In view of the fact that a false-negative result in a dog with leptospirosis can have severe consequences, further studies on the sensitivity of the IgM POC tests FASTest® LEPTOSPIRA IgM (MegaCor) and Test-itTM Leptospirosis (Life Assay) in confirmed cases of canine leptospirosis are recommended. Here, CD40LG is linked to leptospirosis.