Background. Glucometers or portable sensors are used to quickly measure blood glucose at low cost. They are used in veterinary practice and by guardians to monitor diseases that require, as in diabetes mellitus. However, not all commercially available glucometers (human and veterinary) are suitable for this purpose. Hypotheses/Objectives. The objective was to evaluate the analytical and clinical precision of three human-use portable glucometers. Animals. This study evaluated 115 samples in three glycemic ranges (hypoglycemia, normoglycemia, and hyperglycemia) from 82 dogs recruited from veterinary services. Methods. The portable glucometers are the FreeStyle Freedom Lite®, FreeStyle Optium Neo®, and On Call Plus® models. Glucometer results were compared with the enzymatic colorimetric glucose oxidase laboratory reference method. Using descriptive and comparative statistical analysis, there were correlations between these devices and the standard method, ISO 15197 : 2003 and ISO 15197 : 2013 standards, and error grid analysis. Results. Only the Freedom Lite® device observed a statistical difference when compared with the reference method. Despite the underestimated glucose concentrations assessed with humane devices, all three tested herein showed a positive coefficient. However, none of these achieved all ISO guidelines. Conclusion and Clinical Importance. Although there was wide use of portable humane devices for dog glucose measurements on routine, the results are generally inferior when compared to the reference method. The FreeStyle Optium Neo® glucometer obtained the best result and is therefore the best option among the glucometers evaluated; however, for the first attendance on veterinary routine, all three glucometers had a satisfactory glucose measurement until the reference method availability.