Your dog’s pancreas is a small, lightish-pink organ nestled in the folds of its small intestine. Not much different from yours, it is not very striking. An untrained eye might mistake it for ordinary fat. You can see it in the fanciful image I put at the top of this page. Although it is quite small, the pancreas has two very critical functions. It produces the enzymes that allow your pet to digest and absorb food; and it produce a hormone (insulin) that regulates how your dog’s body utilizes and distributes sugar (glucose) in that food. Glucose is the main fuel for all animal cells. Most of that glucose is manufactured in your pet’s liver or liberated from carbohydrate in its meals. The process by which the pancreas regulates your dog’s blood sugar level is considerably more complicated than my simplified explanation. Should you wish to know the process in more detail, go here.
Many types of cells form your pet’s pancreas. The ones that are important in understanding diabetes are found in small islands (islets) scattered throughout its pancreas (islets of Langerhans). These particular insulin-secreting cells are called ß (beta) cells. There are two types of diabetes. The one dogs commonly suffer from is call diabetes mellitus. The much rarer form is called diabetes Insipidus . Even diabetes mellitus (DM) occurs in two forms. The most common form in dogs is similar in many ways to type 1 diabetes in humans. (ref) There are pitfalls in trying to make the types of diabetes we see in dogs conform to the terminology invented to describe diabetes in humans or in assuming that the causes and treatments for dogs and for us should be the same. For one, dogs - designed to eat meat - have less ability to process dietary carbohydrates, the origin of blood sugar, than humans. Some dogs process carbohydrates better than others. (ref1, ref2) So in some ways, diabetes in dogs and humans are similar. But in many ways they are not.
When the other, much larger (~95%), portion of your dog’s pancreas – the part that is involved in producing digestive enzymes - becomes inflamed or injured, it leaks those corrosive digestive enzymes. That situation is called pancreatitis. (ref) If the islet’s beta cells are injured during generalized pancreatitis, that can leave the pet diabetic as well.
The pancreas of healthy, non-diabetic dogs is able to keep its blood sugar level between 80-150mg/dL (4.4-8.3 mmol/L) . (ref1, ref2) Periodic, short blood sugar (glucose) rises normally occur after meals (=postprandial) but for most of the day, the dog's insulin keeps blood sugar levels under control.
Your dog’s kidneys are quite efficient in not allowing blood sugar to enter your pet’s urine. But when the level of glucose in your pet’s blood reaches 180-220 mg/dl, sugar will begin to escape ("spill") into your dog’s urine. (rptref) So repeatedly finding fasting blood glucose levels in your dog that are in excess or about 150mg/dl or finding sugar in its urine sample fulfils a diagnosis of diabetes.
Even though the blood sugar level of diabetic dogs is high, these dogs have problems utilizing that sugar to fuel the cells of their body. That is because insulin is required for the glucose to pass through a cell’s outer wall. (ref) Lacking that sugar energy source these cells normally depend on, the cells switch to fueling themselves using fatty acids. Those fatty acids do not require insulin to pass through the dog’s cell walls. However, the leftover residues of fatty acids are toxic. These residues can cause a dangerous condition called ketoacidosis.
In the majority of dogs the first signs of diabetes that owners notice is drinking more water than usual (polydipsia) and peeing more than usual (polyuria). That alone motivates most dog owners to bring their pets in for a check up. Others put off bringing their pets to veterinarians until more advanced signs like weight loss, dehydration, poor hair coat, enlarged tummy (enlarged liver=hepatomegaly), urinary tract infections or cataracts are present. A few arrive already showing the toxic signs of ketoacidosis.
Many pre-diabetic and early diabetic dogs are flagged on yearly “wellness” blood and urine exams. Those dogs show no serious outward signs of ill health, but their lab results are abnormal. Their blood sugar and triglyceride levels are too high and their ALP, ALT, and AST levels are often mildly elevated as well. (rptref1, rptref2)
The physical signs that you and your veterinarian see are never specific or unique to diabetes alone. Many medical conditions can have similar signs. Even the stress and anxiety of a visit to the vet can elevate your dog’s blood glucose levels. Both fever and kidney disease can cause increased thirst and urination. A number of non-diabetic liver and thyroid gland issues can be responsible for elevated triglycerides, ALP, ALT and AST too. The only way to be sure that your pet is diabetic is to document that its blood glucose level is persistently elevated or that sugar is persistently present in its urine.
The incidence of diabetes in dogs is not that high - certainly not as high as heart, kidney or liver disease. It seems to be about one in 500-700 dogs, depending on the study quoted. When it does occur, the signs of diabetes mellitus (DM) usually start between 5 and 12 years of age. It is very uncommon to see it in pets under the age of three. Considerably more female pets (about 72% are female) develop diabetes than males and certain breeds are genetically predisposed to the disease. Those breeds include the Samoyed (the dog in my drawing), schnauzers, keeshond, pulis, poodles, beagles, Tibetan terrier, dachshunds, schnauzers and cairn terrier. Other breeds, such as the boxers, golden retrievers and German shepherd dog, seem least susceptible. (ref)
For general information, when cats develop diabetes, their condition is more similar to human Type II diabetes. Those cats still produce some insulin, but it is no longer as effective as it should be. So what needs to be done for cats with diabetes is quite different from the best treatment plan when the disease occurs in dogs. (ref) If you want to read more about the problem in cats, go here. Interesting to me also is that as the frequency of diabetes has risen in people, it has risen in dogs (ref) as well as in cats. (ref) The veterinary community in the USA is accustomed to thinking about blood glucose levels in your dog in milligrams per hundred milliliters of blood. The rest of the World is accustomed to thinking about blood glucose levels in millimoles per liter of blood. If you wish to convert one unit of measure to the other, go here.
