Tuberculosis is a disease of bacterial origin that affects all types of warm-blooded creatures: humans, wild and domestic animals, birds. The pathology is characterized by high contagiousness (infectiousness) and lethality. Tuberculosis occurs latently or chronically in cattle. Infected individuals are a potential danger to the herd and humans. Cattle owners should know all the information on how to suspect the first signs of pathology.
Historical reference
Tuberculosis has a long history of study. According to official sources, its symptoms were identified during studies of ancient Egyptian mummies. This discovery confirms the fact that the disease existed several thousand years ago. The “Father of Medicine,” Hippocrates, was the first to describe the clinical manifestations of pathology.
The French doctor Villemin established the contagiousness of tuberculosis. The scientist also proved that animals are also susceptible to the disease, and described the routes of transmission between them and humans. The causative bacterium was discovered by Robert Koch in 1882. This put an end to all scientific debate about whether there is a connection between animal and human tuberculosis.
It was found that cows, pigs and horses kept in captivity are more susceptible to pathology.
Economic damage
Tuberculosis is one of the most significant and especially dangerous animal diseases. The epizootic situation remains tense not only in Asia and Africa, but also in developed countries - England, Germany, and the USA. In Russia, more than 25 million heads of cattle are infected annually. The most disadvantaged regions for tuberculosis are the Moscow region, Tatarstan, and Bashkortostan.
The disease causes significant damage to farms and private lands. A sharp decrease in productivity, premature culling, forced slaughter of animals, lengthy and expensive preventive measures - all this significantly impacts the pockets of cattle owners. The economic damage from tuberculosis in Russia over the past 40 years has amounted to more than 84 billion rubles. The country has lost millions of tons of meat, milk, and offspring. Costs to improve the epizootic situation exceeded 27 billion.
Pathogen and source of infection of cows
The disease is caused by mycobacteria (Koch bacilli). These are elongated, immobile, bent microorganisms.They develop without access to oxygen and have no means of movement. Mycobacterium tuberculosis is common in the environment and can remain active for a long time. For example, mycobacteria survive in soil and manure for up to 2 years, in water for up to 5 years, and in frozen meat for a year.
There are 3 known subtypes of the pathogen: bovine, avian and human. Cows and other cattle are susceptible to infection by any of these species. Only the course of the disease differs: with the human type, the symptoms are less pronounced. The tuberculosis pathogen enters the body through the mucous membrane of the respiratory organs and through the digestive tract. Routes of transmission: aerobic, nutritional, transplacental (intrauterine). List of causes and sources of cattle infection:
- One individual in the herd fell ill. The causative agent of tuberculosis is released into the external environment with any liquids (urine, feces, sputum).
- Keeping in a stall after a sick individual. The bacterium remains alive in manure, straw heaps, and in the soil under the floor.
- Infection of young animals through colostrum/mother's milk.
Aggravating factors are crowded housing of cattle, unsanitary conditions and dirt in stalls, and lack of normal temperature conditions. Often the cause of infection is a person with open tuberculosis. With an inadequate diet, cows' immune defense decreases and the risk of developing tuberculosis increases.
You should also pay attention to pastures; they must be equipped for walking cattle.
Symptoms and signs of the disease
The duration of the incubation period for tuberculosis in cattle is from 14 days to 6 weeks. Most often, the disease develops latently, with the first noticeable symptoms appearing several months or even years after infection. Acute disease is typical only for young animals and calves.Based on the location of the lesion, several types of tuberculosis in cattle are distinguished:
- Lungs.
- Intestines.
- Uterus.
- Udder.
- Generalized type - dispersion of pathogens throughout the blood, affecting 2 or more systems simultaneously.
Specific symptoms for different types of bovine tuberculosis.
| Infected organ | Signs |
| Lungs | 1. Severe dry and painful cough.
