The label says, word for word:
vetsulin® (porcine insulin zinc suspension) is indicated for the reduction of hyperglycemia and hyperglycemia-associated clinical signs in dogs and cats with diabetes mellitus.
Dogs and cats known to have a systemic allergy to pork or pork products should not be treated with vetsulin®. vetsulin® is contraindicated during periods of hypoglycemia.
For use in animals only. Keep out of the reach of children. Avoid contact with eyes. In case of contact, immediately flush eyes with copious amounts of water for 15 minutes. Accidental injection may cause clinical hypoglycemia. In case of accidental injection, seek medical attention immediately. Exposure to product may induce a local or systemic allergic reaction in sensitized individuals.
Owners should be advised to observe for signs of hypoglycemia. Use of this product, even at established doses, has been associated with hypoglycemia. An animal with signs of hypoglycemia should be treated immediately.
Any change in insulin should be made cautiously and only under a veterinarian's supervision.
Overdosage can result in profound hypoglycemia and death.
The safety and effectiveness of vetsulin® in breeding, pregnant, and lactating dogs and cats has not been evaluated. The safety and effectiveness of vetsulin® in puppies and kittens has not been evaluated.
From the sheet the maker writes for owners:
Approved by FDA under NADA # 141-236; original approval April 1, 2004 for dogs (FOI summary; sponsor Intervet, Inc.); a supplemental approval dated March 24, 2008 extended use to cats. Label revised 03/2025. The owner information sheet lists signs of hypoglycemia as "Weakness, Depression, Behavioral changes, Muscle twitching, Anxiety, Seizures, Coma, Death". Storage: "Store in an upright position under refrigeration at 2°C to 8°C (36°F to 46°F). Do not freeze." Label precaution: "Progestogens, certain endocrinopathies, and glucocorticoids can have an antagonistic effect on insulin activity."
The emergency page sorts the signs by how long you have, and the symptom checker asks what you are seeing. Reactions to a medicine can also be reported to the FDA yourself: how to report a problem.
These answers come from the approved label on DailyMed, read on 2 October 2026. Where the label does not say, the answer says so, and the vet or the pharmacist is the one to ask.
The approved use is quoted at the top of this page. It is an insulin given by injection to dogs and cats with diabetes, to bring down high blood sugar and the signs that come with it.
The label gives times for the insulin's action, not for when a pet looks better. In diabetic dogs it says there are two peaks of activity after an injection, the first at 2 to 6 hours and the second at 8 to 14 hours, and that the action lasts 14 to 24 hours. In diabetic cats it says the peak comes between 1.5 and 8 hours and the action lasts 8 to 12 hours. In its laboratory studies in healthy dogs and cats, the action began 0.5 to 2 hours after the injection.
It is an injection given just under the skin, and the owner sheet in the label lists the steps for giving it. From a vial it is drawn up with a U-40 insulin syringe only, and the vial is shaken thoroughly first, until the liquid is evenly milky. The label says to let any foam settle before use, and not to use the insulin if clumps or white particles are still there after thorough shaking. Cartridges are used only with the VetPen. The injection goes in 3/4 to 2 inches from the midline of the back, anywhere from behind the shoulder blades to the middle of the lower back, on alternating sides. For dogs the label starts with one injection a day, given with a meal or right after it, and moves to two a day if the vet finds that one does not last long enough. For cats it is two injections a day about 12 hours apart, given with or right after each meal in cats fed twice a day. The vet sets the number of units.
The owner sheet in the label says a missed or too-small dose may bring the signs back for a while, such as excess thirst and urination, but is not life-threatening. It says to contact your vet as soon as possible for advice on the next dose. If you cannot reach the vet and your pet is eating and acting normally, the sheet says: "give your pet the usual dose at the next regularly scheduled injection time."
The studies and the warnings are quoted above. The owner sheet says the most common side effect is low blood sugar, and it lists weakness, depression, changes in behavior, muscle twitching, anxiety, seizures, coma and death. For a pet that is unconscious or having a seizure, the sheet says this is a medical emergency and to take the pet to the vet immediately. For a pet that is conscious, it says to rub corn syrup or honey on the gums, to give more by mouth once the pet can swallow, and then to feed its usual meal and contact the vet. For dogs, Diabetes in dogs has the steps in more detail, including how to do it without putting your fingers in the mouth. The sheet also says to contact the vet immediately if you think your pet has a medical problem or a side effect, and the signs it lists include drinking a great deal for more than 3 days, urinating a great deal, a reduced or lost appetite, weakness, constipation, vomiting or diarrhea, signs of a bladder infection and swelling of the head or neck. If a pet is given too much, the sheet says to contact the vet immediately.
Store it upright in a refrigerator, between 36° and 46°F. Do not freeze it, and protect it from light. A VetPen loaded with a cartridge can lie on its side in the refrigerator. The label says to use the contents within 42 days of the first puncture. Keep it out of the reach of children.
The owner sheet says to dispose of a used syringe in an appropriate manner, as sharps. The FDA says the best way to get rid of most unused or expired medicines is a take-back option: a drug take-back location, which can be at a pharmacy or a police station, or a prepaid mail-back envelope. If you cannot use one and the medicine is not on the FDA's flush list, the FDA says to mix it with something unappealing such as dirt, cat litter or used coffee grounds and to seal the mixture in a plastic bag before throwing it away. Flushing is only for medicines on that list, such as opioids. Do not give leftovers to another pet.
Write the dose, the times and the stop date here, then print this page for the fridge.
Dose and times: _____________________________________________
Stop date: _____________________________________________
The 2026 dog diabetes guideline, in plain English: what well controlled actually means, every insulin with its starting dose, the syringe that has to match the bottle, the meal rule, and what to do when the sugar goes too low. Diabetes in dogs.