Insulin for dogs explained: the types vets use, matching syringes, switching and storage

What insulin does

A diabetic dog can't make enough of its own insulin, the hormone that lets the body use sugar from food. The injections replace it. Given with meals, at steady times, they keep blood sugar in a safer range so your dog feels well.

Insulin is a medicine your vet prescribes and adjusts for your dog. Everything on this page is about understanding it and handling it safely, never about changing the amount. How much insulin to give is always on your vet's plan.

The insulins vets use

Dog insulins are made either from purified pig insulin or from human insulin produced in a lab.

Pig-based insulin is typically recommended for diabetic dogs, and it's a first choice for many vets.

Another option is a lab-made human insulin that is approved for dogs. Your vet may also prescribe a human insulin for your dog in some circumstances. Use one only if your vet has prescribed it, with the syringe they name.

No type is "the best" for every dog. Your vet chooses the insulin that suits your dog, their routine and how they respond. Insulin types: questions for your vet lists good things to ask.

Reading your insulin label

Every bottle is labelled with the insulin type and its strength. Get to know your label: the name, the strength, and the expiry date.

Check the label each time you collect a new supply. If anything on it looks different from last time, ask the pharmacy or your vet before you use it.

Matching the syringe to the insulin

There are two common strengths of insulin, and each has its own matching syringe. The markings on the syringe must match the strength of the insulin you're using.

This matters more than almost anything else on this page. Using the wrong type of syringe means your dog won't get the right amount of insulin, even if you fill it to the usual line. It can be far too much or far too little, and too much can drop blood sugar dangerously.

If your insulin comes with a pen, don't draw it up with a syringe unless your vet has told you to. So: only use the syringes your vet or pharmacy gave you for this insulin, check the syringe packet against the insulin label, and never mix syringe types. If you're ever unsure, ask before the next injection. Which syringe matches my insulin? and which syringes and needle size to buy go further.

Pens are another option for some insulins. Are insulin pens an option for dogs? covers them, and your vet can tell you whether one suits your dog.

Shake or roll?

Different insulins are mixed differently. Some should be gently rolled and not shaken, while others should be shaken thoroughly.

Some are shaken until they look evenly milky, and others are gently rolled until they look evenly cloudy and white. Follow the leaflet that came with yours.

That's why advice that says "never shake insulin" can be wrong for your bottle. The rule that's always right: follow the leaflet that came with your insulin. If it doesn't look the way the leaflet describes after mixing, or there are clumps, don't use it, and call your vet or pharmacy.

If your vet switches the insulin

Sometimes a vet changes a dog's insulin, because of supply, how a dog is responding, or a new plan. Never make that switch yourself, and never swap to a different brand or syringe type on your own. Changing treatment: speak to your vet explains why.

When your vet does change it, expect a talk about the new plan and follow-up checks. It's common for a dog's control to shift for a while after a switch, so your vet will want to watch closely, including for signs of low blood sugar.

A new insulin can come with a new syringe, a new strength or a new timetable, and that can be confusing. Ask your vet to write the new plan down, and copy it onto the blank insulin schedule. Keep an eye out for low blood sugar in the weeks after.

If your usual insulin is out of stock or recalled, what to do starts with a call to your vet, not a swap from the shelf.

Storing insulin, and when to throw a vial away

Keep insulin in the fridge, but never let it freeze. Keep it away from the freezer compartment and the back wall of the fridge, where things can ice up.

Heat and direct sunlight make insulin lose its strength, so don't leave it on a windowsill, in a hot car or in a bag in the sun. How should insulin be kept at home? and power cuts and keeping insulin cool cover the practical side.

A vial that has frozen should be thrown away and a new one used. If a vial was left out of the fridge, call your vet or pharmacy and ask whether it's still safe.

An opened vial only lasts a limited time after the first use, and the time is different for each product. Check your insulin's leaflet, write the date you opened it on the box, and ask your vet when to start a new one. Throw used needles away safely: how to dispose of used syringes.