A water deprivation test for the differentiation of polyuric disorders in birds

A water deprivation test was developed for the differentiation of polyuric disorders in birds using the racing pigeon as a model. For a period of 3 days of food and water deprivation, urine and plasma osmolalities and body weight of 40 clinically healthy racing pigeons were monitored. Reference values for urine osmolality after 40 hours of food deprivation were 79 to 480 mOsmol/kg. After 64 hours of food deprivation and 24 hours of water deprivation these values were 450 to 875 mOsmol/kg. No significant rise in urine osmolality was seen after the first 24 hours of water deprivation. It is concluded that an urine osmolality greater than 450 mOsmol/kg is indicative of a normal concentrating capacity of the kidney in the pigeon. Data from the literature suggest that these values can be applied to other avian species.