Diabetes

Is your dog or cat too “sweet”?

June 4, 2015

From the desk of Dr. Dennis Voorheis

The last medical blog that I wrote back in October was on the pancreas. My discussion in that blog was the exocrine pancreas. I also mentioned in that blog that the pancreas had an endocrine function as well. The endocrine function is what we will talk about today. Put into more concise terms, we will be talking about Diabetes Mellitus which is an endocrine disorder. In thinking about how to address this topic, I have decided to take a new approach this week and speak as if you were in my exam room presenting me with a dog or cat who was exhibiting symptoms that would lead me to think “possible Diabetic”.

Endocrine is defined as “secreting into the blood or lymph”. When an organ secretes a chemical into the blood, that chemical is referred to in general terms as a hormone. There are several hormones that the pancreas secretes, but this blog will focus on insulin. Diabetes mellitus a disorder of carbohydrate, fat and protein metabolism caused by an absolute or relative insulin deficiency.

The dog or cat that presents to me in an exam room does not come in with a sign over his forehead that says, “Hi! I’ve got Diabetes Mellitus”.  Veterinarians get hints of what may be wrong through taking a thorough history. I will hear things like “Due to the heat he is now drinking more and now he is urinating in the house. He must be getting old and forgetting to ask to go outside”. The owner’s presenting complaint only has a vague reference to thirst and a presenting complaint with urinating inside. This is something that may be perceived as a behavior problem by an owner. Other times, the dog’s signs will have progressed to noticeable weight loss and increased thirst. Since there are a number of other conditions that can come in with identical signs, the veterinarian will recommend baseline lab work.  This will often include a urinalysis and a general blood profile.

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The uncomplicated diabetic dog will have an elevated blood sugar, certainly greater than 250 mg/dl and the dog will be “spilling” sugar into the urine (something that happens when the blood sugar increases above 180 mg/dl). The dog’s urine will be checked for concurrent urinary tract infection. This is common. Warm, sugar filled solution is a great place to grow bacteria, the sugar being a nifty source of “food” for the bacteria.

The complicated diabetic is sick. This dog will require hospitalization with intensive fluid and electrolyte management. It may have developed a condition called diabetic ketoacidosis (DKA) which can be fatal. DKA develops as a compensatory mechanism, when sugar is not available to cells as an energy source the body turns to breaking down fat. The result is a product called ketones. Excessive ketones cause the body’s pH to decrease (this is called acidosis) and that triggers several negative cascading events. Insulin therapy (injections) is a key to treatment along with numerous other supportive measures. These animals can be saved but often survival depends on when we diagnose them and also on the presence of other complicating diseases such as pancreatitis, vacuolar hepatopathy, or hepatic lipidosis.

Not every dog or cat with an elevated blood sugar has diabetes mellitus. The degree of elevation is considered. Mild elevation may be dismissed or rechecked. In addition, the clinician will evaluate if other signs are present.  Below is a list of conditions that will cause the blood sugar to elevate.

Causes of Hyperglycemia in Dogs and Cats

Diabetes mellitus

Hyperadrenocorticism (Cushing’s Disease)

Stress, aggression, excitement, nervousness and fright (more cats than dogs)

Acromegaly (Cat)

Postprandial (within 2 hours of eating)

Diestrus (in heat)(female dogs)

Pancreatitis

Pheochromocytoma (dogs)

Some pancreatic cancers

Renal insufficiency

Head trauma

Drug therapy (glucocorticoids, (cortisones)

progesterone, megestrol acetate

dextrose containing iv fluids

parenteral nutrition solutions

 

The most common cause of diabetes mellitus in dogs is the loss of insulin secreting ability by pancreatic islet cells through presumed immune-mediated destruction of pancreatic beta cells. Huh? Here comes the in depth explanation of Diabetes Mellitus. Dogs are almost always insulin dependent. In cats, diabetes is caused by both an absolute insulin deficiency (type 1) and a relative insulin deficiency and insulin resistance (type 2). Type 2 diabetes is characterized by inadequate or delayed insulin secretion relative to the needs of the patient. Some of these cats can be managed without insulin.

 

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Absolute or relative insulin deficiency results in accelerated tissue breakdown, an impaired ability to maintain carbohydrate, lipid and protein metabolism and subsequent insulin resistance. This gives us weight loss which is one of the cardinal signs of diabetes mellitus. Lack of insulin and insulin resistance results in persistent hyperglycemia of sufficient severity which overloads the kidney’s ability to reabsorb glucose and therefore glucose spills into the urine. When glucose spills into the urine, it pulls water with it which is called an osmotic diuresis. When this occurs two more, of the cardinal signs of diabetes are formed. Those being increased urination and a compensatory increased thirst. Turns out, there is an insulin dependent glucose mediation satiation signal in the brain. It’s lost when there is no insulin so polyphagia (ravenous appetite) comes about. Therefore, there are four common signs to the diabetic dog or cat. They are weight loss, increased urination, increased thirst, and increased appetite.

In dogs, we diagnose diabetes mellitus more in females than males. Certain breeds such as Samoyeds, Tibetan Terriers, Cairn Terriers, Poodles, Dachshunds, Miniature Schnauzers, Beagles, Golden Retrievers and Chocolate Labs are over represented.

In cats, one of the early signs is obesity. Your obese cat is at a higher risk to develop diabetes than a thin cat. Here’s a tip before a cat gets obese or if you have an obese cat that has not developed diabetes yet. Consider feeding the Hill’s prescription diet “Metabolic” I think this is simply the best food available for cats.  I could write an entire blog on the proper feeding of cats. Simply put, for years we have “fed cats wrong” and a growing body of evidence is changing how we feed cats. There is a blog coming on this topic alone.

