent for white mice.

Pasteurella resistance is low, natural conditions they die relatively quickly. In manure, blood, cold water, pasteurellas remain viable for 2 - 3 weeks, in corpses - up to 4 months, in frozen bird carcasses - for a year. Direct sunlight kills pasteurellas in a few minutes, at a temperature of 70 - 90 °C they die in 5-10 minutes All well-known disinfectants in normal concentrations are destructive Act within a few minutes

Epizootological data. All types of domestic and wild mammals, animals and birds are susceptible to pasteurellosis. Humans also suffer from pasteurelosis. Among chickens and rabbits, the disease usually manifests itself as an epizootic. Epizootic outbreaks of the disease are also common in other animal species, but they are observed relatively rarely. Carnivores and horses have some resistance to pasteurellosis.

Epizootic outbreaks of pasteurellosis with acute manifestation diseases such as hemorrhagic septicemia in adult cattle and wild ruminants in our country are usually caused by P. multocida type B, and in Africa - by P. multocida type E; in young cattle and buffaloes - P. multocida type B and in birds - P. multocida type A. Sporadic incidence of pasteurellosis, usually manifested by a subacute and chronic course of the disease, like enzootic pneumonia, is more often caused in calves by P. multocida type A and P. haemolytica; and in pigs - P. multocida types A and D and P. haemolytica.

The source of the pathogen is sick and recovered animals - carriers of Pasteurella. The duration of carriage can be up to a year. Pasteurellosis is characterized by widespread carriage of the pathogen by healthy animals. Most researchers consider the importation of animals carrying the pathogen from disadvantaged farms to be one of the main ways of spreading the disease. Carriage of Pasteurella by healthy animals in prosperous farms can cause a spontaneous outbreak of pasteurellosis without the introduction of the pathogen from the outside. Typically, such outbreaks are recorded on farms; they arise against the background of exposure of animals to all kinds of unfavorable factors.

Epizootic features of pasteurellosis are enzootic nature and the formation of stationary epizootic foci.

The spread of pasteurellosis is facilitated by mass movements of animals without taking into account the welfare of farms due to pasteurellosis, crowded housing of animals, all kinds of violations of production technology and veterinary and sanitary rules, and the use of unrecovered slaughterhouse waste.

Morbidity and mortality from pasteurellosis can vary greatly depending on the virulence of the pathogen, the immunological structure of the herd, housing and feeding conditions, the presence of concomitant infections and the timeliness of health measures.

Pathogenesis. Under natural conditions, pasteurella more often penetrate into the body of animals through the respiratory and nutritional routes and less often through disorders skin. At the sites of penetration, Pasteurella multiply, penetrate into the lymph and blood, causing septicemia and death of the animal in most cases after 12 - 36 hours. The generalization of the process is facilitated by the suppression of phagocytosis by Pasteurella (incomplete phagocytosis), their formation of toxic substances, which leads to massive damage to the capillaries. As a result, extensive swelling develops in the subcutaneous and intermuscular tissue and hemorrhagic diathesis. Septicemia occurs the sooner, the more virulent the pathogen.

In animals resistant to the disease and when weakly virulent pasteurella penetrate the body, septicemia does not develop. Their disease takes a subacute or chronic course with localization of the pathogen in individual organs, most often in the lungs, where lobar or serous-catarrhal inflammation develops. In hyperacute and acute cases lobar pneumonia does not have time to develop, and only the phenomena of edema and hyperemia are found in the lungs.

Course and symptoms. The incubation period ranges from several hours to 2 - 3 days. In all animals, pasteurellosis can occur hyperacutely, acutely, subacutely and chronically.

In cattle and buffaloes, the hyperacute course of pasteurellosis is manifested by a sudden increase in temperature to 41-42 ° C and general septic phenomena. The death of the animal occurs within a few hours with symptoms of rapidly increasing heart failure, pulmonary edema and sometimes bloody diarrhea. The animal may die before any clinical signs appear.

The acute course of pasteurellosis is most characterized by general depression of the animal, manifested by lethargy, anorexia and hyperthermia, reaching 40 °C and above. Nasal speculum cold and dry. Chewing gum and lactation stop, at the beginning of the disease, peristalsis and defecation slow down, then the stool becomes watery, sometimes mixed with fibrinous flakes and blood. Bloody nasal discharge often occurs, acute conjunctivitis and bloody urine. Animals develop a pronounced picture of septicemia, heart failure and die within 1-2 days.

