What are the prevention and treatment methods for bovine viral diarrhea
Bovine viral diarrhea in dairy cattle is also called mucosal disease. The disease belongs to the genus Pestivirus in the family Flaviviridae. Most cases are inapparent or mild infections that are not easily noticed. Acute infection is characterized by fever, anorexia, nasal discharge, coughing, diarrhea, weight loss, leukopenia, inflammation and erosion of the gastrointestinal mucosa, and marked damage to lymphoid tissue.
Clinical symptoms
In acutely affected cattle, the disease comes on suddenly, with body temperature rising to 40°C-42°C, lasting only 2-3 days, then falling; some animals also show a second rise in body temperature. As body temperature rises, leukopenia occurs, lasting 1-6 days, followed by an increase in white blood cell count. Affected cattle are anorexic, with nasal discharge, salivation, and foul breath. Severe diarrhea usually occurs after damage to the oral mucosa; initially it is watery, later containing mucus and blood. Some cases often have laminitis and erosion and necrosis of the skin between the toes, leading to lameness. In chronically affected cattle, fever is not obvious and body temperature is only slightly above normal; chronic cases generally do not have diarrhea. The most obvious symptom is erosion on the nasal mirror, with ocular discharge, gingivitis, and laminitis, along with erosion and necrosis of the skin between the toes. Cattle infected with this disease usually develop severe immunosuppression from 7-14 days or until recovery, during which they are highly susceptible to secondary infections and readily develop secondary complications when harmful bacteria (such as Pasteurella, Haemophilus somnus, Mycoplasma, etc.) are present.
Diagnosis
During severe outbreaks, a preliminary diagnosis can be made based on the disease history, symptoms, and pathological changes. However, fewer than 50% of affected cattle show clinical symptoms and lesions, and most cattle show subclinical or mild infection, making diagnosis somewhat difficult. A definitive diagnosis ultimately depends on virus isolation and identification and serological testing.
Prevention
1. Identify and cull persistently infected cattle. Because persistently infected cattle continuously shed the virus to the outside through secretions, failing to cull them will expand the disease.
2. Adhere to the principle of self-breeding and self-raising. If cattle must be purchased, avoid buying cattle that have not undergone quarantine, effectively reducing the risk of introducing the virus.
3. Use inactivated vaccines for adequate immunization. Initial immunization requires at least 2 doses, 30 days apart, to ensure sufficient immunity is produced.
Treatment
1. Replenish fluids and electrolytes, and protect the gastrointestinal mucosa.
2. Apply astringent antidiarrheal treatment, cardiac support, and fluid replacement, which can also shorten the recovery period and reduce losses.
3. Antibiotics and sulfonamides can be used, such as potent cephalosporin + Wudu Tongmie + sodium bicarbonate by intravenous injection; Libeiling by intramuscular injection.