Veterinarians cannot tell you with any certainty why your dog developed diabetes. As I mentioned, we know that the disease is more common in some breeds than others. So breed genetics must play a part. We also know that diabetes is considerably more common in dogs that are overweight. We know it occurs more frequently in female dogs – so sexual differences must play a part as well. We also know that medications that favor high blood sugar levels (like corticosteroids) and hormones associated with a recent heat cycle or pregnancy seem to make diabetes more likely. So do adrenal gland issues like Cushing’s disease. Some believe that about 28% of the cases of diabetes in dogs are accompanied by or due to recurrent or chronic pancreatitis. (ref) Others believe the number is more likely 40%. (rptref) I can give you no explanation why, but more cases of diabetes are discovered during the cold winter months. In one study in Wisconsin, it peaks in January and February, (ref) in another in England, the same pattern occurred. (ref)
Here are my thoughts on some of those proposed causes:
Veterinarians like myself have no information as to how your dog being fat increases its risk of developing diabetes. That’s not surprising; human physicians do not know why being fat increases your chance of becoming diabetic.
In humans, it had long been observed that being overweight increases the risk of Type II diabetes. But Type I diabetes, the type most similar to what our dogs develop, was not traditionally associated with being overweight. Since 2015, opinions on that in human medicine have changed. Physicians now know that fat children are more prone to develop both type II and type I diabetes. Which type they develop and their underlying susceptibility probably depend on their individual genes. (ref1, ref2)
There are unproven theories on how body weight influences diabetes risk. Most of those theories revolve around the endoplasmic reticulum (=ER), the protein factories that almost all cells contain. In the ER, newly created protein need to be “folded” properly before they can be dispatched to their final destinations. High fat diets and obesity encourage the liver to produce more glucose and release it into the blood stream. High levels of glucose might cause the endoplasmic reticulum enough stress to cause it to miss-fold the newly synthesized proteins. Some believe that that eventually leads to the death of the insulin-producing beta cells in the pancreas. (ref) Of course, that’s just one of many theories. Others theorize that fat releases free fatty acids (NEFAs) that cause pancreatic inflammation and beta cell death. (ref)
Although the positive connection between diet ingredients, obesity and diabetes is clearer in humans and cats, it appears to apply to some dogs as well. (ref1, ref2) Fat also reduces the effectiveness of insulin. Compounds called adipokines and leptins are involved in insulin's effectiveness. You can read more about them and how they might pertain to diabetes here: (ref1, ref2, ref3, ref4)
When one removes a dog’s gonads (ovaries or testes), one removes a key player in the animal's endocrine system. All endocrine glands keep track of what the other endocrine glands are up to. When they sense abnormalities in the system, they attempt to rectify them - sometimes in ways that are not conducive to general good health and wellbeing. One of the most obvious effects of spay/neuter is weight gain. In dogs and other species, weight gain has been linked to diabetes (rptref) and chronic pancreatitis. (rptref) Weight gain has also been linked to a sluggish thyroid gland (hypothyroidism) which has also been linked to the neutering of male and female dogs. Neutering also increases the risk of hyperadrenocorticism (Cushing’s disease) Cushing’s disease often increases your dog’s blood sugar level. Cushing’s disease also increases your dog’s risk for diabetes. (ref)
I understand why many of us feel the need to neuter female dogs. The best advice I have for your is to consider personal responsibility as an alternative to surgery, wait for the dog to mature before having this surgery performed and concentrate on keeping your dog lean there after. (ref)
Autoantibodies are defensive molecules that your pet’s body mistakenly produces against its own tissue (in the case of diabetes,, the dog’s own pancreatic beta cells or the compounds those tissues produce, eg proinsulin). There is some evidence that this might be occurring in some diabetic dogs. Similar things occur in humans. (ref1, ref2)
Some studies report that almost a third of dogs that develop diabetes have chronic pancreatitis. Only a small portion of your dog’s pancreas is devoted to insulin production. The much larger portion produces the enzymes needed to digest food. When that larger portion of the dog's pancreas becomes inflamed, these highly corrosive enzymes leak into the surrounding tissue. The pet's insulin-producing beta cells can be a casualty of that inflammation. (ref) Immature keeshonds and golden retrievers occasionally develop sudden (acute) diabetes related to sudden pancreatitis. More recently, a number of greyhounds developed a similar problem.. You can read an article about the problem in greyhounds here.
It is apparent that certain dog breeds see more diabetes than others and that certain family lines within breeds are even more prone to it. That means that some combination of genes must be at play in promoting the disease. Genes often work in tandem with environmental and other factors that one does have control over. So the fact that your pet carries increased genetic susceptibility to a disease does not necessarily mean it will develop that disease. There have been great advances in the understanding of dog genetics as it relates to disease susceptibility. A study (limited to one breed) did not find genes that increased some dog's susceptibility to diabetes; but it did suggest that some gene combinations might protect against it. (ref) A missing "policeman gene" can be just as dangerous as a defecting instructional gene. A more recent study listed breeds in order of their genetic susceptibility to diabetes. Australian terriers, schnauzers and samoyeds top the list. (ref)
Your intact female dog’s heat (estrus) cycles have four different stages. The time just before ovulation, when the pet’s vulva begins to swell is proestrus. Once bleeding begins to occur, the dog is in estrus. Fertility occurs in the later part of estrus. After fertility (the time of ovulation) the dog begins a diestrus period of about 60 days. During that period, the increased levels of hormones associated with the heat cycle slowly drop to their baseline levels. Once those baseline lower hormone levels are reached, the dog enters an anestrus period. The length of anestrus is very variable. In larger breeds, it tends to be longer.
