Diabetes mellitus affects 1 in 400 cats and is on the rise, possibly because of increased obesity rates, according to Morris Animal Foundation. Intervet Schering-Plough, now owned by Merck Animal Health, makers of Vetsulin (porcine insulin zinc suspension), says about 1 in 500 dogs suffer from the signs of diabetes mellitus.
A Merck market study of more than 200 veterinarians showed that 70 percent had between one and 10 diabetic canine patients, while 26 percent said they treat 11 or more diabetic canine patients.
With such a significant number of feline and canine patients affected by the disease, primary care veterinarians and specialists alike have voiced concern about a significant industry issue—the availability of insulin brands they have grown to rely on.
“There’s always a concern that something will go off the market,” says Richard Goldstein, DVM, Dipl. ACVIM, Dipl. ECVIM, associate professor of small animal medicine at Cornell University in Ithaca, N.Y. “The trend in human medicine decides if an insulin brand will be available for veterinary use, considering many insulin forms vets use are actually created for the human market.”
Dr. Goldstein says human medical practitioners are trending toward using combinations of short- and long-acting insulins, which means owners of canine patients who primarily use insulin with an intermediate effect like NPH (Isophane) insulin, could have difficulty acquiring the preferred medication. Owners of diabetic dogs are typically required to give two-times-a-day insulin administration using NPH. A short-term insulin would be challenging for owners to administer, given its frequent need for dosing.
Elizabeth Hodgkins, DVM, J.D., of Yorba Linda, Calif., director of veterinary services for Ceva Animal Health, says bovine-derived insulin tends to be the most effective insulin for diabetic feline patients, while porcine insulin works well in canine patients.
“It would be ideal to have feline-specific and canine-specific insulin,” says Dr. Hodgkins, the manager of yourdiabeticcat.com and author of “Your Cat, Simple New Secrets to a Longer, Stronger Life.” “It may not be a realistic request, however, and unfortunately we’re stuck with using other species’ insulin.
“Eli Lilly made bovine-derived insulin for the human market that worked best for my feline patients, but it was discontinued, and so was Idexx’s Protamine zinc insulin (PZI),” Hodgkins continues. “Boehringer-Ingelheim’s ProZinc (protamine zinc recombinant human insulin) is FDA-approved for use in cats. [But no one product] is the best product for every patient.”
Steven Marks, BVSc, MS, MRCVS, Dipl. ACVIM, clinical associate professor of critical care and internal medicine at North Carolina State University in Raleigh, says animal-use-only products aren’t always the best, noting that most of the drugs he uses in a day are made for people.
“If I restricted my day to using veterinary-only drugs, it would start at 8 a.m. and end at 8:10 a.m.,” Dr. Marks says. “My concern for diabetic animals isn’t with only insulin availability, but with administration. I’d like a company to market an oral or non-injectable way to give insulin.”
While Hodgkins and Marks warn veterinarians not to get caught up in direct marketing, Goldstein says the industry could benefit from more companies marketing directly to veterinarians and investing in the industry.
“Companies like Boehringer-Ingelheim will care if there’s a problem with your feline patient using ProZinc, whereas the companies that make insulin just for human use will not,” Goldstein says. “If a company that manufactures insulin for human use plans to discontinue the product, there won’t be a notice, just one day you won’t be able to order it for animal patients. The makers of Vetsulin worked with veterinarians in recommending substitute insulin and even had a critical need program in place for a while.”
Although Merck Animal Health said Vetsulin was useful in both canine and feline patients, some say it was best for use in dogs only. Whether vets used it in all diabetic patients or only dogs, it has been missed by many practitioners. Since the critical need program was discontinued, veterinarians wonder if the product will ever be available again in the U.S.
“Vetsulin is currently not available in the U.S. due to manufacturing issues related to stability specifications,” says Paul Geurts, manager of media relations animal health for Intervet International B.V., the Netherlands.
“The Vetsulin critical need program was discontinued due to a different manufacturing issue that prevented consistent supply to the market,” Geurts continues. “Merck Animal Health is working diligently to resolve the stability and manufacturing issues so that we can reliably and consistently provide Vetsulin again to the U.S. market. We cannot provide a definite date of availability at this time.”
Some veterinarians wonder if other manufacturers have plans to release a new veterinary-specific insulin. While none of the companies talked to for this article said they are working on a new insulin formulation, Merck said it was not out of the question for future endeavors.
“There are no immediate plans to market another insulin in the U.S.,” Geurts says. “As a global leader in diabetes management, of course, we are always evaluating new and advanced technologies to help veterinarians and pet owners better manage diabetes in dogs and cats.”
Veterinary compounding pharmacies are another option for procuring insulin. Some veterinarians say compounded insulin is a great choice, while others are leery of the stability of insulin, although they use compounding pharmacies for other drugs.
“BCP Compounding [an animal-only pharmacy] makes PZI that I really like to use in cats,” Hodgkins says. “That’s the only insulin I prefer to use that’s available today. This insulin doesn’t get a lot of attention, but I’ve found it to be reliable.”
Now that glucose home testing is available, veterinarians say they’d like more clients to take pets’ glucose measurements at home.
“I prefer owners use a paw or ear stick to measure glucose levels,” Goldstein says. “I don’t think measuring glucose in urine is as reliable. I’d love clients to be able to monitor their pet by using a subcutaneous device, but we’re not at the point where this is an easy thing for owners to use.”
Cats and dogs are being treated more like family members than in the past, Goldstein says, but veterinarians need to discuss the commitment of properly caring for diabetic animals.
“The all-or-nothing approach used by some vets when it comes to caring for diabetic pets doesn’t work—owners may feel like they just can’t do it,” Goldstein says, referring to extensive lists of do’s and don’ts that are sometimes given to clients. “As veterinarians we need to help them find a care plan that works for them, like altering the pet’s diet.”
Veterinarians who have a special interest in diabetes say nutrition and the appropriate insulin form and dose are key to maintaining diabetic patients’ health. While veterinarians regularly recommend a high-protein, low-carbohydrate diet for diagnosed patients, Hodgkins contends that this diet can prevent a cat from becoming diabetic.
“Not every fat cat gets diabetes and not every diabetic cat is overweight,” Hodgkins says. “You can never divorce genes from a disease, but cats are more sensitive than dogs to processed carbohydrates. Giving a diabetic cat dry food is like feeding candy bars to a human diabetic. This is all after the disease has been diagnosed, but for cats, there’s a heightened possibility of preventing the disease in the first place if dry food is never fed.”
Hodgkins says that when she practiced medicine at her feline clinic, she required that clients feed their cats a high-protein diet. Aside from cats who became patients as diabetics, Hodgkins says, none of her patients became diabetic while under her care.
Not all veterinarians are convinced that a high-protein diet prevents diabetes, and they call for more evidence.
“Research suggests diabetes is more preventable in cats by helping them maintain a healthy weight,” Marks says. “However, there is not enough evidence, in my opinion, to suggest a high-protein diet from the start will reduce the cat’s risk of disease.”
Kristen Nelson, DVM, author of “Coated with Fur,” of The Animal Hospital at Tatum Ranch in Cave Creek, Ariz., and founder of Veterinary Creative LLC, notes that exercise is also necessary.
“I hope pet owners develop more thoughtful diets and lifestyles for themselves and their animals,” Dr. Nelson says. “The optimal condition is to prevent rather than treat diabetes.”