A potential causal association between gastrointestinal disease and primary polydipsia in three dogs

Polydipsia, defined as a water intake of over 100 ml/kg/day, is a common presenting medical complaint in dogs. Polydipsia can be secondary (eg, to central or nephrogenic diabetes insipidus) or primary in origin, where increased water intake cannot be explained as a response to obligatory water loss. Primary polydipsia is confirmed by ruling out other known causes of polydipsia and demonstrating that renal concentrating ability is intact. The causes and associations of primary polydipsia in dogs are poorly defined. This report describes three dogs presented with signs of gastrointestinal disease with concurrent polydipsia. Investigations (including water deprivation testing) showed normal renal urinary concentrating ability and indicated primary polydipsia. Treatment of the gastrointestinal signs resulted in resolution of the polydipsia in each case. This is the first description of a possible association between gastrointestinal disease and primary polydipsia in the dog, the pathophysiology of which remains obscure.