2. Shallow, rapid breathing. 3. Mucous discharge when coughing. 4. Wheezing and groaning are heard. When pressing the area between the ribs, the animal reacts sharply due to severe pain. Infected individuals quickly lose weight and become emaciated. |
| Udder | 1. Swells greatly, becomes hard and lumpy.
2. The suprauterine lymph node enlarges. 3. Wrinkling and deformation of the nipples is possible. 4. Watery colostrum or curd mass with blood clots during milking. |
| Intestines | Chronic diarrhea. Severe exhaustion, weight loss. Pus and blood in the stool. |
| Uterus, genitals | In male cattle, swelling occurs, orchitis and uveitis begin. Females have barrenness and foul-smelling green discharge. |
| Generalized type | Enlargement of all lymph nodes, extensive lung damage, respiratory dysfunction, intoxication. |
Diagnostic measures
The main method of intravital diagnosis of cattle is tuberculinization. This is an intradermal allergy test using a tuberculin test. Tuberculin is a sterile filtrate of killed bacteria. The procedure is carried out on a regular basis, starting from the age of two months. Frequency – 2 times a year (spring, autumn).
How is cattle diagnosed:
- A place is chosen. In bulls this is the infracaudal fold, in cows it is the middle of the neck, in young animals it is the shoulder blades.A small area is cut off and treated with alcohol.
- 0.2 ml of tuberculin is injected.
- The animal is left for observation for 3 days.
Based on the information received, the result is determined: if a swelling of more than 3 mm appears at the injection site, this is a positive result for tuberculosis. If the skin temperature at the injection site increases and pain appears, this is also a positive result.
How to treat tuberculosis in cattle
There is no cure for bovine tuberculosis in veterinary practice. It is impossible to cure infected cows. The farm where the disease is recorded is classified as prosperous or unfavorable. In the second case, quarantine restrictions are imposed on him.
Wellness work takes place in 2 directions. The first is regular samples and laboratory tests. The goal is to identify tuberculosis and slaughter all infected individuals. Inspections and culling of cattle are carried out every 60 days. The second is a complete replacement of the cattle population, including young animals. This direction is applicable if the percentage of infected individuals in the herd exceeds 15. It is accompanied by treatment and disinfection of housing areas - removal of floor coverings, treatment with formaldehyde and caustic soda. Manure, garbage, equipment, 10-14 cm of topsoil (if the floor is laid on the ground) are removed for disposal.
Prevention of the problem
Thorough prevention is an effective measure to protect cattle from tuberculosis. To develop immunity, it is permissible to use the BCG vaccine and tuberculosis toxoid. Interval – 10-14 days.But such protection from the disease does not last long enough. Therefore, compliance with other measures is recommended.
Mandatory preventive actions:
- Compliance with hygiene norms and standards when keeping, feeding and walking cattle.
- Registration of animals in veterinary institutions.
- Compliance with quarantine for new individuals (30 days). They are tested by a veterinarian.
- Thorough examination of the entire livestock at least 2 times a year.
- Annual x-ray for people who work with cattle.
- Periodic disinfection of places of detention.
Routes of transmission of tuberculosis from animals to humans
In total, there are 3 ways of transmitting tuberculosis from cattle to humans. Through meat and dairy products, since meat and milk contain many pathogenic bacteria. The risk of infection is present in the absence of proper heat treatment. The next path is contact. Farm workers are at risk: infection occurs when cleaning the barn, since pathogens are present on the bedding of livestock.
The last route is airborne. The animal releases microparticles of mucus and bacteria into the air. Koch's bacillus remains active for a long time if the barn is hot, humid, and there is no ventilation. By inhaling such air, a person becomes infected with tuberculosis.
Bovine tuberculosis is an incurable disease. Its danger lies in its latent course and long-term absence of typical symptoms. Cows are susceptible to all types of pathogens; any organ can be affected: from the lungs to the uterus. Tuberculosis is the real reason for the loss of entire livestock. And only careful prevention and compliance with sanitary standards act as a barrier and protection for cattle from Koch’s bacillus.
