Case Report: Congenital caudal tibial curvatures in two alpaca crias

Congenital deformities of the tibia are rare conditions in animals as well as in humans. The cause is often unknown. Although congenital defects in South American Camelids are more frequent than in other species, to our knowledge, there are no previous reports of congenital tibia deformities in alpacas (Vicugna pacos). Both unrelated presented crias showed a caudal curvature of the tibial diaphysis of either one or both legs soon after birth. Radiographs revealed a focal circumferential endosteal and intramedullary, increased mineralization in the curvature area of the diaphysis of one or both legs. One cria suffered a spontaneous fracture in this area. A histological examination, which was carried out only on the second cria, identified a circumscribed osteosclerosis in the affected region. Descriptions of tibial deformities in various animal species and in humans show similarities but do not fully correspond to the changes we observed in the crias. Whether the described congenital deformities are of hereditary origin can only be clarified through further future investigations.