Primary polydipsia in a cat

Area of Science:

• Veterinary Medicine
• Comparative Physiology

Background:

• Polyuria (PU) and polydipsia (PD) in cats are defined by urine specific gravity (USG) <1.035 and water consumption >100 mL/kg/day.
• These clinical signs necessitate a thorough diagnostic workup to determine the underlying cause.

Observation:

• A 2-year-old castrated male domestic shorthair cat presented with PU/PD.
• Extensive diagnostics, including bloodwork, imaging (radiography, ultrasound, MRI), urinalysis, and a water deprivation test, were performed.
• The water deprivation test yielded a USG >1.036, and cranial MRI showed no abnormalities.

Findings:

• Administration of desmopressin did not reduce water consumption or increase USG.
• These results confirmed a diagnosis of primary psychogenic polydipsia (PD).
• This case is unique as it represents the first reported instance of feline primary PD without evidence of structural pituitary gland pathology.

Implications:

• This case highlights the importance of a comprehensive diagnostic approach for PU/PD in cats, even in the absence of apparent structural lesions.
• It expands the understanding of feline primary PD, suggesting that central nervous system factors beyond structural pituitary abnormalities may be involved.
• Further research into the neurobiological mechanisms of primary PD in felines is warranted.