The state of diabetes: An industry review of diabetes (Sponsored by Abbott Animal Health)

Even with the advances in diabetic care, diabetes in pets has remained a particular point of interest and discussion among veterinary professionals. This report is the result of input from animal health associations, sources from the animal health industry, and practitioners of veterinary medicine, who each contributed information and their unique points of view about diabetes in pets. The "State of Diabetes" is intended to provide not only appropriate background on diabetes in cats and dogs, but also practical strategies on how veterinarians and veterinary technicians can address risk factors and provide effective management by using the latest blood glucose monitors calibrated for veterinary use, veterinary insulin products, and special diets that address the individual needs of a diabetic cat or dog.

Every time veterinarians use the knowledge gained from human diabetes management to control the disease in dogs and cats, they honor the canines that played a key role in the medical advancement and understanding of human diabetes. In 1890, Drs. Joseph Von Mering and Oskar Minkowski inadvertently created an animal model of diabetes when they discovered dogs displayed signs of polyuria and polydipsia associated with glucosuria when the pancreas was removed. And in 1921, Dr. Frederick Banting and his Toronto team isolated insulin from the pancreas of dogs. They spent the next year testing the new hormone in diabetic dogs, forever changing the way human diabetes is treated.

The goal of diabetes management for dogs and cats is the same as for people: good glycemic control. And the cornerstones of this management are insulin, diet, monitoring—including home monitoring—and exercise, according to recent American Animal Hospital Association recommendations.

Successful insulin therapy and diabetes control require consistent timing, accurate dosing, and careful monitoring, which rely heavily on pet owner participation. Owners should check their pets' blood glucose, give insulin on a regular schedule, and feed their pets a regimented diet.

Additional information on canine and feline diabetes

Pet owners are essential to producing accurate glucose measurements and implementing recommended treatment changes, but they cannot be successful unless they know how to establish and follow a routine schedule, properly administer insulin, and measure blood glucose. In addition, owners must know how to recognize what is and isn't normal so they will know when something is wrong with their pets.

Routine blood glucose monitoring offers great benefits to pet owners. For example, knowing that the blood glucose concentration is normal reassures owners when they have to leave the house. And a glucose concentration above or below normal tells the owner that the pet should see the veterinarian. Home glucose monitoring also provides valuable information to the veterinarian, who must decide whether or not to change the animal's treatment regimen.

Today veterinarians and pet owners can manage diabetes mellitus with the help of veterinary calibrated blood glucose monitors, diets that address their special nutritional needs, and insulin products indicated for veterinary use. This was not always the case, says Sara Ford, DVM, DACVIM, chief of internal medicine at the VCA Emergency Animal Hospital and Referral Center in San Diego.

In the past, management was based primarily on clinical signs, largely because blood glucose curves could only be performed in the hospital, and many animals were euthanized because of complications stemming from poor glucose control. "They would just crash and burn," says Jack Stephens, DVM, founder and president of Pets Best Insurance.

Standard glucose curve Acceptable ranges

Now we have good research to support current diabetes management recommendations, and owners can expect their pets to live a fairly normal lifespan if they partner with their pets' healthcare team to manage their pets' disease, says David S. Bruyette, DVM, DACVIM, medical director at VCA West Los Angeles Animal Hospital in Los Angeles.

"While diabetes is a chronic disease, it is something that clients are capable of managing," he says. "We always try to reassure the owner that this is something they can do, and it will not interfere with their life."

Talking to pet owners

The first step is to explain the disease to pet owners. "Diabetes is a common endocrine disorder in which the body either does not produce insulin or does not use it properly," says Bonnie Bragdon, DVM, a veterinary liaison with Abbott Animal Health, which makes glucose monitors calibrated for veterinary medicine. When blood glucose concentrations are elevated, the beta cells in the normal pancreas produce and secrete insulin, which binds to cells to absorb the glucose from the blood and provide the body with energy. The amount of insulin produced is directly proportional to the blood glucose concentrations; when glucose concentrations are high, the normal pancreas releases more insulin. As glucose concentrations stabilize, the normal pancreas releases less insulin.

Insulin must be present for tissues to absorb glucose, and the tissue cells must be responsive to that insulin. When there is a lack of insulin or if the normal secretion of insulin does not help the absorption of glucose, the tissues essentially starve, causing the body to break down fat and muscle tissue to find energy. This can lead to poor body condition and weight loss, despite an increased appetite, Bragdon says.

Insulin resistance

Insulin resistance occurs when cells become less responsive to the effects of insulin; therefore, more insulin is needed to achieve the same effect. Eventually, the pancreas cannot keep up with the body's increased demand for insulin, and type 2 diabetes results. Many factors can cause insulin resistance, including obesity, acromegaly, hyperthyroidism, and some medications, such as corticosteroids or progestins.

