Leishmaniosis is a common infection in the canine population. Domestic dogs are the main reservoir hosts for zoonotic human visceral leishmaniosis in both the Old and New Worlds. In fact, canine leishmaniosis is not just a veterinary problem. In the light of some recent advances in the field of diagnosis, the author evaluated the medico-legal aspects of buying and selling dogs that are potentially affected by leishmaniosis. This paper clarifies why it is impossible to attribute redhibitory vice (an essential defect in a product which renders it useless or so diminishes its usefulness or value that it must be presumed that, if he had been aware of it, the buyer would not have bought it, or would have paid a lesser price) to this disease and highlights the necessity to improve Sicilian regional law no. 15 of 3 July 2000 concerning the creation of a dog register by giving every animal a health book. With this aim in mind, the author suggests that leishmaniosis be included in the list of notifiable diseases that appears in article 1 of the Italian Veterinary Police Regulations so as to reduce the possibilities of fraudulent trade in dogs known to be infected before purchase.