Diabetes Mellitus: Principles of Treatment in Dogs

This handout provides detailed information on the principles of treatment in diabetes mellitus. For more information about diabetes mellitus and its treatment, see the handouts "Diabetes Mellitus in Dogs - Overview" and "Diabetes Mellitus - Insulin Treatment."

What is diabetes mellitus?

Diabetes mellitus is caused by the failure of the pancreas to 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 of the beta-cells that produce insulin in the pancreas. As the name implies, dogs with this type of diabetes require insulin injections to stabilize 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 seen in diabetes mellitus are related to the elevated concentrations of blood glucose, and the inability of the body to use glucose as an energy source.

Some people with diabetes take insulin shots and others take oral medication. Is this true for dogs?

In humans, there are two types of diabetes mellitus. Both types are similar in that there is a failure to regulate blood sugar, but the basic mechanisms of the disease differ.

Type I diabetes mellitus (sometimes called insulin dependent diabetes mellitus) results from total or near-complete destruction of the pancreatic beta-cells. This is the most common type of diabetes in dogs. As the name implies, dogs with this type of diabetes require insulin injections to stabilize blood sugar.

Type II diabetes mellitus (non-insulin dependent diabetes mellitus) is different because some insulin-producing cells remain. However, the amount of insulin produced is insufficient, there is a delayed response in secreting it, or the tissues of the dog's body are relatively resistant to it (also referred to as insulin resistance). Type II diabetes may occur in older, obese dogs. People with this form of diabetes may be treated with an oral drug that stimulates the remaining functional cells to produce or release insulin in an adequate amount to normalize blood sugar. Unfortunately, dogs tend not to respond well to these oral medications and usually need insulin to control the disease.

How is diabetes mellitus treated in dogs? Is treatment expensive?

Dogs with diabetes mellitus require one or more daily insulin injections. Many will also require some sort of dietary change. In general, they must be fed the same food in the same amount on the same schedule every day. Although the dog can go a day or so without insulin and typically not have a crisis, this should not be a regular occurrence; treatment should be looked upon as part of the dog's daily routine. This means that you, as the dog's owner, must make both a financial commitment and a personal commitment to treat your dog. If you are out of town or go on vacation, your dog must receive proper treatment in your absence. Costs of treatment can vary depending on how quickly your dog’s glucose is regulated with insulin and if there are any other underlying conditions contributing to diabetes.

"It is important that you pay close attention to all instructions related to administration of medication, diet, and home monitoring."

Initially, your dog may be hospitalized for a few days to deal with any immediate crisis and to begin the insulin regulation process. The "immediate crisis" is significant if your dog is so sick that it has quit eating and drinking for several days and has abnormal blood and urine test results. Dogs in this state, called diabetic ketoacidosis, may require several days of intensive care. Otherwise, the initial hospitalization may only be for a day or two while the dog's initial response to insulin injections is evaluated. At that point, your dog returns home for you to administer medication. At first, regular return visits are required at intervals recommended by your veterinarian to monitor progress. It may take a month or more to achieve good insulin regulation.

Your financial commitment may be significant if complications arise during the initial regulation process. Your veterinarian will work with you to try to achieve consistent regulation, but some dogs are difficult to regulate and keep regulated. It is important that you pay close attention to all instructions related to administration of medication, diet, and home monitoring. One serious complication that can arise is hypoglycemia, or low blood sugar, which can be fatal. This may occur due to inconsistencies in treatment.

What specifically is the treatment of diabetes?

Consistent treatment is a vital component of the proper management of a diabetic dog. Your dog needs consistent administration of insulin, consistent feeding, and a stable, stress-free lifestyle. Although it is not essential, your dog should live indoors to minimize uncontrollable variables that can disrupt regulation.

