Effect of manual and motorized dental rasping instruments on Thoroughbred's heart rate and behavior

Inadequate research exists to justify the choice of dental tools used in equine prophylactic dentistry; usage is unregulated, with choice usually based on the practitioner’s preference. Dental procedures could cause stress (through handling or equipment used), as they are potentially painful if contact is made with soft-tissues. Anecdotally adverse reactions are documented and differ when comparing manual with motorized rasping, particularly during rasping the lower arcade. The study aimed to investigate these claims.Forty-five Thoroughbreds were divided into groups: (A): manual rasping, (B): motorized rasping, and (C): control. Horses were accustomed to prophylactic dentistry (6-12 months previously) and required a routine float. A standardized protocol was used; heart rate (HR) and scale-graded interactive behavioral responses (BR) were recorded to evaluate subjects’ stress and pain pre-, peri-, and posttreatment.Increased HR and BR were observed in group A compared with groups B and C (P < 0.001). Motorized rasping produced a significant increase in HR (P < 0.001) and BR (P < 0.001) from the controls. The results support postulation of higher sensitivity in the lower arcades, with these arcades exhibiting significantly higher HR and BR in both motorized and manual groups (P < 0.001). “Bit-seating” recorded higher responses (HR and BR: P < 0.001) compared with routine rasping.The study could inform routine dentistry; motorized rasping produced less-reactive horses, potentially providing a safer working environment for dental technicians and increased welfare for their equine patients.