Diabetes in Dogs

Dogs and humans are much more alike than we tend to think. And unfortunately, that means we also share some diseases, such as diabetes mellitus, both type 1 and type 2. This disease is characterized by elevated blood glucose levels.

Below, we'll go over the symptoms that should make us suspect our dog has this condition. It's very important to seek veterinary care to bring glucose back into balance and avoid the complications that come from it staying elevated.

What is diabetes?

Diabetes is a common disease in dogs. It can be type 1 or type 2:

1. Insulin-dependent diabetes, or Type I. In these cases, the body is no longer able to produce insulin; the disease arises from a progressive destruction of the beta cells in your pet's pancreas. This is the most common type in our furry companions and is usually caused by cases of pancreatitis (inflammation of the pancreas).
2. Non-insulin-dependent diabetes, or Type II. Here, the pancreas may keep producing insulin at normal levels, but the rest of the tissues, liver, and muscles are less sensitive to it. This disorder occurs when the body becomes resistant to insulin; it's less common in dogs but more frequent in people and in cats. Predisposing factors for this type of diabetes include obesity, genetic predisposition, and sedentary lifestyles.

Insulin works by helping glucose enter cells throughout the body, where it undergoes various processes to produce the energy the body needs to function.

Normally, blood glucose levels are high after eating (postprandial hyperglycemia), until the pancreas secretes the necessary insulin and glucose levels drop as it's taken up into the cells.

In this disease, however, we get chronic fasting hyperglycemia — that is, constantly high blood glucose levels even without having eaten, because there's no insulin available to move it into the cells so the body can use it.

When there's no insulin, cells can't detect that glucose is present, but they do detect that they aren't receiving any, and they send signals for more glucose to be produced. This causes more fat and protein to be burned to produce glucose. The body keeps accumulating this glucose, which the cells can't use due to the insulin deficiency, and it ends up being filtered into the urine, dragging a large amount of water along with it.

Which dogs can develop diabetes?

This disease can affect any dog, but a higher incidence has been found in certain breeds such as the Golden Retriever, Poodle, Dachshund, Pinscher, Westie, and Schnauzer, among others. So there does appear to be a genetic predisposition.

It also affects females more, especially intact ones (unspayed/unneutered females). Onset typically occurs between six and nine years of age, and the older our dogs get, the higher their risk of developing diabetes.

Symptoms of diabetes in dogs

Among the different symptoms we might notice with what's colloquially known as a blood sugar spike or crash, the following stand out:

• Glucosuria, which is the presence of a large amount of glucose in the urine.
• Polyuria, the dog urinates in large amounts due to glucosuria, since glucose pulls more water through the kidneys via osmotic diuresis.
• Polydipsia, since urinating so much causes fluid loss, this is offset by an increase in water intake, to avoid dehydration.
• Polyphagia, the initial increase in appetite happens because the dog can't metabolize enough glucose. Later on, this fades as the animal becomes malnourished.
• Weight loss and muscle loss due to protein catabolism.
• When the disease is advanced, it can affect every organ and cause symptoms such as lethargy, vomiting, weakness, and, in the most severe cases, coma.
• Associated complications include cataracts, kidney and neurological problems, urinary tract infections, or high blood pressure.

What is diabetic ketoacidosis?

This is a disorder that arises as a result of severe hyperglycemia, either from undiagnosed chronic diabetes or an insufficient insulin dose. It causes ketone bodies to build up in the blood. Ketones are byproducts of fat metabolism, which the body turns to because it has no glucose available for energy.

Its symptoms are generalized weakness, vomiting, rapid breathing, and a smell of acetone on the breath. This is an emergency — the dog needs to be taken to a veterinary clinic immediately, as it carries a high risk of death.

How is diabetes diagnosed?

To confirm that the clinical signs correspond to this disease, a blood and urine test are required. The blood test will show fasting hyperglycemia, a moderate rise in liver enzymes such as ALT and alkaline phosphatase, high cholesterol, and high triglycerides. The urinalysis will show glucosuria, proteinuria, and, depending on severity, possibly ketonuria as well.

Fructosamine levels can also be measured — a protein that reflects blood glucose over the past 3 weeks and will be elevated in diabetic dogs.the dog should exercise daily, since it increases insulin absorption.

