Tuberculosis in cattle: prevention, diagnosis and treatment

Tuberculinization of cattle is a veterinary measure aimed at identifying animals with tuberculosis. It should be done twice a year. Tuberculinization is performed with the help of a special drug - purified tuberculin, which causes an allergic reaction in cattle, which makes it possible to determine the degree of pathology. Tuberculin is injected subcutaneously, and if there is a suspicion of tuberculosis, an additional set of cattle studies is carried out.

What is bovine tuberculosis

Koch's wand

Bovine tuberculosis is an infectious disease occurring in a chronic form, characterized by the formation of certain nodules in the affected organ - tubercles. The disease is diverse in its course, manifestation, and can affect different organs. Bovine tuberculosis is widespread in many countries, the degree of danger of the disease continues to increase: at the beginning of the 21st century, the situation in the world with regard to tuberculosis has worsened. The disease causes damage to large and small farms due to a significant decrease in animal productivity, early culling, high costs for therapeutic measures and preventive measures.

Despite the fact that tuberculosis has been known for a long time, was described by Hippocrates, effective measures to combat the disease have not yet been found.

Many species of domestic and wild animals, birds and humans are susceptible to tuberculosis. The disease is characterized by massiveness, which depends on many reasons - reduced functions of the immune system, the presence of chronic pathologies in cattle, unbalanced feeding, lack of walking, high humidity in the barn and other provoking factors. That is why it is necessary to identify the infected individual in the herd as soon as possible.

The causative agent of tuberculosis in cattle

The causative agent of tuberculosis in cattle is the microorganism Mycobacterium tuberculosis. It is considered a non-spore forming anaerobic bacterium. The forms of the pathogen are diverse, resemble straight or slightly bent at an angle sticks. There are rounded shapes, in the form of a chain. There are practically no single organisms in the colony.

Bovine tuberculosis has 3 types of pathogen that lead to infection: bovine, avian and human forms of the microorganism. However, they are able to disguise themselves and be reborn:

• the human strain infects cattle, pigs, fur-bearing animals, less often dogs and cats are infected;
• bovine strain (paratuberculosis) infects cows, is transmitted to humans, as well as domestic and wild animals;
• the avian strain infects birds but is occasionally found in pigs.

The main differences between these forms include different virulence for animal and human species.

The main routes of infection:

• airborne, in which the disease is quickly transmitted to other cattle, especially in cramped, poorly ventilated areas;
• alimentary (the pathogen enters the body of a healthy animal through the digestive system);
• contact, which is quite rare in cattle;
• intrauterine infection at the hotel.

The causative agent of tuberculosis is quite viable: in air-dried lungs, it remains active for 200 days, in soil, manure for up to 3-4 years. The sun disinfects the bacteria after 2-3 days; in the infected corpses of cattle, the microorganism continues its harmful activity for about a year. Heating and boiling have a detrimental effect on Koch's wand. Chemicals disinfect the bacteria no earlier than an hour later, depending on the activity of the substance.

Tuberculinization of livestock

Sources of infection are:

• air contaminated during coughing and sneezing;
• infected milk;
• saliva;
• urine and feces of sick cattle;
• contact with infected wild animals.

Types of tuberculosis in cattle

Distinguish between pulmonary and intestinal tuberculosis in cattle according to the location of the pathology. Less commonly, they diagnose lesions of serous integuments, genitals, tuberculosis of the udder in cows or a generalized form of the disease.

However, most often, with tuberculosis in cattle, the lungs are affected. This form of the disease is characterized by a cough, a slight increase in body temperature, while the appetite and productivity of the animal are within normal limits.

As tuberculosis develops, there are signs of pneumonia, pleura. The cough becomes painful, rapid breathing, accompanied by wheezing. Coughing attacks are worse in the morning and at night, and phlegm is profuse. In the chest of cattle, wheezing is heard during percussion. A cow experiences severe pain syndrome with pneumonia during palpation. In addition, there is a rapid depletion of the animal, the skin looks dry, the coat loses its shine, and the lymph nodes enlarge. This leads to narrowing of the esophagus and subsequent disruption of the rumen and digestion in general.

With tuberculous lesions of the mammary gland in cows, the supra-udder lymph nodes increase. The udder turns red, swells. During milking, watery milk with cottage cheese flakes is released, blood clots may be contained.

Infected individual

With damage to the genitals in bulls, pathologies of the genital organs are noted, including orchitis (inflammation of the testicle), uveitis (inflammation of the choroid of the eyeball) is often observed. In cows, barrenness, fetid discharge from the genitals, and increased hunting are noted.

