|Mercy Animal Hospital
Dr. Thomas B. McMillen
1395 New London Avenue
Cranston, Rhode Island 02920
Diabetic Management in Pets
Diabetic Management of the Dog
Diabetes is a condition in which the patient is not producing enough insulin to meet their needs. The role of insulin is to allow the transport of glucose, (or sugar, the two terms are interchangeable,) from the bloodstream into the cells. Thus, if the dog does not produce enough insulin then the glucose builds up in the bloodstream to dangerous levels. Unlike people and cats, dogs very rarely get Type 2 diabetes, which can be managed by diet and weight control, thus dogs almost always need to take insulin. So the dog needs insulin, we give it insulin, just as if you had an underactive thyroid and needed thyroid medication. In theory all very simple.
However, there is a major complication with diabetes as opposed to other hormone supplementation- there is a very narrow window of effective dosage. Thus, if a dog needs 10 units of insulin 7 units will not do him any good at all, and 10 will lower his blood glucose to where he goes into a coma. So diabetic control is all about 'finding the number'.
It is important to 'find the number' as quickly as it is reasonable to do so. If a dog's blood glucose is too low, from too much insulin, they can go into a coma. HAVING A BLOOD GLUCOSE WHICH IS TOO HIGH FROM TOO LITTLE INSULIN IS MUCH LESS DANGEROUS THAN HAVING A LOW BLOOD GLUCOSE FROM GIVING TOO MUCH. We must be careful to avoid that one day when too much insulin is given, so we must be patient when finding the number. However, if it remains too high, then they will go into a condition called 'keto-acidosis', an acute shock reaction of extreme dehydration, which can rapidly be fatal. In addition, diabetic dogs are very prone to cataracts, which are even more likely without proper regulation.
So we have two considerations - initially, how do we find a 'working number' expeditiously, and then how do we know we are maintaining good control.
When we choose a reasonable first approximation and begin treatment it takes 3-5 days for the dog's body to stabilize to the amount of insulin given, thus changing doses every day according to glucose levels is not logical- we have to be on a certain dose for a few days to see what levels are reached
So initially we keep the patient in the hospital for two separate days to run glucose curves- give the insulin then check glucoses throughout the day to see what levels are reached and for how long. This ensures we are on a safe, if probably conservative, dose. After this we have the patent in every 5 days or so until we are reasonably confident that we are on the correct dose
Some numbers to consider- normal blood glucose ranges from 80-120. (You will read 60, but we get nervous below 80.) Above 200 is, by definition, diabetes. Thus, since we want to err on the side of caution for reasons described above, we are looking to maintain glucoses in the 150- 200 ranges.
Once we have established a baseline, how do we measure how well an animal is regulated? We use several indicators -
1) Weight - The single best indicator. A poorly regulated diabetic loses weight rapidly. A well-regulated diabetic rapidly gains it back. So if on a recheck the weight is up they are doing well, if it is down they are probably not.
2) Urine production- This is generally why we see the patient in the first place. If the dog can now go through the night without getting up to urinate, when it could not before, that is a very good sign. Owners notice a significant decrease in urine production in a well-regulated diabetic.
3) Behavior- A little vague, but a very consistent finding. Owners invariably say 'I can't believe I have my old dog back. He's running and playing with his toys again.' They do not realize how much the disease had been affecting their dog.
The experienced owner of a diabetic dog can judge at home how the animal is doing by these 'behavioral' signs. If he is drinking more, playing less, and looking thinner then they need to up the insulin or be seen. Laboratory tests:
1) Fructosamine - This is a little pricey, but an extremely valuable test as it tells what the average glucose has been for the past 10 days to 2 weeks, as opposed to a snapshot of what it is at the moment. A very good test to see if the regulated dog is on a good dosage. 2) The glucose curve- The dog stays at the hospital for the day and we measure the response to insulin throughout the day.
3) The 'snapshot' blood glucose- Though this is generally our most commonly used test, it gives us the least information. What a patient's glucose is at 4:00 on a Thursday afternoon does not say a great deal about how well it is being regulated. However, certainly it can be useful, or even critical. A glucose of 30 tells us we need to change dosage quickly. A glucose of 450 tells us we had better look more closely.
Just realize that the 'glucose recheck' is not simply a blood test. All the parameters need to be considered. If a dog is gaining weight and urinating less, a snapshot blood glucose of say 280 does not overly concern us, since we do not know exactly where we are on the daily curve.
Feeding - Many clients wonder how they should feed their diabetic patient. Most commonly. the answer is that you should not change. True, there are diabetic management diets, basically high fiber, and low fat. However a key to diabetic management is that the patient eats roughly the same amount at roughly the same time each day. You cannot manage your diabetes properly if you eat 500 calories on Monday and 1800 calories on Tuesday. So it is generally less of a complication to stay on the current food (unless the diet is poor), rather than switch to a 'hospital food' the patient may not eat well. For 'problem diabetics' - those who do not regulate well, for example those who have a blood glucose of 50 one day and 300 the next on the same dose - then we will use a diabetic management food.
Types of Insulin - There are many different insulin products available. For dogs we prefer the standard drug Humilin-N. Unfortunately this can be a little pricey, and since the passage of the Affordable Care Act the price has nearly doubled. There is a generic equivalent, Novilin, which is very reasonably priced. Frankly, it is hard to say if in fact it works as well. Generic drugs are fine, we use them for most of your medications, but they become a little iffier when precise dosing and careful handling are paramount, and no drug meets those criteria more than insulin. We generally begin with a bottle of Humilin. If things go well, we consider switching to Novilin, especially for larger dogs. This simply, in our opinion, cuts down on the variables for initial regulation.
Diabetic Management - Where Cats are Different
Our essay on diabetes was specifically targeted at our canine diabetic patients to avoid the confusions of species variability.
We shall now look at the important differences between diabetic cats and dogs.
The cat, unlike the dog and the human, is very unlikely to develop diabetic cataracts. In addition cats do not flip into the acute 'crash' syndrome of ketoacidosis very easily. Generally they need to be poorly regulated for some time before this occurs.
For these reasons we have a little less urgency, and we can start with a low, safe dose and work up over time.
Glucose curves in the hospital can be very misleading in cats. They generally do not eat the way they would in a home environment. When a cat is stressed, (and 40 minute wait in a hospital waiting room among barking dogs is a pretty extreme stress,) their blood glucose can be markedly elevated. This means that 'snapshot' blood glucoses in the cat are even less reliable in cats than in dogs, and the entire picture must be considered on the recheck. We do less glucose curves and more fructosamines in cats than in dogs because hospitalized glucose curves are problematic.
A cat can be very well regulated in the glucose range of 200-300. Even higher is not a major concern if the cat is gaining weight, cutting down on urination and playing and acting well.
Because regulation does not need to be so 'tight' in the cat, the fact that they tend to feed 'free choice' rather than specific meals of a specific amount at a specific time relative to insulin administration is usually not a problem. But, again, all cases are individual.
Our primary choice of insulin in the cat is PZI - feline specific insulin designed for the lower doses cats generally need. It is pricey, though this is generally not too much of a problem as most cats are only on 2-3 units twice a day. However some cats require 5-8 or so, and these can be switched to Humilin or Novolin in many cases.
You cannot 'cookbook' diabetic management in a one size fits all format. All patients are individuals, and the methods we use to regulate them vary. Some animals regulate quickly and easily, others can be confusing and frustrating. Please feel free to call us when questions arise.