FYI
Summary:
A professor of veterinary medicine has identified and named a previously unknown eye disease. Immune-Mediated Retinopathy, or IMR, causes loss of function in retinal cells and, in some cases, blindness.
IMR is very similar to a previously known malady called Sudden Acquired Retinal Degeneration Syndrome or SARDS. Both diseases occur when the dog produces auto antibodies that attack the retinal cells. The antibodies mistake retinal cells for cancerous tumors or tissues that need to be destroyed.
In the process of attacking the retinal cells, the auto antibodies cause the retinal cells to lose function and the dog to lose some or all of its vision.
The difference between IMR and SARDS that Grozdanic identified is that the auto antibodies that attack the retinal cells in SARDS patients are produced in the eye. In the newly identified IMR, Grozdanic found that these auto antibodies are produced elsewhere in the dog and travel to the eyes in the blood.
This is a critical step in treating the disease because the source of the problem is better understood, according to Grozdanic.
"The whole purpose is to start to understand the disease better," he said. "The more we understand these diseases, the more proficient we will be developing new treatments."
Grozdanic says the evidence shows that approximately 2,000 cases of SARDS occur every year. Some of those cases may now be identified as IMR, and treated differently.
Tests show SARDS-affected eyes have almost no electrical activity. IMR-affected eyes have some electrical activity, and the retinal cells are not destroyed but have only lost function. These are the retinal cells that Grozdanic thinks can function again now that the origin of the problem is known.
https://www.sciencedaily.com/releases/2008/03/080304173310.htmSARDs and IMR are autoimmune diseases, which can frequently cause kidney damage (proteinuria, microalbuminuria, membranous glomerulonephritis), pancreatitis, low level of thyroid hormones (hypothyroidism), liver function abnormalities (elevation of liver enzymes, increased sensitivity to systemic steroid therapy), high blood pressure (systemic hypertension), pseudo-Cushing’s disease symptoms (excessive thirst and urination, excessive appetite and weight gain) and neurological symptoms (loss of vision, hearing, smell sensation, ataxia, depression, lethargy, change in mentation). These changes can be dangerous to the overall health of affected dogs. A detailed evaluation of the systemic organ status is highly recommended for these patients, even if no therapy for the possible vision restoration is planned.
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Are SARDs and IMR treatable diseases? – Over the last 10 years, our team had developed a completely novel diagnostic and treatment protocols for these diseases. We usually pursue systemic immunosuppressive therapy in combination with the systemic or intraocular intravenous immunoglobulin (IVIg) treatment with a goal of restoring some vision. In many patients, additional medical therapy is recommended to address possible abnormalities associated with function of different organs (kidneys, liver, endocrine glands, brain, etc.). We give the maximum effort to carefully tailor medical treatment for each patient with a goal of minimizing any possible side effects, and maximally increasing the chance for the successful treatment outcome. Based on our data, the most frequent cause of death in SARDS patients are pancreatitis, kidney failure and uncontrolled immune-mediated diseases affecting the gut, liver, brain and spinal cord. Similar causes of death are observed in IMR patients, however the patients with the history of the cancer, usually die as a result of the cancer progression.
Advanced SARDs and IMR: These dogs are characterized with a complete day and night vision loss, have abnormal chromatic pupil light reflex responses, and completely extinguished ERG responses "flat ERG". Frequently these patients will have a history of the abnormal weight gain, excessive appetite, excessive thirst and urination, and history of elevated liver enzymes or presence of protein in the urine. These patients have 65% therapeutic success rate in terms of recovering visual navigation skills in bright light conditions, 30% success rate in terms of recovering menace response (hand motion detection) and 20% success rate in terms of tracking small objects in the visual field when treated with immunosuppressive medications in a timely manner. For more detailed information on the diagnosis, clinical findings and molecular mechanism of advanced SARDS you can view our conference presentation (ACVO 2022) and read our peer reviewed articles which are published online:
https://animal-eye-iowa.com/sardsimr/#:~:text=Early%20SARDs%20and%20IMR%3A%20Dogs,inability%20to%20see%20small%20treats%2C
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