Strategies for monitoring diabetes mellitus in dogs (Sponsored by Intervet/Schering-Plough Animal Health)


Strategies for monitoring diabetes mellitus in dogs (Sponsored by Intervet/Schering-Plough Animal Health)

Monitoring the effectiveness of therapy is an important part of managing canine diabetes mellitus. The success of treatment for this disorder greatly depends on the complete cooperation of the pet owner, as the majority of day-to-day patient care is done at home. The pet owner must be trained to carefully observe and even interpret signs of possible illness. Monitoring must be frequent enough to be effective, but not so frequent as to discourage client compliance. It is also essential to foster a strong veterinarian-client relationship at the time of diagnosis and maintain that relationship throughout the pet's lifetime. The time and effort the veterinarian devotes to client education will improve the client's ability to accurately relate what is observed at home and to monitor the dog according to the veterinarian's instructions—both of which facilitate the veterinarian's ability to assess the long-term efficacy of treatment.

Variables in choosing a monitoring program

The goals of a monitoring program are improvement and maintenance of patient health through optimization of antidiabetic therapy and minimization of diabetic complications. Several published clinical reviews outline the various clinical and laboratory measures available to veterinarians for monitoring diabetic dogs.1,2 Unfortunately, few published studies are available to guide clinicians' recommendations as to the best monitoring strategy to achieve these goals.

Table 1. Comparison of select features of moderate and intensive canine diabetes monitoring programs
An effective monitoring strategy should provide sufficient information and room for adjustments until the dog is free of clinical signs for the majority of each day. For example, a moderate monitoring program, the strategy veterinarians most commonly recommend, might have as its endpoint the suppression of clinical signs of diabetes. An intensive monitoring program, on the other hand, might gather the detailed physiologic and metabolic information needed to achieve specific endpoints associated with excellent diabetic control. Evidence from human medicine indicates that intensive diabetic monitoring is associated with improved long-term results in clinical variables and reduced rates of diabetic complications. Unfortunately, intensive diabetic monitoring is also associated with a higher frequency of severe hypoglycemic episodes in people.3 A relationship between the optimization of clinical endpoints via intensive monitoring and improved clinical results has not been shown in veterinary medicine. Given the increased morbidity and diminished quality of life that might result from chronic or recurrent hypoglycemia, veterinarians must carefully consider the pros and cons of intensive monitoring and management before routinely recommending such a strategy for canine diabetics. Table 1 summarizes a comparison of moderate and intensive monitoring approaches.

Clinical and laboratory parameters

Clinical signs

Common signs of diabetes in dogs, particularly polyuria and polydipsia, are directly related to hyperglycemia and glucosuria, which in turn are direct consequences of absolute or relative insulin deficiency. One or more of the clinical signs of diabetes are usually listed among the major complaints at the time of diagnosis. Owners may be taught to observe these clinical signs at home to monitor the effectiveness of diabetic therapy. For dogs with long-term diabetes, owner observations of clinical signs and physical examination findings correlate well with objective criteria of glucose management, such as the serum fructosamine level and mean eight-hour blood glucose concentration.4

As part of the monitoring program, instruct the owner to observe the dog for specified clinical signs of diabetes and record the observations for later review. Water consumption, urination habits, appetite, activity level, and body weight are usually the easiest parameters for most dog owners to observe at home. Because glucosuria occurs once the threshold for renal resorption of glucose is exceeded, polyuria roughly corresponds to the degree of hyperglycemia. Likewise, polydipsia is related to the degree of hyperglycemia. Polydipsia results from activation of thirst mechanisms by plasma hypertonicity and mild volume reduction caused, respectively, by hyperglycemia and increased renal fluid loss. Polyphagia or the preservation of appetite is a common finding in dogs with uncomplicated diabetes. In untreated dogs, weight loss may occur despite adequate nutritional intake as a result of the catabolic state induced when circulating insulin is deficient. Thus, an increase in body weight or maintenance of body weight is expected during insulin therapy. Persistence of polyphagia and failure to gain or maintain body weight are indirect indicators of inadequate blood glucose regulation in an otherwise uncomplicated diabetic dog.