With a longer course of the disease, in addition to the general signs of fever, local lesions may develop; Based on their clinical manifestations, edematous, thoracic and intestinal forms of pasteurellosis are distinguished. In the edematous form of the disease, rapidly increasing, painful, hot and non-crepitative swelling of the subcutaneous tissue appears in the area lower jaw, neck, abdomen and limbs. With swelling of the tongue and neck, breathing is wheezing and labored, viscous saliva is released; visible mucous membranes are cyanotic with multiple hemorrhages. In some animals the disease is accompanied by agitation (pasteurella meningoencephalitis of calves).

The chest form is characterized by symptoms of lobar (fibrinous) pneumonia: depression, anorexia, rumen atony, rapid and difficult breathing, dry painful cough and serous foamy nasal discharge. Towards the end of the disease it often appears bloody diarrhea. Most animals die on the 5th to 8th day.

In the intestinal form, the main symptom is severe damage to the intestinal tract; signs of pneumonia are less pronounced. Appetite remains, but animals develop progressive anemia and general depression.

In case of chronic course in animals functional disorders breathing and digestion are less pronounced than in the intestinal form, but diarrhea gradually leads to exhaustion and cachexia.

In sheep, the acute course of pasteurellosis with its inherent general clinical signs of septicemia is observed relatively rarely. A febrile state and severe depression are usually accompanied by the development of edema of the subcutaneous tissue of the anterior part of the body and fibrinous pleuropneumonia. Animals usually die on the 2nd -5th day. The subacute and chronic course of the disease is characterized by symptoms of prolonged fibrinous pleuropneumonia, keratitis, mucopurulent rhinitis, arthritis and progressive emaciation. Pasteurellosis, caused by P. haemolytica, often manifests itself as pneumonia and less often as mastitis.

In pigs, the hyperacute and acute course of pasteurellosis is characterized by fever with an increase in temperature to 41 ° C and above, pharyngitis, strained breathing, heart failure and often swelling in the intermaxillary region and neck. Animals die due to asphyxia within 1-2 days. With a more protracted course, fibrinous pleuropneumonia develops, shortness of breath, cough and mucopurulent rhinitis appear. The disease usually ends fatal on the 5th -8th day. The chronic course of pasteurellosis is manifested by symptoms of pneumonia, weakness, progressive emaciation, sometimes swelling of the joints and scabby eczema.

In birds, a hyperacute course of pasteurellosis is usually noted at the beginning of an epizootic. Birds suddenly fall and, after flapping their wings several times, die without any symptoms of illness. In the vast majority of cases, the disease is acute. Birds become lethargic, sit with lowered wings, the plumage is ruffled, the head is often tucked under the wing or thrown back. Body temperature rises to 44 °C and higher, anorexia and thirst develop. Foamy mucus is secreted from the nasal openings and beak. Then profuse diarrhea appears, sometimes bloody. The comb and beard become cyanotic in color. Breathing is intense, with moist wheezing. Birds die due to convulsions or drowsiness. In the subacute and chronic course, anemia, exhaustion, and inflammation of the joints gradually develop, followed by abscess formation. In some -gits, the earrings swell and become dense (Fig. 14 and VII); Then abscesses and necrosis appear. If the earrings are affected, the previous state of health is not affected (beard disease). Chronic tasterellosis sometimes manifests itself only with signs of rhinitis, sinusitis and accumulation viscous exudate around the nasal openings and on the conjunctiva.

In rabbits, the acute course of pasteurellosis is manifested by hyperthermia, depression, anorexia and symptoms of damage to the upper respiratory tract (runny nose, sneezing). Sometimes diarrhea develops. Animals weaken and die after 1-2 days. In permanently disadvantaged farms, pasteurellosis occurs chronically, with signs of rhinitis and conjunctivitis. Diarrhea, fibrinous purulent pneumonia and subcutaneous abscesses are often noted.

In fur-bearing animals (sable, fox, mink, beaver), during the acute course of the disease, severe depression and anorexia are observed. slow and unsteady gait, temperature rise to 42 °C and above. As a rule, symptoms of hemorrhagic gastroenteritis develop, especially in silver foxes. Minks develop swelling of the subcutaneous tissue in the head area, paresis and paralysis of the hind limbs. The duration of the disease is from 12 hours to 2 - 3 days.

