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10 Facts You Need To Know About Diabetes In Dogs (Including Symptoms, Diet and Treatment)
Dog diabetes is a subject that exemplifies all that is wrong with the modern veterinary nutrition landscape.
It is a horrible, deadly disease. One that causes dogs to suffer and their owners to hemorrhage money. But despite all this (and despite being noncommunicable) it is nevertheless growing more prevalent by the day.
How could this be? Don't we all love our dogs? Aren't we constantly being told that our devotion to their health and wellbeing at an all-time high? Isn't veterinary medicine being practiced at the most sophisticated level in the profession's history?
To my eyes, the problem at the heart of the chronic disease epidemics plaguing cats and dogs in the United States is the outsized and disingenuous role that legacy pet food companies play in shaping what practicing veterinarians believe about nutritional science. All too often this unholy arrangement causes well-settled science and all semblance of common sense to take a backseat to profits.
And nowhere is this reality better demonstrated than with dog diabetes.
This makes it vitally important for the owners of diabetic dogs to understand the truth about the disease -- what does the science actually say, what are veterinarians being taught, and where do those two bodies of information diverge?
I may be a complete fraud with a massive conflict of interest, but I did spend four years writing a book about bad science and misinformation in the veterinary nutrition community. And I know as much as anyone on the planet about the "dirty tricks" being practiced by Big Kibble.
As you'll see, some of the facts are scientific in nature while others have to do with the cultural matters. If your dog has recently been diagnosed with the disease (or you're afraid that such a diagnosis may be forthcoming) and you want to make sure you know enough about it to be an informed participant in her treatment plan, this one's for you.
10 facts about diabetes in dogs that every pet owner should know:
1) Dog diabetes is common.
Diabetes is one of the more common nutritionally-mediated diseases in domestic dogs and is likely the single most common endocrine disorder overall. Recent studies put the incidence rate in Western countries at somewhere between 23 and 130 cases for every 10,000 dogs.
That means there may be a million diabetic dogs in the United States right now. It also means that diabetes is 20 to 100 times more common than DCM (dilated cardiomyopathy), the rare dog heart disease that has received an absurdly disproportionate amount of press coverage and public health attention since 2018.
It's not the single most prevalent chronic disease among American dogs (cancer, obesity, and osteoarthritis are certainly more common), but it's up there. And, unfortunately, the numbers appear to be getting worse, not better.
2) Diabetes in dogs is becoming more and more prevalent.
The explosive rise of diabetes prevalence rates among American human beings is well-documented. According to the CDC, diabetes is more than ten times as common today as it was in 1958. Consider this shocking chart:
Unfortunately, our dogs seem to be on at least as bad a trajectory.
According to a 2016 "State of Pet Health" report prepared by Banfield Pet Hospital, the prevalence of diabetes in dogs, in the United States, has grown by approximately 80% since 2006. In other words, the growth rate in the dog population since 2006 is roughly three times the already-staggering rate seen among their owners.
3) Some breeds are genetically predisposed to greater diabetes risk.
In a 2013 study published in The Veterinary Journal, a group of British researchers concluded that some dog breeds are far more likely than others to contract the disease. A complete list of at-risk breeds is available in the body of the paper.
Interestingly, many of the highest-risk breeds fall into one of two groups: sled dogs and small terriers. Siberian Huskies, Samoyeds, Tibetan terriers, Cairn terriers, and Scottish terriers are all at least three times as likely as most breeds to contract the disease.
While any genetic predisposition for a potentially deadly disease was surely bred into these groups inadvertently, it is worth noting that one of the key physiological focuses of sled dog racing is also at the core of how diabetes works. That issue is glucose metabolism.
4) Diabetes is a disease of insulin deficiency and dysfunctional glucose metabolism.
So what is diabetes? At its essence, it is a disease characterized by a body's inability to regulate the amount of glucose ("sugar") in the bloodstream.
Glucose is the fundamental building block of all carbs -- it is literally what carbs are made up of. What we call "complex" carbs are those that are composed of long, complicated chains of glucose molecules. While "simple" carbs are made up of just a few.
In order to be put to use by the body, the carbs consumed as food first need to be broken down into individual glucose molecules. So during digestion enzymes and other digestive mechanisms cause starches and other dietary carbs to be converted back into individual glucose molecules, which then get absorbed into the bloodstream.
