Cattle viral diarrhea: symptoms, causes, veterinary advice on treatment and prevention

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The bovine diarrhea virus in the farmstead often penetrates with purchased young animals. The disease causes material damage to the economy.

Bovine viral diarrhea mainly affects calves under the age of 5 months, and mortality in some farms is 90% of the total livestock. Several factors increase the likelihood of infection, so owners need to be very careful when caring for their livestock.

Case history

Viral bovine diarrhea was first diagnosed in America. It was discovered by scientists Olofson and Fox in the 40s of the 20th century, research was carried out near New York. Olofson and Fox were able 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 widespread throughout the world. Epidemics have been repeatedly recorded in countries with a developed livestock industry. In the Soviet Union, the study of the bovine diarrhea virus, startingsince 1965, Buchnev was engaged. Outbreaks of the disease were recorded in the following countries: England, Germany, Moldova, USA, Belarus, Russia, Ukraine, Ireland.

Virus prevalence

It's not just cattle that suffer from the disease. Viral diarrhea is common among roe deer, deer, sheep, pigs, buffaloes. Despite the fact that the global veterinary community is trying to resist the disease, the incidence rate of animals is quite high. For example, a few years ago an epidemic of bovine viral diarrhea was reported in Germany. In 2013, a questionnaire was compiled to monitor farmers' awareness of the disease itself and how it is transmitted. The survey showed that farm owners know very little about the disease.

Low public awareness of bovine viral diarrhea is associated by veterinarians with the ambiguity of symptoms. Sometimes this disease is even called a ticking time bomb. The risk of infection in livestock varies from country to country, and veterinarians attribute this to local climate patterns, eradication programs or regional control measures. For example, in England, up to 95% of cows get sick, while in Germany only 60%.

In Europe, since 1970, experts began to collect data on viral diarrhea of cattle. From the information received, it follows that farms located in regions where there is no systematic control over the disease are at the greatest risk. Thanks to the bovine viral diarrhea control program, there are countries that are considered free from the disease. The disease is no longerregistered in Norway, Sweden and Denmark.

Pathogen

Diarrhea in young cattle is caused by a small RNA genomic virus, the size of which is 40 nm. The pathogen can be isolated from the feces or blood of infected cows in the acute phase of the disease. It affects every tissue in the body. The highest concentration of bovine diarrhea virus, the treatment of which is best started immediately, is isolated in the respiratory tract and organs of the gastrointestinal tract.

The pathogen is easily reproduced in various tissues and organs of animals. It disrupts the cells, as a result of which they degenerate. Especially dangerous is the effect of the bovine 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 oC. The virus is sensitive to acid-base reaction, and if the pH is close to 3, then it quickly dies. The exciter can withstand up to 5 freeze and thaw cycles.

What is bovine viral diarrhea?

The disease has a second name - a disease of the mucous membranes. Viral diarrhea of cattle is characterized by emaciation, refusal of food, severe diarrhea. Occasionally, infected individuals may experience fever, lameness, and other he alth problems.

The virus enters the body of a cow and after 2 days gets tospleen, affecting other organs. On day 4, it is present in most tissues. The main site of localization of the bovine diarrhea virus is the oral cavity and the gastrointestinal tract.

The pathogen affects the animal's immune system, resulting in a decrease in resistance to other diseases. The virus destroys leukocytes, therefore it is undesirable to give immunity stimulants drugs, as this leads to a faster development of the disease, and not to a cure.

Especially dangerous is the penetration of the pathogen into the body of a pregnant cow. In this case, the treatment of viral diarrhea in cattle is difficult. If the infection occurred from 90 to 150 days of pregnancy, then a miscarriage will occur. At a later date, the disease does not adversely affect the fetus.

Mechanism of disease transmission

The ways of infection are not fully understood by scientists. Cows, pigs, roe deer and other animals get sick. The main source of infection is infected animals. The disease in carriers can occur both in a latent and in an explicit form. In many developed countries, when conducting serological studies on farms that were previously free of viral diarrhea in cattle, infected ones are found. The disease proceeds in a latent form, which, unfortunately, makes it possible to infect their fellows.

Most likely, the virus enters the body of livestock orally or nasally, as it is unstable in an acidic environment. Not only sick animals can serve as a source of infection. The pathogen is transmitted through untested feed, contaminated water, contaminated equipment. If the farm is badhygiene standards are observed, then the workers themselves who are engaged in servicing cows can infect livestock.

Between animals, the virus is transmitted from one individual to another through personal contact. Infection is possible 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 - young animals under the age of 2 years. Especially calves are susceptible to viral diarrhea of cattle. Epidemics usually occur during the cold season, since the pathogen is not afraid of low temperatures, but sometimes outbreaks of the disease were recorded in the summer. The disease is most often found on farms that do not care about sanitary conditions, feed cattle poorly and do not drive cows to graze.

Symptoms

The incubation period for viral diarrhea in cattle is most often 1 to 3 weeks. During this time, the disease is asymptomatic, so the owner may not be aware that his animals are infected. After the expiration of this period, the first signs appear.

Cows begin to refuse to feed, they graze poorly, they are feverish, the temperature rises to 40-42 degrees. The feces gradually become liquid and soon turn into diarrhea. Uncharacteristic discharges appear from the nose and eyes, sometimes with a purulent admixture. If the animal has strong immunity and the disease is mild, then after a few weeks it recovers.