Symptoms of tuberculosis in cattle

Typically, tuberculosis in cattle is chronic, in calves, most often in acute. The majority of infected animals do not differ from healthy individuals in general condition, behavior, appearance. The appearance of symptoms, pronounced forms of the disease, indicates a long-standing infection.

In the development of tuberculosis in cattle, several stages of the disease are noted:

1. Primary tuberculosis... It has several forms - from the initial complex and the period of early generalization.
2. Secondary pathology... Has a period of late generalization or tuberculosis of a specific organ.

Primary tuberculosis is the stage of the disease that occurs after infection and manifests itself as a primary complex.

The primary complex, which is localized in several systems of the cattle body at once, is called complex. Early generalization of the disease is its spread throughout the body. Secondary tuberculosis develops as a continuation of the primary one or occurs as a result of re-infection (reinfection).

There is an open (active) form of tuberculosis in cattle and a closed (latent) form of the disease. With open tuberculosis, the pathogen is released into the environment with feces, urine, milk, sputum. Tuberculosis of the intestine, uterus, breast is always considered an open form. The closed form of the disease is characterized by the presence of foci without the release of the pathogen into the external environment.

Cattle tuberculosis in the photo

Despite the fact that the disease occurs more often in a latent form, the owner of the animal should be alerted to the following signs of tuberculosis in cattle:

• dyspnea;
• increased body temperature;
• sharp depletion of the animal;
• loss of appetite;
• decreased productivity;
• dry skin;
• cough, sputum production;
• mucus from the nose, increased salivation;
• enlargement of the pharyngeal glands;
• disruption in the digestive system.

With generalized tuberculosis, an increase in lymph nodes throughout the body of cattle is noted.

Diagnosis of tuberculosis in cattle

Diagnostic measures should include clinical, laboratory, pathological methods, as well as an allergic intradermal tuberculin test. It is necessary to exclude diseases with similar symptoms: pericarditis, contagious pleuropneumonia, pasteurellosis, pseudotuberculosis, helminthic invasions.

The main and most reliable method for diagnosing tuberculosis in cattle, other animal species and humans is an allergy test. For this, the classic version of tuberculin is used, which contains the dead cultures of the tubercle bacillus. The drug can be administered to cattle subcutaneously or by instillation into the eyes. Tuberculinization should be carried out 2 times a year before the animals are taken to pasture in the spring and before the transition to winter housing. For the young, each calf is tested at two months of age. After administration of the drug, it is necessary to track the reaction to tuberculin in cattle after 72 hours. It is counted if the skin fold in cows differs in thickness by more than 3 mm, in bulls - in the presence of edema. In addition, you need to track the reaction of the skin (swelling, redness, temperature). Sometimes, to clarify the diagnosis of tuberculosis, to identify a nonspecific reaction of the body, cattle are subjected to differential diagnosis using a simultaneous test.

Calf diagnostics

Also important is the clinical method for diagnosing cattle, in which the veterinarian pays attention to the clinical symptoms of the disease.

Treatment of tuberculosis in cattle

Veterinary medicine does not have an effective treatment against bovine tuberculosis. Thus, it is impossible to cure infected animals. But according to the results of a study of the entire livestock, this farm is classified as dysfunctional, a number of recreational activities are carried out in the herd.

Some restrictions are imposed on the herd taken under control by the decision of the district administration, which will prevent the spread of infection. Also, a specialist is assigned to the farm who will monitor the strict implementation of the instructions for combating tuberculosis in the cattle herd.

Improving activities in the farm are carried out in the following ways:

1. Regular laboratory tests to identify all infected cattle. Checks are carried out at intervals of 60 days. If infected cows are found, they should be discarded immediately. Analyzes are carried out until all animals in the herd show a negative result. Only in this case, the cattle tuberculosis quarantine will be lifted from the livestock, and the farm will be considered healthy.
2. Complete replacement of a herd of cattle with healthy animals with mandatory disinfection of the barn and adjacent areas. This method is effective if the percentage of positively responding cows is too high (more than 15% of the total number of cows in the herd). Then the farm is quarantined.

Measures to improve the health of the livestock

Complete herd replacement activities include the following:

• all animals, including young animals, are sent for slaughter;
• milk obtained from all cows is boiled for about 5 minutes at a temperature of 90 ° C before disposal;
• the barn is cleaned of dirt, manure, the old cover is removed;
• the entire area is treated with a solution of caustic salt and formaldehyde;
• garbage is taken out of the farm, as well as manure, the topsoil;
• all inventory must be recycled.

After all the work, the barn is restored, the rest of the premises, the adjacent territory, are mounted drinkers and feeders. Then everything is re-treated with disinfectant solutions, after which samples are taken for the presence of the pathogen. After receiving negative results, the quarantine is removed, the owner can purchase a new herd of cattle from those farms that are listed in the veterinary service as safe. The new flock is also tested with tuberculin.

