Diabetes insipidus is a rare condition causing extreme thirst and urination in cats, distinct from diabetes mellitus and requiring specific diagnosis and management.
Cats with diabetes insipidus require constant access to water or they rapidly become severely dehydrated. Dehydration causes lethargy, depression, and in severe cases neurological signs. Cats confined without water access may develop life-threatening hypernatraemia within hours. Diagnosis requires distinguishing from psychogenic polydipsia and other causes of polyuria through systematic testing. Treatment with desmopressin dramatically improves quality of life by normalising water intake and urination.