The diarrhea virus of cattle in the compound often penetrates with the young stock purchased. The disease causes material damage to the household.
Cattle viral diarrhea affects mainly calves under 5 months of age, and mortality in some households accounts for 90% of the total population. Some factors increase the likelihood of infection, so owners need to be very careful when caring for livestock.
Medical history
Cattle viral diarrhea was first diagnosed in America. Scientists Olofson and Fox discovered it in the 40s of the 20th century, studies were conducted near New York. Olofson and Fox managed to establish that 90% of cattle have antibodies to the causative agent of the disease. But despite them, the cows did not have a single clinical sign of infection.
Later it turned out that the disease is common throughout the world. Epidemics were repeatedly recorded in countries with developed livestock industry. In the Soviet Union, the research of cattle diarrhea virus, starting in 1965, was carried out by Buchnev. Outbreaks of the disease were recorded in the following countries: England, Germany, Moldova, USA, Belarus, Russia, Ukraine, Ireland.
Virus prevalence
Not only cattle are ill . Viral diarrhea is common among roe deer, deer, sheep, pigs, and buffalo. Despite the fact that the world veterinary community is trying to resist the disease, the percentage of animal incidence is quite high. For example, several years ago a cattle viral diarrhea epidemic was reported in Germany. In 2013, a questionnaire was drawn up to monitor the awareness of farmers about the disease itself and the ways of its transmission. The questionnaire showed that farm owners know very little about the disease.
Veterinarians associate low population awareness of cattle viral diarrhea with the ambiguity of symptoms. Sometimes this ailment is even called a time bomb. The risk of livestock infection differs in different countries; veterinarians associate this with local climate patterns, eradication programs, or regional control measures. For example, up to 95% of cows get sick in England, while in Germany only 60% get sick.
In Europe, since 1970, experts began to collect data on cattle viral diarrhea. From the information received, it follows that the most at-risk are farms located in regions where there is no systematic control over the disease. Thanks to the program for combating cattle viral diarrhea, there are countries that are considered free from the disease. The ailment has long been not registered in Norway, Sweden and Denmark.
Pathogen
Young cattle diarrhea is caused by a small RNA genomic virus, the magnitude of which is 40 nm. The causative agent can be isolated from feces or blood from infected cows in the acute phase of the disease. It affects any body tissue. The highest concentration of cattle diarrhea virus, the treatment of which is best started immediately, is isolated in the respiratory tract and organs of the gastrointestinal tract.
The causative agent is easily reproduced in various tissues and organs of animals. It disrupts the functioning of cells, as a result of which they degenerate. Especially dangerous is the effect of the cattle diarrhea virus on the immune system. Its cells are depleted, which leads to the fact that secondary infections begin to stick to the animal. Immunity drops so much that it becomes unable to protect a living organism.
The causative agent of the disease is not afraid of low temperatures, it is able to survive for several years at a temperature of -40 ° C. The virus is sensitive to an acid-base reaction, and if the pH is close to 3, then it quickly dies. The causative agent can withstand up to 5 cycles of freezing and thawing.
What is cattle viral diarrhea?
The ailment has a second name - mucous membrane disease. Cattle viral diarrhea is characterized by exhaustion, refusal of food, severe diarrhea. Sometimes infected individuals may experience fever, lameness, and other health problems.
The virus invades the body of the cow and after 2 days reaches the spleen, affecting other organs. On day 4, it is present in most tissues. The main location of the cattle diarrhea virus is the oral cavity and the gastrointestinal tract.
The pathogen affects the immune system of the animal, which leads to a decrease in resistance to other diseases. The virus destroys white blood cells, therefore it is undesirable to give medicinal stimulants of the immune system, as this leads to a more rapid development of the disease, and not to cure.
Particularly dangerous is the penetration of the pathogen into the body of a pregnant cow. In this case, treatment of viral cattle diarrhea is difficult. If the infection occurred from 90 to 150 days of pregnancy, a miscarriage will occur. At a later date, the disease does not adversely affect the fetus.