Otherwise the symptoms get worse. Affected cattle begin to limp, and miscarriages occur in pregnant cows. Owner in diarrheamay notice bloody inclusions. The cattle is very thin, she begins to show dehydration. The cows look emaciated and sick. Ulcers may appear on the mucous membranes, the cornea becomes cloudy, vision decreases. Later, the affected cattle have enlarged lymph nodes and hair falls out. Without antibiotic treatment, diarrhea in cattle will soon die.

Variants of viral diarrhea in cows

Diagnosis of the disease is complicated by the presence of different types of disease. Viral diarrhea in cattle can take several forms:

• spicy;
• chronic;
• subacute;
• asymptomatic.

Treatment doctor selects individually depending on the type of disease. Veterinarians recommend mandatory use of antibiotics for diarrhea in cattle.

In the acute course of the disease, cows have a high temperature, they are feverish. Against this background, the animals refuse to feed, the formation of chewing gum stops, and atony of the rumen develops. The state of the cattle is oppressed, the eyes begin to flow. In the area of the nose and mouth, pimples are observed, which then degenerate into ulcers. The strongest diarrhea opens. At times, foam may come out of the mouth, which is especially frightening for the owners. In the feces, clots of blood and mucus are clearly distinguishable, and 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. Ulceration is noticeable on the mucous membranes. Diarrhea begins, which sometimes endsprolapse of the rectum. Animals lose weight and look sickly. If bovine viral diarrhea is not treated, the entire herd will become infected and die within 1-2 months.

Subacute form of the disease is most often diagnosed in calves under the age of six months. They have runny nose and diarrhea. Animals are in a fever, they have discharge from the nose. Pregnant cows have miscarriages. After a few weeks, some of the animals recover. In the asymptomatic form of the disease in infected animals, there are practically no signs of ill he alth. In this case, the diagnosis can only be made after laboratory tests.

Patological changes

Sometimes the animal dies very quickly, in this case an autopsy is performed and a post-mortem diagnosis is made. With viral diarrhea in cattle, the main changes occur in the gastrointestinal tract, in which numerous ulcers and erosions are found at autopsy. Visible signs of stomatitis and gastritis. Necrotic areas are visible on mucous membranes.

In the oral cavity, vessels overflowing with blood, numerous ulcers and erosions are visible. The nasal mirror is covered with a rash that goes far into the organ. In the intestines of a cow there are food residues that have a nauseating odor. Content mixed with mucus and blood, watery, unpleasant in appearance.

Traces of necrosis are visible on the small intestine, ulcers are clearly visible over its entire surface. There are traces of inflammation in the large intestine. Liver of unhe althy color, increased in size. flabby kidneys,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 to cows that are in remission acquire immunity for a period of 1 month. But this is only if they were drunk with maternal colostrum within 60 minutes after birth.

To create sustainable immunity to the disease on farms, a variety of vaccines against bovine viral diarrhea are used. They contain modified strains of the pathogen. Vaccines are great for creating passive immunity to a disease.

Diagnosis

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 suspect viral diarrhea in cattle if the animals have diarrhea and fever. Also an indirect sign is the rapid spread of the disease and the constant infection of new individuals with it.

Viral diarrhea in livestock can be reliably detected only in the laboratory. Specialists isolate the virus in cell cultures, and also find out its resistance to different groups of antibiotics. If there is doubt about the diagnosis, then a biological test is carried out on rabbits. In the laboratory, it is possible to accurately confirm the presence of virus in the herddiarrhea.

If the veterinary specialist does not have the opportunity to conduct research, then he has to make a diagnosis based on clinical signs, which is undesirable. The doctor needs to carefully study all the symptoms so as not to confuse viral diarrhea in cattle with rhinotracheitis, parainfluenza, adenovirus infection, chlamydia and pasteurellosis.

Treatment

Veterinarians use vaccines and sera to fight disease. These drugs are used to treat diarrhea in cattle in combination with antibiotics. The use of immune stimulants is not recommended, as they can increase the effect of infection on the body.

A good effect is the use of serum in the form of aerosols. It can process the entire farm at once, if you use powerful fog generators. Animals are placed in airtight boxes and sprayed with serum, cattle are treated for 1 hour. If vaccines are given by injection, the results will be less impressive.

Antibiotics must be used to fight a bacterial infection. The following drugs have proven themselves well: Ditrim, Levomycetin, Synthomycin, Sulfodimesin. Superficial ulcers can be treated with Furacilin. Veterinarians recommend lubricating formations in the mouth with Ichthyol.

Prevention

An infectious disease is easier to prevent than to treat later. Prevention of bovine viral diarrhea is to quarantine all animals arriving at the farm. Even if the cows were brought from a farm that is safe fordisease, precautions are necessary. During quarantine, animals are tested, according to which a veterinarian determines the presence or absence of an illness 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 breeding age. This is done in order to exclude the harmful effects of whey on the fetus. The vaccine with dead pathogens is used twice for pregnant cows in the second half of pregnancy. Immunity in animals lasts up to 5 years.

Vet advice

If an epidemic of viral diarrhea in cows has begun in the region, then it is necessary to limit the movement of livestock. In no case are sick and suspicious animals kept together with he althy ones. When cows arrive from another farm, they must be quarantined, even if the farm is considered free from viral diarrhea.

If the animals are still sick, you should immediately invite a veterinarian. It is recommended that the entire farm be disinfected. It is advisable to destroy sick animals in serious condition, and burn the carcasses. For prevention, you can use vaccines with both live and dead pathogens.