Diabetes Mellitus: Principles of Treatment in Dogs

What is diabetes mellitus?

Diabetes mellitus is a chronic condition that results in constantly high blood sugar levels because the pancreas can no longer regulate blood sugar (glucose). In dogs, diabetes mellitus is usually insulin-dependent diabetes mellitus (also called Type 1 diabetes). This type of diabetes typically results from the destruction of most or all the beta-cells that produce insulin in the pancreas. Dogs with this type of diabetes require insulin injections to stabilize their blood sugar levels.

Insulin regulates the level of glucose in the bloodstream and controls the delivery of glucose to the tissues of the body. The clinical signs of diabetes mellitus are related to elevated concentrations of blood glucose and the inability of the body to use glucose as an energy source.

Can dogs take oral medication instead of insulin shots?

No, dogs cannot take oral medication to regulate diabetes. Oral medication is sometimes used in humans to help regulate type II diabetes; however, dogs rarely get this type of diabetes.

Type I diabetes mellitus (sometimes called insulin-dependent diabetes mellitus) results from total or near-complete destruction of the pancreatic beta cells (insulin-producing cells). Type 1 is the most common type of diabetes in dogs. Dogs or humans with this type of diabetes require insulin injections to stabilize their blood sugar levels.

Type II diabetes mellitus (non-insulin-dependent diabetes mellitus) is different, because some insulin-producing cells remain, but they produce insufficient insulin, or there is a delayed response in secreting it, or the body’s cells are resistant to it. Humans with type II diabetes may be treated with ral drugs that either stimulate insulin release from pancreatic cells or lower blood sugar levels, giving the cells a chance to recover their ability to produce insulin. Dogs rarely develop type II diabetes mellitus, so this treatment is not a good option for them.

How is diabetes mellitus treated in dogs?

Initial treatment varies, depending on how sick your dog is when they are diagnosed with diabetes and if there are any other health issues. Regardless, all dogs with DM will need insulin supplementation in the form of injections.

If your dog has a reduced appetite or signs of other severe illness, like vomiting and diarrhea, they may have a life-threatening condition called diabetic ketoacidosis (DKA). This condition is often confirmed with blood and urine testing. Your veterinarian will recommend in-hospital treatment to reverse DKA as they regulate your dog’s glucose levels.

Dogs that show mild signs without severe blood changes can often be treated at home, once you are comfortable giving them insulin injections.

• Insulin injections are generally recommended to be given twice daily, every 12 hours.
• Your veterinarian will carefully review your dog’s specific treatment and offer advice on how to best administer insulin injections. If you have any questions or concerns, let your veterinary team know. They want the best for you and your dog.
• It is essential to maintain a consistent feeding schedule, as meals should be given at the same time as insulin injections to try to avoid hypoglycemia (low blood sugar).
• Your veterinarian may recommend a special diet based on your dog’s individual needs. There is no one diet that is beneficial for all diabetic dogs.
• Avoid snacks between meals or keep them to an extreme minimum to avoid spikes in blood glucose (hyperglycemia). Ask your veterinarian if your dog can get snacks and what is best to give them.
• During the first few months of treatment, your dog will need frequent follow-up visits, as recommended by your veterinarian. These visits are needed to adjust your dog’s insulin dose to be most effective and avoid complications.
• Once your dog’s glucose is regulated and your vet determines they are clinically stable, they may need less frequent monitoring.

It is important to note that treating diabetes mellitus in dogs not only carries a financial cost, but also a time commitment for pet owners. Feeding and insulin injections must be maintained on a strict schedule. Your dog needs consistent administration of insulin, consistent feeding, and a stable, stress-free lifestyle. Although it is not essential, ideally your dog should live indoors to minimize uncontrollable variables that can disrupt regulation.

Do I need to change my dog’s diet?

There is no single diet that is beneficial for all diabetic dogs. Your veterinarian will let you know if a specific diet would help your pet. For example, if your dog has a history of pancreatitis, they may recommend an ultra-low-fat diet to reduce recurrence.

Your dog’s feeding routine is usually considered more important than diet. A dog receiving insulin injections needs to receive most of their daily food intake around the time of the insulin injection to reduce hypoglycemia (low blood sugar). This usually means that your dog needs to be fed two meals a day, just before each insulin injection.

If your dog is currently eating on a free-choice basis, it is important to try to make the change to twice-daily meals. If a two-meals-per-day feeding routine will not work for you, you must find some way to accurately measure the amount of food that is consumed and, ideally, to encourage your dog to eat most of the food at or around the time you give them insulin.

How often do diabetic dogs need to be monitored?

You must work closely with your veterinarian to monitor your dog’s progress regularly. Most dogs require frequent monitoring, initially. After the dog is stabilized, and you are comfortable administering insulin and feeding the recommended diet, your veterinarian will perform blood and urine testing every one to three months.

What is involved in diabetic monitoring?

At home, you will need to closely monitor your dog’s appetite, weight, water consumption, and urine output. Any significant changes may indicate that the diabetes is not well controlled, and you should schedule an appointment with your veterinarian for blood testing.

• Weigh your dog at least monthly and notify your veterinarian if there is any weight loss. Use the same scale each time.
• Watch for any changes in food consumption.
• Measure water consumption. Keep a record of your dog’s water consumption for a few weeks to establish what is normal for your dog. To get a rough estimate of whether your dog is drinking normally, count the number of times they drink each day. If they drink more than six times per day, there may be a problem, so it’s important to to take an accurate measurement.

