Diagnosis and treatment of Bovine viral diarrhea with High risk Infectious Diseases

Raising cattle

Bovine viral diarrhea is an infectious disease caused by bovine viral diarrhea virus. Cattle of all ages are easily infected, and young cattle are the most susceptible. It can be transmitted through direct or indirect contact with secretions, excreta, blood and spleen of diseased cattle.

1. Symptoms

The incubation period of the disease is 7-14 days.

1.1.The acute type had a sudden onset, and the body temperature increased to 40 ℃ ~ 42 ℃, which lasted only 2-3 days, and only showed the second increase (bipolar high fever). With the increase of body temperature and leukopenia, it lasted for 1-6 days, followed by a slight increase of leukocytes. Diseased cattle have anorexia, rhinorrhea, salivation, and smelly breath. Severe diarrhea usually occurs after damage to the intraoral mucosa, beginning with watery diarrhea, followed by mucus and blood. In some cases, there is erosion and necrosis of the skin between the hoof and toes, leading to claudication.

Acute infection can cause severe immunosuppression in cattle for 14 days or until convalescence, during which it is very sensitive to secondary infection and is easy to cause secondary diseases (such as pneumonia) when infected by harmful bacteria (such as Pasteurella multocida, Haemophilus sleeping, mycoplasma, etc.).

When cows are infected with the disease during pregnancy, the virus invades the fetus through the placenta, causing miscarriage or congenital defects of calves. The most common is cerebellar hypoplasia (that is, infected at 100 to 200 days of pregnancy). The affected calves show only mild ataxia or complete loss of coordination and standing ability.

1.2 the chronic type has fewer obvious symptoms, but the change of body temperature may be higher than the normal fluctuation. The most noticeable symptoms are erosion on the nose, serous secretions in the eyes, gingivitis, hoof leaf inflammation, and erosion and necrosis of the skin between the toes. There is no diarrhea in general.

2. Pathological changes.

30% to 50% of the diseased cattle oral mucosa (gingiva, upper jaw, tongue and buccal mucosa) erosion, 80% of cattle with clinical symptoms have erosion and superficial ulcers in nasal endoscope and nostrils, and pharyngeal mucosa in severe cases have ulcers and diffuse necrosis. the characteristic lesions are erosive plaques of different sizes and linear arrangement of esophageal mucosa, and varying degrees of edema, bleeding, ulcer and necrotizing inflammation in rumen abomasum and intestine. Aborted fetuses also have digestive tract damage.

3. Diagnosis

During the epidemic of the disease, a preliminary diagnosis can be made according to its history, symptoms and pathological changes, but less than 50% of the diseased cattle have clinical symptoms and pathological changes, and most of the cattle show subclinical infection or mild infection, so the diagnosis is difficult. Virus isolation and identification and serological examination should be carried out for diagnosis.

4. Treatment

Cases with mild symptoms do not require special treatment, but fresh feed and drinking water should be provided, and external stress, transportation or immunization should be avoided. Sick cattle with specific clinical symptoms such as mucosal erosion and diarrhea can be treated symptomatically, that is, replenishing water and electrolytes, protecting gastrointestinal mucosa, and using antibiotics to prevent and reduce the possibility of secondary infection of conditioned bacteria.

5. Prevention

5.1 identify and eliminate diseased cattle with persistent infection, as this type of cattle is not easy to detect, but always carries the virus and continues to detoxify the body through secretions.

5.2 strictly prohibiting the purchase of unquarantined cattle can effectively reduce the risk of introducing the virus.

5.3 Immunization with inactivated vaccine requires at least 2 initial immunizations at an interval of 30 days to ensure adequate immunity.