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 fact sheets "Diabetes Mellitus - General Information", and "Diabetes Mellitus - Insulin Treatment".

What is diabetes mellitus?

Diabetes mellitus is caused by the failure of the pancreas to regulate blood sugar. In the dog, diabetes mellitus is usually Insulin Dependent Diabetes Mellitus (also called Type 1 Diabetes). This type of diabetes usually results from 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 disease differ somewhat between the two.

"Type I Diabetes Mellitus is the most common type of diabetes in dogs."

Type I Diabetes Mellitus(sometimes also caused Insulin Dependent Diabetes Mellitus), results from total or near-complete destruction of the 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 (sometimes called 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 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 some 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, and almost all 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 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 are out of town or go on vacation, your dog must receive proper treatment in your absence. Once your dog is well regulated, the treatment and maintenance costs are minimal. The special diet, insulin, and syringes are not expensive. However, the financial commitment may be significant during the initial regulation process, or if complications arise.

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 only great if your dog is so sick that it has quit eating and drinking for several days. Dogs in this state, called diabetic ketoacidosis, may require several days of intensive care. Otherwise, the initial hospitalization may be only 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, return visits are required every five to seven days to monitor progress. It may take a month or more to achieve good insulin regulation.

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

The financial commitment may again be significant if complications arise. Your veterinarian will work with you to try to achieve consistent regulation, but some dogs are difficult to 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 the 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 is important in the treatment of diabetes mellitus."

What your dog eats is important in the treatment of diabetes mellitus.  In dogs, diabetes mellitus has been shown to be a "fiber-responsive disease." Fiber is  a mainstay of a "low glycemic index" diet. Diabetic patients need to avoid the peaks of blood sugar related to eating a high carbohydrate diet. Fiber rich diets are preferred because they are generally lower in sugar and slower to be digested, meaning that their sugars are absorbed more slowly. This means that the dog does not have to process a large amount of sugar at one time. Additionally, the fiber may help stimulate insulin secretion in Type II diabetes. Since obesity is a risk factor for diabetes mellitus and can make regulation difficult, a high fiber diet can have the added benefit of promoting appropriate weight loss for the Type II diabetic. Your veterinarian will discuss specific diet recommendations for your pet's needs.

"Your dog's feeding routine is also important."

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 at the same time of the insulin injection. If your dog is currently eating on a free choice basis, it is important to try to make the change. If a meal 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.

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

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. However, this fear is unfounded, since the disposable injection needles are extremely sharp and cause minimal pain, the insulin does not sting or otherwise hurt on injection, and the injections are given under the skin in areas where it is impossible to damage internal structures.

How is insulin stored?

Insulin is a hormone that will lose its effectiveness if exposed to direct sunlight or high temperatures. It should be kept in the refrigerator, but it should not be frozen. If you have any doubt about the storage of your pet's insulin, it is safer to replace it rather than risk using ineffective insulin. Insulin is safe as long as it is used as directed, but it should be kept out of the reach of children.

Insulin comes in an airtight bottle that is labeled with the insulin type and the concentration. It is important to make sure you match the insulin concentration with the proper insulin needles. Insulin needles show their measurement in "units per ml", which must correspond to the concentration of the insulin you are using. There are two common forms of insulin and corresponding syringes: U-100 and U-40. Your veterinarian will instruct you on which type of insulin you are using and which type of syringe you should use.

How should I draw up the insulin?

Before administering the insulin, you must mix the contents. Be sure to roll it gently between your hands; do not shake it. The reason you do not shake insulin is to prevent foam formation, which will make accurate measuring difficult due to the tiny air bubbles. Some insulin will have a strong tendency to settle out of suspension. If it is not shaken properly, it will not mix well and dosing will be inaccurate.

"The trick is to mix it vigorously enough to blend it without creating foam."

Therefore, the trick is to mix it vigorously enough to blend it without creating foam. When you have finished mixing the insulin, turn the bottle upside down to see if any white powder adheres to the bottom of the bottle. If so, more mixing is needed.

Have the needle and syringe, insulin bottle, and dog ready. Then, follow these steps:

1.  Remove the cap from the needle, and draw back the plunger to the appropriate dose.

2.  Carefully insert the needle into the insulin bottle.

3.  Inject air into the bottle. This prevents a vacuum from forming within the bottle.

4.  Withdraw the correct amount of insulin into the syringe.

In order to ensure that you have the correct amount of insulin in the syringe, make sure that it starts at the "0" on the syringe barrel, and that the edge of the plunger nearest the needle is on the correct unit mark on the barrel.

Before injecting your dog with the insulin, check that there are no air bubbles in the syringe. If you get an air bubble, draw twice as much insulin into the syringe as you need. Then withdraw the needle from the insulin bottle and tap the side of the barrel of the syringe with your fingernail to make the air bubble rise to the tip of the syringe. Gently and slowly expel the air bubble by moving the plunger upward. When you have removed all of the air bubbles, double-check that you have the correct amount of insulin in the syringe.

