Page 239 - Problem-Based Feline Medicine

15. The cat with polyuria and polydipsia

Jacquie Rand

KEY SIGNS
● Drinking more than normal.
● Increased frequency of urination and increased volume and/or nocturia.
● Urinating outside litter box.

MECHANISM?
● Polyuria and polydipsia usually occur in cats because of an inability to concentrate urine.

WHERE?
● Kidney (the kidney controls urine production, but it is influenced by many other organs).
WHAT?
● Most cats with polyuria and polydipsia (PU/PD) have renal failure, diabetes mellitus or hyper-
thyroidism.

QUICK REFERENCE SUMMARY
Diseases causing polyuria and polydipsia

DEGENERATIVE
● Chronic renal failure*** (p 235)
Inappetence or anorexia, weight loss, PU/PD, vomiting, increased or decreased renal size.
METABOLIC
● Diabetes mellitus*** (p 236)
Usually older than 6 years of age, PU/PD of 1–12 weeks duration, weight loss, polyphagia or inap-
petence, may have been previously obese.
● Hyperthyroidism*** (p 242)
Older than 7 years of age, weight loss, polyphagia or inappetence, palpable cervical mass, vomit-
ing, tachycardia, restlessness.
● Diabetes insipidus* (p 243)
Central form is rare, nephrogenic form is common, and associated with renal failure, hyperthy-
roidism, pyometra, etc. Urine specific gravity often <1.007.

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