[The determination of free thyroxine (FT4) in dog serum]

Free thyroxine (FT4) was determined in canine serum by use of a commercially available test kit. The measurement of intra- and interassay precision showed very good results. Accuracy was examined by adding known amounts of thyroxine and by biological response testing. The results were also good. The reference value was determined in 129 dogs. It was calculated on the basis of a 95% percentile, and ranged from 0.6 to 3.7 ng/dl (7.7 to 47.4 pmol/l).