What are Ehrlichiosis?
Equine ehrlichiosis is a tick-borne disease in horses that results from infection with Ehrlichia bacteria. The offending ticks are from the Ixodes family, which are often known as deer ticks. While not all ticks carry viruses and bacteria, those that do, such as the Ehrlichia equi, can cause serious illness – even death - in an animal or human. There are three ticks that bite horses, and all transmit their bacteria to the horse during their feeding cycle. Though it’s often said that a tick must be attached to the animal for over 24 hours to spread infection, it’s impossible to know if that is true. The best strategy for the horse owner is to check the body of the horse consistently throughout peak tick times. Any type of window post-bite provides a chance to separate the tick from the horse. Even if the horse does not wind up becoming diseased, you will likely still see some localized swelling and irritation in the bite area. It’s important to watch the site for signs of localized infection.
While horses of all ages suffer from tick-diseases each year, younger horses typically become more ill due to not fully-formed immune systems. Equine ehrlichia, however, is proving to be somewhat different as horses under the age of three years old are experiencing fewer and less severe symptoms of illness. Even after being bitten by Ehrlichia equi, younger horses are remaining asymptomatic, or presenting merely with a low fever. Adult horses, however, are experiencing serious symptoms such as fever, colic, heart arrhythmia, jaundice, unsteadiness, limb swelling, loss of appetite, confusion and anemia. Improvement, if it happens at all, typically will not occur for 3-4 days.
As compared to humans, horses are particularly susceptible to being bitten by ticks due to their environment and way of life. Most horses live in constant contact with ticks for at least two to three seasons. Since tick-borne illness are on the rise, more horses will be falling ill with potentially life-threatening diseases such as equine ehrlichia. Since there is currently no vaccine for equine ehrlichiosis, the only way to prevent your horse from being bitten by a tick is reducing their exposure. Environmental treatment is a primary way to avoid tick bites. Pest control companies often treat farm areas for ticks. Long grasses should be cut, and if possible, horses should be kept from deeply wooded areas.
Equine ehrlichiosis is a tick-borne disease caused by infection with Ehrlichia bacteria. The resulting illness may be mild, severe, or possibly even fatal.
Book First Walk Free!
Symptoms of Ehrlichiosis in Horses
- Reluctance to move
- Mild limb swelling/lack of coordinated movement
- Heart arrhythmias
- Colic-like symptoms
Causes of Ehrlichiosis in Horses
Equine ehrlichiosis is a seasonal disease that is most prolific in the months between late fall to spring. The most documented cases of equine ehrlichiosis in the United States have occurred in Northern California, but New England states such as Maine and Connecticut are coming in as close seconds. Over the last three years, increased incidences of equine ehrlichiosis have cropped up in most parts of the country, including Illinois, Arkansas, Washington, Colorado, Minnesota, and Florida. Cases have also been documented outside of the United States, occurring in British Columbia, Sweden, Great Britain, and South America.
Diagnosis of Ehrlichiosis in Horses
Horses are diagnosed with Equine Ehrlichiosis based on a physical examination, owner or caretaker report of disease-associated symptoms, noted seasonal and environmental factors, and blood testing. Veterinarians may also diagnose by watching the horse for a positive or negative (absent) response to treatment. If illness, and probable infection, are noted by the owner early enough to get the horse early care, the horse may respond well to treatment.
Treatment of Ehrlichiosis in Horses
Horses with a severe case of tick-borne disease may not survive past 48 hours. Hospitalization will be required for aggressive care. If the condition is treatable, the horse may respond well to recovery efforts. Intravenous oxytetracycline will often be administered. Horses will with tick-borne diseases respond well to IV fluids, diuretics, and wrapping. Improvement may not be noticeable for at least 3-4 days. More significant recovery will occur after one week.
Recovery of Ehrlichiosis in Horses
The veterinarian will provide information pertaining to the horse’s recovery period. At this time, fewer incidences of tick-borne disease will only be achieved by reducing exposure. No vaccine is currently available. Recovered horses have immunity for two years.