Vetsulin is of pork origin and is similar to canine insulin. Vetsulin can also be used in cats, although feline insulin is closer in structure to beef insulin. Vetsulin is considered to be intermediate-acting insulin.

PZI insulin is used almost exclusively in the cat and is beef origin. It is long-acting insulin. Unfortunately, in 2008 its manufacturer exhausted its supply of beef pancreas and discontinued production and currently only limited supplies are still available. PZI is available through compounding pharmacies, but these sources do not have adequate quality control, meaning the relative strength from batch to batch is not predictable. If one opts for PZI, it is preferable to “bite the bullet” regarding cost and order the reliably manufactured products or change to insulin that is more readily available.

Lantus Insulin (Glargine) was marketed for human diabetics as a “peakless” insulin, meaning that it maintains glucoses in a narrow range. It is long-acting insulin used in humans to provide a basis for glucose control which is then fine-tuned with short-acting insulins. Lantus has proved very effective for diabetic cats and is available at most regular drugstores.

Humulin R – fast acting and is similar to insulin secreted by one’s body. This insulin acts too fast and lasts too short a time to be useful in the home setting for pets. It is often used in the hospital setting to quickly reduce dangerously high blood glucoses.

Humulin N – intermediate acting. Most commonly used forms of insulin and is usually used twice a day in pets.

There are two types of insulin syringes: U-40 (for insulin of the 40 units per cc concentration) and U-100 syringes (for insulin of the 100 units per cc concentration). The type of syringes used must match the insulin used. Most human insulin’s (Lantus and Humulin) are 100 units per cc while most veterinary insulin’s (PZI and Vetsulin) are more dilute at 40 units per cc.

Insulin syringes may be available through your veterinarian’s office or through your regular drugstore but do not be surprised if a prescription is needed from your drugstore. Insulin purchased at the drugstore may or may not require a prescription. Insulin is considered an over-the-counter medication for humans, but when it is used in pets, it is technically “off-label” so a prescription may be needed.

Insulin syringes are made extra fine so that human diabetics will not feel them. Veterinary syringes are similarly fine and your pet should not object to injections.

How to Give Insulin Injections