Pathological changes depend on the duration and form of the disease. In hyperacute and acute cases, hemorrhagic diathesis is found in dead animals (in most organs, on the mucous and serous membranes there are multiple hemorrhages and inflammatory hyperemia), the liver and kidneys are degenerated, the spleen is slightly swollen, the lymph nodes are swollen and dark red. In the subcutaneous tissue, especially in the edematous form of the disease, diffuse serous-fibrinous infiltrates are expressed in various parts of the body.

The lungs are swollen, with changes characteristic of initial stages lobar pneumonia. In the intestinal form, fibrinous-hemorrhagic inflammation of the stomach and entire intestine is pronounced.

The corpses of animals that died due to subacute and chronic pasteurellosis are severely emaciated and anemic. On the serous membranes of the thoracic and abdominal cavities There may be dense fibrinous deposits. The peribronchial lymph nodes are enlarged, hyperemic, with many hemorrhages. Found in the lungs various stages red and gray hepatization, in some areas there are foci of necrosis; in case of complications - purulent-fibrinous foci. The spleen is slightly enlarged, and there are small foci of necrosis in the liver and kidneys.

Pathological changes in chickens are almost the same as in mammals, and mainly depend on the course of the disease.

Diagnosis of pasteurellosis established on the basis of epidemiological data, clinical signs and pathological changes with mandatory bacteriological examination (isolation of a pure culture of Pasteurella, virulent for white mice). For laboratory research send pieces of the spleen, liver, kidneys, affected parts of the lungs with lymph nodes and tubular bone, taken no later than 3 - 5 hours after the death of an animal that was not treated. The corpses of small animals are delivered to the laboratory whole. In summer, pathological material is preserved with 40% aqueous solution glycerin.

Differential diagnosis. Special attention pay attention to the exclusion of anthrax, piroplasmosis and emphysematous carcinoma in adult cattle, and in young cattle - staphylococcal and streptococcal infections, salmonellosis, colibacillosis and respiratory viral infections(parainfluenza-3, infectious rhinogracheitis, etc.), manifested as enzootic bronchopneumonia.

In pigs, pasteurellosis must be differentiated from plague, erysipelas and salmonellosis, in sheep - from anthrax, piroplasmosis, clostridiosis and streptococcal infection; in chickens - Newkael's disease, spirochetosis, mycoplasmosis and infectious laryngotracheitis.

basis differential diagnosis for the above and other diseases, manifested by massive pneumonia and enteritis, is complex method research in which the results laboratory diagnostics are crucial.

Treatment. Sick animals are placed in warm, dry pens, provided with complete feed, and tetracycline antibiotics and sulfonamide drugs are used according to accepted guidelines.

The use of anti-pasteurellosis serum can be effective in case of acute pasteurellosis in an animal only at the very beginning of the disease, when the first clinical signs appear. It is administered intramuscularly or intravenously in double prophylactic dose according to the instructions.

The therapeutic effect is noticeably increased when the serum is used in combination with long-acting antibiotics, sulfonamides and symptomatic means. The course of treatment depends on the condition of the animal. Birds with pasteurellosis are not treated.

Immunity. Animals that have recovered from pasteurellosis acquire immunity for 6-12 months.

For specific prevention of animal pasteurellosis in the USSR, it is recommended inactivated vaccines: precipitated formol vaccine against pasteurellosis (hemorrhagic septicemia) of cattle, sheep and pigs (N. M. Nikiforova), semi-liquid formol aluminum hydroxide vaccine AzNIVI against pasteurellosis (hemorrhagic septicemia) of cattle and buffaloes i M. K. Ganiev), concentrated polyvalent formol vaccine against paratyphoid, pasteurellosis and diplococcal septicemia of piglets (GSD), emulsified vaccine against pasteurellosis in cattle, buffaloes and sheep (N. M. Nikiforova, A. V. Lukyanchenko); emulsified vaccine against porcine pasteurellosis (N. M. Nikiforova, A. V. Lukyanchenko).

Vaccines are used for preventive purposes and involuntarily in stationary unfavorable areas, on farms during an acute outbreak of pasteurellosis and in endangered areas.

Animals are vaccinated twice with precipitated, semi-liquid and concentrated vaccines. Intense immunity is formed on the 7-10th day after the second vaccination and lasts 6 months. Emulsified vaccines are administered once: immunity for at least a year.

