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In practice in brief
How to diagnose polyuria and polydipsia in dogs
  1. Yvonne McGrotty and
  2. Susan Randell
  1. CHV Atlantia, 22 Rue René Viviani, 44200 Nantes, France
  2. IDEXX Laboratories, Grange House, Sandbeck Way, Wetherby LS22 7DN
  1. E-mail for correspondence: yvonne.mcgrotty{at}

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It is very common for the veterinary practitioner to be presented with canine patients suffering from polyuria and polydipsia (PUPD); that is, increased urine output and water intake, respectively. But determining a diagnostic approach can be very difficult as there are many causes.

PUPD can be due to either primary polydipsia with secondary polyuria or primary polyuria with compensatory polydipsia. Primary polyuria is when decreased urine concentrating ability – due to a lack of antidiuretic hormone (ADH), renal insensitivity to ADH, or an osmotic diuresis – leads to compensatory polydipsia. Most water balance disorders fall into this category. Primary polydipsia is when increased thirst leads to compensatory polyuria to excrete the excess water. Primary polydipsia is uncommon, and is normally due to behavioural disorders (ie, psychogenic polydipsia) or defects in the thirst centre.

Fig 1 shows a diagnostic algorithm that we have designed for investigating PUPD in dogs.

Fig 1: Diagnostic algorithm for polyuria/polydipsia (PUPD) in dogs. ACTH Adrenocorticotropic hormone, DDAVP Desmopressin


Detailed history taking provides essential clues to guide investigation of PUPD. Ideally, water intake should be accurately quantified before embarking on further investigations to avoid unnecessary and potentially expensive diagnostics. It is also imperative to distinguish between …

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