Disease transmission mechanism
Ways of infection by scientists are not fully understood. Cows, pigs, roe deer and other animals are sick. The main source of infection is infected animals. The disease in vectors can occur both in a latent and explicit form. In many developed countries, when conducting serological studies on farms that had previously been successful in livestock viral diarrhea, they are infected. The disease proceeds in a latent form, which, unfortunately, makes it possible to infect your brothers.
Most likely, the virus enters the livestock by the oral or nasal route, as it is unstable in an acidic environment. The source of infection can serve not only sick animals. The causative agent is transmitted through unverified feed, infected water, seeded equipment. If hygiene standards are poorly observed on the farm, then the workers themselves who care for the cows can infect cattle.
Between animals, the virus is transmitted from one individual to another through personal contact. Possible infection during the mating of a bull with a cow. With artificial insemination, especially if the sperm has not been tested for infection, you can also bring the disease.
At risk is young animals under the age of 2 years. Especially susceptible calves to cattle viral diarrhea. Epidemics usually occur in the cold season, since the pathogen is not afraid of low temperatures, but sometimes outbreaks were recorded in the summer. The disease is most often found on farms where they do not care about sanitary conditions, poorly feed livestock and do not drive cows for grazing.
Symptoms
The incubation period of livestock viral diarrhea most often takes 1 to 3 weeks. During this time, the disease is asymptomatic, so the owner may not suspect that his animals are infected. After this period, the first signs appear.
Cows begin to refuse food, graze poorly, they are in a fever, the temperature rises to 40-42 degrees. Feces gradually become liquid and soon turn into diarrhea. Uncharacteristic outflows appear from the nose and eyes, sometimes with a purulent impurity. If the animal has strong immunity and the disease proceeds in a mild form, then after a few weeks it recovers.
Otherwise, the symptoms intensify. Affected cattle begin to limp, miscarriages occur in pregnant cows. In diarrhea, the host may notice bloody inclusions. The cattle are losing much weight, and dehydration begins to appear in her. Cows look haggard and sick. Ulcers may appear on the mucous membranes, the cornea becomes cloudy, and vision decreases. Later, affected nodes enlarge the lymph nodes, hair falls out. Without antibiotic treatment for diarrhea, cattle soon die.
Variants of the course of viral diarrhea in cows
The diagnosis of the disease is complicated by the presence of different types of the disease. Livestock viral diarrhea can occur in several forms:
- spicy;
- chronic
- subacute;
- asymptomatic.
The doctor selects the treatment individually, depending on the type of disease. Veterinarians recommend using antibiotics for cattle diarrhea.
In the acute course of the disease, cows have a high fever, they are in fever. Against this background, animals refuse to feed, they cease the formation of chewing gum, develops an atony of the scar. The condition of the livestock is depressed, eyes begin to flow. In the area of the nose and mouth, pimples are observed, which then degenerate into ulcers. Severe diarrhea opens. From time to time, foam may come out of the mouth, which is especially scary for the owners. Blood clots and mucus are well distinguishable in feces, an unpleasant odor emanates from them. Later, damage to the central nervous system develops, and the animal dies.
In the chronic course of the disease, cows refuse to eat, their temperature rises slightly. On the mucous membranes, ulceration is noticeable. Diarrhea begins, which sometimes ends with prolapse of the rectum. Animals lose weight and look painful. If you do not start treatment for cattle viral diarrhea, then the whole herd will become infected and die within 1-2 months.
The subacute form of the disease is most often diagnosed in calves not older than six months. They have a runny nose and diarrhea. The animals are in a fever, they have nosebleeds. In pregnant cows, miscarriages occur. In a few weeks, some of the animals recover. With an asymptomatic form of the disease in infected animals, there are practically no signs of ill health. In this case, the diagnosis can only be made after laboratory tests.
Pathological changes
Sometimes an animal dies very quickly, in this case an autopsy is performed and a posthumous diagnosis is made. With viral diarrhea in cattle, the main changes occur in the gastrointestinal tract, in which, when an autopsy is detected, numerous ulcers and erosion are detected. Signs of stomatitis and gastritis are visible. Necrotic areas are visible on the mucous membranes.