What your dog eats can be important in the treatment of diabetes mellitus. In dogs with diabetes mellitus, diets with high insoluble fiber may help stabilize blood glucose levels. Diets high in insoluble fiber may reduce the peaks of blood sugar related to eating a high-carbohydrate, low fiber diet. High fiber diets can also have the effect of promoting weight loss, which can be beneficial in overweight dogs but not thin dogs. Dogs with underlying conditions contributing to diabetes, such as pancreatitis, may require different diets, such as ultra-low-fat diets. Your veterinarian will discuss specific diet recommendations for your pet's needs.

"The main treatment for regulating blood glucose is the administration of insulin by injection."

Your dog's feeding routine is also important. Some owners feed their dogs by leaving food in the bowl at all times, so that the dog can eat whenever it wants (called free-choice feeding). However, this is not the best way to feed a diabetic dog. The preferred way is to feed twice daily, 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 the majority of the food at or around the time of insulin administration.

In diabetic dogs, the main treatment for regulating blood glucose is the administration of insulin by injection. Many people are initially fearful of inflicting pain or harm by giving insulin injections. Fortunately, this fear is unfounded. Modern disposable insulin injection needles are extremely sharp and cause minimal pain, newer formulations of insulin do not sting or otherwise hurt on injection, and the injections are given just underneath the skin in areas where it is impossible to damage internal structures. Specific details about the use and storage of insulin are provided in the handout: "Diabetes Mellitus - Insulin Treatment in Dogs."

Although the above procedures may at first seem complicated and somewhat overwhelming, they will very quickly become second nature. Your veterinarian will carefully review your dog’s specific treatment and offer advice on how to best administer insulin injections.

How often do diabetic dogs need to be monitored?

Your dog's progress must be checked on a regular basis. Monitoring is a joint project on which owners and veterinarians must work together. Most dogs will require more frequent monitoring initially. After the dog is stabilized, and you are comfortable administering insulin and feeding the recommended diet, blood and urine testing will typically be performed every one to three months.

What is involved in home monitoring?

Your part in the monitoring process can involve several types of monitoring. First, you need to be constantly aware of your dog's appetite, weight, water consumption, and urine output. You should be feeding a consistent amount of food each day, which will allow you to be aware of changes in consumption. You should weigh your dog at least monthly and notify your veterinarian if there is any weight loss. It is best to use the same scales each time.

You should develop a way to measure water consumption. The average dog should drink no more than about 7 1/2 ounces (225 ml) of water per 10 pounds (4.5 kg) of body weight per 24 hours. Since water intake may be highly variable from one dog to another, keeping a record of your dog's water consumption for a few weeks will allow you to establish what is normal for your dog. You can get a rough estimate of whether your dog's drinking is normal by counting the number of times it drinks each day. When properly regulated, it should drink no more than six times per day. If this is exceeded, you should take an accurate measurement.

"Any significant change in your dog's food intake, weight, water intake, or urine output is an indicator that the diabetes is not well controlled."

Any significant change in your dog's food intake, weight, water intake, or urine output may be an indicator that the diabetes is not well controlled. If you observe changes, schedule an appointment with your veterinarian for blood testing.

Another method of home monitoring is to determine the presence of glucose in the urine. This can be valuable in cases where there is concern for hypoglycemia. No glucose in the urine often indicates hypoglycemia.

There are several ways to detect glucose in urine. You may purchase urine glucose test strips in any pharmacy. They are designed for use in humans with diabetes, but they also work well in dogs. A fresh urine sample should be collected and tested with the test strip. It is ideal if you can test the first urine of the morning. Regardless of when you test the urine glucose, you need to try to be consistent. If you can test in the morning, try to perform all tests in the morning. If no glucose is detected 2 mornings in a row, your vet should be notified as there may be a need to change the insulin dose.

Keep a small container to catch urine as the dog urinates. The test strip requires only a small amount of urine. Because the female dog usually squats to urinate, a shallow pan or dish (disposable metal pie plates are ideal) may be placed under her hindquarters when she begins to urinate. For male dogs, urine can be collected as soon as the dog lifts the leg to void. Male dogs often urinate small amounts in several different places and on vertical objects, such as bushes and trees.

"Some dogs may also have their blood glucose monitored at home."

