grovecenter grovecenterTrue VKH syndrome is a human disease, well described for nearly a century. A similar disease in dogs has been described but since we do not know the relationship between the canine and human disease, we are hesitant to call the canine version VKH syndrome as well. Until we know what is really going on in dogs, we will leave it at VKH-LIKE syndrome or, more accurately, uveodermatologic syndrome.
A syndrome is a collection of symptoms. In humans, VKH syndrome consists of the following:
- Deep inflammation of the eye tissues (a process called uveitis) leading to at least partial blindness. Approximately 70% of people with VKH syndrome become blind and it is usually the inflammation in the eyes that appears as the first sign of VKH syndrome.
- Premature whitening of the hair (present in 90% of affected people).
- Whitening of the skin (present in 50% of affected people).
- Inflammation of the membranes of the nervous system (a process called meningitis). This leads to deafness in about half of the people affected with VKH syndrome.
Affected people are typically of Mediterranean, Hispanic or Asian descent. There are numerous links for more information regarding this condition in humans.
The syndrome in dogs includes:
- Uveitis leading to blindness that, as in humans, is usually the first sign to show. The owner would notice that the eyes seem painful and/or bloodshot. The patient may bump into things and show diminished vision. The pupils are classically constricted and the eye may seem cloudy or may seem to change color from normal.
- Whitening of the coat, sometimes confined to the face (present in 90% of affected dogs) This typically begins 3 to 6 months after the eye disease has started.
- Whitening of the skin, usually most obvious on the nose, lips, eyelids, footpads, and scrotum (occurs in 50% of affected dogs).
Unlike the human disease, deafness or meningitis is not a feature. The most detrimental part of the syndrome is blindness.
What Causes this Syndrome?
Uveodermatologic syndrome is an immune-mediated disease where the body inappropriately attacks its own melanocytes (the pigment-producing cells). These cells seem most prevalent in the skin, retina, and uveal tract of the eye. It is speculated that the immune reaction is initially triggered by a virus though research is ongoing.
- Male dogs are affected more than female dogs.
- Akitas and Nordic breeds are primarily affected. (Actually, 80% of reported cases involve Akitas and as many as 4.1% of Akitas are affected.)
How is the Diagnosis Made?
The best way to confirm this diagnosis is by a skin biopsy (the lip is said to be the best location). Treatment, however, is focused on the eye disease as this has the most serious outcome ‒ blindness ‒ while skin disease is generally cosmetic.
Uveitis is most literally inflammation of the uveal tract of the eye. The uveal tract consists of the iris (the colored portion), the ciliary body (the area inside from which the lens is suspended), and the choroid (the vascular coating of the inside). The treatment for uveitis due to a VKH-like syndrome is the same as for other causes of uveitis.
Thanks to the Animal Ophthalmology Clinic, Ltd. for these pictures. See the complete case study of Sheila.
Treatment
Uveitis, whether it is caused by VKH-like immune-mediated inflammation or something else, is treated by suppressing the inflammation. This means corticosteroids (such as prednisone) are taken orally as well as topically.
VKH-like syndrome will require ongoing immune suppression to prevent blindness and since long-term steroid use is undesirable therapy often switches to azathioprine, cyclosporine, or some other stronger immunomodulating agent. Topical therapy is also necessary; steroid-containing eye drops or injections of steroids into the conjunctival membranes are commonly used.
With aggressive treatment, some dogs are able to regain some vision but in general, vision cannot be preserved and a more realistic goal is to control the eye pain. Blind dogs still have a good quality of life as long as the pain is controlled.
A 2018 study published in the JAVMA by Zarfoss et. al., reviewed 50 dogs with uveodermatologic syndrome
At the initial evaluation, 36% of dogs had glaucoma (increased eye pressure) and 57% were blind in both eyes. Some dogs were able to regain vision and 50% of subjects could see in at least one eye at the end of the study. Of the dogs that ultimately became blind in both eyes, blindness came on over 13.5 months (median). At least 10 eyes had to be removed in order to provide long-term comfort.
