Insulin for Dogs

If you’ve ever had a relative—or even a pet—with diabetes, you’re likely familiar with the drug insulin. This medication is used to regulate blood sugar in diabetic patients, including our four-legged friends. Insulin can be a bit daunting at first. There are many types available and every dog requires individual dosing. But once you get the hang of it, administering insulin to your pet is fairly easy to do. Read on to learn more about this important drug and how it is used in canine patients.

What is Insulin?

Insulin is a hormone made by the pancreas that helps regulate blood sugar levels. After eating, carbohydrates are broken down into glucose, which is then absorbed into the bloodstream. Insulin helps move glucose from the blood into the cells of the body. Insulin also promotes energy storage, increases DNA replication, and increases protein synthesis. When insulin is deficient, glucose is not adequately metabolized, leading to high blood sugar levels. 

Diabetes is a condition characterized by a deficiency of insulin. Type I diabetes (also known as insulin-dependent diabetes) is the most common type of diabetes in dogs and occurs due to a lack of insulin production by the pancreas. In this case, insulin must be supplemented for patients. In veterinary patients, often the same types of insulin used in humans are prescribed. There are also two FDA-approved veterinary insulin products available on the market: Vetsulin, which was approved in 2004, and ProZinc, which was approved for use in dogs in 2019.

What is Insulin Used For in Dogs?

Insulin is used to treat diabetes mellitus in dogs. Less commonly, it may also be used to prevent the progression to diabetes mellitus in canine patients with pituitary-dependent hyperadrenocorticism (Cushing’s Disease) and hyperglycemia.

Dog Insulin vs Human Insulin

It is important to note that human insulin and veterinary insulin have different concentrations and require different syringes to administer appropriately. Human insulin formulations typically have concentrations of 100 units per ml, requiring a U-100 syringe to administer correctly. Veterinary insulin formulations have concentrations of 40 units per ml, requiring a U-40 syringe to administer correctly. Administering insulin with the wrong size syringe can result underdosing your dog’s insulin, leading to worsening of their diabetes symptoms, or an an accidental overdose, leading to hypoglycemia in dogs. Always make sure you know whether your dog’s insulin is a human or veterinary formulation, and be extra careful to use the correct size syringe with it. 

How to Give Insulin to Dogs

Insulin is administered twice daily by subcutaneous injection, which is an injection under the skin. These injections are easy to perform and pet owners can be trained to do this at home. First, read the insulin manufacturer’s instructions to determine how to handle and mix the insulin. Some brands must be handled gently to avoid inactivating the insulin, while other brands, such as Vetsulin, must be shaken vigorously to mix them prior to administration. 

Once mixed, use the proper size insulin syringe (U-40 or U-100) to draw up the correct dose of insulin for your dog, making sure there are no air bubbles in the syringe. Next, gently pinch up a fold of your dog’s skin, forming a tent shape. Gently insert the needle into the center of this tent and push down the plunger until it stops. Pull the needle straight out and dispose of it in an appropriate hard-sided container. Be sure to put the insulin back in the refrigerator when you are done.

Insulin Side Effects in Dogs

The primary side effect of insulin is hypoglycemia, or low blood sugar. This can occur when too much insulin is given, causing the blood sugar to drop too low. Signs of hypoglycemia in dogs that pet owners should watch for include:

• Weakness
• Lethargy
• Stumbling gait
• Falling down
• Depression
• Disorientation
• Collapse
• Seizure
• Death

Less commonly, some dogs may experience a reaction at the injection site, which includes swelling, pain, bruising, or crusting.

Insulin is a lifelong medication and there are no concerns with using it long term, as long as dosages are monitored and your veterinarian is overseeing your dog’s treatment.

Reactions With Other Drugs and Medications

There are a number of drugs that can change your dog’s insulin requirements by altering glucose tolerance, increasing the risk for hypoglycemia, and altering the glucose lowering effect of insulin.  These drugs include commonly used medications, such as steroids, diuretics, beta-blockers, and thyroid hormones, among others.  

Insulin Dosage for Dogs

The dosage of insulin for dogs varies widely between patients. Even dogs of the same breed or size can have very different insulin dosages. Your veterinarian will start your dog on an initial dose of insulin and then will perform a blood glucose curve to evaluate your dog’s response to the insulin.  

A blood glucose curve involves measuring your dog’s blood glucose at set intervals throughout the day, usually about every two hours. Plotting these numbers on a graph allows your veterinarian to evaluate how your dog’s blood glucose fluctuates throughout the day. If your dog’s blood glucose is trending too high or too low, your veterinarian will adjust your dog’s insulin dosage accordingly and will likely recheck a blood glucose curve at a later date. This process helps ensure that your dog gets exactly the amount of insulin his body needs.

What If My Dog Misses a Dose of Insulin?

If your dog misses a dose of insulin, simply administer the next dose as usual. Do not add extra doses or increase the insulin dose, as this can put your dog at risk for developing hypoglycemia. If your dog has missed multiple doses of insulin, contact your veterinarian for advice before proceeding.

How Much Does Insulin Cost for Dogs?

The cost of insulin varies depending on the type of insulin used and the dose your pet needs. In general, it costs approximately $150 for a 10 ml vial of insulin, although some types of insulin may be more or less expensive.

Insulin Storage Instructions

Store insulin upright in the refrigerator. Do not freeze. Check the label or package insert for further instructions.