Some dogs may also have their blood glucose monitored at home. This requires special veterinary (pet) blood glucose monitors (AlphaTrak 2™). Your veterinarian will recommend this type of monitoring to you if your dog is a suitable candidate. Not all pet parents or dogs will allow, or enjoy, this type of monitoring that requires you to obtain small blood samples from your dog.

A new option for home monitoring is a continuous glucose monitor (FreeStyle Libre™) that is inserted into the skin and stays in place for up to 14 days. The sensor tracks glucose every minute and stores up to 8 hours of data. The owner passes a scanner over the device several times a day and this records glucose levels reflective of blood glucose. Ask your veterinarian if this is a good option for your dog.

How will my veterinarian monitor my dog's diabetes?

There are two common blood tests that can be used to monitor your dog, the blood glucose curve and the fructosamine test. New tests are also becoming available that can aid your veterinarian in accurately monitoring your dog’s diabetes. One of these tests may be recommended at periodic intervals for monitoring, even if your dog is well regulated. Testing should also be done any time clinical signs of diabetes are present.

The most common diabetes monitoring test, a blood glucose curve, involves monitoring the level of glucose in the blood over a 12–24-hour period. Blood glucose curves generally start around the time of insulin administration 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. Feed your dog its normal morning meal and then bring your dog to the hospital immediately before administering insulin. If you cannot get your dog to the hospital within thirty minutes, do not feed him and bring your dog's food with you. Also, be sure to bring your insulin to the veterinary hospital.
2. A blood sample will be taken immediately to assess your dog's pre-insulin glucose level.
3. The veterinarian will give your dog's dose of insulin and feed your dog if necessary. 
4. Blood samples will be taken every one to three hours throughout the day, generally for an eight- to ten-hour period or longer. This will allow your veterinarian to determine the peak insulin effect and how your pet is responding to insulin over the course of the day. This is 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, it is best to admit your dog to the hospital the morning (or afternoon) before testing so it can settle down for testing the next day. Other methods of monitoring daily fluctuations in glucose may also be considered, such as home glucose curves or continuous glucose monitoring.

"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."

An alternative test is called a fructosamine test. Fructosamine gives your veterinarian an approximate average of blood glucose levels for the last 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 the day. It can also be useful if there is worry about hypoglycemia. Your veterinarian will discuss this test and if it is appropriate for your dog's monitoring program.

Does hypoglycemia occur in dogs?

Hypoglycemia means low blood sugar. If the 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. Although most dogs will require the same dose of insulin for long periods of time, it is possible for the dog's insulin requirements to suddenly change. The most common causes for change are a reduction in food intake and an increase in exercise or activity. The dog should eat before giving the insulin injection, because once the insulin is administered it can't be removed from the body. If your dog does not eat, skip that dose of insulin. If only half of the food is eaten, give only a half dose of insulin. Always remember that 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. These are only general guidelines and may vary in your dog.
2. When too much insulin is given. This can occur because the insulin was not properly measured in the syringe or because two doses were given. You may forget that you gave it and repeat the dose or two people in the family may each give a dose. A chart to record insulin administration will help to prevent the dog being treated twice.

The most likely time that a dog will become hypoglycemic is the time of peak insulin effect (generally 5 to 8 hours after an insulin injection). When the blood glucose is only mildly low, the dog will act very tired and unresponsive. You may call your dog and get little or no response. Within a few hours, the blood glucose will rise, and your dog will return to normal. Since many dogs sleep a lot during the day, this important sign is easily missed. Watch for any subtle signs of hypoglycemia. It is the first sign of impending problems. If you see it, please bring your dog in for blood glucose testing.

If your dog is slow to recover from this period of lethargy, you should give corn syrup (one tablespoon for every twenty pounds (15 ml/10 kg) by mouth) or a commercially prepared diabetic sugar solution. Sugary syrups can be absorbed from the gums, so do not force liquids to the back of your dog’s mouth; doing so could risk them aspirating the solution into their lungs if they are unable to swallow properly. 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. This 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 veterinarian's emergency phone number for instructions.