It often surprises medical clinicians to learn that pet dogs can suffer from diabetes mellitus which is diagnosed and treated by veterinary surgeons in much the same way as in human patients. Unfortunately, research into the pathogenesis of canine diabetes has failed to keep pace with its human counterpart, particularly when it comes to understanding the genetic and immunological basis of the disease.
Diabetes is one of the most common endocrine disorders of dogs, who present with clinical signs of polydipsia, polyuria and weight loss. The prevalence of canine diabetes in the UK is around 1 in 500 dogs and disease is typically seen in middle-aged animals between 5 and 12 years of age. Certain breeds, including the Samoyed, Cairn and Tibetan terriers seem to be predisposed to developing diabetes, whereas others, including the Boxer and German shepherd dog, seem to be less susceptible. Such breed differences suggest that there is a genetic component to disease susceptibility.
Canine diabetes is not easily classified, although there are clear similarities and differences between the human and canine diseases. There is no evidence of a canine equivalent to type 2 diabetes, despite obesity being as much a problem in pet dogs as it is in their owners. The disease can be broadly divided into insulin deficiency diabetes (IDD) and insulin resistance diabetes (IRD). IDD is the most common type, although the underlying cause for the pancreatic beta cell loss is currently unknown. The commonest reason for IRD is dioestrus diabetes in female dogs, which is similar to human gestational diabetes. We, and others, have proposed that canine IDD might be a model of latent autoimmune diabetes of the adult (LADA) and there is some evidence that circulating autoantibodies are present in a proportion of cases as well as a genetic association with canine MHC genes.