Pregnancy increases the risk of diabetes. Usually, the diabetes subsides after pregnancy ends, but occasionally it doesn’t. We think that the increased risk is due to high levels of progesterone that occur during pregnancy and in non-pregnant dogs for the two months following their heat period (diestrus). Female dogs that develop gestational diabetes tend to be middle-aged and in the latter part of their pregnancy. Certain breeds, including elkhounds and spitz, appear more prone to this problem. (ref) Here are some additional pdf files on the subject, should you care to read them: (ref1, ref2)
Veterinarians have noticed that the dogs that develop diabetes tend to be older females that are overweight. In spayed female dogs, the disease can develop anytime during the year. In overweight dogs such as elkhounds, it tends to develop soon after they pass through their heat cycles (during diestrus), a time when their blood progesterone levels are high. (ref1, ref2, ref3)
The simplest answer is that water follows sugar. As your pet’s blood sugar level rises, osmosis draws more body tissue water (interstitial fluid) into its blood. That increases blood volume. As that diluted blood passes through your dog’s kidneys, it enters the many filtering elements (nephrons) that are there. Normally the nephrons would reabsorb most of that water. But in the presence of elevated sugar, osmosis prevents its re-entry and excessive urine is produced. That lost urine water accounts for the pet’s thirst. (Water balance and kidney function are considerable more complex than my simplified explanation). If you would like to read a detailed explanation, go here.
When dogs have unmanaged diabetes for an extended period of time, they often loose weight. This can occur even when their appetite appears normal or even increased (polyphagia). By the time these pets become underweight, they have usually lost their normal energy level and sleep more as well. They are in a state of malnutrition. They often have elevated blood ketone levels because their body metabolism shifts from metabolizing the glucose that is now no longer available to their cells and draws on its body fats and stored proteins for needed energy. A few ketones are always present, but at high levels (ketoacidosis), they are toxic. Their appetite drops, they may refuse water; they may vomit. As a result these dogs also become dehydrated. If that is allowed to continue, the dog’s body temperature will become sub-normal and it will progress to coma.
The speed with which each diabetic dog’s health declines is variable. Some eventually develop cataracts in their eyes. At that stage, they often have enlarged livers, abnormal liver enzyme tests. They may have increased susceptibility to infections and delayed wound healing as well. When a pet’s blood is examined early in the disease, the most striking feature is its abnormally high blood sugar (glucose) level. When it is examined late in the disease, many other test parameters are usually abnormal as well. Urine is usually positive for sugar and bladder and kidney infections are not uncommon. Because diabetes in dogs is a disease of middle and old age, other body systems can have health issues that are unrelated to the diabetes. So it can take your veterinarian some time and a number of tests to sort things out. The American Animal Hospital Association (AAHA) developed a complete guideline for veterinarians to use in diagnosing and treating dogs and cats with diabetes. You can read it here.
After you have explained to your veterinarian the symptoms you have noticed in your dog, your vet will do a complete physical examination. With that background, and particularly with the clues of increased thirst and urination, your vet will almost certainly run some blood tests (CBC+blood chemistries). A urinalysis that examines a sample of your pet’s urine is essential as well.
Normally a dog's blood glucose level is between ~ 80-150 milligrams of glucose per deciliter of blood. (=mg/dL). If you live outside of North America, a normal value would be reported as 4.4-8.3 millimoles per litre (=mmol/L). Your dog’s urine should contain no glucose. In diabetic dogs, blood glucose levels can reach 300+ mg/dl (=hyperglycemia). In those high blood sugar dogs, glucose is usually also present in the pet’s urine (glucosuria). In serious or advanced cases, it is common for the pet’s liver enzymes to be elevated and for blood electrolyte (sodium, potassium, chloride, bicarbonate, phosphate and calcium) imbalances to be present as well. Ketone levels in the pet’s blood and urine are often elevated too.
Your veterinarian might suggest other tests depending on his/her suspicions. Occasionally, over-active adrenal glands (Cushing’s disease) rather than diabetes are the cause of moderately elevated blood sugar levels. So your vet might order tests like the urine cortisol/creatinine assay to screen for that. The vet might order tests like the cPL test to detect other pancreatic problems. If your pet’s blood glucose is only moderately above normal, the vet might suggest a fructosamine assay or glycosylated hemoglobin assay that indirectly measure average blood glucose levels over longer periods of time (fright and anxiety at the animal hospital can cause “sugar spikes”). (ref) Fructosamine tests are quite helpful in diagnosing marginal cases of diabetes and even more helpful in determining the most effective insulin doses, frequency and treatment plan for your dog. With this test, your veterinarian can tell you how well your pet’s blood glucose level has been controlled over the last few weeks. In locations outside of the USA, other tests provide the same information just as well (hemoglobin A1c, glycated hemoglobin, glycated albumin). There are a few rare conditions that can lead to false fructosamine test results. (ref)
The mainstay of your diabetic dog’s treatment plan is providing it with the insulin its pancreas can no longer produce. There are a large number of insulin formulations on the market. None perfectly duplicate the insulin that your dog produces. Among those many formulations, the ones most commonly used by veterinarians to treat dogs are porcine (pig) lente insulin (U-40 porcine insulin zinc suspension, Vetsulin, Merck Animal Health) and NPH insulin (isophane insulin, Humulin I ® 100 IU/ml). (ref) Vetsulin is a resurrection of an old Lilly product, LENTE®/ ILETIN® II (ref) that was first produced in 1922. Veterinarians became comfortable using lente in dogs and cats until recombinant insulins like Humulin replaced its use in people beginning in the mid-1980s. After that, it became difficult for veterinarians to obtain.
A 2017 study found that both are almost equally effective in dogs. (ref) Until the publication of that article, most veterinarians believed that NPH insulin has a shorter period of effect in dogs. But choosing one or the other product for your dog is the easy part. Determining the best dose size and the best injection interval for your dog is the extremely difficult part. To see how that is best done, refer back to the previous AHAA reference, given again here.
A diagnosis of diabetes in your dog insures that you and your veterinarian must form a close working relationship. It will not be easy; it will be stressful. It will require a close and amicable relationship with a veterinarian you trust - perhaps not the one that initially discovered the problem, perhaps not the one most conveniently located to your home. For your happiness, satisfaction and success, spend a lot of thought choosing a vet that is a good fit for you and your dog. Shop around. Diabetes will be a lifelong challenge for your dog and for you. To be successful in dealing with it, you must find a team whom you trust and whose personal philosophies and practice styles matches yours. Not all veterinarians and staff are good communicators and no veterinarian pleases every single pet owner. It is just not possible due to the nature of the services we deliver. Some practices are too rushed or pass patients between multiple practitioners. Some practices concentrate on the upsell. If you don’t feel entirely comfortable with your veterinarian and the office staff, keep looking. Always ask your friends and pet care professions whom they recommend. Join support groups. There are plenty of wonderful, supportive veterinarians out there - but it is your job to search for them.
