In the VitDAL’s most recent study which was published this week, the team explored whether the vitamin D status of a cohort changed during the seasons. In humans, it is well known that peak vitamin D status occurs in late summer with a nadir at the end of winter which coincides with peak UVB exposure. However, in dogs it is not known if similar seasonal variation occurs. This is an important issue to definitively resolve since if it occurs then seasonal reference ranges may be needed to objectively assess vitamin D status and equally, it may mean that animals might need more vitamin D during winter months. The study discovered that vitamin D status remains relatively constant throughout the year providing further support to the notion that dogs solely rely on vitamin D accessed from their diet and do not cutaneously produce vitamin D in meaningful amounts. The study also showed that there was a significant amount of variation in 25(OH)D concentrations in dogs fed the same diet indicating that other genetic or environmental factors are likely to play an important role in regulating vitamin D metabolism. The paper can be accessed by this link