The reason diabetes causes more thirst and urination is that in an effort to rid the blood of excess sugar, also called glucose, the sugar spills into the kidneys, pulling water with it and thereby leading to the creation of more urine. Where glucose goes, water follows. And the more a dog urinates, the more he’s going to want to drink.
Weight loss is common, too, even though a dog with diabetes may exhibit a much heartier appetite, sometimes to the point of almost seeming insatiable. That’s because the cells are literally starving — they can’t take in the glucose from the bloodstream even though the dog is eating enough. In some cases, a dog will actually become weak — not just because he’s so hungry but also because the excess blood sugar can adversely affect nerve conduction. He may have a harder time getting up and have intolerance to exercise as well. (West Highland terrier Mac, featured in the accompanying story, never got to that point.)
All of this happens because the pancreas stops producing insulin, a hormone that’s critical for making sure sugar is properly transferred from the bloodstream to all the cells of the body’s various tissues. Normally, the pancreas secretes just the right amount of insulin based on what a dog eats, in a very tight range, from the day he is born until the day he dies. But if the insulin-producing cells in the pancreas give out, the dog simply doesn’t make enough to handle the sugar that ends up in the bloodstream after meals and snacks, and blood glucose levels creep up.
It’s the equivalent of type 1diabetes in people, where adequate amounts of insulin stop being produced and insulin injections are necessary. Type 2 diabetes, which afflicts many people but not dogs, is a situation in which the pancreas still makes insulin, and pills rather than injections can often do the trick of stimulating more insulin production by the body.
People whose dogs develop diabetes need to be aware that it’s not just they who need to give the shots religiously twice daily at 12-hour intervals. Such dogs also need to be given their regular shots at the proper times if they are left with a pet sitter or are boarded. There are no vacations from the injections.
It’s important, too, to educate any caregiver to whom you entrust your dog’s health. For instance, because of the way the syringes are marked, it’s easy to give a 10-fold overdose — 40 units of insulin instead of four. The difference in those two numbers amounts to less than a tenth of a teaspoon. That is, it’s truly something that has to be learned, because it’s not something that can be seen.
Finally, you always need to make sure you have enough insulin on hand. We can’t tell you the number of people who call on Christmas Eve to say they don’t have enough insulin to make it through the holiday.