Additional things, like daily exercise, diet modification and weight loss for chubby dogs are important too. But managing your dog’s blood sugar level with insulin is the critical factor. In doing so, you will try to keep its blood glucose level as close to normal as possible without ever dropping to dangerously low levels (hypoglycemia).
Do not assume that because your dog appears stable, that it does not need continuing checkups. Currently, the safest and most important test to monitor your diabetic pet’s health over time are periodic blood fructosamine assays (rptref) performed 3-4 times a year in dogs that appear well regulated based on their glucometer readings; more frequently if they don’t. If you cannot afford all these tests, you will need to be very scrupulous and frequent in the use of your glucometer.
Not every dog owner can, or wants to take on this responsibility. Yet many owners derive great satisfaction and personal growth from the experience. Dog owners may find that caring for their diabetic pet produces an intense bond and personal satisfaction that they had never, until then, experienced. (ref) The decision needs to be a family decision because it will affect every member of your family, your spouse, your children, your co-workers, your other pets. Not only will you have to decide if you will treat your dog, you will have to decide on the level of treatment. These are things that veterinarians are not taught in school to help you with. Some intuitively understand it; others do not. The most worrisome factors for some owners are the difficulty of finding pet-sitters and boarding facilities when you travel, some loss of control in your life due to the added responsibility, more difficult interacting with family and friends, more worry, less time for social life, added costs and interference with your work life. The same issues are faced by owners of diabetic cats. (ref) Probably the least important fact for you to worry about is your ability to perform the procedures that will be involved. None of these procedures are that difficult to master and there are plenty of dog owners and veterinary staff willing to instruct you. If you live in an isolated area, the Internet is full of instructional videos. Try not to be motivated by guilty feeling that you were in some way responsible for your pet’s diabetes. Dr. Vicki Rackner wrote an excellent article on caregiver support. You can read it here. To see at what point many owners can no longer cope with the situation, go here.
The biggest pitfall in administering insulin is inadvertently giving too much, due to distractions, a new formula or bottle size, or an incorrect syringe size. Your veterinarian or his/her technician will demonstrate how and where the injections should be given. Don’t attempt to use syringes designed for one insulin product with a different insulin product until you are absolutely certain the gradations (numbers) on the syringes are accurate for the product. If you are in doubt, have a pharmacist (not a busy pharmacy technician) confirm that the syringe and the insulin product are compatible. Some communities regulate how used syringes can be disposed of. If this is a potential problem, call your local sanitation department and ask what is allowed in your area.
Insulin injections are always given under the skin (subcutaneously). On either side of the pet’s spine, is a convenient location. Alternate the sides and exact locations to minimize pain.
1) Feed your dog. Meanwhile, let the insulin bottle warm up to room temperature.
2) Swirl the bottle around to be sure it is well mixed. Don’t shake the bottle violently.
3) Withdraw the insulin into the syringe to the proper gradation- being careful not to draw in air bubbles. If bubbles appear – gently force the product back into the bottle and try again or tap the syringe with your finger until the bubble rises high enough to be expelled.You may have been holding the bottle at the wrong level or the product may be foamy from excessive agitation.
4) Place the syringe on a clean surface and call your dog.
5) Lift up a fold of skin along the dog’s back. Insert the needle almost parallel to the surface of the back but angular enough to be certain you are under the skin and not in it.
If you are in the skin, rather than under it, there will be resistance in the syringe when you inject and the pet will feel pain.
Part the pet’s fur to be sure the needle has actually penetrated under the dog’s skin. There is no reason you cannot clip the hair to make this an easier and more hygienic process.
If you give the injection properly, the dog will probably not fuss or even be aware that the injection was given. Skin sensation varies according to breed. Hunting and fighting breeds of dogs have considerably less reaction to injections than terriers and toy breeds.
Reward your dog with love and praise.
Some dog owners find pre-loaded insulin pens that deliver a rapid, measured amount of insulin more convenient. It is a more expensive option than syringe and needle, but for owners or pets that dislike injections for one reason or another, it is a convenient option. The pens are not very accurate with the very small doses required by very small pets. Talk to your veterinarian to see if this is an option for you and your pet. I still prefer needles and syringes; I feel that I have more control in placing the injected liquid under the skin and not into the muscle. Intramuscular injections of insulin cause a too rapid drop in blood glucose with a shorter period of effect. Read more about insulin pens for dogs here.
Blood sugar level in some pets is harder to control than others. Some call this “insulin resistance”. But that is a confusing term because true “cellular insulin resistance” is a phenomenon that occurs in human Type II diabetes – not the form of diabetes common in dogs. The first thing to do is to be sure you are really giving the amount of insulin suggested by your veterinarian. The biggest cause of unexpected or poor results is giving the insulin product incorrectly. Be sure your bottle of insulin is not expired and that it has been properly stored (most formulations must not be frozen). The next thing to do is to verify that your glucometer is accurate and that you are making your glucose level determinations correctly. The best way to do this is to check your dog’s blood sugar level on two different meters. Blood glucose levels are constantly changing. You will need to do the two tests simultaneously or one right after the other. If neither of the above problems are occurring, your veterinarian will probably increase or lower your dog’s insulin dose. Generally, veterinarians begin pets on a low or moderate dose of insulin. That leaves room to adjust the dose upward if need be. If changing your dog’s insulin dose still does not solve the problem, your veterinarian may try your pet on another brand or formulation of insulin. Trying alternative subcutaneous injection sites; have another experienced person administer the injection to see if the results are the same; and changing the hour of the injection(s) and feeding schedule sometimes also solves the problem.
