Why should urine dipsticks not be used to read specific gravity in veterinary samples?
Urine specific gravity, as offered on other urine dipsticks, was designed for use in human medicine only. For veterinary samples, which have a significantly broader range of pH, the test is unreliable. As noted in Fundamentals of Veterinary Clinical Pathology by Stockham and Scott (pg 304), “the reagent strip method is not recommended for estimation of urine solute concentration or specific gravity in urine of domestic mammals.” Furthermore, urine dipstick specific gravity pads only measure up 1.025 and are inadequate for measuring the urine concentrating abilities of dogs and cats, which are typically greater than 1.040. The refractometer is more precise and has a more appropriate testing range.
