Basal glucose excretion in dogs: The impact of feeding, obesity, sex, and age

Background: The urine glucose (UG) measurements are an integral part of urinalyses, especially in dogs with polyuria and polydipsia. A positive dipstick result is considered pathologic for disease. This paradigm has been challenged by new ultrasensitive tests, where the manufacturers recommend tolerating slightly positive results. It implies that, as in other species, basal urine glucose losses can exceed the lower limits of detection using ultrasensitive glucose dipsticks in healthy dogs.

Objectives: We aimed to determine whether glucose is routinely detectable using a sensitive quantitative wet chemistry method in the urine of nondiabetic, nonazotemic dogs, and investigate the impact of food intake, obesity, sex, castration status, and age.

Methods: Serial UG measurements were performed in healthy clinic-owned Beagle dogs that were randomly fasted or fed. Glucose was measured in morning urine samples from normal-weight healthy and obese dogs, and the university's electronic database was searched for quantitative UG measurements (Gluco-quant Enzyme Kit/Roche Diagnostics).

Results: Small amounts of glucose were detected in 555 (99.1%) of 560 urine samples analyzed. All urine samples from the clinic-owned Beagle dogs, as well as from privately owned obese and normal-weight healthy dogs that tested positive for glucose. The median (range) UG concentration obtained from the university's electronic database was 0.39 (0-1.55) mmol/L, and 2.2% of the samples tested negative. Feeding, obesity, gender, castration status, and age did not affect UG concentrations.

Conclusions: Studies, including a larger number of healthy dogs, are warranted to define a cut-off between physiologic and pathologic glucosuria.

Keywords: canine; quantitative urine glucose measurement; urine dipstick; urine glucose; urine glucose-to-creatinine ratio.