Why is the incidence of three-day fever in dairy cows high in summer and its spread wide, and how can it be prevented and treated?
In summer, temperatures rise quickly, and dairy cows are prone to epidemic fever, which leads to a drop in milk production. To ensure the profitability of dairy farming, dairy farms (households) must do a good job of preventing and controlling epidemic fever in dairy cows.
Dairy cows
Epidemic fever in dairy cows is an acute infectious disease caused by a rhabdovirus. It spreads very quickly, has a wide epidemic range, and a high incidence. Dairy cows of different sexes and ages can all be infected. Most cows recover to normal about 3 days after onset, so it is also called “three-day fever”, and it mostly occurs in summer or in seasons with persistently high temperatures.
1. Pathogen: The pathogen of this disease is a rhabdovirus belonging to the genus Vesiculovirus. It is not strongly resistant to heat and can be inactivated at 56°C in 10 minutes. This disease spreads through the air, and cows in the same trough or on the same farm spread it to each other quickly.
2. Symptoms: The epidemic fever virus of dairy cows mainly attacks the respiratory system and locomotor system of dairy cows, and the clinical symptoms are diverse. General symptoms include elevated body temperature, which can reach 39.5°C to 43°C, hyperactive heart sounds, listlessness, conjunctival congestion, tearing, drooling, and runny nose, and in a few acute cases, difficulty breathing. Appetite is poor, rumination is reduced, gastrointestinal peristalsis is weakened or stops, and feces are dry and scant. Milk production suddenly drops, joints are painful, lameness occurs, the muscles of the forequarters and hindquarters tremble, the gait is unsteady, or the cow lies down and cannot stand. It is often complicated by emphysema or paralysis, and can lead to abortion or stillbirth.
3. Prevention and treatment: For dairy cows with excessively high body temperature, 5 mL × 10 ampoules of Qingzengan injection should be used promptly for intramuscular injection; for non-pregnant cows, 5 mg × 10 ampoules of dexamethasone sodium phosphate injection should be used for intramuscular injection. In milder cases, recovery can occur within 2 to 3 days.
For dairy cows whose main symptoms are respiratory, use 30 mL of 30% analgin injection and 3 million to 4 million units of procaine penicillin for intramuscular injection, 1 to 2 times daily, and generally they recover after 2 to 3 days. In severe cases, 4 to 8 g of streptomycin or kanamycin can be added for intramuscular injection, 1 to 2 times daily. Alternatively, bleed 1000 to 2000 mL from the jugular vein, then slowly inject an equal amount of glucose sodium chloride injection into the vein. When breathing is extremely difficult, oxygen can also be delivered through the nasal cavity or into the abdominal cavity and subcutaneously.
For dairy cows whose main symptom is paralysis, in addition to the above treatment measures, 1 g of thiamine hydrochloride can be injected daily, or 0.2 to 0.3 g of furanthiamine injection can be given intramuscularly, and 500 to 1000 mL of 10% calcium gluconate injection can be given intravenously, while also supplementing with 100 mL of 10% potassium chloride injection. Generally, therapeutic effects can be achieved after 1 to 3 days. In severe cases, thiamine hydrochloride can be injected into the Baihui acupoint and the Dakua acupoint, or electric needles can be used to stimulate acupoints such as Baihui, Shenshu, and Shenjiao, or specific electromagnetic wave (TDP) irradiation can be used.
For sick cows that still cannot stand after symptomatic drug treatment, the vinegar bran moxibustion method can be used: mix 10 kg of bran with 10 kg of edible vinegar, stir well, fry in an iron wok until hot at 60°C, then divide into two burlap bags, tie the openings, and alternately warm-compress the waist and hip area of the sick cow, for 1 hour each time, once daily, for several consecutive days, until the sick dairy cow can stand on its own.