Tuesday, December 11, 2012

Equine Anaplasmosis

Equine Anaplasmosis is a tick borne disease caused by  Anaplasma phagocytophilum. This disease used to be known as Equine Granulocytic Ehrlichiosis and is caused by a intracellular gram negative organism that is carried within the common deer tick (Ixodes scapularis) , this is the same tick that carries Lyme Disease. Once inside the horse the organism replicates inside the white blood cells and makes its way throughout the body. Initially you will see signs of depression and occasionally limb swelling, jaundice and ataxia (stumbling). Some horses will also show petechiation or small red pin point lesions on the gums and sclera. The typical course of the disease is 1-2 weeks and may be self limiting but can also be quite debilitating with multiple complications involved. Diagnosis requires a good history and physical examination since many common illnesses can present with vague signs initially seen in early or mild cases. Lab tests such as a CBC and serum chemistry can be very helpful in elucidating the cause. Common findings include 1.anemia 2.thrombocytopenia 3.leukopenia and 4. inclusion bodies within the white blood cells.

 A serum chemistry can help rule out other causes of similar symptoms and any possible organ involvement. Treatment consists of using specific antibiotics such as Tetracycline  or doxycycline, antiinflammatory medication such as Banamine or Phenylbutazone and general supportive care. Frequently these horses will not want to eat or drink and may require IV fluid support to prevent dehydration. Hydrotherapy for swollen limbs along with soft bandaging can also be helpful. To confirm suspected cases of Anaplasmosis there is are several specific diagnostic tests available such as the SNAP 4dx test for antibodies , PCR and  serology for raising titers to the organism. Additionally attention to the possibility of laminitis must be included such as standing in ice and sole support. The Prognosis for the horse is usually excellent with a complete recovery provide complications are limited. Tick prevention is important and there are reports of the use of fipronil containing products being successful.
KEY POINTS TO WATCH FOR:
Signs of depression and lethargy
Swollen limbs
Fever
Yellow mucous membranes with possible petechia
History of tick bites


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