Here are other factors that sometimes cause this problem:
Overly plump dogs and dogs eating high fat, greasy diets sometimes have problems utilizing injectable insulin. (ref) Some dogs are known to produce antibodies against certain insulin formulations that prevent their proper action. This seems to be a particular problem when cow pancreas, rather than pig pancreas, was the source of the insulin. (ref) Pets that are receiving corticosteroids for other health problems may appear to be more resistant to the benefits of their insulin injections. This is because corticosteroids raise blood glucose levels. Corticosteroid levels are also elevated in Cushing’s disease (hyperadrenocorticism). You vet may screen your pet for this condition when insulin appears less effective than it should be in lowering your pets blood glucose level. As I mentioned earlier, If your pet is an un-spayed female, high progesterone levels that accompany and follow her heat periods can affect her blood glucose level and can make insulin doses less effective.
Occasionally, what appears to be an ineffective insulin dose is really due to receiving too large a dose of insulin. This is called rebound hyperglycemia (somogyi Overswing effect) . When it occurs, the dog’s blood sugar level drops drastically and rapidly after receiving too large a dose of insulin. But the dog’s body quickly releases its own cortisone and adrenalin that cause its blood sugar to soon rise to abnormally high levels again. Careful examination of your pet’s blood glucose curve will detect this phenomenon. The treatment is smaller and possibly more frequent insulin doses.
Keeping a close watch on your pet’s blood sugar level at home is the key to keeping it healthy. The best way to do this is for you to purchase and learn to use a hand held glucometer. Obtain the small blood samples by pricking its skin with commercial lancets. You will find, through experience, which sites bother your pet the least. The pet’s upper and lower lips, (near the base of the jaw) generally works well. So do the calluses to the side and rear of their elbows and their metacarpal foot pads (the one on the rear of the front leg that does not touch the ground) The base of the tail works well, if you first shave the area. Generally, the least painful areas are contact points with the floor when the pet is at rest. Although many owners prick their dog’s ears, I find them more sensitive than these other locations. Most dogs accept this procedure readily. Those that don’t will have to rely on periodic glucose testing at their veterinarian’s office, the services of a house-call veterinarian or periodic blood fructosamine tests. Checking for the presence of glucose in your pet’s urine is not sufficient. Sugar does not enter your pet’s urine until its blood sugar level is quite high and it may only appear intermittently. But I suppose urine test strip testing is better test than no testing at all. Refer back to a prior reference for more details. (rptref)
At one time, more dog owners used human glucometers to test their pets blood sugar levels than the meters designed specifically for dogs and cats. That was primarily due to the difference in their cost. What should concern you more than the price of the unit is the price of the test strips. Over time, the strips represent most of your true cost. Cheap strips are also often short-dated.
The problem with using a glucometer designed for human on a dog or a cat is that blood glucose is distributed differently in the blood of humans versus the blood of dogs and cats. In humans, about 58% of the glucose is free in the blood plasma and 42% is tied up in the red blood cells. In dogs it has been reported that 87.5% of the glucose is free in the plasma and only 12.5% is tied up in the red blood cells (cats 93% in plasma, 7% in the red blood cells) . The way human glucometers are calibrated at the factory, that means that they will likely read a lower blood sugar level than actually exists in your dog. I suggest you purchase a glucometer designed for dog and cat use - although formulas exist that allow approximate conversion of human meter readings into dog and cat readings.
No matter what brand you buy, check your unit and your strips periodically against the one used by your veterinarian as well against your test solutions. Remember that blood serum and plasma glucose levels run at a lab are often 10-15% higher than results obtained on meters. The most important attributes to look for in a meter are accuracy and repeatability of results. A very small amount of required blood sample – particularly if your dog is small is also important. Another important meter feature is that its test strips be very absorbent in drawing up blood from your test prick site (“sipping”). Unless you are uploading your dog’s results to a graph on your computer, additional features, that are added to many meters, are really an unnecessary complication and expense.
Be aware that meters marketed to the US give their glucose reading in milligrams/deciliter (mg/dL). In the rest of the World, the meters usually display in millimoles/liter (mmol/L). There are websites that will do automatic conversions.
Pets that are anemic may appear to have higher blood glucose levels than they really have. If your dog is not consuming enough water or if it is dehydrated, it may also test higher. Testing after your pet eats a fatty meal can also influence the meter reading as can vitamin C supplements. Other things that commonly cause inaccurate readings are low batteries, expired test strips, insufficient or too much blood on the strip, dirty meters and failure to regularly check your meter’s calibration against the test solutions.
Persistently high glucose levels damage your dog’s health over time. Occasional spikes are not that important, what is important is that your treatment plan keeps glucose at as close to normal as possible over the majority of time.
Plotting the curve will let you do that. It is the only intelligent way to adjust your pet’s insulin dosage. It will tell you the highest and lowest blood glucose reading of the day, how long it takes the injection to affect the pet and the length of time the insulin remains effective. You will use the graph results to adjust your pet’s not only to adjust its dose, but also to choose the best insulin type for your pet, best injection interval, best diet, exercise plan and lifestyle in a way that keeps its blood glucose level as stable and close to normal as possible with the fewest dramatic peaks and valleys (nadirs). That was the job of your dog’s pancreas. It is your job now.
Recommendations vary as to how to prepare glucose curve charts. I prefer clients prepare their curve at home where there dog is relaxed, not at an animal hospital. I tell clients to obtain their first glucose reading one hour prior to their dog’s morning insulin injection, one hour after the injection and then every hour until the reading has reached its lowest point and begun to rise again. From then on, the sampling can be done every two hours. You can read an extensive explanation of glucose curves published in the Clinician’s Brief here.
You should always allow your pet to become accustomed to a particular insulin dose and treatment plan for a few days before attempting to prepare a full glucose curve. You should also be aware that the test has limitations - it is hard to get reproducible curves on consecutive days, and that there is considerable day-to-day variability. Sometimes the curve you obtain will not mesh with your dog’s clinical picture. Occasionally, the curve may show that the pet’s glucose is under good control when it isn’t. If your dog is continuing to drink and urinate excessively, experiences periods of weakness, or fails to normalize its weight, go with your intuition that something is wrong and call your veterinarian. I prepare graphs similar to the one in my illustration using Graph 4.3. You can also use the Vetsulin insulin curve generator .
