Diabetes mellitus is the official name of the disease and it is considered a disease of the pancreas where the cells either can’t produce insulin or the body can’t use the insulin that is produced. The very basic concept of this disease is very simple, but the control and regulation is often complex and has very serious consequences. This article is not written to for owners to diagnose or treat—rather it is intended to facilitate understanding when speaking with and obtaining treatment plans from your veterinarian.
Diabetes mellitus (DM) is often suspected when an owner brings a dog to their veterinarian with a simple complaint like, “My dog is drinking a lot of water,” “My dog is having accidents in the house, I think she/he has a urinary tract infection,” or, “My dog isn’t acting right.” During the usual check-in process a weight is obtained, and often the dog has lost weight. Occasionally the dog will have other clinical signs that are perhaps subtle but give a veterinarian an indication to suggest lab work to gain further information and insight on what may be occurring with your dog.
In general, the minimum lab work that should be offered for an older dog includes:
- Blood work including a CBC (complete blood count), biochemistry profile, thyroid panel, and heart worm testing. This grouping of tests gives a nice, broad view of what is happening to some of the major organs, electrolytes, glands, and cells. It should also include a value for the blood sugar, often measured as glucose.
- Urinalysis to determine the output and biochemical characteristics of the urine.
- Fecal for completion and to check for parasites and blood which could open alternate diagnostic possibilities.
The normal canine blood sugar is 80-120 mg/dl (in other countries the units vary). It is important to note that some dogs can have blood sugar levels that elevate greatly after a meal, but normal dogs return to normal blood sugar values rather quickly. A dog with DM can have blood sugar elevations as high as 6-800mg/dl. Diabetic dogs have a consistently elevated blood sugar level that changes the biochemistry of the blood itself.
The blood changes from a fluid that–by circulating–provides water and nutrients to the tissues of the body, to a fluid that pulls them away because of the action of the consistently-elevated sugar overload.
The reason that dogs (and cats) often have elevated blood sugar levels is that very often the pancreas beta-cells are not producing insulin. Insulin is a protein molecule that acts essentially like a key that unlocks a lock in the cell membrane. Once that lock is opened a channel is created for the sugar from the blood to flow through into the cell center where it is used for energy.
The very basic concept of DM is simple: water follows sugar and salt. Both sugar and salt exert forces on water that draws water toward them. So, if you are eating normally and the food you eat is converted into blood sugar through normal channels, then that sugar is meant for your metabolic tissues to use for energy. If for some reason, the amount of insulin is not produced, then the sugar remains in the blood stream, denying the cells of much needed energy. Since sugar draws water toward it, it also acts as a dehydrating factor pulling water from tissues (especially in the capillary beds) creating a lot of urine. The dog has to drink a lot of water to keep up with water loss, which is why owners often complain of both drinking a lot of water and urinary accidents in the house.
So, if the cells in the pancreas (specifically the beta-cells) are not producing insulin and the body needs insulin for both energy and water balance, then the treatment is to provide external insulin. Insulin therapy is one that needs to be directed by your veterinarian. Insulin therapy is often a life-saving therapy but can take a long time to find the right dose and the right insulin. Using “exogenous” insulin needs to be explained by the veterinarian and understood by the owner. What needs to be understood and explained is how to administer it, what to do if the dog doesn’t eat/drink or gets sick, and what negative side effects are possible, and what to do if a something unexpected happens.
All in all, diabetes mellitus is often not a curable disease, but it can be managed very successfully. In dogs (and cats) the goals of therapy are not the same as humans, but they are somewhat similar. The most important goal of canine insulin therapy for diabetes is to improve the negative clinical signs and hence to improve quality of life.
Dr. Dannell Davis
Astoria Animal Hospital