Use of progestagens and their adverse effects in small animal clinical practice: a narrative literature

The indiscriminate use of progestagens in small animal practice remains a common reproductive control method despite the known risks. This study aimed to review the adverse effects associated with contraceptive drugs in dogs and cats, highlighting their implications for animal health. A narrative literature review was conducted through searches in PubMed, Scielo, Google Scholar, and the Virtual Health Library, including studies published between 2012 and 2022. Out of 8,926 initial references, 9 articles met the inclusion criteria. The findings indicate that the use of synthetic progestagens, such as medroxyprogesterone acetate and megestrol acetate, is strongly associated with pathological conditions, including cystic endometrial hyperplasia, mammary hyperplasia, pyometra, mammary neoplasms, and reproductive failures. Studies also reveal that many owners administer these drugs without veterinary guidance, often influenced by low cost and easy accessibility. It is concluded that surgical sterilization remains the most effective and safe method for population control and prevention of hormone-related diseases. Educational measures and public awareness campaigns are necessary to reduce the indiscriminate use of contraceptives in veterinary medicine.