What are Anaplasmosis?
Anaplasma phagocytophilum was previously referred to as Ehrlichia. The disease is transmitted to the horse, through the bite of an infected deer tick which carries Anaplasma phagocytophilum. Once the organism is in the horse’s bloodstream it causes the inflammation of the white blood vessels. The disease may vary from showing no noticeable symptoms to potentially becoming life threatening. Horses that are younger than four years old usually only develop mild symptoms such as a fever and or depression. Adult horses typically may have more critical symptoms. Signs of the disease may be visible 1 to 12 days post-inoculation.
Clinical infection of Anaplasma phagocytophilum have been confirmed in Connecticut, Washington, Arkansas, Pennsylvania, Illinois, Colorado, New York, Massachusetts and in Florida. It has also been found in other countries such as Sweden, Great Britain and South America.
Anaplasmosis in horses (Equine Granulocytic Ehrlichiosis) is a seasonal tick-borne transmitted disease. The disease is caused by the intracellular organism Anaplasma phagocytophilum.
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Symptoms of Anaplasmosis in Horses
Symptoms will be more severe as the disease progresses; clinical signs may also vary depending on the age of the horse. Symptoms may include one or more of the following:
- Edema - retaining fluids
- Respiratory infection
- Less active
- Body soreness
- Lack of appetite
- Increased heart rate
- Yellow gums
- Small red lesions on the gums and sclera
Causes of Anaplasmosis in Horses
Anaplasmosis (Equine Granulocytic Ehrlichiosis) is caused by the organism Anaplasma phagocytophila. Anaplasma phagocytophila is transmitted by the bite of an infected deer tick. It is commonly believed that a tick must be attached for 24 hours before the disease is transmitted.
Diagnosis of Anaplasmosis in Horses
The equine veterinarian will take a thorough medical history of your horse. He will discuss what clinical signs you have observed. Let him know if you have seen ticks on your horse or on another horse in the stalls. The veterinarian will then perform a physical exam on your horse which may include taking the horse temperature, listening to his heart and lungs, and palpation of the abdominal and chest area.
The veterinarian will take a complete blood count (CBC), serum chemistry panel and perform a urinalysis. The CBC will determine if your horse has decreased platelets and low red and/or white blood cells; all clinical signs of anaplasmosis. A serum chemistry panel can help rule out any underlying diseases. Urinalysis will show if the horse has any kidney issues and if there is bacteria, sugar, crystals or blood in the urine. The veterinarian may also recommend a standard blood smear and SNAP 4dx, which tests for antibodies.
Treatment of Anaplasmosis in Horses
If your horse is diagnosed with anaplasmosis he will be treated with antibiotics (tetracycline or doxycycline) and anti-inflammatory (phenylbutazone or banamine) medications. Initially, medications may be given intravenously and then administered orally. If your horse has leg edema (retained fluids) he may be placed on corticosteroid medication. Anaplasmosis may have caused your horse not to drink and eat normally. He may be dehydrated and will need fluids administered through an IV. Stalls will need to be cleaned out and inspected for ticks.
Recovery of Anaplasmosis in Horses
The horse will need follow-up visits to check on his progress and to have a retake on the bloodwork. Horses usually feel better with 24 hours of the start of treatment. It is important to follow the veterinarian’s treatment plan, to ensure that the anaplasmosis has been eradicated from the horse’s bloodstream. In rare cases, horses recovering from anaplasmosis may suffer a relapse. Contact your veterinarian if your horse starts to show any of the previous symptoms.
Horse that have recovered from anaplasmosis are immune to the disease for approximately two years. There is no vaccine for anaplasmosis; it is important to protect your horse from ticks. There are insecticides that can be sprayed along that perimeter of the pasture to help kill ticks. There are also tick repellants that can be used directly on the horse; ask your veterinarian what he recommends. Ticks like damp, overgrown, shady areas; horses should not be allowed to be where there is tall, unmaintained grass.
Horses should be checked daily for ticks. If you find a tick on your horse; use a fine-tipped tweezer to remove it. Use the tweezer to grab the tick as close to its head (where he is attached to the horse) and pull it straight out. Do not grab the tick by the swollen belly, which is full of blood. You can apply a local antiseptic to clean the bite area.
Anaplasmosis Questions and Advice from Veterinary Professionals
Does Anaplasmosis cause back and hip tenderness? My vet was out today and diagnosed my 7 year old mare with this condition with no bloodwork or any clinical testing. Just concerned for 2 years ago I had a 7 year old pony gelding that was diagnosed the same by the same vet with no bloodwork as well.I find this strange for both my mare and gelding are chesnuts. My vet has recommended 2 weeks of Doxycycline for the mare and the same 2 years ago for the pony gelding. The gelding never did get his back soreness straightened out thus the reason I sold him. Am I worrying for no reason? We show in the Hunter world and I have been loyal to my vet for years. I'm just not sure now.
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