In this case report, the occurrence of thoracomelia in a female sheep is reported. Thoracomelia is acongenital malformation that can affect several animal species and is characterized by the presence ofa supernumerary limb in the thoracic region. Scientific studies regarding the etiology of changes of thisnature are limited in veterinary medicine, especially concerning sheep. So far, there is no consensusregarding if the origin of this congenital malformation is genetic or environmental. Here, we provide thehistorical and photographic record of thoracomelia in a female sheep, and relate the malformation to anenvironmental cause: physical aggression suffered during embryonic development. The sheep underwenta surgical procedure for removal of the accessory limb and subsequently remained in the breeding line,giving birth to healthy descendants without thoracomelia.