"The pancreas secretes another hormone besides insulin called amylin, which is thought to be related to appetite and other functions," explains Dottie Laflamme, DVM, PhD, DACVN, at Nestlé Purina PetCare, which makes Purina DM and DCO, diets specially formulated for cats and dogs with diabetes.

This islet cell amyloidosis can lead to beta cell loss or dysfunction, resulting in a decrease in insulin production and type 1 diabetes or a worsening of type 2 diabetes. Chronic pancreatitis can have similar effects.

Prevalence

The true incidence of diabetes among cats and dogs is unknown, but experts believe that it is increasing because of the obesity epidemic and the longer lifespans of cats and dogs. The estimated incidence of obesity among dogs is 22% to 40%, according to a review by Alexander J. German from the University of Liverpool.1 Many studies have estimated the incidence of obesity among cats to be between 19% and 52%.2 A 2004 Queensland University report found that the prevalence of diabetes in dogs was 58 per 10,000 in 1999, up from 19 in 10,000 in 1970.3

Diabetes is more common in cats than dogs, according to unpublished data by the Banfield Applied Research and Knowledge (BARK) team, which looked at almost 1.9 million canine records and more than 406,390 feline records in 2009. Diabetes tends to afflict neutered male animals older than 10 years—the BARK team found that the prevalence of diabetes in dogs between 3 and 9 years old was 0.3%, and it was 1% in those 10 or older, according to Elizabeth Lund, DVM, MPH, PhD, senior director of research at Banfield, The Pet Hospital.

A 2007 study in the Journal of Feline Medicine and Surgery put the incidence of feline diabetes in a 1999 tertiary care population at 124 per 10,000 cats, or 1.2%.4 A more recent study by Dr. Lund that looked at the population of cats seen at U.S. Banfield hospitals found that the prevalence increased by nearly 70% from 40.3 per 10,000 cats in 2002 to 67.3 per 10,000 cats in 2008.5

"We have been assuming a national incidence of diabetes in cats to be 1:200," says Kurt Peterson, DVM, of Boehringer-Ingelheim Vetmedica Inc., maker of ProZinc, a long-acting insulin with a feline indication. "ProZinc is being used in more than 10,000 veterinary clinics in the United States, and its use is growing."

In the last four years, Pets Best Insurance paid out claims for a diagnosis of diabetes in 90 dogs out of 25,078 insured dogs and 80 cats out of 3,654 insured cats, according to Dr. Stephens. The incidence rate was 0.4% for dogs and 2.2% for cats.

In a typical year, 64% of medical professionals diagnose up to 20 cats or dogs with diabetes. Of those who treat or diagnose diabetes, 86% recommend a treatment program that includes some form of ongoing monitoring of glucose concentrations, and most recommend blood glucose monitoring, according to Abbott Laboratories market research.

Diagnosis

The clinical signs of diabetes are similar for cats and dogs. The disease is often diagnosed after owners bring their pets to the veterinarian because they notice polydipsia, polyuria, polyphagia, and weight loss.

Additional signs include lethargy, weakness, and poor body condition as well as cataracts in dogs and peripheral neuropathy in cats. Some animals develop diabetic ketoacidosis with anorexia, dehydration, and vomiting.

Diagnosis is based on the presence of clinical signs and persistent glycosuria and hyperglycemia—more than 200 mg/dL for dogs and 250 mg/dL for cats, according to 2010 diabetes guidelines issued by the American Animal Hospital Association (AAHA).

"However, blood glucose [testing] has limitations in cats. Cats often have stress hyperglycemia because of visiting the doctor. Stress hyperglycemia is difficult to distinguish from a disease-associated hyperglycemia," Dr. Laflamme says.

"Putting them in a carrier makes them stressed. Putting them in a car makes them stressed. Doing a blood draw makes them stressed," Dr. Ford says. "If the cat is really upset, the blood glucose will go into the diabetic range, and there will be glucose in the urine."

Measuring serum fructosamine concentrations, a glycosylated protein that represents an average blood glucose concentration over time, can confirm the diagnosis. "If that value is elevated, then you know that the cat has a blood glucose that has been elevated for a few weeks, and you know that the glucose is not high because the cat is stressed," Dr. Ford says.

Elevated blood glucose levels due to stress are another reason some veterinarians advocate working with owners of diabetic pets to institute a home monitoring program. Home monitoring can improve glycemic control by minimizing interference from stress, in addition to accurately reflecting the pet's typical daily environment where feeding and exercise levels are also normal.

