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Frequently Asked Questions 

Learn more about Caninsulin® and about the management of diabetes in dogs and cats.

General Caninsulin® Questions

Vetsulin (porcine insulin zinc suspension) is the name of Caninsulin® in the USA. Vetsulin is the first and only insulin approved by the US Food and Drug Administration for treating both canine and feline diabetes mellitus. Vetsulin and Caninsulin® are produced by Merck Animal Health and are usually available only on prescription.

Caninsulin® is an intermediate-acting, lente insulin containing 40 IU per mL of highly purified porcine insulin. As a lente insulin, Caninsulin® is an aqueous suspension containing approximately 35% amorphous zinc insulin and 65% crystalline zinc insulin.  The amorphous fraction is the short-acting fraction, while the crystalline portion is absorbed more slowly and is the longer acting fraction. 

Refrigerate at 2-8°C. Store in an upright position in the dark. Do not freeze.

The contents should be used within 6 weeks (vials) or 28 days (cartridges) and stored below 25°C after the first dose is removed.

Caninsulin® contains a porcine insulin zinc suspension. Suspensions, such as Caninsulin®, can separate out during storage and need to be thoroughly mixed before use. Please refer to the product labels for complete preparation instructions for Caninsulin® vials and Caninsulin® cartridges. Do not use if clumps, particles, or flocculation are visible after thorough mixing.

No. Caninsulin® is a mixture of amorphous (soluble) insulin and crystalline insulin. The crystalline part is relatively insoluble which is why the insulin activity lasts more than a few hours. Caninsulin® has a balance between the amorphous and crystalline parts. If Caninsulin® is diluted, this may result in an alteration of the pharmacokinetics of the product.

Caution should be exercised when changing from one insulin product to another. Any change in insulin should be made carefully, and only under a veterinarian’s supervision. Changes in insulin strength, manufacturer, type, mode of administration (syringe, insulin pen) and source (animal, human recombinant, analog) may result in altered regulation and lead to the need for a change in dosage.

No, the use of a syringe other than a U-40 insulin syringe will result in incorrect dosing. Using a U-100 syringe with Caninsulin® would result in an animal receiving 2½ times less insulin than required. Human insulins are formulated at a concentration of 100 IU/mL. If clients use a U-40 insulin syringe with a 100 IU insulin preparation, they would be injecting 2½ times the amount of insulin necessary, which could result in fatal hypoglycemia.

Caninsulin® porcine insulin has the same amino acid sequence as natural canine insulin, whereas the commonly prescribed biosynthetic human insulin has a different amino acid sequence. The similar structure may provide more effective regulation of blood glucose and decreases the risk of anti-insulin antibody development in dogs. Unlike the dog, anti-insulin antibodies do not appear to be a problem in cats.

Caninsulin® in dogs

The recommended starting dose is 0.5 IU/kg once daily, with the option to change to twice daily dosing if required. It is expected that around two-thirds of dogs will require twice daily dosing¹. In other words, around one-third of diabetic dogs can be managed well on once daily treatment with Caninsulin®.

1. Graham PA, Nash AS, McKellar QA. Pharmacokinetics of porcine insulin zinc suspension in diabetic dogs. J Small Anim Pract. 1997;38(10):434–438

A lente (intermediate-acting) form of insulin, Caninsulin® contains approximately 35 percent amorphous insulin for rapid onset of activity, usually peaking about 4 hours after injection and lasting 8 hours in dogs. The remaining 65 percent of the formula is crystalline insulin which is absorbed more slowly and peaks around 11 hours after administration in dogs. This formulation allows for a more continuous utilization of glucose to support the body’s energy requirements. Caninsulin® is administered subcutaneously once a day initially, although approximately two-thirds of dogs require twice-a-day administration for effective diabetes management.

Diabetic dogs in clinical trials responded to porcine insulin zinc suspension in the following ways:

  • Reduced incidence of clinical signs such as polyuria, polydipsia, and ketonuria in most dogs.
  • Substantially reduced mean 12-hour blood glucose concentration and mean blood glucose nadir post treatment, compared to pre-treatment levels.
  • Adequate blood glucose control in most dogs with less than one-third having hypoglycemic episodes.

Clinical studies have demonstrated that approximately one-third of diabetic dogs can be maintained adequately on once-daily doses of Caninsulin®. The other two-thirds of dogs will require twice-daily administration of Caninsulin®.

It is estimated that up to 23.6 per 10,000 dogs suffers from the signs of diabetes mellitus (Banfield State of Pet Health 2016 Report. p 12-13).

Caninsulin® in cats

A lente (intermediate-acting) form of insulin, Caninsulin® contains approximately 35 percent amorphous insulin for rapid onset of activity. The remaining approximately 65 percent of the formula is crystalline insulin which is absorbed more slowly. This formulation allows for a more continuous utilization of glucose to support the body’s basic functions. In cats, the peak activity following subcutaneous administration of Caninsulin® occurs between 1.5 and 8 hours (with an average of about 4 hours), and a duration of activity varies between 8 and 12 hours. Caninsulin® should be administered subcutaneously twice a day in cats.

Cats are usually started on 0.25-0.5IU/kg of Caninsulin® per injection twice daily. Glycemic control is evaluated based on clinical signs and blood glucose curves, supported by other laboratory results. Adjustment of the Caninsulin® dose is made according to clinical improvement, as well as average blood glucose concentrations and blood glucose curve nadirs. Treated cats have significantly lower blood glucose concentrations and a reduction in hyperglycemia-associated clinical signs compared with pretreatment levels. Diabetic remission may also be observed.

In cats, the initial recommended dose is 0.25-0.5 IU/kg, for a max of 2 IU per dose, and the injections should be given twice daily (BID) at 12-hour intervals. Initial dosing is based on a per animal basis. The duration of activity of Caninsulin® in the cat is between 8 to 12 hours, which is shorter than in the dog. Peak activity level occurs between 1.5 to 8 (average of about 4) hours in the cat.

Estimates of the incidence of diabetes mellitus in cats is 68 per 10,000 (Banfield State of Pet Health 2016 Report. p 12-13).

Diabetic clinical remission is a complete or partial disappearance of the clinical signs of diabetes in response to insulin treatment. It is important to remember that remission is not necessarily permanent, and any recurrence of clinical signs prompts the need for reevaluation.

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CANINSULIN® is a registered trademark of Intervet International B.V. Used under license.