Clinical safety evaluation of F(ab')₂ antivenom (Crotalus durissus-Bothrops asper) administration in dogs

Antivenoms consisting of selective antigen binding antibody fragments, or F(ab')(2), are becoming more popular in human and veterinary medicine, owing to their preferred kinetics, tissue distribution, and removal of the Fc binding portion of IgG. Consequences of antivenom administration can include acute and delayed reactions, dependent, in part, on the antivenom's donor source, purity, and composition. This study evaluated an equine-derived polyvalent F(ab')(2) pit viper antivenom in healthy dogs of various size, age, and breed under controlled conditions. Dogs were allocated into 6 treatment groups (n = 10 per group) based on weight (3 weight groups) and dose (2 dose groups) and administered F(ab')(2) antivenom over 1 hour by IV infusion. Dogs were observed for adverse events at 3, 6, 12, and 24 hours after administration and blood was collected for CBC and serum biochemistry before and at 24 hours postadministration.

No abnormalities were noted in the 3-vial group. In the 6-vial group, 3 dogs developed mild self-limiting edema around the head or neck, suggestive of a type 1 hypersensitivity, while another dog vomited and developed mild hypocalcemia at 24 hours, reflecting a 13% reaction rate at high doses. However, no dogs exhibited clinical signs of hypocalcemia or had any severe adverse events. CBC remained normal in all groups.

This study demonstrated that the polyvalent F(ab')(2) pit viper antivenom is well tolerated in dogs given large doses in a short period of time.