Malocclusion in dogs and cats

Occlusion describes the way in which teeth contact each other, particularly the relationship between the maxillary and mandibular teeth as they approach each other during chewing or at rest. It is difficult to define normal occlusion as the arrangement of teeth and their supporting structures commonly found in health and that which is the common or standard arrangement varies both between and within breeds. The state in which teeth are in a normal relationship with each other is dependent on number, size, shape and position of teeth and the length, width and relative relationship of the jaws and therefore there is in both cats and dogs (the species which will be considered in this article) considerable variation around what is considered normal.

The development of occlusion is controlled primarily by genetic factors. It has been shown that tooth bud position, tooth size and jaw length are inherited (Stockard, 1941; Thomas et al, 1998; Hlusko et al, 2006; Suto, 2008) and that the control of tooth eruption and the growth of the maxilla and mandibles are regulated independently. Development and growth of the facial muscles and other soft tissue is also important in the growth and development of the jaws. Disruption of the normal development of any of these tissues, either through genetic mutation or environmental factors such as trauma or nutritional changes, can result in malocclusion.