Anaplasmosis (Equine Granulocytic Ehrlichiosis)

Anaplasmosis in horses is caused by bacteria called Anaplasma phagocytophila, which are spread by a tick-bite. This bacterium was formally known as Ehrlichia equi and the disease was previously called “equine ehrlichiosis” or “equine granulocytic ehrlichiosis” (EGE). 

Ehrlichia equi was thought to be a separate bacterium unique to horses, but recently has been found to be genetically the same as Anaplasma phagocytophila and thus the name was changed. Anaplasma phagocytophila also causes “canine anaplasmosis” in dogs and “human granulocytic ehrlichiosis” (HGE) in people. Anaplasmosis is not considered contagious & is only transmitted via a tick bite or transfer of blood. We have seen cases of Equine Anaplasmosis in our practice area.

The tick:  “deer tick” = Ixodes scapularis- can transmit Anaplasmosis as well as Lyme's disease;  The deer tick is a very small tick:  see the following links for photos of deer ticks & more info:
 http://www.health.state.mn.us/divs/idepc/dtopics/tickborne/ticks.html  
 http://www.aldf.com/deerTickEcology.shtml

Reservoirs that carry this tick:  -small rodents-
                                                       white-footed mouse, chipmunks, voles
                                                   -white-tailed deer

Symptoms in horses: 
-fever, depression, decreased appetite, limb swelling (“stocked-up”), jaundice, reluctance to move &/or weakness/wobbliness, small red dots on gums

Treatment:
-a specific antibiotic- IV +/- oral (some horses with mild signs may get over it on their own, but some horses can get very sick)

Prevention:
Tick-control is the primary means of prevention (there is no vaccine available). Avoid tick-infested areas (tall grass/brush; woods). Use fly/mosquito repellents that also repel ticks. Spray the tail hairs on your horse- ticks often crawl up the tail hair & then attach at the tip of the tail. Always follow label instructions. Apply before going out on trail-rides or when your horse is at risk of getting exposed to ticks. Do a “tick-check” and remove ticks.
Here’s a link on how to safely remove a tick manually:  http://www.cdc.gov/ticks/removing_a_tick.html 

**In addition to your horse, consider tick control for your pets as well as yourself. There are excellent topical treatments available for your pets: Certifect®, Advantix®, & Vectra® (these are for dogs only), and Frontline® (for dog & cats). These products help kill ticks before transmission of bacteria occurs & are applied once a month. Front-line spray has been used extra-label on horses for tick control. Call us at Fredonia Veterinary Clinic, (262) 692-2439, for more information on controlling ticks to help keep your horses and pets healthy.