Canine Uveodermatologic Syndrome
A condition known as the Vogt-Koyanagi-Harada or uveomeningoencephalitic syndrome is seen in human beings. It is characterized by moderate to severe uveitis (anterior and posterior ), secondary retinal separation, poliosis (whitening of hair), vitiligo (loss of cutaneous pigment melanin), dysacousia and meningitis. Not all patients have all symptoms and the degree of symptomatology differs from patient to patient.
A syndrome similar to this syndrome is recognized in dogs and is called canine uveodermatologic syndrome. It is a rare condition that is thought to represent an autoimmune attack against melanocytes. Heavily pigmented tissues such as the uveal tract, skin, and mucous membranes are primarily involved. Hearing impairment has not been seen in dogs.
Breeds at increased risk include the Akita, Samoyed, Siberian husky, Alaskan malamute, and Chow chow. The condition has also been reported in the Shetland sheepdog, white Sherman shepherd, Irish setter, Ainu, and Shiba.
Eye abnormalities usually precede skin lesions and consist initially of bilateral uveitis
to severe, granulomatous panuveitis. Later retinal detachment, posterior synechiae with secondary glaucoma, and cataracts may develop. Skin and hair abnormalities consist of depigmentation that often involves the eyelids, nasal area, lips, scrotum, vulva, and pads of the feet. Inflammation, ulceration and crusting of the skin in the depigmented areas are also present signs. Dogs with this condition may develop mild-to-severe itchiness. Abnormalities of the lymph nodes are commonly seen.
Initial development of lesions has been noted in animals ranging from 13 months to 6 years of age. Most affected animals are young adults.
Diagnosis The diagnosis of uveodermatologic syndrome is based on history, physical examination and skin biopsy findings.
Treatment Topical or subconjunctival corticosteroids and topical cycloplegics are beneficial in patients with anterior uveitis. Oral prednisolone at the dose of 1 to 2 mg/kg daily is recommended until remission. Long term alternate day therapy is often needed to maintain remission. Azathioprine at the dose of 2.2 mg/kg q 24 h PO with tapering after clinical resolution to 0.5 mg/kg q 24h PO may allow for a reduction of the corticosteroid dose. In some patients it may be possible to discontinue the corticosteroids and rely on azathioprine alone. Long term alternate day therapy is often needed to maintain remission. Some dogs can be maintained on azathioprine alone.
Prognosis Prognosis is poor overall. The uveitis tends to recur and may result in permanent blindness due to cataract and retinal degeneration after long term separation or inflammation. Even vigorous therapy may not control the situation. In patients in whom inflammation is controlled, useful vision may be retained and melanosis of the skin may recur. The cause of this syndrome is unknown in people or dogs. It is hypothesized that there may be an immune response mediated against the patient's melanin. Viral initiation has been put forth as a possibility.
References
1. Nesbitt G.E. & Ackerman L.J. Canine Immune-Mediated Skin Diseases. In: Canine and Feline Dermatology: Diagnosis and Treatment. Veterinary Learning Systems, Trenton, New Jersey, 1998
2. Comparative Ophthalmology Notes (http://www.vetmed.ucdavis.edu)
Go Pets America recommends seeking the advice of your local veterinarian for the most appropriate vaccination program and for the diagnosis and treatment of your pet's health problems. For vaccination requirements please contact your state and local licensing authorities.
|