Measuring Free-Thyroxine (fT4) by modified equilibrium dialysis (MED) is considered the only preferred test to assess thyroid function in dogs. Several methods are currently available to measure the serum fT4 including the chemiluminescence (CH). This study aims at evaluating the accuracy of the CH assay (Immulite® Siemens Healthcare Diagnostics) in canine serum samples with the canine specific CH immunoassay (cCH) and the CH human assay adapted for veterinary use (hCH). In the diagnosis of canine hypothyroidism, the preliminary results showed that the accuracy of the cCH specific immunoassay is comparable to the MED and unreliable results are offered by the CH human assay adapted for veterinary use.