EGA education

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Equine ehrlichiosis is an infectious, noncontagious, seasonal (late fall-to-spring) disease reflecting the activity of ticks in the areas where horses are ridden or worked. equine ehrlichiosis is seen chiefly in the US in northern California, but is also seen in several other states, including Connecticut, Maine, Illinois, Arkansas, Washington, Pennsylvania, Colorado, Minnesota, and Florida. The disease has also been confirmed in British Columbia, Sweden, Great Britain, and South America.

Equine erlichiosis has been seen with increasing frequency over the past few years. It affects horses of all ages, and the symptoms are usually appear suddenly. Unlike many diseases, this condition causes less severe symptoms in horses that are less than three years old.

Equine ehrlichiosis is transmitted by ticks of the Ixodes family known as deer ticks. This condition is related to several other better-known diseases, such as Lyme disease and rocky mountain spotted fever. The clinical symptoms are seen most frequently in the winter, spring, and fall.

The bacteria from the tick bite tends to be engulfed by white blood cells and this causes the destruction of these infection- fighting white blood cells. After being infected, horses will be normal for 10-20 days prior to developing clinical signs.

After clinical signs develop, the horse will deteriorate rapidly and often will show mild signs of colic and become jaundiced over the next 3-4 days. Most horses will survive after 10-14 days of severe illness, but some will develop subclinical infection.

Severity of symptoms varies with the age of the horse and duration of the illness and may be mild. Horses that are younger than a year old may have a fever only. Horses 1-3 years old may develop fever, depression, mild limb edema, and ataxia. The fever, which is highest during the first 1-3 days of infection at 103-104°F (39.5-40°C), persists at 102-104°F (39-40°C) for 6-12 days. Signs become more severe over several days.

• Fever
• Depression
• Reluctance to move
• Jaundice
• Refusal to eat
• Heart arrhythmias
• Colic-like symptoms
• Anemia
• Mild limb swelling
• Exacerbated concurrent infection (e.g., a leg wound or respiratory infection)
• Loss of limb coordination