For the prevention of pasteurellosis in poultry farms It is recommended to use dry live vaccines made from French (Pasteur) avirulent and domestic weakly virulent strains (K and AB Krasnodar NIVS), as well as inactivated emulsion vaccines. Live vaccines are used to inoculate chickens and waterfowl in farms that are unfavorable (acute outbreak) and threatened by pasteurellosis, with the strictest culling of all sick and suspected birds. Immunity is formed by the 5th day and lasts up to 4 - 6 months. Emulsin vaccine is used mainly in endangered and permanently unaffected farms with pasteurellosis, as well as during outbreaks of the disease. On the 4th day after vaccination, all birds are given sulfadimezin or norsulfazole with food for 3-4 days. Immunity appears by the 8th day and lasts in chickens up to 6 months, in waterfowl - up to 7 months, after which revaccination is carried out without sulfonamide drugs.

For passive immunization, hyperimmune serum is available against pasteurellosis in cattle, buffaloes, sheep and pigs. The serum is administered mainly for prophylactic purposes to adult animals before their transportation, as well as to young animals (calves, piglets, lambs) in the first days of admission to livestock farms.

Prevention and control measures. To prevent pasteurellosis, it is necessary to ensure the protection of healthy farms from the introduction of the pathogen with sick animals and pasteurellosis carriers, as well as with feed, etc. Particular attention is paid to compliance with general veterinary and sanitary rules and providing animals with normal zoohygienic living conditions and rational feeding. If the disease was previously recorded on farms, all animals are vaccinated against pasteurellosis within a year. Such farms should be stocked only with vaccinated animals.

When pasteurellosis is established among pigs, large and small livestock, restrictions are introduced on the farm. All livestock in the disadvantaged group are examined clinically, animals that are sick or suspected of having a disease are isolated and treated, and the rest are vaccinated. Routine disinfection is carried out after each case of isolation of a sick animal and subsequently every 10 days until the restriction is lifted. Animal corpses are disposed of or burned.

Restrictions on the farm are lifted 14 days after the general vaccination of animals and the last case of the disease, subject to final disinfection.

If there is an outbreak of pasteurellosis among birds, the farm or enterprise is declared unsafe and restrictions are introduced. A bird that is sick or suspected of having a disease is killed. Sometimes it is advisable to kill all the birds in a dysfunctional poultry house. The corpses are burned. Eggs are disinfected with formaldehyde vapor. Birds at risk of infection are immediately isolated and vaccinated. At widespread diseases before vaccination, emergency prevention is carried out by group treatment healthy bird antibiotics and sulfonamides. Restrictions are lifted after the slaughter of all poultry previously unaffected by pasteurellosis, cleaning of the area, disinsection, deratization and final disinfection with bacteriological control of its quality.

Pasteurellosis (pasteurelesis)

Pasteurellosis (pasteurelesis) is an infectious disease of many species of mammals and birds, characterized in acute cases by the phenomena of septicemia, hemorrhagic diathesis, in subacute and chronic cases - lobar or catarrhal pneumonia, arthritis, mastitis, keratoconjunctivitis, less often enteritis.

It is registered in all countries of the world, including the Republic of Belarus.

Economic damage consists of the death of sick animals, forced slaughter, decreased weight gain of animals, costs of treatment, general and specific prevention and elimination of the disease.

Etiology

The causative agent of the disease (Pasteurella multocida 4 serological variants B, A, D, and E and Pasteurella haemolytica serological variants A and D) is a small polymorphic rod, gram-negative, non-motile, not forming spores. Pasteurella resistance is low. Pasteurella can be stored in manure and water for up to 2-3 weeks, and in corpses for up to 4 months. All well-known disinfectants have a detrimental effect on the pathogen; it is sensitive to antibiotics.

Epizootological data

All types of domestic animals are susceptible to pasteurellosis. The source of the infectious agent is sick and recovered animals, as well as pasteurization carriers. Pasteurellosis can last up to a year. Factors of transmission of the infectious agent are contaminated air, feed, care items, etc. Infection occurs through aerosol and nutritional routes, as well as through damaged skin. Pasteurellosis is classified as a factor disease. The disease is characterized by spring-autumn seasonality and stationarity. The disease occurs, as a rule, in the form of enzootics, the mortality rate is from 10 to 75% and higher.

Pathogenesis

Pasteurella enters the body through the respiratory or nutritional route, less often through damage to the skin. Generalization of the infectious process contributes to the suppression of phagocytosis, the development of septicemia, intoxication, which leads to damage blood vessels, the appearance of edema and hemorrhagic diathesis. In a subacute or chronic course, lobar or catarrhal-purulent pneumonia develops.

