Although considered relatively common in horses, there is little information on the prevalence, distribution and aetiology of peripheral caries of the equine cheek teeth (CT). The objective of this study was to investigate a possible association between this lesion and diastemata or 'gaps' between the CT which facilitate the entrapment of food material. Video recordings of oroscopic examinations of all dental cases at an equine hospital over a 3-year period were reviewed, and the location of all diastemata, peripheral caries, trapped food, and of gingival recession were recorded. A total of 108 cases met study inclusion criteria and 298 diastemata and 445 CT with peripheral caries were noted. Diastemata were found predominantly in the mandibular arcades (80%) and 75% of animals had at least one diastema. Peripheral caries was uniformly distributed between the maxillary and mandibular CT, being most prevalent on the most caudal three teeth (87%). Overall, diastemata were not associated with peripheral caries at either a tooth or individual patient level. However, a highly significant association was found between the presence of trapped food within diastemata and gingival recession.