Veterinarians and pet owners are being warned about possible problems with Caninsulin, a drug used to treat diabetes in dogs and cats. (Associated Press)

Veterinarians and pet owners are being warned by Health Canada about possible problems with Caninsulin, a drug used to treat diabetes in dogs and cats.

The problems relate to varying amounts of crystalline zinc insulin in the product, which could cause either a delay in the time it takes to become effective or lead to longer-lasting effects. The result could be unpredictable fluctuations in the glucose levels of treated animals.

Health Canada and the manufacturer, Intervet/Schering-Plough Animal Health, are asking veterinarians and pet owners to watch for signs of either low or high levels of blood sugar.

The classic signs of high blood sugar include increased thirst and urination, weight loss and lethargy. Signs of low blood sugar include disorientation, unsteadiness, weakness, lethargy and seizures.

Health Canada encourages veterinarians to report any adverse events to Intervet/Schering-Plough through the Technical Services Department at 1-866-683-7838. Consumers requiring more information can contact Health Canada's public inquiries line at (613) 957-2991, or toll-free at 1-866-225-0709.