Diabetes Insipidus in Dogs
Dr. Arnold Plotnick
Veterinary Care should include diagnostic tests and subsequent treatment recommendations A complete medical history review and physical examination are important in determining the potential cause of excessive thirst and urination. This may include a request to quantify how much water the pet is drinking
Diagnostic tests are mostly geared toward ruling out the more common causes of excessive thirst and urination. Once the common disorders are ruled out, specific tests for DI can be performed.
A complete blood count to rule out pyometra (uterine infection)
A serum biochemistry panel to assess the function of the major organs and rule out many diseases like diabetes mellitus, chronic kidney failure, liver failure, high calcium, and low potassium
Urinalysis and urine culture to rule out kidney infection, diabetes mellitus, kidney failure, and other illnesses
X-rays or ultrasound, depending on the history and physical exam findings, to evaluate the kidneys, liver, adrenal glands, and uterus for potential diseases that could have similar signs as DI
A bile acid test to assess liver function
Specific tests of the adrenal gland to rule out overactivity or underactivity of these glands as possible causes of excessive thirst and urination
A thyroid hormone test to assess the status of the thyroid gland
The modified water deprivation test is the most important test for confirming a diagnosis of diabetes insipidus once all other causes of excessive thirst and urination have been ruled out. This is a labor intensive test that may require a full day of hospitalization.
Desmopressin acetate (also called DDAVP) is a synthetic form of the hormone ADH. It is the standard therapy for central DI. It comes in two forms: injection and nasal drops. The nasal spray can be transferred to a sterile eye dropper bottle and applied to the eye if the dog won't tolerate nasal drops. One to four drops administered once or twice a day usually controls the clinical signs.
Chlorpropamide may reduce urine output in some dogs, although results can be inconsistent. Severe forms of central DI often don't respond.
Thiazide diuretics – while it may seem paradoxical to give a dog with DI a diuretic to increase urine output, the net result is usually a reduction in overall urine output.
Salt restriction has a net effect of reducing urine output, and may be used sometimes as the sole therapy for central DI.
Therapy is not mandatory for DI as long as the pet has unlimited access to water, and is kept in an environment where constant urination is not a problem. This usually applies to outdoor pets. Therapy with DDAVP can be administered intermittently, when severe thirst and excess urination is especially undesirable, for example, if guests are visiting. Unrestricted access to water is absolutely imperative.
Optimal treatment for a pet with diabetes insipidus requires both home and professional care, with follow up being critical. Administer prescribed medications and alert your veterinarian if you are experiencing problems treating your pet. Follow up includes:
Periodic rechecks by your veterinarian, especially if the diabetes insipidus is suspected to be caused by a tumor affecting the part of the brain responsible for making ADH.
Seek immediate veterinary care if any illness develops that causes vomiting or causes the pet to reduce his water intake, as there is a risk of life-threatening dehydration if water is withdrawn from pets with DI for even a few hours.