Primary polydipsia in a cat

Abstract

Case summary In cats, polyuria (PU) and polydipsia (PD) are defined as a urine specific gravity (USG) consistently 100 ml/kg/day. A 2-year-old castrated male domestic shorthair cat with PU/PD was brought to our hospital. Diagnostic tests for PU/PD included physical examination, blood analyses (complete blood count, serum chemistry profile, electrolytes, ionised calcium, symmetric dimethylarginine and thyroxine concentration), thoracic radiography, abdominal ultrasound examination, urinalysis, urine cortisol:creatinine ratio, urine protein:creatinine ratio and urine culture. A modified water deprivation test resulted in a USG >1.036 and cranial MRI did not identify any abnormalities. Therefore, the cat was administered desmopressin, which failed to decrease water consumption or increase the USG above the untreated level; thus, primary PD was confirmed. Relevance and novel information This rare case of feline primary PD is the first reported that did not identify evidence of structural pathology of the pituitary gland.