title: Association between urine osmolality and specific gravity in dogs and the effect of commonly measured urine solutes on that association.
abstract: OBJECTIVE
  To determine the association between urine osmolality and specific gravity (USG) in dogs and to evaluate the effect of commonly measured urine solutes on that association.
  
  
  METHODS
  60 dogs evaluated by an internal medicine service.
  
  
  METHODS
  From each dog, urine was obtained by cystocentesis and USG was determined with a refractometer. The sample was divided, and one aliquot was sent to a diagnostic laboratory for urinalysis and the other was frozen at -80°C until osmolality was determined. Urine samples were thawed and osmolality was measured in duplicate with a freezing-point depression osmometer. The correlation between mean urine osmolality and USG was determined; the effect of pH, proteinuria, glucosuria, ketonuria, bilirubinuria, and hemoglobinuria on this relationship was investigated with multiple regression analysis.
  
  
  RESULTS
  The Pearson correlation coefficient between urine osmolality and USG was 0.87. The final multivariable regression model for urine osmolality included USG and the presence of ketones; ketonuria had a small negative association with urine osmolality.
  
  
  CONCLUSIONS
  Results indicated a strong linear correlation between osmolality and USG in urine samples obtained from dogs with various pathological conditions, and ketonuria had a small negative effect on that correlation.
authors.affiliation: Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Ayoub
authors.forename: Hugues
authors.initials: H
authors.lastname: Beaufrere
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Acierno
mesh_terms: D000818:Animals; D001663:Bilirubin / Q000652:urine; D004285:Dogs / Q000652:urine*; D006029:Glycosuria / Q000652:urine / Q000662:veterinary; D006456:Hemoglobinuria / Q000652:urine / Q000662:veterinary; D006863:Hydrogen-Ion Concentration; D007662:Ketosis / Q000652:urine / Q000662:veterinary; D009994:Osmolar Concentration; D011507:Proteinuria / Q000652:urine / Q000662:veterinary; D012031:Refractometry / Q000662:veterinary; D012044:Regression Analysis; D013046:Specific Gravity; D016482:Urinalysis / Q000662:veterinary; D014556:Urine / Q000737:chemistry*
chemical_list: D001663:Bilirubin