Evaluation and Comparison Under Field Conditions of the Stress Response Induced in Horses When Administered Endoparasiticides in Tablet or Paste Formulations

CLINICAL RELEVANCE Administering equine anthelmintics in paste formulations has been integral to the management of equine parasites. The objective of this clinical trial was to assess whether a new palatable tablet presentation reduces stress in the horse when administering an anthelmintic. Horses (n=122) were randomly allocated into three homogenous groups: Group 1: tablets (Equimax (R) Tabs; Virbac); Group 2: paste A (Equimax (R) Gel; Virbac); and Group 3: paste B (Equest (R) Pramox; Fort Dodge). Stress response to deworming was assessed by monitoring heart rates (Horse Heart Rate Monitors, Polar Equine) before, during and after the administration of the allocated anthelmintic. In addition, eight scored behavioural reactions indicative of stress were assessed. The increase in heart rate was significantly less (p<0.0001) in Group I in comparison to Groups 2 and 3. Approximately 40% of Group I presented no behavioural reaction. More than 70% and 90% of the horses showed at least one reaction in Groups 2 and 3, respectively. Flehmen and pinning ears back reactions were significantly less frequent in Group 1 than in the paste groups (p=0.0013 and p=0.0277, respectively). According to the parameters monitored, this study demonstrates that the administration of an equine endoparasiticide in palatable tablet formulation induces less stress compared to a paste formulation.