Encephalitis in Small Dogs

Encephalitis is an inflammation of the central nervous system, specifically the brain. In fact, encephalitis is one of the most common causes of neurological disease in veterinary medicine at its clinic, notes the North Carolina State University College of Veterinary Medicine. The disease exists in two forms: infectious and idiopathic. Several breeds of small dogs are more susceptible to idiopathic encephalitis, and Pugs and Yorkshire Terriers are predisposed to specific forms of the disease.

  1. Symptoms and Diagnosis

    • Symptoms of all types of encephalitis include fever, depression, aggression, imbalance, head tilt, uncoordinated gait, blindness, seizures, paralysis and coma. Symptoms vary in type and intensity depending on the area of the brain the inflammation affects. Animals suffering from encephalitis generally show symptoms quickly, within days or weeks of onset. Diagnosis is most commonly done via a spinal tap. Blood work and other common diagnostic tests often fail to conclusively demonstrate encephalitis. Spinal taps are considered routine procedure but do carry a slight degree of risk.

    Infectious Encephalitis

    • Different infections agents around the country cause Infectious Encephalitis. Bacterial encephalitis is rare as the bacteria that causes the disease in humans does not seem to work in dogs. Fungal infections are also rare. Tick-born diseases such as Lyme Disease infrequently cause encephalitis. Viral infections such as canine distemper or rabies most commonly cause of the disease, with distemper the most likely agent.

    Idiopathic Encephalitis

    • Idiopathic Encephalitis describes all cases where an infectious agent cannot be determined or does not exist. Because no diagnostic tests exist to confirm these diseases, only an autopsy can determine a positive diagnosis. Granulomatous Meningoencephalitis is most common in small dogs. Females are more likely to be affected than males, and most animals are younger than 6 at onset. The cause is unknown but may be related to the immune system attacking healthy cells. It shares symptoms of infectious encephalitis. A rare form of the disease affects the ocular nerve, resulting in blindness. Necrotizing Leukoencephalitis is also known as Necrotizing Encephalitis of the Yorkshire Terrier, as it is most common in that breed. Other breeds commonly affected include the Chihuahua and Shih-Tzu. Inflammation occurs in the forebrain and brainstem and may be related to an immunological problem. Dogs up to 10 years old can have symptoms. Necrotizing Menginogencephalitis predominantly exists in the Boston Terrier, Chihuahua, Maltese, Papillion, Pug and Shih-tzu. In the Pug, this disease is known as Pug Disease Encephalitis. It typically affects dogs up to 7 years old. In this version of encephalitis, inflammation occurs in the forebrain, and seizures are common.

    Treatment and Prognosis

    • If you suspect your dog may be suffering from symptoms of encephalitis, bring your pet to the veterinarian as soon as possible. All forms of Idiopathic Encephalitis are typically fatal, with survival usually lasting only a few weeks. Dogs diagnosed with the ocular form of Granulomatous Meningoencephalitis may live as long as six months. Treatment may bring short-term improvement, but most animals eventually succumb. Treatment consists of corticosteroids to reduce brain swelling and immunosuppresive drugs. The prognosis for Infectious Encephalitis is better. With proper treatment, most dogs recover. Vets routinely give antibiotics in almost all cases of infectious encephalitis as well as corticosteroids. Animals experiencing seizures receive anticonvulsants. Viral infections are susceptible to tetracycline or doxycycline. Vets prescribe anti-fungals only if blood work indicates a fungal cause. Dogs who recover from encephalitis may develop long-term seizure disorders or other neurological problems.