Diabetes Mellitus in dogs

by Shane Jackson M.A., Vet MB.,MRCVS



At our practice in Stroud, we see a steady trickle of new cases of diabetes mellitus or sugar diabetes thoughout the year, and although the initial reaction of owners is one of concern, when the routine of treatment is established, owners are usually very confident. 

When food has been digested, the blood stream carries sugars, notably glucose, around the body to the cells where it is needed.  In order for these sugars to get into the cells and be used, insulin (a hormone produced from cells of the pancreas) is required; if no insulin is available, the cells resort to other methods of making energy.  In the short term, that is all right, but in the longer term, these other methods lead to illness.  So, sugar diabetes is seen when insulin is either not produced in sufficient quantities, or if the body cannot respond to that insulin. 

Diabetes is more common in middle aged and older dogs; certain breeds such as the Scottie, miniature poodle and Dachshund are more prone to it, though any breed may be affected.  It is three times more likely to occur in bitches than in males and symptoms often follow the onset of the season of a bitch.  One of the causes of diabetes is due to the effect that female sex hormones have on sugar uptake by the cells.  The condition is also seen in obese dogs and in dogs where there has been an infection or inflammation of the pancreas.

Dogs can present with a variety of clinical signs.  In the early stages, one may only see a dog that is passing urine far more frequently than usual, with a corresponding increase in appetite too.  Later, if untreated, there will be weight loss, depression, a lack of appetite, vomiting and dehydration.

A preliminary diagnosis is usually made by testing the urine to ascertain the level of glucose in it; if there is too much glucose in the blood, the excess spills over into the urine.  Confirmation is by blood test.

Treatment in all but the mildest cases must be by daily injection of insulin; this is another reason why owners are initially concerned.  A totally new daily routine has to be established for the dog – and owners too!  The important points are the regularity of the new regime – it must be performed day in day out with very little variation – and the balancing of energy input (food intake) with the energy output (exercise).  Each case is an individual and I have instigated different routines for different dogs, but broadly along the same guidelines.

First thing in the morning a sample of the dog’s urine is collected and tested which enables the vet and owner to know how much glucose is in the urine and therefore in the blood, and from this sample, the day’s insulin requirement can be worked out.  The dog is fed about one third of its daily food intake at breakfast and, after eating, the calculated insulin is injected.  The amount of exercise throughout the day (the frequency of walking and the length of walks) should be kept constant.  In the evening, about eight hours after breakfast, the remaining two thirds of the food is fed.  No titbits should be given to the dog as this will upset the routine.

Most dogs respond quite well and fairly quickly, although we do have the odd failure.  After diagnosing diabetes in one Labrador recently, this poor chap had to be euthanized despite all our best efforts.  Another dog, a female Westie, took two or three months to stabilise; she is now doing famously.  If you have the misfortune to find your dog has sugar diabetes, try not to be alarmed.  With support from your vet, especially in the early stages, the worry about the health of your dog and the concern about daily routine and injections should be quickly allayed.  

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INTERESTING FACTS ABOUT DIABETES MELLITUS
In 1889, Mering and Minkowski were the first to discover the association between the pancreas and carbohydrate metabolism.  When they removed the pancreas of dogs they found that they developed symptoms of diabetes mellitus.  Later they discovered that injection of extracts from the pancreas could alleviate the symptoms of diabetes mellitus in both dogs and humans.   Able was the first to crystallise insulin but it was not until the late Fifties that Frederick Sanger identified its chemical structure and for this achievement, he won his first Nobel prize in 1958.