For these graphs to be accurate, they are best prepared at home. At an animal hospital, your pets eating habits, ability to exercise and stress level will be quite different than at home. That will often affect the results. There is no one firm rule as to what your dog’s “normal” blood sugar level should be because it is constantly fluctuating. But a value that I often used is about 75 – 175mg/dL (4.2-9.7mmol/L) , with the average being around 80mg/dL (4.4mmol/L). Don’t attempt to maintain your dog at or below 100mg/dL. That would leave too little down space between what is normal and what might lead to hypoglycemic shock. Instead, consider an 100mg/dL – 185mg/dL (5.5-10.3mmol/L) average or so as your ideal goal. Some owners of easy-to-regulate pets succeed in keeping their average blood sugar level lower. But it is not something you should attempt until you are thoroughly comfortable with how your pet responds to its injections. Do not become frustrated if you cannot maintain an ideal blood glucose level in your pet. Many owners must be content with higher peak levels. If your dog’s blood sugar reading reach peaks over 180 - 270 mg/dL (10-15mmol/L), sugar will begin to appear in its urine. Dogs with persistent readings over 250mg/dL (16.6mmol/L) are at risk of developing health complications. These pets often have ketone-positive urine. When contemplating your pet’s insulin curve, look for trends – not specific points.
BE VERY CAUTIOUS WHEN YOU ATTEMPT TO CHANGE YOUR DOG’S INSULIN DOSE. ALWAYS DO SO IN CONSULTATION WITH YOUR VETERINARIAN. GIVE NON-HYPOGLYCEMIC DOGS AT LEAST FOUR DAYS BEFORE DECIDING THE TRUE EFFECT OF THE CHANGE AND BEFORE ATTEMPTING ANOTHER CHANGE.
Many pet owners follow the ten percent rule – never changing their dog’s insulin dose by more than 10% in 4 days. Every pet is different. A few require more than the typical twice-a-day injection procedure. Insulin dose and frequency adjustment is more of an art than a science. There is quite a bit of variation in blood glucose from day to day in the same pet. That is why there is so little agreement on exact figures and procedures. I am sure that many seasoned owners of diabetic dogs have discovered schedules and procedures different from mine that work great for them. If you are new to diabetes care, you can be overwhelmed by these conflicting opinions. At some point you will just have to choose a protocol that appears reasonable to you and is offered by a person you trust. There is one thing I do not want you to do. I do not want you to base the treatment of your diabetic pet on this article. You need a hands-on veterinarian coaching you, not a provider of Internet advice, or information you read on some blogsite. Online veterinary advice can be an important aid to you, but it is not a substitute for your local veterinarian. Repeat your curves every 3-6 months – more frequently if you are having glucose control issues. Most veterinarians believe that that the flatter your pet’s glucose curve remains - with the least dramatic peaks and valleys- the less likely it is that diabetes-related health problems will occur in your dog.
Some veterinarians believe that oral metformin can be helpful in minimizing peaks and valleys between your dog's insulin doses. (ref)
When your pet is not eating, its insulin needs are lower. It is also more likely that its blood sugar level will drop to dangerously low levels if you give it its usual insulin dose. Sometimes, fairly minor things like excitement, stress, indigestion or human family emergencies prevent your pet from eating on schedule. In those instances, be cautious and give the pet less insulin than you normally do. Remember, a day of high blood sugar is not nearly as serious as an hour of dangerously low blood sugar.
Most veterinarians think it is.
In Type II diabetes, the common form in humans, we know that feeding diets with added fiber, reduced fat and complex carbohydrates substituted for simple sugar are all helpful in regulating blood glucose levels. Less information exits regarding dogs. But we do know that fatty diets, in addition to making your pet obese, reduce your dog’s ability to utilize insulin (ref) and it did initially appear that canine diets with added insoluble fiber (sugar beet pulp) help stabilize blood glucose levels in dogs. (ref1, ref2, ref3) But a more recent study did not find any advantages in feeding high-fiber, reduced carbohydrate diets to diabetic dogs and warned against their use in dogs with thin body condition. (ref) Two studies found that low carbohydrate, high protein, moderate fat content appeared to improve how dogs handled blood sugar. (ref1, ref2)
Despite all the hype from prescription dog food manufacturers, that is all the legitimate science we have to back up their claims. You know how many people tell you what you should, or should not eat. It is no different with our pets. Basing diet formulations on a compound (glucose) that bounces up and down due to multiple factors and doing it in only a few purpose-bred beagle dogs for short periods does not yield much practical information.
Here are some suggestions:
1) If your dog is overweight, limit its total caloric intake and optimize its weight. Crash diets are never appropriate. Just gradually reduce the total amount of food calories the pet consumes in a day. Adding high fiber ingredients to your pet’s diet will allow you to do that without your pet being hungry all the time.
2) Do not feed food ingredients or dog foods that are greasy or high in fat. Most dry dog foods have fat sprayed on the baked kibble after heat extrusion. Dogs naturally like grease, so this process makes the food more palatable and allows the inclusion of ingredients that dogs would not readily accept. An added problem is that this grease is often rancid. Rancid (oxidized) fat contributes to oxidative stress on the body. (ref1, ref2, ref3)
3) Feed a diet low in simple sugars. You can substitute complex carbohydrates if you include them at all. There is no evidence that dogs need carbohydrates. Most commercial brands add them because they are cheap.
4)Feed your dog at very regular, consistent intervals, preferably soon after its insulin injections. Avoid caloric snacks as much as possible. When you do give treats, find low-cal treats your dog enjoys.
5) Do not feed low cost, low quality or generic dog foods. See to it that the bags are not old or stale or improperly stored.
6)Do not feed your pet semi-moist, embalmed, dog food or treats. Many are preserved with propylene glycol, dextrose, fructose or glycerin – all ingredients diabetic dogs should avoid.
