The safety of injectable rafoxanide in cattle

Thirty-two weaned steer calves were injected subcutaneously with rafoxanide solution to determine the lethal dosage. The recommended therapeutic dosage is 3 mg/kg. Eight of 12 calves treated at 45 to 60 mg/kg displayed signs of toxicity 24 hours to 8 days after treatment. These included recumbency, polypnoea, muscle tremors and clonic spasms, opisthotomus, paddling movements of the feet, and blindness with mydriasis and death. An easily detected histopathological lesion was status spongiosus of the central nervous system. This study demonstrated that injectable rafoxanide has a wide safety margin when used at the recommended therapeutic dosage.