Content
Bovine mycoplasmosis is a difficult to diagnose and, most importantly, difficult to cure disease, causing significant economic damage to farmers. The pathogen is widespread throughout the world, but due to successful “camouflage” the disease is often misidentified.
What kind of disease is “mycoplasmosis”
The causative agent of the disease is a single-celled organism that occupies an intermediate position between bacteria and viruses. Representatives of the genus Mycoplasma are capable of independent reproduction, but they do not have the cell membrane inherent in bacteria. Instead of the latter, mycoplasmas have only a plasma membrane.
Many species of mammals and birds, including humans, are susceptible to mycoplasmosis. But these single-celled viruses, like many viruses, are specific and are usually not transmitted from one species of mammal to another.
Mycoplasmosis in cattle is caused by 2 types:
- M. bovis provokes bovine pneumoarthritis;
- M. bovoculi causes keratoconjunctivitis in calves.
Keratoconjunctivitis is a relatively rare occurrence. Calves are more likely to get it. Basically, bovine mycoplasmosis manifests itself in 3 forms:
- pneumonia;
- polyarthritis;
- ureaplasmosis (genital form).
Since the first two forms smoothly flow into one another, they are often combined under the general name pneumoarthritis. Only adult cattle suffer from ureaplasmosis, since in this case infection occurs through sexual contact.
This is approximately what the causative agents of bovine mycoplasmosis look like under an electron microscope.
Causes of infection
Calves are most sensitive to mycoplasmas, although cattle can become infected at any age. The main carriers of mycoplasmosis are sick and recovered cattle.
From sick animals the pathogen is released into the external environment along with physiological fluids:
- urine;
- milk;
- discharge from the nose and eyes;
- saliva, including when coughing;
- other secrets.
Mycoplasmas end up on bedding, feed, water, walls, equipment, infecting the entire environment and being transmitted to healthy animals.
Also, infection with bovine mycoplasmosis occurs in “classical” ways:
- orally;
- airborne;
- contact;
- in utero;
- sexual.
Mycoplasmosis does not have a pronounced seasonality, but the largest number of infections occurs in the autumn-winter period, when cattle are moved to farms.
The area of distribution and intensity of infection largely depend on the conditions of detention and feeding and the microclimate of the premises. Bovine mycoplasmosis stays “in one place” for a long time. This is explained by the long period of bacteria persisting in the body of recovered animals.
Symptoms of mycoplasmosis in cows
The incubation period lasts 7-26 days.Most often, symptoms of mycoplasmosis are observed in calves weighing 130-270 kg, but clinical signs can also appear in adult animals. A clear manifestation of mycoplasmosis occurs only 3-4 weeks after infection. The disease spreads most quickly in cold, damp weather and when there is a large crowd of cattle. The initial symptoms of mycoplasmosis are very similar to pneumonia:
- difficulty breathing: cattle make every effort to draw air into the lungs and then push it out;
- frequent sharp cough, which can become chronic;
- nasal discharge;
- sometimes conjunctivitis;
- loss of appetite;
- gradual exhaustion;
- temperature 40° C, especially if a secondary infection has become hooked on mycoplasmosis;
- When the disease passes into the chronic stage, the temperature is only slightly higher than normal.
Arthritis begins a week after the onset of pneumonia. With arthritis in cattle, one or more joints become swollen. Death begins 3-6 weeks after the appearance of clinical signs.
Arthritis in cattle is a “normal” phenomenon with mycoplasmosis
With the genital form of mycoplasmosis in cattle, profuse purulent discharge from the vagina is observed. The mucous membrane of the vulva is completely covered with small red nodules. A sick cow will no longer become pregnant. Inflammation of the udder is also possible. In bulls, swelling of the epididymis and spermatic cord is determined by palpation.
Diagnosis of mycoplasmosis in cattle
Due to the similarity of the symptoms of mycoplasmosis with other cattle diseases, the diagnosis can only be made using a comprehensive method. When determining a disease, the following are taken into account:
- Clinical signs;
- epidemiological data;
- pathological changes;
- laboratory test results.
The main emphasis is on pathological changes and laboratory studies.
Pathological changes
Changes depend on the area of the main mycoplasma lesion. When infected by airborne droplets and contact, the mucous membranes of the eyes, mouth and nasal cavity are primarily affected.
