OBJECTIVE: To assess the accuracy of obtaining body temperatures in dogs with a 
noncontact infrared thermometer (NCIT) on the cornea compared with a rectal 
digital thermometer (RDT).
DESIGN: Prospective single center study.
SETTING: University teaching hospital.
ANIMALS: Three hundred dogs presented with low, normal, or high body 
temperatures.
INTERVENTIONS: Three body temperature readings were measured by an RDT and by an 
NCIT on the cornea of the left eye by 2 investigators (experienced and 
inexperienced). Results obtained by the 2 methods were compared.
MEASUREMENTS AND MAIN RESULTS: Median body temperature measured by the 
experienced investigator with the RDT and the NCIT were 38.3°C (range 
35.5°C-41.1°C; 95% CI: 38.2-38.4°C) and 37.7°C (35.9°C-40.1°C; 95% CI: 
37.7°C-37.9°C), respectively. Measurement of RDT as well as of NCIT correlated 
well between both investigators (rRDT = 0.94; rNCIT = 0.82; respectively, P < 
0.001 for both methods). Mean RDT and NCIT-temperature correlated poorly (r = 
0.43; P < 0.001) when taken by the experienced investigator and even less by the 
nonexperienced investigator (r = 0.38; P < 0.001). Repeatability of the NCIT 
revealed an unsatisfactory value (0.24°C) compared to RDT measurement (0.12°C). 
Agreement between both devices in measuring low, normal, and high values, 
calculated by Cohens-Kappa, was unsatisfactory (к = 0.201; P < 0.001). 
Calculating the receiver operating characteristic curve to determine the best 
threshold for fever (defined as RDT temperature >39.0°C) showed an area under 
the curve of 0.76. Mean discomfort score was significantly lower using NCIT 
compared to RDT measurement (P < 0.001).
CONCLUSIONS: There was poor agreement between body temperatures obtained by RDT 
and NCIT. The corneal NCIT measurement tends to underrecognize hypothermic and 
hyperthermic conditions. Although the use of the NCIT yields faster results and 
is significantly more comfortable for the dog than the RDT measurement, it 
cannot be recommended in dogs at this time.