Agreement between two methods for measuring urine pH in cats and dogs.

Objective: To compare urine pH of cats and dogs determined by use of a dipstrip and a pH meter.
Design: Prospective study.
Sample Population: 109 urine samples from 88 cats that were clinically normal or had signs of irritative urination, 52 samples from 13 clinically normal dogs, and 3 samples from 3 dogs with urinary tract infections.
Procedure: Measurements of urine pH were obtained by use of a dipstrip and pH meter, and degree of agreement between measurements was evaluated.
Results: Mean difference (+/- 2 SD) between the 2 methods was 0.1 +/- 0.9 pH units. Only 65 of 164 (40%) samples measured by use of a dipstrip were within 0.25 pH units of results obtained by use of the pH meter.
Clinical Implications: When an accurate measurement of urine pH is critical for clinical decision making, the measurement should be made by use of a pH meter. Dipstrips typically are not accurate enough to be clinically useful.