Ticks: Diseases & Prevention

Health and insect experts are calling it a perfect storm of conditions coming together to create what is expected to be an extremely heavy tick season. And with ticks, come the dangers of tick-borne disease for horses, dogs, and humans.

Ticks are more prevalent in tall grass and wooded areas inhabited by deer. While most people may be aware of deer ticks, which carry Lyme disease and are found in the Northeast region of the country, it’s important to remember that different species of ticks are found across the U.S. and that they carry a variety of other diseases.

Horses in Northern Virginia commonly affected by two tick borne diseases.


Anaplasmosis is the tick-transmitted disease that most commonly causes illness in horses. The causative organism, Anaplasma phagocytophilum, is a bacterium that was previously called Ehrlichia equi, hence the persistent older disease name, Equine Ehrlichiosis. Ticks can also transmit this organism to humans and other animal species, including dogs and livestock, resulting in similar clinical illness.

Once bitten:

  • The horse generally becomes sick 3-14 days after the infected tick bite.
  • The fever in the early stage of the disease is generally very high (103° to 106° F).
  • Younger horses under 4 years old tend to have mild or no clinical signs where as geriatric horses may become more ill.
  • Others clinical signs may include lower limb edema, depression, reluctance to move, depressed appetite, and occasionally staggering.


Diagnosis is based on clinical signs, as well as testing for Anaplasma from a blood sample. The SNAP 4DX test can be used stallside to get confirmation quickly.


Antibiotic treatment is usually very effective if the horse is treated soon after the signs of illness begin. The antibiotic of choice is oxytetracycline, which is administered intravenously followed by oral doxycycline. Relapses may occur if antibiotic treatment is too short. Other supportive care, such as nonsteroidal anti-inflammatory drugs (NSAID, eg. Banamine), and leg support wraps, are often employed.

Ticks should be removed and destroyed. Other horses on the same farm should also be checked for both ticks and early signs of illness. There is no vaccine for this disease, so a horse owner’s best defense is to minimize tick habitat in their horse’s environment, use topical insecticides that include a label claim for ticks, and to remove any ticks found on the horse as promptly as possible.

Lyme disease

Lyme disease is caused by the bacterium Borrelia burgdorferi. Clinical signs of Lyme disease vary and can be non-specific.

These include:

  • Lethargy
  • Stiffness
  • Skin sensitivity
  • Change in behavior
  • Unspecified lameness
  • Neurologic abnormalities


Diagnosis can be made with the SNAP 4DX test for a quick stallside result and can be confirmed with the multiplex test that differentiates among vaccine titers, chronic, and acute infections. 

Prevention and Treatment

Lyme disease can best be prevented through combined vaccination and monthly topical treatment with Vectra 3D. Initial vaccination requires two injections, two to four weeks apart. Lyme vaccines are then given every six months for optimum disease prevention.

If infected, treatment consists of oxytetracyline, doxycycline, or minocycline.  Treatment usually lasts 30-60 days.

Most Common Species of Ticks in Northern Virginia
(note: blacklegged tick = deer tick)

Download Our Instructions for Applying Vectra 3D to Equine Here


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