New canine eye disease discovered at Iowa State

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May 01, 2008

AMES, IOWA— A previously unknown eye disease that can cause canine blindness has been discovered and named at Iowa State University.

Immune-Mediated Retinopathy (IMR) is similar to a known ailment — Sudden Acquired Retinal Degeneration Syndrome (SARDS) — in that both occur when dogs produce auto-antibodies that mistakenly attack retinal cells as cancerous tumors, impacting vision.

But unlike SARDS, which produces antibodies only in the eyes, IMR creates antibodies in other parts of the body that then travel to the eye, according to Sinisa Grozdanic, DVM, PhD and assistant professor of comparative ophthalmology at Iowa's College of Veterinary Medicine.

"The whole purpose is to start to understand the disease better," he says. "The more we understand these diseases, the more proficient we will be developing new treatments."

Some of the 2,000 annual SARDS cases — once considered untreatable — can now be correctly identified as IMR and addressed with relatively affordable treatments including steroids and doxycycline. "In approximately 60 percent of the IMR cases, we have been able to treat it," he says. "In some cases very successfully, in some cases moderately successfully."

Eye tests have been developed to differentiate SARDS and IMR, using colored lights to determine the retinopathy type. SARDS-affected eyes respond to blue light but not red, while IMR patients react normally to red but not blue, Grozdanic says.

"We still have 40 percent of IMR dogs that do not respond to treatment, and we want to see what is the difference in these dogs that makes them non-responsive to medications. When that discovery is made, we will be in much better shape to modify a therapeutic approach and become successful in treatment of these patients," he says.

Grozdanic also hopes that human treatment is not far off.

"This was a giant leap. We are getting better at understanding it and, based on this information, we may be able to modify and improve treatment of dogs and eventually human patients," he says.