Course and symptoms of the disease

The incubation period lasts from several hours to 2-3 days. The disease occurs hyperacutely, acutely, subacutely and chronically. In cattle, there are thoracic, edematous and intestinal forms. In sick animals, an increase in body temperature to 41-42 ° C, increased heart rate, general weakness, lack of appetite, swelling in the intermaxillary space, dewlap, extremities (edematous form), frequent and difficult breathing, dry cough, foamy discharge from the nose (thoracic form), progressive anemia, constipation, then diarrhea, there are blood impurities in the feces ( intestinal form, found in young animals). The disease lasts 1-2 days, in subacute and chronic cases - 2-3 months. Often in calves, P. multocida serogroups A and D causes chronic bronchopneumonia - pulmonary pasteurellosis.

In pigs, body temperature rises to 41.0 °C above, pulse and respiration quicken, swelling in the intermaxillary area, cyanosis of the skin of the ears and abdomen are observed. In the subacute course, symptoms of fibrinous pleuropneumonia are noted, in the chronic course - emaciation, cough, swelling of the joints. The duration of the disease ranges from several hours (with a hyperacute course) to 3-6 weeks (with a chronic course).

Pathological changes

When autopsying corpses, they find: edema (in the edematous form); lobar lobar pneumonia and serous-fibrinous pleurisy and pericarditis (in the chest form); hemorrhagic diathesis; serous lymphadenitis; granular dystrophy of the liver, kidneys and myocardium; unchanged spleen; acute catarrhal or catarrhal-hemorrhagic gastroenteritis.

Diagnostics

It is carried out taking into account epidemiological data, clinical signs and the results of a pathological autopsy. Bacteriological research is of decisive importance.

Differential diagnosis

In cattle, anthrax, emkar, rhinotracheitis, parainfluenza are excluded; in pigs - CSF, erysipelas, salmonellosis, anthrax, hemophilus polyserositis.

Treatment

Hyperimmune serum, tetracycline antibiotics, long-acting antibiotics, and sulfonamides are used.

Immunity

Specific prevention has been developed - a number of inactivated mono- and associated vaccines are used.

Prevention and control measures

In complex preventive measures the leading place should be given to measures that increase immune status animal body (compliance with general veterinary and sanitary rules, ensuring normal conditions keeping and feeding animals, etc.). When a diagnosis is made, sick and suspected animals are isolated and treated. The rest are vaccinated. Disinfection is carried out. Restrictions are lifted 14 days after the last case of death, recovery or forced slaughter.

Pasteurellosis (Pasteurellosis) - hemorrhagic septicemia - an infectious disease of many species of mammals and birds, characterized in acute cases by symptoms of septicemia, in subacute and chronic cases - predominant damage to the lungs.

The causative agent of the disease

Pasturella multocida is a small, gram-negative, non-motile, non-spore-forming bacterium that occurs singly, in pairs, and less commonly in chains. The size and shape of the microbe varies depending on the origin of the strain; Can be painted with all aniline dyes. The bacteria found in the tissues of sick animals are small, have an ovoid shape (0.3 - 1.25 x 0.20 - 0.5 µm), they are well stained with bipolar methylene blue or Ramonovsky - Giemsa. In fresh cell cultures they have a clearly visible capsule.

Pasteurella are facultative aerobes that grow well on ordinary nutrient media at 37°C. When reseeding freshly isolated crops, it is necessary to use media with the addition of blood serum or media obtained by enzymatic hydrolysis of meat. The growth of bacteria in the broth causes uniform turbidity of the medium; 3 forms of colonies are formed on MPA: smooth (s), rough (R) and mucoid (M). Enzymatic properties are weak. The most characteristic is the formation of indole in the broth with tryptophan and the reduction of nitrates into intrites.

P. multocida is antigenically heterogeneous. Based on the results of the seroprotection reaction, 4 immunological types are distinguished - 1, 2, 3 and 4 (Roberts, 1947), which makes it possible to distinguish, in the RNGA, 4 serological groups of Pasteurella based on the capsular antigen - A, B, D and E (Carter, 1961). The serotyping of Pasteurella has not been fully resolved; serotype B is used to prepare a vaccine against bovine pasteurellosis.

The pathogenic and virulent properties of various serogroups of the pathogen vary widely. They are most pronounced in relation to the species of animal from which they are isolated. Group D – found in all animal species. In Pasteurella, there is a certain relationship between virulence, capsule formation and toxin formation (lipopolysaccharide endotoxin). Epizootic strains of Pasteurella are highly virulent for white mice.

