Encephalitis is inflammation of the brain. It frequently occurs alongside spinal cord inflammation, which is myelitis, and inflammation of the brain and spinal membranes or meningitis. According to the North Carolina State University College of Veterinary Medicine website, the clinical term for inflammation that affects all three areas is meningoencephalomyelitis. However, because inflammatory disease principally affects the brain, encephalitis is accepted as the general term for central nervous system inflammation.
Two basic causes of encephalitis exist: infectious and idiopathic. Infectious causes include parasites including worms and tick-borne diseases Rocky Mountain spotted fever, lyme disease, ehrlichia canis; viruses including rabies, parvo, and distemper; fungi including histoplasmosis, aspergillosis, blastomycosis; or various bacteria. Idiopathic encephalitis is diagnosed when an infectious cause cannot be found. Many such cases are the result of an underlying immune system disorder such as necrotizing menginogencephalitis, granulomatous meningocencephalomyelitis or necrotizing leukoencephalitis.
According to PetMD, symptoms of encephalitis appear suddenly and progress quickly. Neurological abnormalities can occur in one area of the brain, called focal, or in multiple areas, termed multifocal. Symptoms, which vary depending on the affected areas, include behavioral changes, depression, decreased consciousness, disorientation, seizures, blindness, unequal or dilated pupils, sensitivity to light, circling, facial paralysis, head tilt, tremors, lack of coordination and imbalance.
Your veterinarian will ask for a full history on your dog regarding symptom onset and about any recent events that may have contributed to your dog's behavior or illness. He will conduct a full physical examination. Preliminary tests will include a complete blood count, a biochemistry profile and urinalysis. These tests may indicate infection but, according to the North Carolina State University College of Veterinary Medicine, they are rarely enough in cases of encephalitis. Further testing may include X-rays, abdominal ultrasound, lymph node aspiration, spinal tap, CT scan and MRI. Dogs with severe encephalitis may need to be hospitalized until they are stable.
Treatment for infectious encephalitis begins with antibiotic therapy aimed at targeting your dog's specific type of infection. Further medication may be warranted depending on your dog's symptoms. For example, anticonvulsants may be given for seizures, and steroids may be prescribed if spinal inflammation is present. Once you return home with your dog, you must continue drug therapy exactly as prescribed by your vet and be sure to return for followup appointments.
Treatment for idiopathic encephalitis usually requires immune system suppression, which is why your vet will be careful to rule out all infections before proceeding with treatment. Once an idiopathic cause has been confirmed, your dog will likely be prescribed a three to six month course of high dose steroids -- usually prednisone. If your dog's encephalitis is severe or recurrent, stronger chemotherapeutic drugs may be prescribed. As always, you must be vigilant in following your vet's instructions once you and your dog return home. Watch your dog closely for signs of worsening symptoms, illness or side effects, and notify your vet immediately.
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