Viral infections are not uncommon on livestock farms. They can spread quickly and infect a significant number of individuals. Sick animals are economic losses that are the consequences of a decrease in their productivity, temporary deterioration in health or death. Consider the causes and symptoms of cattle viral diarrhea, forms of the disease, diagnostic methods and methods of treatment.
What is viral diarrhea
Viral diarrhea in cows is an infectious cattle disease characterized by inflammation and ulceration of the mucous membrane of the digestive tract, with characteristic symptoms - fever, diarrhea, rhinitis, conjunctivitis. Abortion is possible in sick pregnant cows.
Episotology has established that the incubation period for viral diarrhea lasts 6-9 days. Cows can become infected throughout the year, but most often during cold periods. The most susceptible to the virus are animals aged 6 months to 2 years. The death of cows from viral diarrhea can range from 4 to 100% and depends on the number of infected animals in the herd, the strain of bacteria, the conditions of the cows and other factors.
Viral diarrhea belongs to diseases that cause great financial damage to farms, especially with intensive meat and dairy farming. In herds in which there are frequent cases of the disease, damage is expressed in slower growth and reduced weight gain, death of calves, abortions in cows throughout pregnancy or infertility.
Cows that have had diarrhea during the initial period of pregnancy (up to 125 days) produce weak offspring or with congenital malformations. Often, calves from such cows are born weak, grow slowly, and die at an early age from respiratory diseases. If they grow up and bear offspring themselves, they too remain the carrier of the virus and infect other cows. If the infection occurs after 150 days of gestation, the calves will not carry the virus.
Diarrhea in dairy cattle provokes reproductive disorders and various diseases of calves and young animals. In calves, respiratory pathologies and diseases of the gastrointestinal tract develop massively, adults are more likely to suffer from mastitis, milk yield decreases. In beef cattle, productivity also decreases due to a decrease in weight as a result of weight loss or a decrease in the growth rate of young animals.
Pathogen and source of infection
The causative agent of diarrhea is a virus of the Pestivirus genus of the Togaviridae family. At t 20 ˚С it can be stored for years, in biological fluids - up to 6 months. Healthy cows become infected from sick, pathogens at different stages of the disease come out with feces, urine, discharge from the nose and eyes, with saliva and with exudate secreted from inflamed organs. Virus shedding can continue for up to 4 months after the animal has recovered. Pathogens enter the body of animals through the digestive tract (with food and water) or through service personnel, care items. Infection is facilitated by a large concentration of cows in one area, their regrouping.
Symptoms of pathology
The disease can occur in 4 forms, which differ in symptoms and duration of the course. There is also an asymptomatic form; in this case, the disease can be determined only by detecting specific antibodies in the blood serum.
In the acute form, the same symptoms are noted as in the subacute, but the depression of the animal is added. After another 1-2 days, the temperature rises again, hyperemia of the nasal mucosa appears, mucus or mucus with pus begins to stand out from it. With a strong outflow, the mucus dries up on the muzzle in the form of crusts, erosion forms under them. Tears flow from the eyes, catarrhal conjunctivitis appears.
Some individuals may have a dry, hard cough. The gums, hard palate, lips, tongue surface and edges turn red, ulcers form on them, and later pus appears in them. Ulceration can be found on the nostrils, nose, and vagina. Sometimes animals limp. Diarrhea, intermittent or continuous, can last from 4 to 14 days, often resulting in the death of the animal. In other cases, acute diarrhea becomes chronic. The feces of diarrhea are thin, offensive, frothy, with mucus.
This form of viral diarrhea begins suddenly; cows and calves have fever, tachycardia, rapid breathing, decreased or no appetite during the day. There may be unexpressed hyperemia, erosion on the oral mucosa, which quickly pass, in some cows - nosebleeds, tears, cough, diarrhea.
With this form of the disease, the cows are aborted, the fetuses have hemorrhagic ulceration on the mucous membrane, necrosis of the tissues of the skin, brain, lungs, inflammation of the skin and amniotic membranes.
If the infection becomes chronic, the cows gradually lose weight, among the symptoms are hyperkeratosis, diarrhea. Erosions on the mucous membranes usually heal or curdled-purulent layers appear on them (with complications). In some cases, necrotic tissue changes are found on the mucous membranes of the esophagus, abomasum and intestines.
Diagnosing the problem
For analysis for the virus, different biological material is taken from animals suspicious of the disease - blood, feces, nasal washings; from dead or killed animals, tissue samples are taken from the intestines, lungs, lymph nodes, spleen, trachea. Samples of parenchymal organs and amniotic fluid are taken from aborted fetuses.
From viral diarrhea, it is necessary to differentiate infectious rhinotracheitis, plague, catarrhal fever, paratuberculosis, foot and mouth disease, necrobacteriosis, hyperkeratosis.
How to treat viral diarrhea in cattle
There is no cure for this disease. Only symptomatic therapy with antibiotics and anti-inflammatory drugs is carried out. If the course of VD is severe, the animals are slaughtered.
After a veterinary examination, meat and offal can be recognized as suitable for processing into sausages. If the result is positive, the meat can be processed, the internal organs must be disposed of. The skins can be used after disinfection in saline solution. The instructions for dealing with this disease indicate that prevention is the best treatment.
Vaccination of livestock, carried out in a timely manner, significantly reduces the number of sick animals, allows you to control the spread of the virus, and prevents deterioration of cow health and abortion. The vaccination program is designed by a veterinarian to prevent the birth of infected calves while still in the womb. For this, cows are vaccinated before mating. Vaccination of cows against viral diarrhea is carried out using live and inactivated vaccines or a combination of both. The duration of immunity is 1-5 years, depending on the type of vaccine.
Other preventive measures
Viral diarrhea often appears in those farms in which cows are kept in poor sanitary conditions. To prevent infection, it is necessary to monitor the cleanliness of the premises, bedding, equipment and the animals themselves.
Infected calves should be removed from healthy calves immediately and treated immediately. It is important that newborn calves receive high-quality colostrum in the first 12 hours after birth, as it is an excellent source of immune activation. All newly acquired animals from other farms should be quarantined for 3 weeks.
Viral diarrhea is a serious infectious disease that can appear in any household. The disease mainly affects young animals and calves in the womb. Given this feature of the disease, which has a negative impact on the productivity of animals and brings significant economic damage, it is necessary to provide the livestock with the most correct conditions of detention, a rich diet, and vaccinate in a timely manner.