Treating diabetes in dogs

It's important to keep in mind that managing diabetes in dogs is completely different from how it's managed in human medicine. For this reason, even if we're familiar with the disease, whether because we know it or even have it ourselves, we should always follow the vet's recommendations.

Treatment is centered on two basic pillars: diet and medication.

The goals are to make the symptoms disappear, avoid the disease's complications (ketoacidosis, cataracts), manage risk factors (obesity, being in heat in females, chronic infections), and avoid hypoglycemia. A dog with insulin-dependent diabetes will need daily insulin administration to make up for what its body can't produce. If we're rigorous about the treatment, the dog can lead a normal life.

Veterinary monitoring needs to be thorough, because each dog will need a different amount of insulin, and even the dose will vary over the course of a single dog's life. That's why, at the start of treatment, the vet will need to monitor glucose levels to see when peaks and troughs occur. With all that information, the dose is adjusted and it's decided when the medication should be given.

Precautions when giving insulin

The consequences of improperly administering insulin can be serious, so it's essential to follow the vet's instructions to the letter regarding the amount and type of insulin, how to store it, how often to give it, and the type of syringes to use.

If we give too much, glucose can drop to alarming levels. This hypoglycemia causes confusion, drowsiness, tremors, stumbling, seizures, and even coma.

Diet and diabetes

A diabetic dog is recommended to eat dry or wet food that is high in fiber, low in fat, rich in protein, low in calories, and containing complex carbohydrates that are slowly absorbed and have a low glycemic index, since these reduce the chance of triggering hyperglycemia. This is because they minimize glucose swings after each meal and largely help avoid stimulating the pancreas's beta cells.

Veterinary clinics sell this type of food in different formats. If we prefer a homemade diet, we need to design a menu together with the vet. Either way, food should be given in two or three meals a day to avoid hyperglycemia after a large meal.

Lastly, the insulin dose is calculated based on daily calorie requirements, which depend on the dog's weight and activity level. That's why it's important not to vary the amount of food we give each day. The dog should also exercise daily, since it increases insulin absorption.

Obesity in diabetic dogs

Besides a diet suited to the dog's condition, it's essential to avoid excess weight. Obesity negatively affects health, complicates diseases, predisposes to others, or makes anesthesia riskier. In the case of diabetes, it reduces the response to insulin, which makes it harder to control.

That's why, if the dog is overweight, in addition to diabetes treatment, the vet will determine its ideal weight and prescribe a suitable diet to reach it. Weight loss should be gradual (2-4 months), giving around 60-70% of the calorie requirements for its ideal weight. Specific commercial diets are now available for these conditions.

Underweight diabetic dogs

If the dog has already lost weight by the time diabetes is diagnosed, it's important for it to return to its ideal weight and also regain its muscle mass, since in many cases protein catabolism ends up causing significant muscle wasting. To achieve this, low-fiber diets are recommended because they have a higher calorie density. These are also available commercially.

What's the relationship between spaying/neutering and diabetes?

As part of diabetes treatment, the vet may recommend spaying in the case of females — that is, surgical removal of the uterus and ovaries. This is because progesterone has a blood-sugar-raising effect.

Prognosis of diabetes in dogs

The prognosis for this condition depends on each case. Other factors also play a role, such as the owner's ability to follow the prescribed treatment, how easy or difficult it is to control glucose levels, and the presence or absence of other diseases.

Monitoring diabetes

During the first month, weekly check-ups are recommended; afterward they can move to monthly until good control of the disease is achieved, and once that's reached, every 3 months. These check-ups take into account symptoms, glucosuria and ketonuria, a physical exam, spot blood glucose (6-8 hours post-insulin), and glucose curves; fructosamine measurements can also be added.

The disease is considered well controlled when our dog shows no symptoms, keeps a stable weight (once the ideal weight has been reached), glucosuria is weakly positive, and both blood glucose and fructosamine values fall within standard ranges.

When the disease isn't well controlled, especially if high insulin doses are being used, the Somogyi effect can occur (hyperglycemia secondary to hypoglycemia from an insulin overdose), a shortened duration of insulin action, or even insulin resistance can appear, generally associated with infections, concurrent illnesses, being in heat, or certain drug treatments.

Fortunately, a diabetic dog with proper treatment and the right veterinary monitoring can have a perfectly normal quality of life, and the same lifespan as a dog without the disease.