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Diabetes in Cats - ear prick for blood samples

I came home from jiu jitsu this afternoon and I was lounging on the sofa in the sunshine. Indi came over to lounge with me, and her little ears inspired me to write this blog! Inspiration can come from anywhere, and these days, most people have their phones on them. It’s easy to type or even do talk to text if you prefer.

There are two aims for this blog post, both educational, but aimed at two groups of people: veterinary students and owners of diabetic cats.

Diabetes in cats is very similar to type II diabetes in people, there is a diet and obesity component to the predisposition to development of this type of diabetes. Dogs are different, so this post is going to focus on cats. Cats are obligate carnivores, which means that they need to eat meat (high protein, low carb - think keto diet for cats). Cat food in kibble form has to have carbohydrates to form the kibble into its shape, so the majority of cat kibble is higher in carbs than the majority of cat canned diets. Then, pate wet food tends to be higher in protein, lower in carbs than the chunks and gravy style wet food, for similar reasons, using the carbs to form the chunky texture. That being said, for me it’s common sense, cats who are prone to diabetes should be fed an all wet, specifically pate only diet. If you think about what cats in the wild would eat, it is mostly small prey items (mice, birds) that are fresh killed, and therefore moist, versus the kibble which is like dehydrated carcass. This is also why wet food is better for cat kidneys, because cats have a natural tendency to get most of their water from the food they eat, so eating all dry kibble makes them slightly dehydrated (think really well-concentrated urine that stinks up the litter box).

Now, let’s say you are a cat owner, and you started to notice your chubby cat is drinking more. Usually cat owners notice first that there is more to scoop in the litter box, or their cat is peeing outside of the litter box. For me, and for the future veterinarians reading, a little alarm bell should go off whenever an owner says that their cats drinks a lot. Again, because cats do not naturally drink a lot.

The concerned cat owner whose kitty is peeing outside of the box, heads into the veterinary office. The veterinarian will ask for blood and urine samples to rule out common diseases in cats that lead to an increase in drinking and increase in urination. There are medical reasons that could be diabetes, or kidney disease, or thyroid disease, or urinary tract infections, and so on. There are behavioural reasons for peeing outside the box, but I won’t get into that. Right now, I want you to focus on Diabetes mellitus. How is it diagnosed?

The blood sample will check for a high blood sugar (also called blood glucose) and the urine sample will check to see if there is glucose lost in the urine. We need both for the diagnosis and we are also checking for ketones in the urine (a bigger complication of diabetes, so let's stay simple for now). If we only have a blood sample and the blood sugar is moderately increased, we cannot tell if this increase is due to stress, or is the increase due to diabetes. Think of fight or flight with cats when they come into the vet office. They don’t really like it there, which means their adrenaline is high and this causes a spike in blood sugar in case they need to fight or run away from the ‘predator’ called a veterinarian.

So your cat was diagnosed with diabetes. Now what? First, your veterinarian will likely prescribe some insulin to manage the high blood sugar, but you may get into a discussion about changing your kitties diet to a higher protein, lower carbohydrate diet. Once your kitty has started the insulin injections, then you need a follow-up test called a blood glucose curve. If you as a cat owner are able to given insulin injections to your cat, I am confident that you will also be able to perform this blood glucose curve at home with the right guidance. I won't get into the types of insulin used, as that is up to your veterinarian. One option available in the U.S. is Vetsulin. In Canada the products have different names (e.g. Caninsulin), but I liked the information on the Vetsulin website.

When I was in vet school, we were taught how to collect a blood sample by the lateral ear margin for our preanesthetic blood sample check. One tiny prick to the ear, and I would pull a hematocrit/capillary tube full for a PCV/TP, a BUN stick, and run a blood glucose reading. So this is a very convenient location to get a capillary sample in diabetic cats. For those of you with a diabetic cat, there is a short video on Veterinary Partner. I have taken a few pictures of Indi's ear with the blood vessel visible, so see if you can see it on your kitty's ear. As with Indi's ear, you can see it especially if it is lit from the underside, as the sun was hitting Indi's ear perfectly.

For those of you in veterinary school, check out this link for more information on how to get your staff trained. Most veterinary clinics have the technician coaching owners on how to administer the insulin to their pets. This also means, these technicians should be trained to teach cat owners how to perform a blood glucose curve at home. Remember that stress hyperglycemia I talked about (high blood sugar due to stress), when we perform the blood glucose curve in the clinic setting, it may not be as accurate due to this phenomenon. If you have more questions about your cat's diabetes, be sure to check in with your veterinarian.

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