7) Feed many small meals throughout the day.
I usually suggest that clients feed their dogs a, nutritionally balanced, homemade diet whenever possible. But I understand that not all of us have that option or inclination. You can find some homemade diet suggestions here. Us humans do not usually rely on professional nutritionists to plan our meals, but if you are hesitant about the homemade foods you feed your dog, there are professionals that will review your plan (link1 , link2) You must be cautious when feeding high fiber commercial or homemade diets to diabetic dogs that are underweight or experiencing health problems that affect their ability to metabolize food. Determine what the optimal weight for your pet is and weigh it frequently to be sure it is not becoming underweight. Pay attention to the luster of its coat, flakiness of its skin and general energy level when on these diets. Some dogs do not like the taste or smell of commercial diets marketed for diabetic dogs. Try various brands. Never give ultimatums or force your dog to eat these diets. Try introducing them to the new foods very gradually. If they refuse to eat it, and they are currently on a nutritionally balanced, sensible diet, proper insulin administration and exercise will allow you to manage their diabetes problem quite will without it. Read other thought on optimal diets for diabetic dogs here.
Always begin exercise programs cautiously and slowly. Keep in mind that you are unlikely to lower your pet’s weight through exercise alone. You will need to control what the dog eats and how much it eats as well. But exercise will certainly help achieving its ideal weight and exercise has great health benefits beyond weight reduction alone.
Simply reducing the food intake of plump dogs will cause them to be more active, alert and exploratory. Exercise also changes the way cells react to insulin. (ref) And, although not as great a risk factor as it is in humans or cats, studies have found that indoor confinement and inactivity are major risk factors in developing diabetes. Exercise can lower your pet's blood glucose even without the action of insulin. (ref)
Diabetic pets have an increased risk for certain problems. If you know what these problems are, you are more likely to discover them early, when treatment is more successful. (I listed them roughly in the order of their importance and frequency.)
Blood sugar levels drop to dangerously low levels in diabetic dogs when you give them too much insulin (less than 55mg/dL). That can be because their dose was too large or because it was more than their current needs. Perhaps they did not eat that morning, exercised more than usual or were under unusual stress. The earliest signs of this problem that you will see are restlessness, trembling or shivering, loss of coordination and behavioral changes. In mild cases, they may just become unusually hungry. If their blood sugar level continues to drop, pets become sleepy, unresponsive and eventually loose consciousness. The speed with which this all occurs is unpredictable. If your dog is still willing to eat, immediately offer it some of its normal diet. Check its blood glucose level with your glucometer. If its blood sugar reading is abnormally low, try to make a list of things in your mind that may have caused the problem and avoid them in the future. Call your veterinarian to discuss the problem and see if the pet needs to come in. If the problem appears serious, just put the pet in your car and take it in immediately.
Not all hypoglycemic dogs are capable of eating food. Never attempt to make a seizuring or confused pet swallow food, or anything else. They make choke. To deal with hypoglycemic pets that cannot eat, owners should have a liquid glucose (dextrose) source readily available in their home. One half gram (500mg) of glucose per pound body weight is often suggested. (One level tablespoon equals about 14 grams of finely powdered glucose, 50% dextrose solution is 500mg/ml).
You can ask your veterinarian for a syringe or container of 50% Dextrose (5% dextrose (D5W is too dilute). I make sure all my clients have some around – particularly when they are just beginning or changing insulin doses. You can also go to your pharmacy or Wal-Mart, purchase some glucose tablets (Dextrosol, B-D glucose tabs, etc.) and dissolve them in warm water. Wait 15 minutes and check the pet’s blood sugar level again. Repeat the dose if need be. Keep unused sugar solutions refrigerated.
Some folks suggest Karo Syrup or anything sweet. That is better than nothing, but not as effective. Products containing table sugar contain sucrose, not glucose (aka dextrose). Sucrose is 50% glucose and 50% fructose. Karo Syrup is a form of high fructose corn syrup. It contains more glucose than generic corn syrups, but it also contains other sugars . Generic Corn syrup is 55% fructose and 42% glucose. Although you dog’s liver can metabolize the fructose into glucose, that takes more time (intermediate glycolysis in its liver). (ref)
The best way to give glucose solution to your pet is by wetting the lining of its lips, mouth and tongue with it. Some suggest smearing it under the tongue. Just be careful not to be bitten or use a toothbrush to “paint” it around the oral surface – dogs that are “spacey” from hypoglycemia do not know what they are doing and their jaw muscles often spasm. Do not pour or squirt liquid into the dog’s mouth - it is libel to go down wrong. Small, periodic amounts of glucose are better than one large amount. Some folks say it can also be given through the other end with a rectal enema. Theoretically, that is possible. I have never tried it. I would prefer you just get a pet in that debilitated a condition to a veterinarian as rapidly as possible.
Many owners are hesitant about giving glucose to their pet – after all, they were under the impression that the whole point of diabetes treatment is to lower glucose sugar. Don’t worry about that in a hypoglycemic emergency. The short period of time your dog’s blood sugar level will be high will have no effect on its long-term health. As soon as the pet is willing to eat, allow it to. Keep a close watch on it, that the problem does not return - the glucose you gave will have only a short time effect (sugar high) and may need to be repeated. As soon as it can eat its normal diet, it will get the more complex carbohydrates that supply sugar in a more steady stream. After the incident has passed, sit down with your veterinarian to re-evaluate your pet’s insulin dose, interval and any other factors that might have caused this crisis and correct them. Remember that the glucose curve graph you made for your dog may not have caught blood glucose at its lowest point between blood-draws. If the curve was headed in a downward slope, it may have dipped even lower sometime before the next time you drew blood. That may have been the point when hypoglycemia occurred.