P. haemolutika causes pneumonia in cattle and sheep of all ages.

The resistance of pasteurella is low; under natural conditions they die relatively quickly. In manure, blood, and cold water, pasteurella remain viable for 2 - 3 weeks, in troupes - up to 4 months, in frozen bird carcasses - for a year. Direct sunlight kills pasteurella in a few minutes; at a temperature of 70–90 °C they die in 5–10 minutes. All well-known disinfectants in conventional concentrates have a destructive effect within a few minutes.

Epizootological data

All types of domestic and wild mammals, animals and birds are susceptible to pasteurellosis. Humans also suffer from pasteurellosis. Among chickens and rabbits, the disease usually manifests itself as an epizootic. Epizootic outbreaks of the disease are also not uncommon in other animal species, but they are observed relatively rarely. Carnivores and horses have some resistance to pasteurellosis.

Epizootic outbreaks of pasteurellosis with an acute manifestation of the disease such as hemorrhagic septicemia in adult cattle and wild ruminants in our country are usually caused by P. multocida type B, and in African conditions - by P. multocida type E; in young cattle and buffaloes - P. multocida type B and in birds - P. multocida type A. Sporadic incidence of pasteurellosis, usually manifested by a subacute and chronic course of the disease, like enzootic pneumonia, is more often caused in calves by P. multocida type A and P. haemolytica; and in pigs P. multocida types A and D and P. Haemolytic

The source is sick and recovered animals - carriers of pasteurella. The duration of carriage can be more than a year. Pasteurellosis is characterized by widespread carriage of the pathogen by healthy animals. Most researchers consider the importation of animals carrying the pathogen from disadvantaged farms to be one of the main ways of spreading the disease. Carriage of Pasteurella by healthy animals in prosperous farms can cause a spontaneous outbreak of pasteurellosis without the introduction of pathogens from outside. Typically, such outbreaks are recorded on farms; they arise against the background of exposure of animals to all kinds of unfavorable factors.

Epizootic features of pasteurelosis are enzootic nature and the formation of stationary epizootic foci.

In piglets, the disease can occur as a complication after vaccination with an anti-plague virus vaccine. Stress factors include inadequate feeding (lack of vitamins, amino acids, microelements) as well as unsatisfactory living conditions (cold, rain, draft, etc.), leading to colds and damage to the respiratory tract in cold weather. According to data on the incidence of pig livestock infectious diseases in Russian farms for 1997-2001. pasteurellosis was observed in 4% of animals, mortality was 32.7%, and the number of unfavorable points was 12.6%. The spread of pasteurelosis is facilitated by mass movements of animals without taking into account the well-being of the farm due to pasteurelosis, crowded placement of animals, all kinds of violations of production technology and veterinary and sanitary rules, and the use of unrecovered slaughterhouse waste.

Morbidity and mortality from pasteurelosis can vary greatly depending on the virulence of the pathogen, the immunological structure of the herd, housing and feeding conditions, the presence of concomitant infections and the timeliness of health-improving measures.

Pathogenesis

Under natural conditions, pasteurella more often penetrate into the body of animals through the respiratory and nutritional routes and less often through skin disorders. At the sites of penetration, Pasteurella multiply, penetrate into the lymph and blood, causing septicemia and death of the animal in most cases after 12–36 hours. The generalization of the process is facilitated by the suppression of phagocytosis by Pasteurella (not complete phagocytosis), their formation of toxic substances, which leads to massive damage to the capillaries. As a result, extensive edema develops in the subcutaneous and intermuscular tissue and hemorrhagic diathesis. Septicemia occurs the sooner, the more virulent the pathogen.

In disease-resistant animals and when weakly virulent Pasteurella enter the body, septicemia does not develop. Their disease takes a subacute and chronic course with localization of the pathogen in individual organs, most often in the lungs, where lobar or serous catarrhal inflammation develops. In hyperacute and acute cases, lobar pneumonia does not have time to develop, and the symptoms of edema and hyperemia are found in the lungs.

Course and symptoms

The incubation period ranges from several hours to 2 – 3 days. In all animals, pasteurellosis can occur hyperacutely, acutely, subacutely and chronically.