Dogs

Dogs tend to develop insulin-dependent diabetes mellitus, often referred to as type 1 diabetes, and they require insulin for the rest of their lives. Canine diabetes is thought to result from an immune-mediated destruction of the pancreatic beta cells, which renders them unable to produce enough insulin. A University of Queensland study supports this idea. Researchers found that more than 50% of diabetic dogs tested positive for pancreatic islet cell antibodies, suggesting the response was mediated by the immune system.3 Studies have also shown that about 28% of dogs with diabetes have a history of severe or chronic pancreatitis.3

A few dogs can develop a noninsulin-dependent diabetes mellitus, or type 2 diabetes, which results from a lack of tissue-cell responsiveness to insulin, leading to beta cell exhaustion. This occurs when the pancreas tries to accommodate the chronic demand for insulin.

Female dogs can also have gestational diabetes during diestrus or pregnancy that may be related to the effects of progesterone. Although this diabetic state might resolve, many dogs still require insulin after giving birth or being spayed.

Canine diabetes is most commonly seen in older dogs, spayed females, and certain breeds with a genetic predisposition for the disease, such as keeshonds, Samoyeds, Australian terriers, and miniature poodles. Standard and miniature schnauzers, spitz, fox terriers, bichon frise, Cairn terriers, and Siberian huskies may also be at elevated risk for developing diabetes.6

Cats

Because 85 to 90% of diabetic cats have type 2 diabetes, their beta cells are still able to produce insulin, and they may be still producing it when they are diagnosed. If type 2 diabetes is detected while the beta cells are still functioning, an appropriate treatment and management protocol can result in clinical remission, experts say.

Many cats diagnosed with diabetes are obese, making it the primary risk factor for the disease. Obesity causes tissues to be less sensitive to insulin when adipocytes produce too much of the hormone leptin and stop producing the hormone adiponectin. Adiponectin allows insulin to bind to blood glucose. In addition, obesity induces a chronic inflammatory state in the body that further reduces insulin sensitivity. These changes lead to insulin resistance, persistent hyperglycemia, and beta cell exhaustion.

Diabetes occurs most frequently in inactive, neutered male cats that live indoors. Burmese cats are genetically predisposed to develop the disease.

Not quite normal

According to the American Diabetes Association, many people experience pre-diabetes, where blood glucose concentrations are higher than normal but not high enough to be called type 2 diabetes. Studies have shown that lifestyle changes can prevent or delay the onset of diabetes.

According to the American Animal Hospital Association guidelines, dogs and cats with early-stage diabetes are classified as having subclinical diabetes. An astute clinician can identify these animals, which often appear healthy, through routine laboratory work. This is one of many reasons why yearly or twice-yearly examinations are advantageous.

"There is a pre-diabetic stage in cats and dogs," says Dr. Ford, "but we are not as savvy at diagnosing it as doctors are with human patients."

Animals would benefit from earlier disease recognition. Research has shown that early detection and correction of hyperglycemia and obesity can prevent the progression of clinical diabetes in cats. Even though dogs will almost always remain on insulin for life, regardless of when diabetes is diagnosed, the insulin will be more effective if owners make lifestyle changes that help the animal reach an ideal body condition.

"Many feel that the disease is on the rise," says Dr. Peterson. "And proactive veterinarians are looking to diagnose it earlier through wellness screening."

Management

The goal of diabetes management for dogs and cats is to maintain good glycemic control and prevent clinical signs and diabetic complications. The cornerstones of this management are insulin, diet, home monitoring, and exercise.

Oral glucose-control products that can be used to manage human diabetes are not normally given to dogs and cats because they are not as effective as insulin and diet.

Insulin is normally given twice a day after the animal has eaten to avoid hypoglycemia. Although there are many insulin products available, only two are approved for use in dogs and cats. The AAHA guidelines recommend the porcine lente product (Vetsulin) for dogs if available and protamine zinc (ProZinc) for cats. AAHA does not recommend using compounded insulin.

"Insulin therapy works in dogs and cats just as it does in people," says Dr. Peterson. "It helps control hyperglycemia when the body cannot produce enough of its own insulin or if there is insulin resistance."

Proper diet is a key player in the control of diabetes in both cats and dogs, according to Deborah S. Greco, DVM, PhD, DACVIM, a senior research scientist at Nestlé Purina PetCare. "Fiber has been shown to be beneficial in dogs," says Dr. Greco.

Cats require a high-protein, low-carbohydrate diet. "I try to limit the carbohydrate content in these cats and use a high-protein, low-carbohydrate diet. The 'Catkins' diet has been associated with the highest remission rates," Dr. Greco says. In a study she performed in 2006, insulin was stopped in twice as many cats on a high-protein, low-carbohydrate diet than cats on a high-fiber, low-carbohydrate diet.

"The high proportion of cats going into remission is a relatively new phenomenon that is related to the relatively new availability of the high-protein, low-carbohydrate diets for cats," says Dr. Laflamme.

