Cataracts are More Common Than You’d Think!
Diabetic pets are prone to ocular disease. And it’s not just cataracts! It turns out that diabetic pets also get a higher incidence of corneal disease, retinal disease and uveitis. Cataracts are our topic today as they are the most notorious and feared complication of the diabetic dog eye. Next week we will discuss some lesser known complications of diabetes.
Diabetic cataracts, here’s the scary statistic: Historically 75% of diabetic dogs will get cataracts within the first year of diabetes diagnosis. Before you throw in the towel, keep reading. There is exciting news of late. With really good blood glucose regulation and supplements and a topical eyedrop soon to be on the market, we can potentially decrease the incidence of pet blindness from diabetic cataracts.
How do diabetic cataracts form? There aren’t blood vessels going into the lens. A lens normally gets nourished by glucose in the aqueous in the eye (That’s the fluid within the eyeball). When there is too much sugar in the aqueous due to diabetes the lens is inundated with sugar. This glucose exceeds the normal metabolic pathways to get rid of the sugar. That’s when an enzyme called aldose reductase up-regulates to take over the task. It’s an alternate pathway of sugar metabolism. Unfortunately the end products of this alternate pathway are fructose and sorbitol. Sorbitol in the cells of the lens pulls water into the lens which causes the lens to swell. That’s how diabetic cataracts form. If ever you needed a really good reason to control your diabetic pet’s blood glucose levels this would be it.
Earlier you probably noticed the statistic was for diabetic dogs. Cat folks undoubtedly wondered about putty tats getting diabetic cataracts. Cats don’t have as much aldose reductase as dogs so luckily they aren’t prone to diabetic cataracts. It can happen but it’s much less likely than with dogs. Cats rarely get diabetic cataracts.
What’s the big deal if a pet gets cataracts? First of all the pet is blind. When the lens swells the lens becomes opaque, the pet cannot see through it. Yes, if a pet is smart and knows the layout of your house it won’t affect the quality of life that much, but there won’t be much squirrel chasing and fine acuity activities. Besides blindness, the concern is that cataracts usually result in uveitis. Uveitis is painful! We’ll talk about uveitis later.
Okay, let’s get down to the good news! There are studies supporting new products that can help! One is called Kinostat (which is an aldose reductase inhibitor). Kinostat is a topical eye drop that you will put into your diabetic dog’s eyes 3 times daily. For most of us that would mean before we go to work, as soon as we get home and then right before bedtime. In a blinded study, Kinostat significantly reduced cataract changes in newly diagnosed diabetic dogs. And some of the dogs with minor, early changes actually had improved lenses after use of the Kinostat. Once the changes leading to cataract formation are severe you are looking at surgery as the only treatment option. Nonetheless, the preventative Kinostat looks promising. On the company website (therapeuticvision.com) they say they hope it comes to market winter 2016 to spring 2017. Of course, we are all anxiously awaiting Kinostat getting final FDA approval.
The other cataract preventive product is already available is called Ocu-GLO. It is a combination of antioxidants, vitamins and alpha lipoic acid. Alpha lipoic acid is an oral aldose reductase inhibitor. Sound familiar? Ocu-GLO has published an impressive study showing their product can inhibit diabetic cataracts in dogs. Dr. David Williams published an article in 2015 about using alpha lipoid acid alone for preventing diabetic cataracts in dogs. His group found that alpha lipoid acid alone also decreased the incidence of diabetic dog cataracts. The dosage in the study was 2.5 mg/kg per day. As a single agent it didn’t appear to stop cataract formation as well as Ocu-Glo, but it did retard the formation. Let me tell you, if I had a dog with diabetes I would religiously use all of these products to hinder cataract formation!
Glucose levels matter! The better the blood glucose control, the less likely a dog is to become blind. Using the products I’ve mentioned does not give you a license to be lax on your pet’s diabetes routine, but will hopefully keep your diabetic pet sighted!
Next week we’ll discuss a few other ocular complications of diabetes in pets.
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NOTE: Consult your veterinarian first to make sure my recommendations fit your pets special health needs.