Tubercles

Pathological changes in tuberculosis in cattle

When opening a cow infected with tuberculosis, the following changes are noted:

• some nodules (tubercles) in organs and tissues ranging in size from several mm to 10 cm, which have a gray color of a dense structure;
• changes in serous membranes in the abdominal cavity;
• bumps and ulcers of the mucous membranes;
• suppuration, cavities;
• violation of gas exchange in the lungs;
• lung necrosis with purulent formations;
• severe exhaustion;
• signs of bronchopneumonia;
• inflammatory processes in the lymph nodes;
• pathological changes in the liver, kidneys, heart, bone marrow.

The main symptom of tuberculosis during an autopsy of an animal is the presence of tubercles, which may be located in different areas of the lesion. When the nodule is excised, a layered cheesy structure is visible.

Prevention of tuberculosis in cattle

Quarantine on the farm

The instructions for combating tuberculosis in cattle provide for the implementation of some sanitary and veterinary standards. Cattle owners need:

• register individuals with the veterinary service, the tag with the number should be kept throughout the life of the animal;
• the movement of individuals, the purchase and sale to be carried out with the permission of the veterinary authorities;
• carefully prepare feed, excluding its infection;
• keep all new animals in quarantine for a month;
• at the slightest suspicion of tuberculosis, notify veterinary specialists;
• timely vaccinate and test cattle for this disease;
• comply with all norms of feeding, keeping and caring for livestock;
• take measures to combat rodents;
• enrich the diet of cattle with vitamins and microelements;
• timely identify and discard infected individuals;
• check meat at the slaughterhouse;
• monitor health status among farm personnel;
• introduce quarantine if necessary, follow all the rules in accordance with the instructions.

In addition to these measures, the BCG vaccine is used to develop immunity and as a specific prophylaxis. It is administered to animals at intervals of 14 days. Such strict measures are necessary, since bovine tuberculosis is not cured, often occurs in a latent form and causes enormous economic damage to farms. Therefore, preventive measures, diagnosis of the disease are extremely important.

Is tuberculosis transmitted to humans from cattle

Tuberculosis is a highly contagious disease, and the bovine strain is dangerous for humans.There are several ways of transmission of the pathogen from a sick cattle to a person:

1. Airborne... A person can become infected, especially with an open form of tuberculosis, when the animal releases microparticles of mucus and bacteria into the environment. If the barn has an elevated temperature, is humid, and there is no ventilation, then the Koch stick can remain in the air for a long time and be viable.
2. Meat and dairy products... With cattle tuberculosis, meat and milk contain a huge amount of pathogens. By consuming products without preliminary heat treatment, a person may become infected.
3. Contact... Suffering from tuberculosis, the animal releases feces, urine, phlegm into the environment. Thus, the litter of livestock becomes infected. Workers with injuries on their skin can become infected when cleaning the barn.

The milk should be boiled

Also, infection can occur from birds, but the disease will proceed in a different way.

Can I drink milk if a cow has tuberculosis?

Milk from infected cows is extremely dangerous for humans, especially for children. Infection is possible by 90-100%. Koch's bacillus is resistant to acidic conditions. Therefore, even in sour milk, it remains viable for 20 days, in cheeses and butter for up to 1 year, in frozen products for up to 6-7 years.

Milk from healthy cows, but obtained from an unfavorable farm, is processed at a temperature of 90 ° C for 5 minutes. Contaminated milk is strictly prohibited. However, after heat treatment, it is permissible to use it for feeding animals on the farm.

Milk from sick animals differs in composition. The amount of albumin and globulin in it doubles, the fat content decreases, and the viscosity rises. Such milk will not make cheeses, yoghurt will be watery, kefir will be heterogeneous.

The quality of meat and dairy products is monitored by a veterinary and sanitary examination, which allows products of proper quality for sale. In the presence of generalized tuberculosis, all carcasses, by order of the VSE, are disposed of, including bones and internal organs. Carcasses with a tuberculous focus in any one organ or lymph node are sent for processing into sausages or canned food, in compliance with all veterinary standards. Bovine organs affected by tuberculosis are sent for disposal.

Conclusion

Tuberculinization of cattle is one of the main measures for the timely detection of infected individuals on farms. The event is held within the framework of a state assignment, it has clear instructions approved by the Deputy Head of the Rosselkhoznadzor. Such strict measures are necessary, since the situation with bovine tuberculosis in our country raises some concerns among veterinarians. The adopted system of farm health improvement made it possible to significantly reduce the number of infected animals, but did not bring the desired result. Therefore, the owners of farms are required to be attentive to this problem and comply with all sanitary rules.

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