David Finlay Pet Health Care Centres

Insulin therapy in the diabetic pet:
Insulin therapy In most diabetic dogs and cats, insulin therapy is the most effective treatment. Insulin is given by an injection under the skin of the scruff and most cats will be stabilised on a regime involving either once or twice daily injections. The exact site of administration should be changed on a daily basis to reduce any scarring or reaction at the injection site which may limit insulin absorption. Special insulin syringes with very fine needles are used so that the cat will hardly feel the injection. Veterinary surgeons often recommend that diabetic cats are offered food just before they receive their insulin so that the cat is distracted by eating and does not notice the injection. It is important that the insulin is given at the same time/s every day as directed by a veterinary surgeon. There are a number of different types of insulin available and different cats respond better to one type than another. Intermediate (eg lente) and long acting (eg protamine zinc) preparations are most commonly prescribed. Protamine zinc insulin has a long duration of action meaning that once daily treatment may be sufficient in some cats. There is a high degree of individual variability meaning that a proportion of cats will need twice daily insulin therapy to control their diabetes. The dose required by each cat is also very variable and it may take several weeks to stabilise the diabetes. Many veterinary surgeons will hospitalise diabetic cats undergoing initial stabilisation. Insulin should be kept in a fridge at all times and a new bottle started for each new diabetic and used for this cat only. Before withdrawing insulin for administration, the contents of the bottle should be gently mixed so that an even suspension is obtained. Excessively vigorous agitation can damage the fragile insulin chains reducing the strength of the suspension. Insulin doses are measured in units with most preparations consisting of either 40 or 100 units per ml. Where possible, insulin syringes should be used since these are calibrated in units and therefore enable accurate measurement of the insulin required. 100 unit and 40 unit syringes are commercially available. In some cases, the cat may be prescribed an extremely low dose of insulin in which case a diluted insulin preparation can be made using sterile water for injection or saline. This should be prepared by a veterinary surgeon and replaced every 2 – 4 weeks. The diluted preparation of insulin should be stored and handled as already described for insulin. The long-term outlook for cats with diabetes mellitus varies according to how old they are, how easy it is to stabilise their diabetes, whether they have any other diseases and how severe these are. In one study, the average survival time for diabetic cats was around 2 years. Many diabetic cats have an excellent quality of life and are extremely rewarding cases to treat.