Rickets in Scottish blackface lambs on five South West Scotland farms

Vitamin D plays a critical role in the regulation of calcium and phosphate homeostasis and in the development and maintenance of skeletal health. Sheep can obtain vitamin D via either cutaneous production following exposure to UV radiation or consumption of vitamin D containing foodstuffs. In northern Europe, sheep are often unable to cutaneously generate vitamin D in late winter due to the lack of UV radiation. Consequently, they are heavily reliant on dietary sources of vitamin D, which, if insufficient, can lead to rickets in growing lambs. Here, we report the diagnosis of rickets in Scottish blackface lambs on five farms in South West Scotland. Cases were diagnosed based on classical skeletal clinical signs alongside extremely low concentrations of 25 hydroxyvitamin D, the major circulating metabolite of vitamin D, which is widely used to assess vitamin D status. This report demonstrates that rickets can be a major health problem in hill sheep.