Excessive drinking and urination in cats is always clinically significant and requires systematic investigation to identify treatable underlying causes.
Polydipsia and polyuria are welfare signals as well as diagnostic indicators. Cats experiencing these signs are often also suffering from nausea (kidney disease), excessive hunger (diabetes), or heat intolerance (hyperthyroidism) as concurrent welfare harms. The diagnostic process matters for welfare: a cat with undiagnosed and untreated diabetes mellitus may develop diabetic ketoacidosis with severe vomiting and collapse, while early diagnosis allows insulin management that prevents this crisis. Systematic investigation of PD/PU as a clinical priority, rather than attribution to 'just drinking more in summer,' protects cats from weeks to months of preventable welfare compromise from untreated underlying disease.