When your pet lacks insulin and can no longer fuel its body’s cells with blood sugar, it switches its metabolism to fuel those cells with the fatty acid portion of its stored body fat and portions of its own muscle protein. This metabolic switchover leads to excess formation of ketone (ketone bodies). Some are always forming in your dog’s body. But when the process accelerates in pets starved for energy due to diabetes, or fasting from a lack of food or appetite, the excess ketone acidifies its blood to dangerous levels. This condition is called ketoacidosis (aka DKA or ketosis). Signs of ketoacidosis can include, vomiting, diarrhea, weakness, dehydration and rapid shallow breathing. The body can only operate in a narrow range of acidity (pH). Blood glucose levels in these cats are usually sky high and ketones are present in the urine. Untreated, severe ketoacidosis can be rapidly fatal. (ref1, ref2) When uncontrolled (unregulated) diabetic dogs are presented to veterinarians in this condition, they require immediate IV fluid administration to correct dehydration, rapidly acting, short-term insulin to bring high blood sugar levels down, often additional intravenous potassium, continuous monitoring and intensive care. Some pets become deficient in blood phosphorus as well and many require intravenous buffers (bicarbonate) to bring their blood pH back into normal range. Many of these dogs have other health problems (like Cushing’s Disease) that make the problem worse. It is not unusual for veterinarians make their first acquaintance with a diabetic client during a ketoacidosis crisis. That is the first occasion that some pet owners realize that something is seriously wrong with their dog. You can monitor your pet’s ketone levels at home. The procedure is simple. It only requires urine dipsticks (Ketostix) available online or at the pharmacy with no prescription. Check your pet’s first urine of the morning. Do not panic if it is occasionally weakly positive. If it remains so for two or more days in a row, consult with your vet. Portable meters are also available to do this if your pet suffers recurrent attacks. (ref)
Dogs that develop diabetes are more prone to develop cataracts in their eye lenses as well. When a cataract problem is advance, your pet may be unable to see. Cataracts are lenses that are no longer clear to the passage of light. There are many kinds of cataracts that affect dogs, the most common form, affecting all old dogs, is not a true cataract at all and it is not related to diabetes. In those old dogs, the fibers that compose the lens become tighter and more densely compressed together, reflecting a hazy cloudiness. This is referred to as lenticular (nuclear) sclerosis. Although lenticular sclerosis may look serious to you, the dog actually retains most or all of its vision and will not bump into objects or walk hesitantly. Read more about that type of cataract here.
When true cataracts such as diabetic cataracts occur, the dog’s lenses appear mottled or appear to be fractured like a broken chunk of ice. True cataracts can occur in one or both eyes. But the normal nuclear sclerosis of aging occurs simultaneously in both eyes to the same degree. When true cataracts form in diabetic dogs, they form because of increased glucose levels in the eye. Your pet’s lenses are alive. Like all living tissue, they need nutrients. In their case, the nutrient is glucose. However, when glucose levels are too high, some is converted into another sugar, sorbitol, that has destructive consequences for the dog’s lens. (ref)
Remember that even if your diabetic dog should loose its vision, it will remain a happy and contented soul. That is because dogs interact with the people they love and their environment much more by scent than by vision (their sense of smell is hundreds of times more sensitive than ours)
There are veterinary ophthalmologists who can remove one or both of these cloudy lens and replace them with artificial ones. But that is not a surgery that I often recommend. Complications are frequent. it is expensive, and it subjects your pet to a lot of unnecessary stress. I do suggest that pets with diabetic cataracts be seen by a veterinary ophthalmologist occasionally to confirm that pressure within the pet’s eyes remains normal and is not elevated (=glaucoma) and that no inflammatory eye changes (uveitis) that need medications are present. Eyes that have cataracts are more subject to those sorts of problems (ref) as well as to dry eye (keratoconjunctivitis sicca). (ref) Although diabetic cataracts do not generally improve on their own, there have been reports of it happening. (ref) There may also be medications that slow the cataract formation process. (ref) Humans with diabetes are more susceptible to various other eye and vision problems. We do not know if dogs are too, but you can read about those additional eye problems in diabetic dogs here and here.
(aka Severe Hyperglycemia, Hyperosmolar Non- ketotic syndrome, HHNK, HHS)
When pets develop hy-po-glycemia, their blood sugar level has fallen below 60mg/dL. However, on rare occasion the blood sugar levels in untreated or inadequately treated dogs will soar to extremely high levels – greater than 650mg/dL. In this extreme = hy-per-glycemia, several things rapidly occur:
A dog’s blood with this elevated amount of sugar in it has an extreme affinity for water. So water is sucked out of the brain and other organs and into its bloodstream. This results in severe depression and weakness. The pet stops drinking and eating and can rapidly become comatose. Water is not only lost from the brain, it is lost from the body through urine. So the dog becomes severely dehydrated as well (hypovolemic shock). The dog’s eyes become sunken and their gums are usually tacky or dry. Their skin looses its normal spring-like and elasticity and remains “tented” when it is plucked upward. This results in dehydration at the cellular level – fluids are literally sucked out of the body cells and intracellular space by the extremely high level of blood glucose. This is not ketosis so the pet’s urine remains relatively ketone-free. In these emergency situation, the pets must receive large amounts of intravenous fluids in an attempt to rehydrate their brain and bodies. They usually need replacement potassium and phosphate as well. Despite aggressive therapy the recovery rate from this condition is quite low.
Dogs that are diabetic are at increased risk of developing elevated blood pressure (hypertension). (ref) High blood pressure can cause kidney damage in dogs. So it is wise for your vet’s periodic health checks to include a check of the dog’s systolic blood pressure. Should it be high, there are medications to lower it. Should it be high, a check of its kidney function (blood creatinine) might be a wise decision as well.
Nerve problems do not seem to occur as frequently in diabetic dogs as they do in diabetic people. But they occasionally do occur. (ref) The most commonly reported sign is weakness of the rear legs. There are many non-diabetic explanations for rear leg weakness in older dogs. When things are unclear, nerve condition studies might be able to sort the problems out. (ref) There is also some evidence that uncontrolled diabetes can affect the nerves that control heart rhythm (vagal neuropathy). (ref)