Overview of Insulin for Dogs and Cats
Insulin, commonly known as Humulin®, Iletin®, Vetsulin™ or Lantus®, is used to control blood sugar.
Diabetes mellitus is a disorder of the pancreas characterized by insufficient production of insulin and high blood glucose (sugar). Insulin acts to move blood sugar into cells after eating, thereby lowering the blood glucose. Diabetes in dogs is typically of the type I variety, meaning there is an absolute lack of insulin. In many cats, as in people, diabetes mellitus is often of the type II variety. In type II diabetes, the cells are resistant to the effects of available insulin.
The only effective treatments for type I diabetes in dogs and cats are appropriate diet, exercise and injections of insulin.
Insulin is a hormone that is formed and released by beta cells residing in the pancreas. Eating prompts the release of insulin. When insulin is not produced in sufficient quantities, it can be administered in the form of an injection.
There are various types of insulin treatments, each with a different duration of effectiveness.
Most currently available insulin for injection is synthetic, but some types are derived from animals (bovine or porcine).
The human formulation is not approved for use in dogs but the veterinary labeled drug is approved for use in dogs by the Food and Drug Administration. The human formulation can be prescribed legally by veterinarians as an extra-label drug.
Insulin is available over the counter in many areas of the US but should not be administered unless under the supervision and guidance of a veterinarian.
Brand Names and Other Names of Insulin
This drug is registered for use in humans and dogs only.
Human formulations: Humulin® R (Lilly), Humulin® N (Lilly), Humulin® U Ultralente (Lilly), Novalin® N (Novo-Nordisk), Iletin® II NPH (Lilly), Regular Insulin (Novo-Nordisk), Lantus® (Glargine) and various generic preparations. Please note that Humulin® L and U were taken off the market.
Veterinary formulations: Vetsulin™ (Intervet) (porcine insulin zinc suspension)
The type of insulin to use in cats has been tricky. Some insulins as you can see have been taken off the market making it difficult to find a long acting one to treat some pets such as cats.
Uses of Insulin for Dogs and Cats
Insulin is used to control blood sugar in diabetic animals.
Insulin has also been used to temporarily reduce life-threatening levels of blood potassium related to certain medical conditions. Potassium ions enter the cell with glucose; this is facilitated by insulin.
Precautions and Side Effects
While generally safe and effective when prescribed by a veterinarian, insulin can cause side effects in some animals.
Insulin resistance has been known to occur. This means the pet will not respond appropriately to the scheduled dose of insulin.
Avoid injecting insulin at the same site day after day.
Insulin may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with insulin. Such drugs include corticosteroids, propranolol, tetracycline, aspirin, epinephrine, furosemide and digoxin.
Overdoses of insulin can result in life-threatening low blood sugar. This can lead to weakness, depression and abnormal behavior. Diabetic coma, seizures or death can occur from inappropriate insulin doses.
Vetsulin should not be used in dogs known to have a systemic allergy to pork or pork products.
Caution must be used to properly store insulin and mix correctly. Vigorously shaking the bottle may breakdown the insulin and renders it non-therapeutic.
Do not use expired insulin.
How Insulin Is Supplied
Insulin is available in several forms, including Regular, Ultralente, Lente, NPH and PZI and various combinations. Your veterinarian will prescribe the insulin preparation most appropriate for the pet (depends on species, severity of disease and response to the various forms of insulin).
Insulin is available in 100 units/ml and, rarely, 40 units/ml.
Dosing Information of Insulin for Dogs and Cats
Medication should never be administered without first consulting your veterinarian.
Insulin is fragile and must be stored according to label directions.
Insulin is supplied as a suspension and must be gently mixed(not shaken) by rolling the bottle back and forth prior to administration.
Insulin must be injected. In order to administer insulin, specific insulin syringes must be purchased. Care must be taken to purchase those syringes that match the type of insulin that is given. The needle on an insulin syringe is very small and sharp and causes minimal, if any, discomfort when inserted under the skin.
The dose and type of insulin vary on the severity of the diabetes. In severely ill pets with ketosis, regular insulin is used at a dose of 0.05 to 0.1 units per pound (0.1 to 0.2 units/kg) every one to four hours.
Once regulated, the animal is prescribed longer-acting insulin and the dose is regulated depending on clinical symptoms, blood sugar and specialized tests that measure the blood glucose over time.
Commonly, animals are started on 0.25 to 0.5 units per pound (0.5 to 1 unit/kg) one to two times daily. The dose may vary with the individual animal and the specific insulin prescribed.
Frequent blood sugar tests must be done to determine the appropriate dose. Doses of insulin are frequently altered throughout the animal's life. Diet and exercise will effect the insulin dosage. Increased food intake typically increases the need; exercise may lower the insulin dose. Special diets can also help to regulate the diabetic. These are often high in fiber.
The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.
Please note that some insulin formulations require refrigeration and others do not. Please check with your veterinarian or pharmacist.