Diabetes insipidus is caused by problems with antidiuretic hormone (ADH or vasopressin), a pituitary gland hormone responsible for maintaining the correct level of fluid in the body. Either the pituitary gland does not secrete enough of this hormone (called central diabetes insipidus), or the kidneys do not respond normally to the hormone (called nephrogenic diabetes insipidus).
Affected dogs urinate in large volumes and drink equally large amounts of water. The urine is very dilute even if the animal is deprived of water (normally, urine becomes more concentrated when an animal is dehydrated.).
Increased urination may be controlled using desmopressin acetate, a drug that acts in a way similar to antidiuretic hormone. Water should not be restricted. Treatment is usually life-long.