Veterinarians have more options than ever for monitoring and treating diabetic cats and dogs
Pancake, a male Siamese cat, had unregulated diabetes six months after first being diagnosed with the disease—by his owner, a physician.
The obese cat had been on various insulins and dosing schemes. His owner measured his blood glucose two to four times daily and gave him an insulin dose on the basis of the measurements, similar to what she might have recommended for her human patients. He had persistently high blood glucose in the face of a rising insulin dose.
Dr. Jessica Pritchard, a clinical assistant professor of small animal internal medicine at the University of Wisconsin-Madison, described Pancake’s case while presenting the session “Updated Strategies for Monitoring Diabetes and Troubleshooting Your Difficult Diabetics” at AVMA Virtual Convention 2021 in July.
Dr. Pritchard picked one dose of insulin for Pancake and did a blood glucose curve using a flash continuous glucose monitor. The cat turned out to be not insulin resistant but overdosed. A follow-up curve found the insulin duration was too long, so Dr. Pritchard switched to an insulin with a shorter duration. She also added a weight-loss plan.
Pancake’s case illustrates a few of the intricacies of managing diabetes mellitus in pets. Diagnosing the disease in cats and dogs is pretty straightforward, but treatment and monitoring can be complex—especially with more options available than ever, including flash continuous glucose monitors, subject of another session at AVMA Virtual Convention 2021.
Banfield Pet Hospital’s State of Pet Health 2016 Report found that diabetes mellitus in dogs increased by 79.7% between 2006 and 2015, to 23.6 cases per 10,000 dogs. Prevalence in cats increased by 18.1% over the same time frame, to 67.6 cases per 10,000 cats. Obesity is one risk factor for diabetes, and more than half of cats and dogs in the United States are overweight, according to the Association for Pet Obesity Prevention.
A committed effort
Among recent resources to help veterinarians treat diabetic pets are the 2018 AAHA Diabetes Management Guidelines for Dogs and Cats from the American Animal Hospital Association and the Diabetes Educational Toolkit for managing cats released in 2019 by the American Association of Feline Practitioners.
“Diabetes mellitus (DM) is a treatable condition that requires a committed effort by veterinarian and client,” according to the AAHA guidelines. “Due to many factors that affect the diabetic state, a pet’s changing condition, and variable response to therapy, management of DM is often complicated. Success requires understanding of current scientific evidence and sound clinical judgment. Each patient requires an individualized treatment plan, frequent reassessment, and modification of that plan based on the patient’s response.”
According to the guidelines, diagnosis of diabetes mellitus is based on persistent glucosuria and hyperglycemia and the presence of characteristic clinical signs such as polyuria, polydipsia, polyphagia, and weight loss.
Insulin and dietary modifications are the mainstays of treatment for diabetes mellitus in cats and dogs. Remission is possible in cats.
According to the AAFP’s Diabetes Educational Toolkit: “Effective treatment is based on a combination of client goals, finances, implementation of the treatment plan, and the patient’s response. It is very important to establish goals with the owner at the initiation of treatment and to maintain a frequent, open dialogue.”
For cats, the toolkit recommends a low-carbohydrate diet along with maintaining weight if the cat has a good body condition score or managing obesity. The toolkit lists lente, glargine, protamine zinc insulin, and detemir as insulin options for cats.
According to the AAHA guidelines, treatment of diabetes mellitus in dogs always requires insulin. The guidelines list lente, glargine, protamine zinc insulin, and neutral protamine hagedorn as insulin options for dogs.
Higher-fiber diets are recommended for diabetic dogs, either diets designed for weight maintenance in dogs that are not obese or diets designed for weight loss in obese dogs.
“Monitoring diabetic pets can be challenging,” according to the AAHA guidelines. Among various monitoring methods, a blood glucose curve is the only way to know how to appropriately change an insulin dose.
The traditional approach to getting a glucose curve involves hospitalizing the patient to have measurements taken. Recently, veterinarians have started to use flash continuous glucose monitors for at-home glucose curves.
A new tool
Dr. Lawren Durocher-Babek, a specialist in small animal internal medicine at 9 Lives Hong Kong, presented “Rational Use of Flash Continuous Glucose Monitors in Small Animal Medicine” in July at AVMA Virtual Convention 2021.
