Posted: September 28, 2014, 7:20 p.m. EDT
In a previous article, I discussed a few of my experiences owning an elderly pet rabbit. With the advancement of veterinary medicine, many people are fortunate enough to have pets live longer now than ever. Much like us humans, our pets also experience age-related changes to their health. It is up to us caretakers to be vigilant in monitoring their wellness in order to detect change. One common problem I see in many exotic small mammals as they age is the development of cataracts.
When the normally clear lens of the eye develops a cloudy spot, this is known as a cataract. At home, owners often notice a white spot or cloudiness to the pupil of the eye. The severity of the cataract can vary significantly from a small focal spot to involvement of the entire lens. Many factors have been implicated in the development of cataracts including a genetic predisposition (inherited), malnutrition, exposure to ultraviolet radiation, inflammation due to infections, trauma and as a symptom of Diabetes mellitus. There have also been reports of cataract development in rabbits, rats, mice and humans when exposed to naphthalene, an ingredient found in some mothballs.
The parasite Encephalitozooon cuniculi has been implicated as a cause of cataract development in rabbits of all ages. Infected rabbits shed E. cuniculi spores in their urine. Thus an uninfected (naïve) rabbit becomes infected if he ingests food items contaminated with urine containing parasites. Parasites can also be transmitted from infected does to developing feti in utero. While the brain and kidney are the most commonly affected organs, the parasites sometimes end up in the eye and can cause lens damage and subsequent cataract formation. This parasite has been reported to be an opportunistic pathogen of immunosuppressed people. Rabbits affected with E. cuniculi are often treated with antiparasitic medications such as fenbendazole or albendazole.
© Leticia Materi, Phd, DVM
These two elderly pets (rabbit on left, prairie dog on right) have each developed cataracts.
I have also seen a number of degus develop cataracts as a complication of Diabetes mellitus. It is believed that the sugar imbalance in the body stimulates a complex chain of events in the eye that ultimately leads to water being drawn into the lens leading to damage of the tissue and cataract development. Diet restrictions and medications to help control blood sugars are the treatments of choice to control diabetes in this species.
While improvements to diet, limiting UV exposure, removing toxins or anti-inflammatory medications may help limit cataract formation, once a cataract has formed it rarely resolves on its own. In general, the only definitive therapy for cataracts is surgical removal of the lens. If a cataract progresses in severity, some side effects include blindness in the affected eye, discomfort, inflammation and glaucoma. Medications may help alleviate some of these symptoms. In severe cases, consulting with a veterinary ophthalmologist is often recommended.
Note: This article is meant for educational purposes only and in no way represents any particular individual or case. It is not for diagnostic purposes. If your pet is sick, please take him or her to a veterinarian.
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