Diabetes in Dogs and Cats Part 1

Diabetes in dogs and cats is an important health problem that often leads to early death.  Up to 30% of cats and 20% of dogs diagnosed with diabetes are euthanized within one year of diagnosis.  Of those, up to 10% of dogs and cats are euthanized immediately after diagnosis and are never treated.  That’s a high death toll for a treatable disease.  Insulin therapy is available for both cats and dogs.  In this series, we’ll take a closer look at pet diabetes.  How is diabetes in pets different from diabetes in people?  What treatment options are available?  What are factors that influence the decision to treat or not to treat?

Understanding diabetes

Diabetes mellitus is a metabolic disease in which the body cannot properly use sugars.  In a healthy person or pet, the pancreas produces a hormone called insulin. Insulin helps sugars in the blood enter cells, where it can be used to make energy to power the body.  If the pancreas does not make enough insulin, or if the cells are not responsive to insulin, sugars become elevated in the blood.  This is called hyperglycemia.  When there is too much sugar in the blood, the kidneys excrete it into the urine.  And when the kidneys excrete sugar into the urine, water follows.  This causes increased urination and increased drinking.

Because the cells don’t take up sugars, there isn’t enough energy for them to function normally.  The body uses proteins and fats for energy, and the body is said to be in a state of metabolic starvation.  For this reason, many people and animals will lose weight when they have diabetes, even though they may be eating more.

In people, diabetes is classified as Type I when the pancreas does not produce enough insulin.  When the cells of the body can’t use insulin properly, this is classified as Type II diabetes.  Diabetes in dogs and cats is sometimes classified similarly, although the distinction in pets is not as clear as it is in people.

Diabetes in Dogs

In dogs, diabetes tends to be similar to Type I diabetes in humans.  That is, the pancreas does not make enough insulin.  Generally, diabetes in dogs begins later in life.  Most dogs are diagnosed between the ages of 7 and 10 years.  Certain breeds may be at risk.  A 2000 cohort study of 43,003 dogs (221 with diabetes) found that Samoyeds, Miniature Schnauzers, Miniature Poodles, Pugs, and Toy Poodles had increased risk of developing diabetes (Hess, 2000).  A 2007 study of 182,087 insured dogs found that Australian Terriers, Samoyeds, Swedish Elkhounds and Swedish Lapphunds were at increased risk of developing diabetes (Fall, 2007).  In this study, hyperadrenocortical disease and female sex were other risk factors for diabetes.  The differences in breeds identified is probably due to the differences in the populations studied in different countries.

In dogs, obesity does not appear to be a significant risk factor for diabetes.  Even in Golden Retrievers, a breed known for a tendency to gain weight, obesity is not associated with diabetes (Davison, 2017).  Obesity contributes to other diseases in dogs, and parents should maintain a healthy weight in their pets.

Diabetes in Cats

Diabetes in cats is more like Type II diabetes in people.  This means that, at least early in their disease, the pancreas makes enough insulin. The problem is that the cells are insulin-resistant.  High blood sugar levels causes damage to the pancreatic cells that make insulin, leading to insulin deficiency.   In contrast to people, most cats are already insulin-dependent by the time of diagnosis.

Obesity is a risk factor for diabetes in cats.  This is one reason why it is not ok to allow a cat to eat excessively and gain too much weight.  Acromegaly, a disease in which excess growth hormone is produced, and inflammation of the pancreas, pancreatitis, are other risk factors (Rand, 2013).

Part 2 of this series will discuss diagnosis of diabetes in dogs and cats.  Future posts will consider treatment options and disease outcomes.

Davison et al, The canine POMC gene, obesity in labrador retrievers, and susceptibility to diabetes mellitus, JVIM, 2017; 31: 343-348.
Fall et al, Diabetes mellitus in a population of 180,000 insured dogs: incidence, survival, and breed disposition, JVIM, 2007; 21:1209-1216
Hess et al, Breed disposition of dogs with diabetes mellitus admitted to a tertiary care facility, JAVMA, 2000; 216: 1414-1417
Rand, JS, Pathogenesis of feline diabetes, Veterinary Clinics of North America Small Animal Practice, 2013; 43:221-231

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