A strict diet and exercise regimen will help prevent hypoglycemia and improve overall health. For example, diabetic dogs should be fed every 12 hours, coinciding with insulin administration, while cats need multiple small meals a day. It's also important to warn owners against free-feeding cats, Dr. Greco says.

"We know that in both cats and dogs, obesity in general is a problem," says Dr. Bruyette. "And obese dogs and cats tend to be resistant to the effects of insulin, so we want to have animals that are at an ideal body weight. If they are too heavy, they can develop insulin resistance. And if they are too thin, they can develop ketoacidosis."

Because it is important that animals eat before they receive insulin, Dr. Greco suggests that owners gradually introduce the new diet to cats. They tend to be more reticent about food changes. "If you give insulin and the cat won't eat the diet you just prescribed, what are you going to do?

"Use a canned product if you can," Dr. Greco says. "Some owners think that a cat will not accept it, but normally that is not the case. It is usually the owner who does not like to give wet food. But you will have the best luck introducing a new food if you feed the cat a food it already likes to eat or boiled chicken, then gradually add the new diet and decrease the chicken over a few weeks."

And remember to tell owners that all food counts. Treats should be less than 10% of the diet, and they should be low in carbohydrates.

People with diabetes regularly check their own blood sugars. The AAHA guidelines recommend that owners do the same for their pets, and the availability of glucose monitors that are calibrated for veterinary use makes this a realistic part of care.

"They are extremely helpful," says Dr. Ford. "For many years, we used human meters, which substantially underestimated blood glucose concentrations. Now, we have a meter that is validated for dogs and cats, and we know it is accurate. We used to have to guesstimate. Now we know what the number is."

Abbott Animal Health surveyed 805 veterinarians and veterinary technicians about home glucose monitoring. About 21% of diagnosed diabetics being monitored for blood glucose are initiated on home monitoring. When recommending home monitoring, 35% of professionals recommend monitoring at least monthly, 18% recommend monitoring weekly, and 12% monitoring daily, Dr. Bragdon says.

Many practitioners who don't recommend daily home monitoring say they believe pet owners have reservations about sampling (59%), and some are concerned about pet owners making insulin adjustments (44%). Only 3% feel pet owners don't see a benefit.

"On average, professionals admit only 37% of those initiated on home monitoring are still compliant with the program after six months," says Dr. Bragdon. She adds that this number can be increased by working with pet owners to ensure they are familiar with their role in managing their pets' diabetes and that establishing clear and regular communication from veterinary technicians can serve to improve compliance.

Tips and tricks

Veterinarians and their team members must help owners establish and follow a routine schedule. This starts with showing pet owners how to properly administer insulin and measure blood glucose and includes teaching them how to recognize when something is wrong with their pets.

"We must come up with feeding strategies and insulin strategies so that the owner does not feel overwhelmed," says Dr. Bruyette. "One study found that one of the most common causes of death among diabetic dogs is euthanasia because owners become frustrated. It is important in the beginning that we reassure people that although diabetes is a chronic disease, it is a manageable disease."

Veterinary technicians are in the perfect place to handle the client education (see the Related Link "How do you control diabetes? Education and follow-up"). They can teach owners how to get a blood sample for monitoring and how to give the injections as well as offer encouragement and moral support.

"Veterinary technicians can play an integral role when used properly," says Dr. Peterson. "They can educate on how to give injections, monitor patients for changes, look for signs of hypoglycemia, and perform follow-up consultations over the phone. The first two months are critical to properly manage owner expectations and ensure regulation success. Thus, education and communication are huge."

Thanks to the human-animal bond, many owners will go to great lengths for their pets. To successfully manage dogs and cats with diabetes, pet owners must be part of the healthcare team, and the most effective way to get them on board is through good communication and education.

REFERENCES

1. German, A. The growing problem of obesity in dogs and cats. J Nutr 136, 1940S-1946S, 2006.

2. Schearer, P. Literature Review – Canine, Feline and Human Overweight and Obesity. Banfield Applied Research and Knowledge Team, 2010.

3. Rand, J et al. Canine and feline diabetes mellitus: Nature or nurture? J Nutr 134, 2072S–2080S, 2004.

4. Prahl, A et al. Time trends and risk factors for diabetes mellitus in cats presented to veterinary teaching hospitals. J Feline Med Surg 9 (5) 351-358, 2007.

5. Lund, E. Descriptive epidemiology of feline diabetes mellitus. Banfield J, Volume 5, Number 2, 13–16, 2009.

6. Guptill, L. et al. Time trends and risk factors for diabetes mellitus in dogs: Analysis of veterinary medical data base records (1970-1999). Vet J 165, 240-247, 2003.