Your veterinarian may also recommend specific home testing including:

• Blood glucose curves using a validated veterinary blood glucose monitor (e.g., AlphaTrak 2 or 3™). You will need to obtain small blood samples from your dog every 1–2 hours over a 12–24-hour period.
• A continuous glucose monitor (e.g., FreeStyle Libre2™) can be inserted into your dog’s skin and stays in place for up to 14 days. This sensor tracks glucose every minute and stores up to 8 hours of data. You pass a scanner over the device several times a day to record blood glucose levels.
• Urine glucose test strips designed for use in humans with diabetes may also work well in dogs and are available at any pharmacy. You collect a fresh urine sample at the same time each day, ideally, the first urine of the morning. If no glucose is detected two mornings in a row, notify your vet, as they may need to change the insulin dose.

How will my veterinarian monitor my dog’s diabetes?

Your veterinarian will ask you to bring your dog for regular checkups so they can evaluate their overall health, along with the results of any recommended home monitoring. Your veterinarian may also recommend specific blood and urine tests to ensure your dog stays in their best health.

"Your veterinarian will ask you to bring your dog for regular checkups so they can evaluate their overall health, along with the results of any recommended home monitoring."

The most common diabetes monitoring test is a blood glucose curve, which involves monitoring the level of glucose in the blood over a 12– to 24-hour period. Blood glucose curves generally start when insulin is administered and continue until the next dose or, in some cases, for a full 24 hours. Blood samples may be collected every 1–2 hours during this period and will reflect how the pet is responding to insulin on that day.

The usual procedure for measuring a blood glucose curve is as follows:

1. If you can get your dog to the veterinarian within 30 minutes, feed your dog its normal morning meal and then bring them to the hospital immediately, before administering insulin. Bring your dog’s insulin with you.
2. If you cannot get your dog to the hospital within 30 minutes, do not feed him; instead, bring his food and insulin with you.
3. When you get to the hospital, the veterinary team will take a blood sample immediately to assess your dog’s pre-insulin glucose level.
4. The veterinarian will then give your dog a dose of insulin and feed your dog, if necessary.
5. The veterinary team will take blood samples every one to three hours, throughout the day, generally for an 8- to 10-hour period or longer. This testing allows your veterinarian to determine the peak insulin effect and how your pet responds to insulin over the course of the day — often referred to as an “insulin-response curve.”

If your dog gets too excited or is very nervous when riding in the car or being in the hospital, the glucose readings may be falsely elevated. If this occurs, your veterinarian may recommend other methods of monitoring daily fluctuations in glucose, such as home glucose curves or continuous glucose monitoring.

Your veterinarian may also choose an alternative monitoring test, called a fructosamine test, which provides an average of blood glucose levels for the preceding two weeks. Stress and inconsistencies in diet and exercise have less effect on this test than on the blood glucose test.

If no glucose curve options work for your dog, this may be the preferred test. It does not require fasting and can be done at any time of day. However, it has limitations, as it doesn’t catch day-to-day fluctuations and may miss episodes of hypoglycemia. Your veterinarian will discuss this test and whether it is appropriate for your dog’s monitoring program.

Does hypoglycemia occur in dogs?

Hypoglycemia means low blood sugar levels. If blood sugar falls below 40 mg/dl, it can be life-threatening. Hypoglycemia generally occurs under two conditions:

1. When the insulin dose is too high. Most dogs require the same dose of insulin for long periods of time, but it is possible for the dog’s insulin requirements to suddenly change, most commonly due to a reduction in food intake and an increase in exercise or activity. Ensure your dog eats before you give the insulin injection. If your dog does not eat, skip that dose of insulin. If the dog eats only half of the food, give only half a dose of insulin. Always remember it is better in the short term for the blood sugar to be too high than too low. Ask your veterinarian for specific guidance on what to do if your pet fails to eat or eats only a portion of its food.
2. When too much insulin is given. Insulin may not be properly measured in the syringe, or two doses may be given accidentally (e.g., you may forget that you already gave a dose, or two people in the family may each give a dose). Use a chart to record insulin administration to prevent the dog from being treated twice.

A dog is most likely to become hypoglycemic at the time of peak insulin effect (generally 5 to 8 hours after an insulin injection) but hypoglycemia can also occur at any time. When the blood glucose is only mildly low, the dog will act very tired. You may call your dog and get little or no response. Alternatively, your dog may be able to walk but appear trembly or unsteady on their feet. Any decline in your pet’s behavior warrants contacting your veterinarian right away to prevent this.

Your veterinarian may recommend giving your dog corn syrup (karo syrup) by mouth if you are concerned. A typical dose is 1 tablespoon for every 20 pounds of body weight. Sugary syrups can be absorbed from the gums, so do not force liquids to the back of your dog’s mouth; doing so could cause them to breathe in the solution if they are unable to swallow properly. Instead, rub it onto their gums. Once you have given the syrup, contact your veterinarian immediately for further instructions. This can be an emergency.

If severe hypoglycemia occurs, a dog may have seizures or lose consciousness. Ultimately, untreated hypoglycemia will lead to coma and death. Severe hypoglycemia is an emergency that can only be reversed with intravenous administration of glucose. If it occurs during office hours, take your dog to the veterinarian’s office immediately. If it occurs at night or on the weekend, call your local veterinary emergency clinic or your veterinarian’s emergency phone number for instructions.