Q: I have a 16-month-old Australian Shepherd and Rottweiler mix named Mauser. When he was 4 months old, he started to urinate frequently. The urine had no odor or color. He was treated for bladder infections three separate times. At 10 months, Mauser was diagnosed with diabetes insipidus. He is being treated with chlorothiazide and still drinks a lot of water with frequent urinating as a result. Is there another method of treating this disease? Are there any serious side effects associated with this disease?
A: Diabetes insipidus is uncommon but results from a lack of the antidiuretic hormone (ADH), a chemical messenger produced in the brain (hypothalmus) and stored in the pituitary gland. When body sensors detect a need for more water or hydration, ADH is released into the dog’s bloodstream. This hormone travels to the kidneys, where it stimulates water conservation by decreasing urine production and increasing its concentration.
Lack of ADH inhibits water conservation and urine concentration. Urine volume is large and diluted; it may look as clear as water. The dog will drink excessively to compensate. The dog risks dehydration and collapsing if water is not always available, especially in hot or stressful situations.
Pituitary disease or brain conditions such as tumors, cysts, granulomas or trauma may affect ADH production and effectiveness. Genetic defects also might be the culprit; this condition is called central diabetes insipidus. Secondary diabetes insipidus results when ADH presence is normal, but the kidneys are unable to respond to the hormone. Many diseases affecting the kidneys impair ADH response. The two conditions’ signs are identical. Disease showing up at an early age, as in Mauser’s case, indicates congenital disease.
Many other diseases cause excessive drinking and urine production. They include kidney infections and failure, diabetes mellitus, Cushing’s disease and liver disease.
For cases with inadequate ADH production, synthetic analogs and drugs in human medicine have proven useful in dogs. Desmopressin, or DDAVP, is available in injectable or topical forms. Check with your veterinarian on the likelihood of this medication’s helping Mauser’s condition.
As for side effects, diabetes insipidus should not cause significant problems, as long as the dog drinks water to compensate for excessive urine output.