Once in the bloodstream, glucose can be put to productive use by a variety of bodily tissues, both in human bodies and dog ones. But problems can arise when supply exceeds demand. If blood sugar levels are allowed to get too high, the resulting condition (hyperglycemia) can cause debilitating damage to the eyes, kidneys, and cardiovascular system.
To put it simply, if glucose hangs around in the blood for too long it becomes toxic.
Fortunately, there's an antidote. The hormone insulin is produced by the pancreas whenever blood glucose levels get too high. Insulin's primary function is to drive down circulating glucose levels. It does this by shunting glucose into tissues like fat and muscle, where it can be stored safely, and by shifting metabolic energy production towards glucose (as opposed to fat) as a primary fuel source.
In diabetics, however, this process becomes dysfunctional. For one reason or another, their bodies aren't able to produce enough insulin to counteract the buildup of glucose. As a result, when blood glucose levels get too high (e.g., after eating a carb-rich meal), they stay high indefinitely. And that's a bad thing.
5) There are two different flavors of diabetes in dogs: insulin-dependent and insulin-resistant.
In human beings there are two primary varieties of diabetes, Type I and Type II.
In Type I (or "insulin-dependent") diabetes, the pancreas is defective and can't produce insulin very well (or at all). As such, Type I diabetes results in an absolute insulin deficiency.
In Type II ("non-insulin-dependent" or "insulin-resistant") diabetes, the pancreas produces insulin perfectly well, but the hormone doesn't do what its supposed to do because the body has become desensitized to its effects over time. In other words, Type II diabetes results in a relative insulin deficiency.
The Type I/Type II distinction has not been adopted in the veterinary community. Still, dogs can develop varieties of both IDD and IRD, with the majority of dog cases appearing to be some form of IDD. For readers interested in developing a deeper understanding of this topic, this paper provides a bit more context about the pathophysiology and classifications of the disease as experienced by dogs.
6) What to Watch For: Dog Diabetes Symptoms, Signs and Diagnostic Criteria.
The most common dog diabetes symptoms are excessive thirst, increased urination, lethargy, weight loss, and cataracts/blindness.
Pet owners should pay particularly close attention to these symptoms over the back half of their dog's expected lifespan. Surveys suggest that diabetes is very much a disease of adulthood, with the average age of diagnosis in dogs being 9-10 years. Here's a graphical summary of the age of diagnosis from a sampling of 500 diabetic dogs in the U.K. (from the 2005 paper referenced immediately above):
If it sounds like your dog might be experiencing the disease, the appropriate next step is a trip to the veterinarian. Diagnostic testing will typically include both a urinalysis and a blood serum profile, which will help your vet to look for the hallmarks of diabetes -- high levels of glucose in the blood and urine.
If testing supports a diabetes diagnosis it is likely that your vet will recommend beginning treatment immediately. This is because the longterm effects of the disease are grievous, painful, and life-threatening. And it is likely that treatment will include two separate components.
7) The two cornerstones of dog diabetes treatment are insulin supplementation and diet changes.
Since diabetes is a disease of insulin deficiency, there are two primary ways to reduce its impact: by increasing insulin supply and by decreasing insulin demand. A typical treatment plan for the disease will embrace both strategies.
Providing a dog with exogenous insulin will be her owner's responsibility. Unfortunately, it is costly and burdensome. It must be given via injection. It is pricey. And while once-daily doses often help, there's evidence that twice-daily injections are more efficacious. The injections won't cure the disease, only help to manage it. As such, they will need to be continued for the entirety of the animal's life.
The amount of exogenous insulin any specific dog requires will depend upon the size of the animal and the severity of her blood glucose abnormalities. The larger the dog and the higher her blood sugar, the more insulin she will need.
This is, of course, why a dog diabetes diet plays a role in the typical treatment plan. As mentioned above, dietary composition has a direct and significant impact on glucose levels. As such, food products shown to lower blood glucose are typically recommended. If diet changes can be used to bring down blood sugar levels then the amount of exogenous insulin needed will drop as well.
Unfortunately, this is where common sense and veterinary nutritional orthodoxy part ways.
8) Most prescription-only foods for diabetic dogs rely on a high fiber content to slow the absorption of glucose into the bloodstream.
