Penny, an 11 year old cross-cred Collie who developed a life threatening illness.

Three years ago, Penny changed from being a normal, healthy eight year old dog into an animal with a life threatening illness. The problem started slowly.  Over a few weeks, it gradually became clear to the owners that she was not quite herself. She started to empty her water bowl and she slowed down on walks, ambling beside the humans instead of charging around with her usual high energy style. When she uncharacteristically wet the floor in the kitchen overnight, it was the final straw: she was brought to the vet for a full check up.

A blood test taken on that first visit was enough to make the diagnosis: Penny was suffering from Diabetes Mellitus, most commonly known as simply “Diabetes”.  The condition develops when the body stops producing enough insulin to control the blood sugar. It’s one of the most common hormonal diseases to affect older dogs. The blood sugar level shoots up to a level of thirty or more, when it should be less than ten. The high level of sugar in the blood causes a wide range of abnormalities in the body, with the increased thirst being the most obvious. Affected animals tend to lose weight, despite being ravenously hungry. If treatment is not given, the signs of illness become increasingly severe, eventually leading to severe weakness, coma and death.

Treatment for diabetes is simple in one way, but complicated in another. A once or twice daily dose of insulin needs to be given, to replace the hormone that’s no longer being produced by the body. The catch is that this insulin cannot be given as a tablet: an injection is needed. After Penny’s diagnosis, the Corcorans were told that she’d need daily injections for the rest of her life. This can be a worrying prospect for pet owners who’ve never given an injection of any sort.

Every diabetic dog needs a different amount of daily insulin to stabilise their condition. Penny was initially given a tiny dose, and this was increased every three days, until after two weeks, her blood sugar had returned to normal. She was a regular visitor to our vet clinic during the first month of her diagnosis, but once she’d reached normal blood sugar levels, there was no need for frequent check ups. Three years on, she only needs to call in for a routine blood test every three months.

The owners are sensitive to changes in Penny’s condition, and they have learned to spot if her blood sugar level is going too high or too low. If she starts to drink more than usual (banging her drinking bowl with her front paws, asking for more water), they know that she needs a little more insulin. Occasionally, if she’s had too much insulin, she develops a so-called “hypo” (or “hypo-glycaemic episode”). When this happens, she begins to stumble and stagger, as if she’s been doped with a sedative. This is an emergency. The owners have learned to give her some sugar in warm milk, which she happily laps up. Within a few minutes, she stops staggering, and they then phone the vet for a check up to make sure that there’s no serious reason for the temporary upset in her blood sugar levels.

Penny has developed some complications associated with diabetes – she’s lost her sight because of cataracts, but she’s adapted to this, learning her way around the home so that she never bumps into anything. She lives a more sheltered life than before, with a strict regular routine, but it suits her very well. She’s as happy as she’s ever been.


  • Diabetes is a common condition affecting older dogs
  • Weight loss and a huge thirst are the most common signs noticed by owners
  • Treatment, with daily insulin injections, can allow dogs to live normal lives for many years after diagnosis

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Please note that I am unable to answer veterinary questions in comments. If you have questions or concerns about your pet's health it is always better to contact your vet.

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