A chemical method for sexual sterilisation and libido suppression in male mammals is indicated to achieve the biological sterilisation of male mammals such as bovines, sheep, goats, equines, swine, dogs, cats and humans. The invention consists in a sterile aqueous solution containing an active sclerosing principle (lactic acid) and an enzyme (papain). The enzyme causes digestion of testicle tissue, intensifying the acid's necrosing effect and causing it to act faster and more efficiently. The association of these two active principles provokes an acute inflammatory reaction with a quick resolution characterised by fibrosing of the organ. This effect leads to the loss of the gametogenic and androgenic functions, and causes sterility and libido suppression, respectively. The biological sterilisation process can be easily carried out and does not require additional treatments, requiring less handling of the animals, with less stress and increased weight gain. The process is not painful either during or after administration, owing to the lesion of the testicle nerve endings at the moment of application, and to the fact that the greatest number of sensitive structures is located in the scrotal sac. The meat of thus treated cattle does not require for consumption a waiting period between application and slaughter, since the biological active principles can be easily metabolised by the animal organism. This method has already been successfully used in more than 3,000 animals, and is the only method available today in which naturally available biological active principles are used.