In pigs incubation period ranges from 5 to 14 days. There is pasteurellosis, which affects pigs of all age groups and only piglets. Pasteurellosis as a secondary infection is observed in other, especially viral, diseases. Pasteurellosis, which affects pigs regardless of age, is called primary; it is recorded relatively rarely. It occurs in the form of an acute septic disease or affects the lungs.

There are hyperacute, acute and chronic course of the disease. hyperacute and acute course of pasteurellosis is characterized by fever with an increase in temperature to 41 ° C and above, pharyngitis, strained breathing, heart failure and, often, swelling in the intermaxillary area and neck. The animal dies due to asphyxia within 1–2 days. With a more protracted course, fibrinous pleuropneumonia develops, shortness of breath, cough and mucopurulent rhinitis appear. /The disease usually ends in death on the 5th – 8th day. The chronic course of pasteurellosis is manifested by symptoms of pneumonia, weakness, progressive emaciation, sometimes swelling of the joints and scabby eczema.

Pasteurellosis, which affects only piglets, occurs as fibrinous pleuropneumonia, often with a fatal outcome. Usually the entire litter is sick. Most often, pasteurellosis in pigs manifests itself as a secondary infection in viral diseases, primarily plague and influenza.

Pathological changes

In pigs, the necropsy picture depends on the severity of the disease. If the disease is acute, then numerous hemorrhages are found on the skin, serous and mucous membranes, gelatinous-serous swelling of the subcutaneous tissue in the larynx and neck, pulmonary edema, enlargement and hyperemia of the lymph nodes.

In acute cases, piglets exhibit enlargement of the submandibular nodes, retropharyngeal and cervical lymph nodes. In the mucous and serous membranes, hemorrhages, lobar pneumonia, and serous-fibrinous pleurisy are detected. Bronchial lymph nodes are enlarged, juicy and reddened. The spleen is unchanged.

Diagnosis and differential diagnosis

The diagnosis of Pasteurellas is established on the basis of a complex of epizootic, clinical, pathological and laboratory studies.

Laboratory diagnosis of pasteurellosis includes:

1) microscopy of smears and blood and impression smears from affected organs;

2) isolation of pure culture on nutrient media by identification by biochemical properties;

3) isolation of pasteurella by infecting laboratory animals with suspensions from pathological material and a culture from a nutrient medium;

4) determination of the virulence of isolated cultures for white mice and rabbits. To determine the virulence of hemolytic pasteurella, 7-day chicken embryos are used;

5) determination of serovariant affiliation of Pasteurella.

As test material, blood from the superficial vessels and nasal mucus are taken from sick animals, and after death or forced slaughter - blood from the heart, lymph nodes, pieces of lungs, liver, spleen, heart, kidney, tubular bone. In summer, during long-term transportation, pathological material is preserved with a 30% sterile glycerin solution.

The diagnosis of pasteurellosis caused by P. multocida is considered established:

1) when isolating established pasteurella from the blood or simultaneously from several parenchymal organs;

2) when isolating the culture only from the lungs of cattle and pigs;

3) in sheep, the simultaneous isolation of P. haemolutica from the lungs, blood and parenchymal organs serves as the basis for the diagnosis of hemolytic pasteurellosis.

Isolation from the lungs of both weakly virulent P.multocida and P.haemolutica indicates a mixed disease of pasteurellosis caused by Pasteurella of both species. Such pasteurellosis is diagnosed as pasteurellosis pneumonia.

When diagnosing pasteurellosis, it is necessary to differentiate from febrile diseases of a septic nature, which are also accompanied by the appearance of inflammatory edema under the skin: anthrax, MCAR and malignant edema. In piglets, exclude plague, erysipelas, hemophilus pleuropneumonia and salmonellosis.

Treatment

Sick animals are placed in warm, dry pens, provided with complete feed and treated with tetracycline antibiotics and sulfonamide drugs according to accepted guidelines.

The use of anti-pasteurellosis serum can be effective in case of acute pasteurellosis in an animal only at the very beginning of the disease, when the first clinical signs appear. It is administered intramuscularly or intravenously in a double prophylactic dose according to the instructions.

The therapeutic effect is noticeably increased when the use of serum is combined with long-acting antibiotics, sulfonamides and symptomatic agents. The course of treatment depends on the condition of the animal. Birds with pasteurellosis are not treated.

