One of the rarer conditions that can strike your dog is known as Vogt-Koyanagi-Harada Syndrome (VKH) or uveodermatological syndrome (UDS). In humans the disease is caused by an autoimmune response in which the person's own T-cells mistakenly attack the body's melanin-forming cells. These are the cells responsible for the color of a person's skin, hair and eyes. Specifically, the disease attacks the front portion of the eye, known as the uvea, which is the dark portion of the eye containing blood vessels. In many cases the iris also is involved, and occasionally the back portion of the eye is affected as well.
It's not yet known how UDS occurs in dogs, but it's believed to also be connected to the autoimmune response. Other potential, but not yet proven, causes include infections, metabolic disease, tumors and trauma or injury to the eye.
When uveodermatological syndrome is present the inside of the dog's eye will become inflamed, as will the retina and iris. The result is extremely painful, swollen and bloodshot eyes. If left untreated, the dog may end up partially or completely blind, due to complications such as cataracts, glaucoma and/or detached retinas. Shortly after the onset of eye symptoms the animal will begin losing color, or pigment, in the nose, lips, nails and eyelashes. This effect also may be seen on the dog's footpads, the roof of the mouth, the scrotum and around the anus. As the disease progresses, the dog's coat also loses pigment, ending up completely or largely white.
UDS is diagnosed through a skin biopsy, in which a small piece of the dog's skin is examined microscopically. The disorder is rare, but can occur in any type of dog. Most commonly affected breeds are: Akitas, Australian Shepherds, Irish Setters, Old English Sheepdogs, Samoyeds, Shetland Sheepdogs and Siberian Huskies. By far, the highest incidence of the disease occurs in Japanese Akitas. Since the disease appears to be genetically inherited, it is recommended that dogs with UDS not be bred.
It is believed that UDS results from a genetic flaw, and as yet there is no cure. However, there are treatments which can make the dog more comfortable and improve its quality of life. First, veterinarians normally use a variety of medications, including steroid drugs like prednisone, to help alleviate pressure within the eyes. These medications also help control the pain and keep the condition from progressing by suppressing the body's immune system. The prescriptions must be taken for the remainder of the animal's life, in order to prevent pain and blindness. The whitening of the dog's coat and other changes in pigment, meanwhile, have a cosmetic effect, but they are not painful or dangerous for the animal.