**5. Concluding remarks**

Vitamin K in animals as a general subject has not been systematically investigated. There are, however, common vitamin K‐related health issues that animals share with man. These are predominantly associated with coagulopathies, but diseases of the musculoskeletal system and kidney injury may have considerable overlaps to the mutual benefit of man and animals.

The requirements for animal health and well‐being are poorly defined for vitamin K, with, in some cases, misconceptions about the contributions to vitamin K status from colonic bacterial sources. Animals may have a distinctly greater reliance on vitamin K2, in large part due to their diet, which is regulated by the feed that is given to them. Furthermore, the upper alimentary canal supply of menaquinones may be of central benefit to support the vitamin K status of several species such as ruminants and possibly in particular rabbit kittens.

An exciting emerging area is the molecular regulation embryological development and growth by the *in situ* generation of the vitamin K2 congener menaquinone‐4, through the prenyltransferase UBIAD1. The work on the zebrafish has the potential to radiate across all species, and this may be of particular importance in conservation breeding programmes.

There is reason to suspect that in some metabolic and inflammatory diseases, there is a pronounced vitamin K deficiency. The prospect of intervening in some of these pathologies with vitamin K, such as kidney disease, is already being proposed for human patients. Defining the vitamin K requirements in different animals, beyond simple hepatic coagulation factor needs, may suggest newer approaches to veterinary medicine that could be investi‐ gated.
