Written by:

PetMD Editorial
Published: November 07, 2012

Drug Info

  • Drug Name: Insulin
  • Common Name: Vetsulin®, Humulin®, PZI Vet®, Novolin®, Iletin®, Velosulin®
  • Drug Type: Synthetic hormone
  • Used For: Diabetes mellitus
  • Species: Dogs, Cats
  • Administered: 40units/ml, 100units/ml, and 500units/ml Injectable
  • How Dispensed: Prescription only
  • FDA Approved: Yes

General Description

Insulin is used in the treatment of diabetes mellitus in dogs and cats. Insulin is a hormone produced by the pancreas that helps convert your pet’s food into energy by allowing the uptake of sugar by cells. By allowing this uptake and use of sugar, insulin decreases the blood glucose concentrations in the body. When you pet does not produce insulin, sugar can’t enter cells, your pet’s body cannot create fat, sugar, or protein. This also results in a dangerously high blood glucose level.

How It Works

Insulin replaces the insulin that your pet’s body does not produce. The type of insulin you give to your pet is a synthetic hormone derived from pigs or cows.

Storage Information

Some forms of insulin need to be refrigerated, pay close attention to the manufacturer’s label. DO NOT FREEZE. Protect from heat and sunlight. Do not use if past the expiration date.

Insulin must be given to your pet by an injection 1 to 2 times a day. Because it is a protein, the acids in the stomach would digest it if you were to administer it orally.

The proper dose of insulin is determined by your veterinarian through a series of glucose level tests. It is best to give this drug to a pet with a full stomach. It is best to give insulin right after a meal.


Proper handling of insulin:

  1. Be sure you have the appropriate size syringe for the concentration of insulin you are using. Variations include: U-40, U-100, and U-500 syringes which go to their corresponding 40, 100, and 500 units/ml insulin concentrations.
  2. Insulin should be stored in the refrigerator
  3. Pay careful attention to the expiration date on the insulin bottle
  4. To mix insulin, NEVER shake the bottle or agitate it too harshly; gently roll the bottle between your palms.
  5. Draw up the correct unit amount of insulin and double check the amount before giving the injection to your dog. Ensure that there are no bubbles in your syringe.
  6. If any amount of insulin leaks from the syringe or injection site, DO NOT repeat the injection. Wait until it is time to give the next scheduled dose. If you have any questions or concerns, call your veterinarian. Giving too much insulin at one time can make your pet sick. Signs of an insulin overdose include: confusion, disorientation, stumbling, shivering, or seizing.
  7. Make sure you follow your veterinarians protocol for feeding in association with the insulin intake
  8. Dispose of needles properly


Missed Dose?

Give the dose as soon as possible. If it is almost time for the next dose, skip the missed dose, and continue with the regular schedule. Do not give your pet two doses at once.

If you are concerned, consult your veterinarian for more exact instructions.

Side Effects and Drug Reactions

Insulin may result in these side effects:

  • Hypoglycemia (low blood sugar)
  • Hyperglycemia (high blood sugar)
  • Lethargy
  • Vomiting
  • Increased intake of water
  • Local reactions
  • Seizures
  • Death if overdose

If you notice mild side effects or strange behavior from your pet, the dosage of insulin may need adjusting, and you should contact your veterinarian as soon as possible to schedule a series of glucose tests.

If you notice signed of hypoglycemia — disorientation, lethargy, increased appetite, nausea, rapid heartbeat, unsteadiness, or seizures — contact your veterinarian IMMEDIATELY, as this is an emergency situation.

Many drugs can alter your pet’s body’s need for insulin. Be sure to notify your veterinarian of your pet’s full medical history and all medications that they are currently taking. Insulin may react with these drugs:

  • Anabolic steroid
  • Beta blockers
  • Diuretic
  • Estrogen agents
  • Glucocorticoid
  • Amitraz
  • Furazolidone
  • Selegine
  • Progestin
  • Thiazide diuretic
  • Thyroid hormone
  • Aspirin
  • Digoxin
  • Dobutamine
  • Epinephrine
  • Furosemide
  • Phenylbutazone
  • Tetracycline