FCGMs consist of a sensor that attaches to an animal for up to two weeks along with a reader or smartphone to collect data. Dr. Durocher-Babek explained that FCGMs are continuous glucose monitors that check glucose one moment at a time.
The sensor has a filament that samples interstitial fluid once a minute to measure glucose. The data points are merged every 15 minutes and held in the sensor for up to eight hours. A reader or smartphone is used to scan the sensor, and then data are transferred to the web, where they are analyzed and stored.
Problems with FCGMs include that they are inaccurate at very low ranges of glucose, dehydration can cause issues, they don’t always last two weeks, pets can have skin reactions, and owners can be overly anxious.
Why should veterinarians consider using flash continuous glucose monitors? FCGMs are able to catch rebound hyperglycemia after an insulin dose that is too high, which can lead to better regulation. There is a decreased stress response in pets, in comparison with blood draws and usually a hospital stay. The system is possibly cheaper in the long run. And FCGMs allow pet owners to be more involved.
The FreeStyle Libre is the type of FCGM that is most commonly used in veterinary practice. Among the ideal patients for FCGMs are the newly diagnosed, difficult-to-control diabetics, pets with diabetic ketoacidosis, cats going into remission, and surgical patients. The ideal clients are those who are not too anxious, will listen to instructions, and want to be involved.
In her practice, Dr. Durocher-Babek usually places the FCGM while the patient is in the hospital. She replaces the sensor every two weeks until the patient is regulated. Then she places a sensor every three to six months. When the sensor is in place, owners email her weekly with updates, and then she looks at the data.
Dr. Durocher-Babek’s take-home points were to still evaluate clinical signs, give clear instructions to owners, and know that FCGMs are not perfect but still good for trends.
She said, “This is a good tool but does not take the place of a good veterinarian.”
Dr. Pritchard, Pancake’s veterinarian, said her goals for diabetes management in dogs and cats are to control clinical signs and have an absence of hypoglycemia. She said difficult-to-control diabetics are pets with recurrent hypoglycemia or pets with persistent hyperglycemia and clinical signs.
Dr. Pritchard started her talk at AVMA Virtual Convention 2021 by covering basic monitoring and glucose curves before delving into investigation of the uncontrolled diabetic.
For the initial investigation, Dr. Pritchard said, start by ensuring proper insulin handling. Watch the owner give the insulin. Questions to ask: Is the insulin shaken or rolled? Where is it stored? Who gives the insulin usually? Are there changes in color, consistency, or clarity?
Next, check mealtime habits. Is the owner feeding meals or free-feeding? Is the owner giving snacks between meals? Have there been diet changes recently? If the pet won’t eat its diet, try changing the diet to something the pet will eat reliably. Other options might be an appetite stimulant or feeding tube. If another pet is eating the food, try a feeder with radio-frequency identification.
Finally, take a thorough drug history. Among the things that are likely to cause insulin resistance are steroids and cyclosporine, plus hormones in intact animals. Don’t forget alternative routes of exposure such as owners’ hormone creams or pets’ eye drops, topical sprays, or ear drops. If the pets’ medications are the problem, ensure the drugs are necessary, evaluate alternative administration routes, evaluate alternative drugs, or increase the insulin dose.
For further investigation of the uncontrolled diabetic pet, Dr. Pritchard said, there is no substitute for a good history and physical examination. Has the owner noticed anything new at home? Have there been changes in the hair coat or dental changes? Has a goiter developed? Has the pet gained weight to the point of obesity?
Dr. Pritchard recommended that baseline diagnostics should consist of weight, the physical examination, a complete blood count, chemistry with triglycerides, urinalysis, urine culture, and a thyroid panel.
Run additional diagnostics on the basis of suspected concurrent conditions. These could include hypothyroidism, urinary tract infection, renal disease, hypertriglyceridemia, feline hypersomatotropism, canine hyperadrenocorticism, and pancreatitis.
Dr. Pritchard concluded her talk by covering additional monitoring strategies, including at-home urine tests.
“Don’t underestimate what your clients can and will do,” she said.