As a specific treatment, hyperimmune anti-pasteurella serum is used, which is administered intramuscularly to piglets at a dose of 20-60 cm³. If necessary, the serum is reintroduced. You can administer penicellin and streptomecin at a dose of 4000-6000 units, as well as biometcin at a rate of 10000-20000 units/kg 1-2 times a day for 3-4 days, oxytetracycline at a dose of 4000 units/kg. They are administered intramuscularly once a day for 3 days. Erythromycin is effective. It is injected into sick 3-4 month old piglets at a dose of 5000 IU/kg intramuscularly 2 times a day for 2 days. With pasteurellosis in piglets with lung damage good results obtained from aqueous and oily solutions of penicelin, dihydrostreptomycin, and an alcoholic solution of erythromycin.

Immunity

Animals that have recovered from pasteurellosis acquire immunity for 6–12 months.

For specific prevention of pasteurellosis in animals in Russia, inactivated vaccines are recommended; precipitated formol vaccine against pasteurellosis (hemorrhagic septicemia) of cattle, sheep and pigs (N. M. Nikiforova), semi-liquid formol aluminum hydroxide vaccine AzNIVI against pasteurellosis (hemorrhagic septicemia) of cattle and buffaloes (M. K. Ganiev), concentrated polyvalent formol vaccine against paratyphoid fever , pasteurellosis and diplococcal septicemia of piglets (PPD), emulsified vaccine against pasteurellosis of cattle, buffaloes and sheep (N. M. Nikiforova, A. V. Lukyanchenko), emulsified vaccine against pasteurellosis of pigs (N. M. Nikiforova, A. V. Lukyanchenko).

Vaccines are used for preventive purposes and involuntarily in case of stationary unfavorable localities, on farms during an acute outbreak of pasteurellosis and in endangered areas. Animals are vaccinated twice with precipitated semi-liquid and concentrated vaccines. Intense immunity is formed on the 7th – 10th day after the second vaccination and lasts 6 months. Emulsified vaccines are administered once: immunity for at least a year.

For passive immunization, hyperimmune serum is available against pasteurellosis in cattle, buffaloes, sheep and pigs. The serum is administered mainly for prophylactic purposes to adult animals before their transportation, as well as to young animals (calves, piglets, lambs) in the first days of admission to livestock farms.

Prevention and control measures

To prevent pasteurellosis, it is necessary to ensure the protection of healthy farms from the introduction of the pathogen with sick animals and pasteurellosis carriers, as well as with feed, etc. Particular attention is paid to compliance with general veterinary and sanitary rules and providing animals with normal zoohygienic living conditions and rational feeding. If the disease was previously recorded on farms, all animals are vaccinated against pasteurellosis within a year. Such farms should be stocked only with vaccinated animals.

When pasteurellosis is detected among pigs, restrictions are introduced on the farm. All livestock in the disadvantaged group are examined clinically, animals that are sick or suspected of having the disease are isolated and treated, and the rest are vaccinated against pasteurellosis. Routine disinfection is carried out after each case of isolation of a sick animal and subsequently every 10 days until the restriction is lifted. Animal corpses are disposed of or burned.

Restrictions on the farm are lifted 14 days after the general vaccination of animals and the last case of the disease, subject to final disinfection.

Historical reference

The infectious nature of the disease was established in 1878 - 1887, after Bollinger (1878) described pasteurellosis in cattle, and Kitt (1885) isolated the causative agent. The causative agents of pasteurellosis in chickens (E.M. Zemmer, 1878; Pasteur, 1880), rabbits (Gafki, 1881), pigs (Loffler, 1886), and buffaloes (Greste, 1887) were identified and described. During these same years, Pasteur conducted the first experiments on weakening bacterial cultures and immunized birds. In honor of his achievements in microbiology, this pathogen was named pasteurella, and the disease it caused was named pasteurellosis.

In science, the zoological approach to the classification of Pasteurella dominated for a long time, and it was believed that in each species of mammals and birds the disease is caused by an independent type of microbe. Only in 1939 did Rosenbush and Mergant manage to prove the inconsistency of this view and describe the causative agent of the disease as an independent species - Pasteurella multocida. In the genus Pasteurella there is also an independent species, P. haemolutica, which can cause a disease similar to pasteurellosis in cattle and especially in sheep.

Pasteurellosis is widespread in all countries of the world. It is usually observed sporadically and occurs chronically, but under conditions conducive to its spread, it manifests itself as an epizootic.

In Russia, P. V. Sizov, V. P. Shamataev, M. K. Ganiev, N. M. Nikiforova, A. V. Lukyanchenko and others made a great contribution to the study of the disease and the development of specific means of protection.