How do I inject the Insulin?

The steps to follow for injecting insulin are:

1)  Hold the syringe in your right hand (if you are right-handed).

2)  Have someone hold your dog while you pick up a fold of skin from somewhere along your dog's back in the "scruff" region of the neck with your free hand. Try to pick up a slightly different spot each day.

3)  Quickly push the very sharp, very thin needle through your dog's skin at about a forty-five degree angle. This should be fast, easy and painless. However, take care to push the needle through only one layer of skin and not into your finger or through two layers of skin and out the other side. The latter will result in injecting the insulin onto your dog's haircoat or onto the floor. The needle should be directed parallel to the backbone or angled slightly downward.

4)  To inject the insulin, place your thumb on the plunger and push it all the way into the syringe barrel. If you are unsure if you administered it correctly, or if you "missed," do not administer additional insulin. Simply resume your normal schedule and give the next insulin injection at the regular time.

5)  Withdraw the needle from your dog's skin. Immediately place the needle guard over the needle and place the used needle and syringe into a puncture-resistant container. Be aware that some communities have strict rules about disposal of medical waste material so don't throw the needle and syringe into the garbage until you know if this is permissible. It is usually preferable to take the used needles and syringes to your veterinary clinic or local pharmacy for disposal.

6)  Stroke and praise your dog to reward it for sitting quietly.

Should I sterilize the skin with alcohol before giving the injection?

It is neither necessary nor desirable to swab the skin with alcohol to "sterilize" it. There are four reasons:

1)  The sting caused by the alcohol can make your dog dislike the injections.

2)  Due to the nature of the thick hair coat and the type of bacteria that live near the skin of dogs, brief swabbing with alcohol or any other antiseptic is not effective.

3)  Because a small amount of alcohol can be carried through the skin by the needle, it may actually carry bacteria with it into the skin.

4)  If you have accidentally injected the insulin onto the surface of the skin, you will not know it. If you do not use alcohol and the skin or hair is wet following an injection, the injection was not done properly.

Although the above procedures may at first seem complicated and somewhat overwhelming, they will very quickly become second nature. Your dog will soon learn that once or twice each day it has to sit still for a few minutes. In most cases, a reward of stroking results in a fully cooperative dog that eventually may not even need to be held.

Although the above procedures may at first seem complicated and somewhat overwhelming, they will very quickly become second nature.

 How often do diabetic dogs need to be monitored?

It is necessary that your dog's progress be checked on a regular basis. Monitoring is a joint project on which owners and veterinarians must work together.

What is involved in home monitoring?

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 7 1/2 oz. (225 ml) of water per 10 pounds (4.5 kg) of body weight per 24 hours. Since this is 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 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 is an indicator that the diabetes is not well controlled. We should see your dog at that time for blood testing.

How will my veterinarian monitor my dog's diabetes?

"...the blood glucose test and the fructosamine test."

There are two common blood tests that can be used to monitor your dog, the blood glucose test and the fructosamine test. One of these should be performed every three to four months if your dog seems to be well regulated. Testing should also be done at any time the clinical signs of diabetes are present.

Determining the level of glucose in the blood is the most commonly used blood test. Timing is important when the blood glucose is determined. Since eating will elevate the blood sugar for several hours, it is best to test the blood at least six hours after eating.

When testing the blood we want to know the highest and lowest glucose readings for the day. The highest blood sugar reading should occur just before an injection of insulin is given. The lowest should occur at the time of peak insulin effect. This is usually five to eight hours after an insulin injection, but it should have been determined during the initial regulation process.

Therefore, the usual procedure for measuring blood glucose as an "insulin-response curve" is as follows:

1) Perform your regular morning routine of food and insulin. 

2)  Bring your dog to the hospital as early in the morning as possible after the routine is completed.

3) We will ask a few questions about how your dog is doing and take a blood sample immediately. 

4)  Blood samples will be taken every two hours throughout the day, generally for an eight- to twelve-hour period. This will allow us to determine the peak insulin affect and how you pet is responding to insulin over the course of the day. This is often referred to as a "glucose curve."

If your dog gets too excited or 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. Otherwise, the tests give us limited information. Alternatively, we may be able to have you do a glucose curve at home.

"For some dogs, this is the preferred test. It does not require fasting and can be performed at any time of the day."

The alternative test is called a fructosamine test. This test is an average of the 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. For some dogs, this is the preferred test. It does not require fasting and can be performed at any time of the day. There is still some controversy regarding the accepted normal ranges for dogs for this test. 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 2.2umol/L, 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. However, 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.

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 it, 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 (5-8 hours after an insulin injection). When the blood glucose is only mildly low, the dog will act very tired and unresponsive. You may call it 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 it corn syrup (one tablespoon for every twenty pounds (15 mls/10 kg) by mouth). If there is no response within fifteen minutes, repeat administration of the corn syrup. If there is still no response, contact your veterinarian immediately for further instructions. This is 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.