A condition known as the Vogt-Koyanagi-Harada or uveomeningoencephalitic syndrome is seen in human beings. A syndrome similar to this condition 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. 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. 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. 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.
The diagnosis of uveodermatologic syndrome is based on history, physical examination and skin biopsy findings. Topical or subconjunctival corticosteroids and topical cycloplegics are beneficial in patients with anterior uveitis. Oral prednisolone is administered until remission. Long term alternate day therapy is often needed to maintain remission. Azathioprine 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 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.
- Nesbitt G.E. & Ackerman L.J. Canine Immune-Mediated Skin Diseases. In: Canine and Feline Dermatology: Diagnosis and Treatment.
- Comparative Ophthalmology Notes www.vetmed.ucdavis.edu