In case of eye disease, clouding of the cornea and its roughness are noted. The conjunctiva is swollen and red. As a result of the autopsy, hyperemia of the mucous membrane of the nasal passages is most often found in parallel with eye damage. Lesions in the middle and main lobes of the lungs are detected during the latent or initial course of the disease. The lesions are dense, gray or red-gray in color. Connective tissue is gray-white. There is mucopurulent exudate in the bronchi. The bronchial walls are thickened and gray. Lymph nodes in the area of infection may be enlarged. When mycoplasmosis is complicated by a secondary infection, necrotic foci are found in the lungs.
The spleen is swollen. The kidneys are slightly enlarged in volume, and there may be hemorrhages in the kidney tissue. Dystrophic changes in the liver and kidneys.
If mycoplasmas penetrate into the udder, the consistency of its tissues is dense, the connective interlobular tissue is overgrown. Abscesses may develop.
When mycoplasmosis affects the genital organs of cows, the following is observed:
- swollen uterine mucosa;
- thickening of the fallopian tubes;
- serous or serous-purulent masses in the lumen of the oviducts;
- catarrhal-purulent salpingitis and endometritis.
Epididymitis and vesiculitis develop in bulls.
Discharge from the eyes and nose must be sent to a laboratory for analysis.
Laboratory research
For samples the following is sent to the laboratory:
- washings from a cow's vagina;
- sperm;
- embryonic membranes;
- milk;
- pieces of lungs, liver and spleen;
- bronchial lymph nodes;
- pieces of the brain;
- aborted or stillborn fetuses;
- the affected joints are in general condition;
- rinses and mucus from the nose if the upper respiratory tract is affected.
Tissue samples are delivered to the laboratory frozen or refrigerated.
For intravital diagnosis, 2 blood serum samples are sent to the laboratory: 1st when clinical signs appear, 2nd after 14-20 days.
Treatment of mycoplasmosis in cattle
Most antibiotics kill bacteria by attacking the cell wall. The latter is absent in mycoplasmas, so there is no specific treatment. For the treatment of mycoplasmosis in cattle, a complex system is used:
- antibiotics;
- vitamins;
- immunostimulants;
- expectorants.
The use of antibiotics for bovine mycoplasmosis is determined by the desire to suppress the complication of the disease by secondary infection. Therefore, they use either broad-spectrum drugs or narrowly targeted ones: affecting microorganisms only in the gastrointestinal tract, lungs or genital organs.
When treating mycoplasmosis in cattle, the following is used:
- chloramphenicol (main area of influence - gastrointestinal tract);
- enroflon (broad-spectrum veterinary drug);
- antibiotics of the tetracycline group (used in the treatment of the respiratory and genitourinary systems and eye diseases).
The dose and type of antibiotic are prescribed by the veterinarian, since there are other drugs for mycoplasmosis that are not intended for the treatment of herbivorous cattle. The method of administration of a particular substance is also indicated by the veterinarian, but brief instructions are usually on the packaging.
One of the tetracycline antibiotics that can be used in the treatment of bovine mycoplasmosis
Prevention measures
Prevention of mycoplasmosis begins with standard veterinary rules:
- do not move animals from farms unaffected by mycoplasmosis;
- inseminate cows only with healthy sperm;
- do not introduce new animals into the cattle herd without a month’s quarantine;
- regularly carry out disinsection, disinfection and deratization of premises where livestock are kept;
- regularly disinfect equipment and tools on the farm;
- provide cattle with optimal housing conditions and diet.
If mycoplasmosis is detected, milk from sick cows is subjected to heat treatment. Only after this is it suitable for consumption. Sick animals are immediately isolated and treated. The animals of the rest of the herd are monitored. Premises and equipment are disinfected with solutions of formalin, iodoform or chlorine.
Vaccinations are not carried out due to the lack of a vaccine against mycoplasmosis for cattle. So far, this drug has been developed only for poultry.
Conclusion
Bovine mycoplasmosis is a disease that requires constant monitoring by the animal owner. This is the same case when it is better to once again mistake a simple clogged eye for mycoplasmosis than to start the disease. The higher the concentration of the pathogen in the body, the more difficult it will be to cure the animal.