There is evidence that, all else being equal, a fiber-rich diet will produce less pronounced blood glucose spikes than an otherwise-equivalent low-fiber diet. This is a well-documented and undeniable phenomenon. The mechanism at play is simple: indigestible fiber gets bound up with digestible carbs, slowing the rate at which the digestible molecules are broken down into glucose. The glucose thus enters the bloodstream more slowly, reducing the amount of insulin needed at any given time.
For this reason, the defining quality of prescription foods for diabetic dogs is a somewhat higher fiber content than found in garden-variety kibbles. There may be a few other bells and whistles, but the greater fiber content is the formulational backbone.
Sounds good, right? Wrong.
9) Rather than merely slowing the absorption of glucose, low-carb dog foods limit glucose absorption altogether.
There is another, more direct, way to blunt postprandial glucose spikes: just eliminate the digestible carbs altogether.
Recommending a high-fiber but otherwise typical kibble for a diabetic dog is akin to recommending a low-tar but otherwise typical cigarette for a lung cancer patient. Is it better than no change at all? Sure. But it also ignores a much more direct and powerful intervention.
Remember, all digestible carbs get broken down into glucose molecules during digestion. And it turns out that minimizing the amount of glucose that's flowing into the blood is a good way to keep blood glucose from spiking. (Who could have known, right?!) As such, the very best way to minimize postprandial blood glucose spikes is by minimizing the intake of digestible carbs (or, even better, by eliminating them outright).
Why switch to a low-tar cigarette when you could quit smoking?
If for some reason this doesn't strike you as clear as day, rest assured that it is well-supported by the scientific record too. Studies consistently show that eliminating digestible carbs from the dog diet causes postprandial blood sugar levels to come crashing down to Earth.
For starters, read:
- influence of diet on glucose tolerance, on the rate of glucose utilization and on gluconeogenic enzyme activities in the dog
- Metabolic and Immunological Effects of Intermittent Fasting on a Ketogenic Diet
- Glycemic and Insulinemic Responses after Ingestion of Commercial Foods in Healthy Dogs
It is a massive understatement to say that the makers of prescription diabetes formulas (and the vets that recommend such products) aren't giving enough credit to this evidence. It's more accurate to say that they are thumbing their noses at it.
Just consider the following table:
This was published in Hand et al.'s "Small Animal Clinical Nutrition," one of the two most popular veterinary nutrition textbooks being used in U.S. veterinary schools today. It purports to show the nutritional content of "commercial pet foods used in patients with diabetes mellitus," arranged according to market share.
As you can see, not one of the prescription diabetes products is less than 42% digestible carb.
Pretty gross, right? Just wait, it gets worse.
What are the authors' "nutritional recommendations for diabetic dogs"? They actually recommend (presumably with a straight face) that dog diabetes patients be fed foods containing "50 to 55%" non-fiber carb. These leading veterinary specialists -- the very ones teaching rising vets what they should think about nutrition -- recommend that at least half of food consumed by diabetic dogs be composed of glucose, the very molecule their bodies can't regulate.
Let that sink in for a minute.
10) Digestible carbs are integral to prescription dog diabetes diets for one reason only: they're cheap.
Domestic dogs don't have a daily carb intake requirement. They didn't consume any carbs whatsoever for more than 99.9% of their genetic evolution. And all digestible carbs are made up of the one thing that diabetic dogs need to avoid most -- glucose. There's literally no nutritional justification for using them in prescription food products for diabetic dogs.
Butt there's something else that's notable about dietary carbs too: as ingredients go, they cost far less to produce than other macronutrients (i.e., fat and protein). More specifically, according to this 2010 study, each calorie of meat costs about three times as much to produce as each calorie of grain.
In other words, a low-carb diet might help your diabetic dog reduce her glucose intake. But that doesn't make it good for Hill's bottom line.
And that's a pretty important reality to understand when you're weighing whether to trust this little article over the advice proffered in one of the country's leading veterinary texts. Why? Because it turns out that Hill's played a pretty significant role in putting that book together.
Two of the four book's editors were full-time employees of Hill's Pet Nutrition at the time of publication. Two of the four authors of the diabetes chapter were Hill's employees too. The book was dedicated to Mark Morris, Sr., the founder of Hill's. And, just in case there was any lingering confusion among readers, here's what you'll find on the back cover:
Don't take my word for any of this. I'm just a fraud with a massive financial conflict of interest. Take a look at the evidence linked above, leave your questions and comments on our social media channels, and consider bringing this all to your next veterinary visit. Then make the best decision you can for your best friend.