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IS PZI INSULIN FOR CATS THE BEST CHOICE

By Tess Thompson

Diabetes in cats is the second most common endocrinal disease after hyperthyroidism. It is a condition in which blood sugar levels are high due to the inability of the pancreas to produce insulin, the hormone responsible for regulating storage of glycogen in the liver. In another type of diabetes, the cells become resistant to the effect of insulin leading to a high blodd sugar level in the body.

Symptoms of diabetes in cats are usually subdued, such as increased urination and thirst, and the condition, more often than not, is diagnosed after blood tests reveal high levels of sugar in the blood.

Although administering insulin is only about half the treatment, the selection of the appropriate insulin for your cat involves a large amount of hard work and experience. Generally there are three types of insulin - human recombinant DNA insulin, animal based insulin (sourced from beef or pork) and synthetic insulin.

PZI (Protamine Zinc Insulin) is insulin that has been combined with protamine and zinc. Protamine is a simple protein found in fish sperm, rich in arginine and normally sourced from the testes of salmon. This combination is used to slow the release of insulin into tissues. Traditionally, the insulin used as the PZI component, even for human use, was obtained from cows and pigs.

PZI insulin appears as a clear liquid with white insulin crystals at the bottom of the ampoule. On shaking, the mixture turns milky. It is typically injected twice a day just before mealtimes. Though some veterinarians recommend a single dose, in some cases a single dose may not be able to control blood sugar levels adequately.

Different types of insulin are classified on the basis of their initial action and duration of their affect on the patient, varying from slow-acting to intermediate to fast-acting. NPH (Neutral Protamine Hagedorn) is an intermediate acting insulin made from crystalline zinc insulin and positively charged polypeptide, protamine. Its action lasts longer than regular insulin. Insulin glargine is long lasting insulin whose affect normally lasts for 10 to 16 hours in cats.

Despite its name ‘human insulin’ does not come from humans. It is manufactured using a chemical process and structured in the same manner as natural human insulin. Beef based insulin is the best for cats as it matches the natural insulin produced by a cat’s pancreas.

Till the 1990s beef or pork derived PZI was the most preferred and recommended insulin for pets. It has since been phased out in most countries but sources still exist in USA and UK. Due to its suitability for cats it is now the preferred choice for cats once again.

The best choice of the insulin brand and type, however, depends upon each pet. Deciding the best choice requires a fair amount of trial and error experimentation. The veterinarian is the best person to decide this since synthetic human insulin may work with dogs but may not work as well for cats.

The rule ‘to each his own’, is highly applicable in this scenario where selecting the best insulin for your cat depends on the specific reactions of your cat. Since cats metabolize insulin must faster than any other animal, choosing the one best suited for your cat requires great care and vigilance.

References:
http://www.felinediabetes.com/pzi.htm
http://www.mvma.org/Proceedings/SAI/Thursday/SAThur4.htm
http://www.bcpvetpharm.com/Insulin.htm
http://www.bddiabetes.com/us/main.aspx?cat=1&id=370
http://www.petdiabetes.org/pzi.htm