Vetsulin / Caninsulin Dose Calculator

Check the syringe before anything else

Vetsulin and Caninsulin are the same product under different names in different markets: a lente porcine insulin zinc suspension at U-40, meaning 40 units per millilitre. Human insulins and the syringes sold alongside them are almost all U-100.

A syringe barrel is printed for one concentration. Draw U-40 insulin into a U-100 syringe and the markings lie to you.

The first mismatch explains a common and frustrating picture: a dog whose dose keeps being increased because it never seems to work. The second is an emergency. Our units-to-mL converter shows the volume difference directly — one unit of U-40 is 0.025 mL against 0.01 mL for U-100.

Starting dose

The AAHA task force recommends lente insulin as the first choice for dogs, starting at 0.25 units per kg every 12 hours, rounded to the nearest whole unit. The Vetsulin label itself quotes a starting figure of 0.5 IU/kg, so both numbers appear in practice and the choice is the veterinarian’s.

Most well-regulated dogs end up averaging around 0.5 u/kg twice daily, within a published range of roughly 0.2 to 1.0 u/kg. That range is wide because canine insulin requirement genuinely varies that much, which is precisely why the maintenance dose is established by glucose curves rather than calculated once from weight.

Why glucose curves, not arithmetic

A blood glucose curve tracks readings across a dosing interval to show three things a single reading cannot: the lowest point, how long the insulin actually lasts, and whether it covers the full twelve hours.

This matters because the same dose fails in two opposite ways that look identical from the outside. Too little insulin leaves glucose high throughout. Too much can cause a rebound, where a low is followed by a counter-regulatory rise — and the owner, seeing a high reading, concludes more insulin is needed. Only a curve separates them, which is why raising the dose after a single high reading is exactly the wrong response.

Watch between visits for weakness, wobbliness, disorientation, unusual quietness, tremors or seizures. Keep a glucose source to hand and know your emergency vet’s number before you need it.

A note on cats

Lente porcine insulin is licensed for cats as well as dogs, but feline dosing does not work the same way. The starting dose for a cat is a flat 1 unit per cat every 12 hours — not a per-kilogram calculation — and the guideline is explicit that even a very large cat should not start above 2 units twice daily.

Cats are also more commonly managed on glargine or protamine zinc insulin than on lente, and they can enter diabetic remission, at which point continuing the previous dose becomes dangerous. Our cat insulin calculator and the dogs and cats guide cover the feline side properly.

Limitations & Safety Notes

• Vetsulin and Caninsulin are U-40. A U-100 syringe delivers roughly 40% of the intended dose — always match the syringe to the concentration printed on the vial.
• These are published starting ranges, not prescriptions. Canine insulin requirement varies widely and is established by a veterinarian using blood glucose curves.
• Lente, PZI, glargine and NPH are not interchangeable unit-for-unit. They differ in concentration, onset, peak and duration.
• Never raise a dose in response to a single high reading. Rebound hyperglycemia after an unrecognised low looks identical to underdosing without a curve.
• Cats are dosed on a flat starting unit rather than per kilogram, and can enter remission. Do not apply canine arithmetic to a cat.

Frequently Asked Questions