Investigating Polyuria and Polydipsia in Cats: Welfare Guide

Excessive drinking and urination in cats signals multiple possible underlying diseases, and systematic investigation protects welfare by identifying treatable causes.

Key Facts

Polyuria/polydipsia (PU/PD) is defined as urine output above 50 ml/kg/day or water intake above 100 ml/kg/day
Common causes in cats include chronic kidney disease, hyperthyroidism, diabetes mellitus, and hypercalcemia
Liver disease, acromegaly, and central diabetes insipidus are less common causes
Urine specific gravity, serum biochemistry, and T4 measurement are first-line investigations
Urinalysis including culture rules out urinary tract infection as a contributing factor
Diabetes mellitus in cats has excellent prognosis with appropriate insulin management
Early diagnosis and treatment of underlying conditions prevents secondary complications

Welfare Considerations

The underlying diseases causing PU/PD in cats range from the highly treatable (hyperthyroidism, diabetes) to the progressive but manageable (CKD). Undiagnosed PU/PD means an underlying disease is causing unrecognized welfare harm. The discomfort of untreated diabetes mellitus - nausea, weakness, weight loss - is prevented by diagnosis and treatment. Systematic investigation is not overtreatment; it is identifying what is causing the cat's symptoms and enabling evidence-based management.

What You Can Do

Measure your cat's water intake if you suspect it has increased - baseline matters for comparison
Seek veterinary assessment for any cat showing increased drinking or urination
Ensure complete first-line workup including urinalysis, biochemistry, and thyroid testing
Treat identified conditions promptly - many causes of PU/PD respond well to treatment
Monitor water intake after treatment as a simple indicator of disease control