Blindness & The Diabetic Dog
By definition, a cataract is any opacity of the lens regardless of the cause. And, what are the causes? The number one cause of cataracts in dogs is predisposed genetics. The second most common cause is Diabetes Mellitus. And, this is due to the increase levels of glucose in the eyes which eventually leads to water accumulating in the lens. This causes the lens fibers to swell and rupture forming vacuoles in the lens cortices and eventually the entire lens becomes opaque. This condition does not occur in cats. It has something to do with older cats not having significant aldose reductase in their lenses as do dogs, and therefore, don’t develop diabetic cataracts. And, finally, the third cause of cataracts is Progressive Retinal Atrophy (PRA).
I discussed Progressive Retinal Atrophy (PRA) in a previous blog. So, I’m not going to repeat my description of what it is and how to prevent or handle it here. As the title states, this is a blog on “Blindness & The Diabetic Dog.” So, let’s talk about diabetes:
The major risk factor for diabetes is obesity. Obesity is defined by weighing 30% over the ideal weight. In the USA, a combination of 80 million dogs and cats are obese, which amounts to 52.5% of dogs and 58.3% of cats (2012). Overweight cats are 4 times more likely to develop diabetes mellitus. And, 42% of dogs and 40% of cats with DM are overweight.
There are two types of diabetes mellitus: Type 1 DM and Type 2 DM. Dogs are prone to Type 1 as the result of beta cells being destroyed by the immune system, or by a history of pancreatitis. One out of 500 dogs and one out of 400 cats, may develop diabetes. In diabetic cats, 60% develop Type 1 DM, and 40% have Type 2 DM. The good news with the cat is that many cases of diabetes can be undone by simply changing the diet.
It’s interesting to note that even feral cats develop diabetes. In the USA, there are 50 million feral cats and 125,000 have diabetes. I’d imagine a life of stress and a poor diet of scavenging in the garbage, a few eaten birds or squirrels, and little old ladies leaving out endless bowls of kibbles in their garden are all contributing to this health issue amongst the strays.
Another risk factor is that certain breeds of dogs are predisposed to diabetes: such as, the Golden Retriever, Lab Retrievers, Schauzer, Beagle, Samoyed, Min pin, Westie, Cairn, Poodle, and the Keeshound. If you own one of these breeds then it’s especially important to keep your dog slim and trim, and avoid carbs and starches in the diet. The best way to do this is to feed your dog (and cat) a species appropriate diet of raw meaty bones. Also, plenty of exercise, and by adding naturally occurring antioxidants in the diet to prevent and reduce inflammation.
The lens of the eyes is a clear structure full of antioxidants. But because of the environment (UV rays, pollution) or diet, or other oxidative stressors, like chronic diseases, it will deplete the antioxidants in the eyes. The natural innate antioxidants in the lens, are: Glutathione, Thiotransferase, Catalase, Superoxide dismutase, and Ascorbic acid (Vitamin C).
The Exogenous Antioxidants are Lutein and Zeaxanthin, which is acquired by eating foods rich in these antioxidants, like, marigolds and egg yolks.
Diabetes causes oxidative stress in every single cell of the body. This causes further Beta-cell dysfunction and deterioration of glycemic control. Increases blood pressure, likelihood of stroke, and opens up 5 pathways involved in diabetes complications.
What To Do?
Once your dog has cataracts, surgery is necessary to restore sight. There are some eye drops on the market for cataracts, but you need to be careful. Here’s a quote from Dr. Carmen Corlitz, Veterinary Ophthalmologist: N-acetyl carnosine is the “eyedrop that is marketed to dissolve cataracts” and it DOES NOT work at all. The evidence is piling up because of claims that this helps cure senile cataracts in humans. Cataracts are multifactorial and addressing one pathway does not make the rest stop. Surgery is the treatment of choice once vision is affected, via phacoemulsification with IOL implantation.
Homeopathy has been known to be effective on cataracts. But, it is slow-working, and can take several months. However, it’s safe and something to consider. But, like all disease, the cause must be addressed.
So, how do we protect our dog against oxidative stress induced diabetic cataracts? You add antioxidants to the diet: Such as, Lutein/zeaxanthin; Astaxanthin (a substance found in some algae). Lycopene (which is 100 times stronger than Vitamin E); Proanthocyanidins, a free-radical scavenger, helps to regulate insulin (Grape Seed Extract, or Pine Bark); Green Tea Extract (10x more potent than Vitamin E); Omega-3 fatty acids; Zinc (improves glycemic control), and Alpha lipoic acid (ALA is found in liver and heart organ meat). ALA is important as it inhibits aldose reductase, which is the key enzyme responsible for diabetic cataracts in dogs and humans.
Other important anti-oxidants to consider is Fenugreek, it inhibits cholesterol absorption, slows carbohydrates absorption which improves glucose control. Cinnamon Extract, improves insulin sensitivity, lowers triglycerides, and has natural statin-like properties. L-Carnitine for fat metabolism, Vanadium, N-acetyl-L-Cysteine (NAC), and glucomannan.
The Immune System
Diabetic dogs are immune system suppressed. So, we’ll need to support the immune system. I would suggest beta-glucans from medicinal mushrooms. But not all beta-glucans are the same. You want to know the size of the micro-particulates. It is recommended to have micro-particulates of 1-2 microns for easier absorption through intestines and ingestion by microphages. And, quicker absorption means quicker action. And, I can’t emphasize enough the importance of nutrition and a species appropriate diet to support a balanced immune system.
FYI: Be careful using chemical insecticides, like flea & tick products, on your dogs and cats. There has been some reports of these products causing blindness in pets. There hasn’t been any thorough studies on whether the blindness occurs because of its effects on the brain (some products causes seizures) or whether it directly effects the eyes.