Climate change may affect reindeer herding and the health and disease of reindeer in several ways. One way of mitigating such changes is supplementary feeding, both in corrals and by bringing fodder to the animals on natural pastures. Feeding, when the right feed and feeding regime are used, may compensate for the loss of natural pastures and increase animal welfare. However, feeding may also cause issues with health and disease. These challenges may be associated with the feed and feeding regimes themselves, but also indirectly, by creating increased animal-to-animal contact and through the difficulty of maintaining hygienic conditions in corrals. In addition, climate change may have an impact on the presence of arthropod species and populations, such as ticks, mosquitoes and midges. These insects may cause increased levels of stress for the animals but can also be vectors for pathogens that may cause severe disease outbreaks, animal welfare issues and economic loss for reindeer herders. This chapter briefly presents the diseases and health problems that are directly or indirectly associated with reindeer feeding, as well as health challenges associated with arthropods and vector-borne diseases that are expected to be affected by climate change in the Arctic and sub-Arctic regions