From late summer to fall, one of the most common causes for down cows or sudden death in central Virginia cattle is Anaplasmosis. This disease is prevalent in the eastern half of the State and far less common in the Shenandoah Valley region. It is a blood-born disease spread by insects, including ticks and horseflies, but also by dirty needles.
When calves are exposed to the disease, they develop reasonably strong immunity and tend not to develop clinical disease. However, they can still become carriers and spread the disease to non-carrying cows. When naive cattle older than two years of age are exposed to Anaplasmosis, they will typically develop clinical signs of the disease, including weakness, inability to stand, aggression or sudden death, within one to two months of exposure. Pale or jaundiced (yellow) mucous membranes in such an animal is a strong indicator that the cow is affected by Anaplasmosis. The diagnosis can be confirmed by bloodwork. Once the cow is down, the prognosis is poor due to the severity of anemia. Mildly affected cows respond to treatment with an appropriate antibiotic. Antibiotics are also effective in disrupting an outbreak.
Taking some steps to prevent this costly disease is worthwhile. Insect control measures and using individual needles when working cattle help control the spread of this disease. In heavily affected areas, it may be appropriate to feed an antibiotic to reduce new infections. This requires a Veterinary Feed Directive and is generally only recommended during the vector season when insects are actively spreading the disease. Most importantly, if you are buying or selling animals, be sure to test them for the disease and quarantine appropriately. Clinical disease is most common when an infected animal is introduced to a naive herd.