Overflowing blood vessels, numerous ulcers and erosions are visible in the oral cavity. The nasal mirror is covered with a rash that goes far into the body. In the intestines of the cow are leftovers that have a sickening smell. Content mixed with mucus and blood, watery, unpleasant in appearance.
Traces of necrosis are visible on the small intestine; ulcers are clearly visible on its entire surface. Traces of inflammation are present in the large intestine. Unhealthy liver, enlarged. The kidneys are flabby, loose. The brain has signs of swelling.
Immunity
Recovered animals in remission become resistant to the disease for more than 1 year. However, they are able to infect other cows, that is, they are virus carriers. Calves that were born in cows that are in remission acquire immunity for 1 month. But this is only if within 60 minutes after birth they were drunk with maternal colostrum.
A variety of vaccines against cattle viral diarrhea are used to create stable immunity to the disease on farms. They contain modified strains of the pathogen. Vaccines are great for creating passive immunity to the disease.
Diagnostics
It is impossible to establish the presence or absence of viral diarrhea in the herd only by symptoms and external signs. The disease has too many different strains, so it is easy to confuse it with other diseases. Sometimes a veterinarian may suggest livestock diarrhea if diarrhea and fever are observed in animals. Also an indirect sign is the rapid spread of the disease and the constant infection of new individuals with it.
Reliably detect viral diarrhea in livestock can be done exclusively in the laboratory. Experts isolate the virus on cell cultures, and also find out its resistance to different groups of antibiotics. If there is any doubt about the diagnosis, then conduct a biological test on rabbits. The laboratory can accurately confirm the presence of viral diarrhea in the herd.
If the veterinarian does not have the opportunity to conduct research, then he has to make a diagnosis based on clinical signs, which is undesirable. The doctor must carefully examine all the symptoms so as not to confuse cattle viral diarrhea with rhinotracheitis, parainfluenza, adenovirus infection, chlamydia and pasteurellosis.
Treatment
To combat the disease, veterinarians use vaccines and serums. These drugs are used to treat livestock diarrhea in combination with antibiotics. The use of stimulants of the immune system is not recommended, as they can enhance the effect of infection on the body.
A good effect is the use of serum in the form of aerosols. She can process the entire farm at once, if you use powerful fog generators. The animals are placed in airtight boxes and whey is sprayed, the cattle are treated for 1 hour. If injectable vaccines are used, the result will be less impressive.
To combat bacterial infection, antibiotics must be used. The following drugs have proven themselves well: Ditrim, Levomycetin, Syntomycin, Sulfodimesin. Superficial ulcers can be treated with Furacilin. Education in the mouth, veterinarians recommend lubricating with the drug "Ichthyol".
Prevention
An infectious disease is easier to prevent than to treat later. Prevention of cattle viral diarrhea is to quarantine all animals that have arrived at the farm. Even if the cows were brought from a farm that is disease-free, precautions are necessary. During quarantine, the animals are tested, according to which the veterinarian determines the presence or absence of the disease in livestock.
To prevent viral diarrhea, all livestock must be vaccinated in a timely manner. A live vaccine is given to young animals and cows that have not reached a random age. This is done in order to eliminate the harmful effects of serum on the fetus. The vaccine with dead pathogens is used for twice pregnant cows in the second half of pregnancy. Immunity in animals lasts up to 5 years.
Veterinarian's advice
If the epidemic of viral diarrhea in cows has begun in the region, then the movement of livestock should be limited. In no case should sick and suspicious animals be kept together with healthy animals. When cows arrive from another farm, they must be quarantined, even if the farm is deemed safe for viral diarrhea.
If the animals are still sick, then you should immediately invite a veterinarian. A disinfection procedure is recommended throughout the farm. It is desirable to destroy sick animals in serious condition, and burn carcasses. For prevention, you can use vaccines with both live and dead causative agents of the disease.