Anaplasmosis is a common tick-transmitted disease of horses. It is caused by Anaplasma phagocytophilum, a bacterium that was previously called Ehrlichia equi and associated with the disease Equine Ehrlichiosis. Ticks transmit this bacteria to horses as well as other animal species, including humans.
Younger horses under 4 years of age tend to have mild or no clinical signs where as older horses may become more ill. Once bitten by an infected tick, the horse generally starts to show early signs of the disease within 3-14 days.
During the early stages of the disease, the horse develops a very high fever of 103 to 106°F (39.4°C to 41.3°C). Other clinical signs include reluctance to move, depression, reduced appetite, occasional staggering, and mild edema in the lower limbs.
Diagnosis is based on clinical signs and testing for the presence of the organism from a blood sample.
Treatment is usually very effective if started soon after the signs of illness begin. Horses are usually given a course of antibiotics (oxytetracycline), administered intravenously followed by oral doxycycline. Other supportive care includes stall rest, nonsteroidal anti-inflammatory drugs (NSAID, eg. Banamine), and wrapping the legs for support.
Keep horse hydrated: Horses with a high fever often will drink and eat less than normal. When horses become dehydrated they have an increased risk of colic. Therefore, it is important to encourage horses to keep drinking by using various strategies such as soaking hay, adding water to feed, dropping treats or pieces of apples in water buckets, etc.