As mentioned before, literally all dogs with diabetes have insulin dependent diabetes. There is essentially no insulin being produced. It is thought there are multiple causes of diabetes in the dog. Genetics play a role as do infection, insulin antagonistic diseases and drugs, obesity, immune-mediated insulitis and pancreatitis. The bottom line is the pancreatic cell, the beta cell that produces insulin, no longer functions. No insulin means blood sugars rise and the blood sugar cannot be transported into cells that need it The high blood sugar spills into the urine because it surpasses the renal threshold and once in the urine it has an osmotic effect drawing water with it and  the increased urination and thirst occur. Cells are essentially starving and this is when weight loss occurs. A condition called ketoacidosis also develops. As I mentioned, ketones are by products of fat metabolism. The body breaks down fat to try to use as an energy source. Ketoacidosis is a life threatening metabolic condition that is beyond the scope of this blog but simply put a deficiency of insulin leads to breakdown of fat which leads to increased free fatty acids available to the liver and that promotes ketogenesis. As ketones accumulate in the blood, the body’s buffering system becomes overwhelmed and metabolic acidosis develops.

 

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Treatment and treatment goals

With Diabetes In people, treatment goals are a bit different than in the dog and they depend on whether that person is a type 2 diabetic or a type 1 diabetic. It is not the aim of this blog to get into a discussion of the diabetic person or his/her treatment. It is helpful to discuss why treatments are different for the insulin dependent dog and cat vs an insulin dependent person.

The insulin dependent person is often on long acting insulin that maintains the blood sugar in a reasonably low level. Then at mealtime, the person will measure blood sugars and give themselves (by injection) a short acting or fast acting insulin. This is all done to keep blood sugar as normal as possible throughout the day. This does not even take into account other delivery devices that have been developed for people. The difficulties of measuring blood sugars at home on our pets should be self evident. Many times I have had clients willing too, and wanting to measure their animal’s blood sugars at home but unfortunately it just is not practical and almost never successful.

In the insulin dependent dog and cat, insulin injections are given, generally twice daily. Different types of insulin are used depending on the individual cat or dog. In cats, we usually recommend an insulin type called glargine (brand name Lantus), and in dogs we usually recommend an insulin type called NPH or PZI. The type of insulin used, is chosen by the length of time it is effective which is something determined by a blood glucose curve. Blood glucose curves are a series of glucose measurements that are made every 2 hours to plot glucose levels and determine if the chosen dose is effective. Changes in insulin dosage are then made based on glucose level as measured throughout the day. Alternatively, some choose to measure a solitary blood sample, measuring serum fructosamine concentrations. Fructosamines are glycated proteins that result from an irreversible, nonenzymatic, insulin dependent binding of glucose to serum proteins. The extent of this glycosylation is directly related to the blood glucose concentrations. This is a similar test (but not the same) as glycosylated hemoglobin, which is a test run in people to determine the average blood sugar over about a 3 month period of time. Glycosylated hemoglobins can be run in dogs and cats but the test costs about double the fructosamine cost with not much benefit in information obtained.

The overall treatment goal is to maintain the blood sugar in as near a normal range as can be safely done. Ultimately, the goals simplify down to:

  1. Are we controlling the excess water consumption?

  2. Can the pet “hold” it’s urine overnight

  3. Is the pet maintaining weight? That is, has the weight loss stopped?

Dr. Ed Feldman, probably the world’s foremost authority on diabetes in cats, has stated over and over that the 3 things listed on the above list are by far and away the most important things for owners and veterinarians to pay attention too.

Feeding your diabetic dog/cat

Turns out snacking on food all day long is not a good idea for diabetes control. Not for any species. It also turns out that there are diets that make it easier to maintain control. For my feline diabetic friends, I suggest to feed one of the following.

  1. Low carb/canned diet (<7% carbs)

  2. If we feed dry food then: Hill’s M/D

  3. EVO dry

  4. Purina D/M

For dogs I suggest:

  1. Many dogs can be maintained on the food they were on. They don’t need another or a different food in many cases. The way that food is offered changes. Feed twice a day. Do not let the food sit out for snacking purposes all day long.

  2. If the dog has smoldering pancreatitis – or a low grade pancreatitis. I change the food to Low Fat Hill’s I/D or Royal Canin GI low-fat.

  3. Wait Doc… I feed Hills W/D…. my answer is… if that is what you are feeding and your dog is doing well… keep feeding it.

The bottom line is to follow the advice of the veterinarian you are working with in regards to what to feed, what type and dosage of insulin to give and how often. In general, we suggest: Feed twice a day. 10 to 30 minutes post meal – give an insulin injection. But you may ask “What if my dog or cat didn’t eat all of his/her food? Do I change the dose of insulin?”  This one drives clients crazy and most veterinarians crazy too. The real answer is there is no absolute correct answer 100% of the time. I will remind you of a few things. Pay attention to how the animal is behaving. Is it behaving normally but just didn’t eat all of its food, or is it acting lethargic or ill? The animal is a diabetic even if it doesn’t eat all of its food. Blood sugars will continue to rise even if it doesn’t eat or doesn’t eat all of its food. I would encourage you to call if the cat/dog is not eating so we can have a discussion about amount of insulin to give.

Well, that’s all I have for today. I’m sure this discussion may have triggered some questions and I certainly welcome those in the comments section below. I enjoy the interaction and your feedback is certainly my biggest reward for my efforts in writing the blog. So please keep those comments coming.

 

Until next time,

Dr. Voorheis

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