Sources of law concerning liability for physical defects of animals in pre-revolutionary and 19th French law – including local customary laws, droit commun, and subsequent normative acts – as well as the literature in the field of veterinary sciences were analyzed and interpreted. It was ascertained that the local customary laws which pertained to the warranty for major defects of selected animal species (primarily horses as well as other equidae, cattle, sheep) had existed throughout France and had also been included in the so-called pays de droit écrit. Buyers’ rights were disproportionately limited, primarily by the existence of a closed catalogue of defects, short deadlines, exclusion of the possibility of price reduction, and the limitation of redhibition. Only a few latent defects were distinguished whose numerous names and scope, as well as the temporal rules, were irrational, anachronistic, and incompatible with the veterinary knowledge. These regulations were applied (contra legem) in judicial practice after the Napoleonic Code came into force, and they were subsequently adopted, virtually unchanged, by later legislation.