Retrospective case review investigating the effect of replacing oaten hay with a non-cereal hay on equine peripheral caries in 42 cases

Background: Equine peripheral caries can cause significant morbidity and can have considerable welfare implications. Recent research suggests that diets with high water soluble carbohydrate (WSC) content are associated with high risk of peripheral caries. Previous work has indicated that the condition may be treatable if the inciting cause is removed and the damaged tooth allowed to erupt out, being replaced by the unaffected tooth previously under the gingival margin. Objectives: To see whether the peripheral caries process can be ceased if oaten hay (typically high WSC) is removed from the diet and replaced with a non-cereal hay (typically lower WSC). Study design: Retrospective blinded longitudinal study. Methods: Forty-two cases with peripheral caries that were on oaten hay were asked if they would change the hay type from oaten hay to a non-cereal hay or straw (meadow, Rhodes hay, lucerne hay or barley straw). Photographs were taken at the time and then again at subsequent visits. The photographs were anonymised, randomised and scored by six equine veterinary dentists using the Jackson et al. ‘Peripheral Caries Grading System’ grading scale. Results: At follow-up, 69.0% of cases were marked as inactive, compared with 47.6% of cases at baseline (OR: 2.45, 95%CI: 1.12-5.36, P =.02). Significantly lower grades of peripheral caries were observed in the gingival, middle and occlusive third of the molars (triadan 9-11’s) at follow-up compared with baseline. However, significant improvements were not observed in the premolars (triadan 6–8’s). Main limitations: This is a review of clinical records, not a prospective study. As such, other changes in the diet and management were not recorded, and there was no control group. Conclusions: Recommending clients change their horse's diet from oaten hay (high WSC) to a typically lower WSC hay was associated with significant improvements in equine peripheral caries located in the molars.