Effect of topical treatment of claw horn lesions with tetracycline-derivatives on plasma and milk concentrations

Abstract

Claw horn lesions frequently result in lameness, and these types of lesions are associated with environment and animal husbandry practices rather than infectious pathogens. The paucity of scientific literature pertaining to intervention strategies for these lesions promote therapeutic trimming techniques with or without the application of a hoof block to the contralateral claw and producer-dependent use of systemic antibiotics and analgesics. In a recent survey of hoof trimmers and veterinarians, 53% of trimmers and 59% of veterinarians reported using topical application of medications to solar lesion, with extra-label use of tetracycline-derivatives being the most frequently reported topical medication. In the advent of modern analytical technology, more sensitive assays are available to detect pharmaceuticals present in consumable animal products. These assays offer a more sensitive evaluation of residues involving the topical application of tetracycline-derivatives, which warrants concerns over the potential for violative residues. Given these lesions result in exposure of raw corium and granulation tissue, the potential of topical medications entering the systemic blood circulation in treated animals is possible, and yet, no research has assessed if extra-label use of tetracycline-derivatives results in violative drug residues in plasma and milk. Our hypothesis is extra-label use of tetracycline-derivatives results in drug residues in both plasma and milk; however, the concentrations would not surpass the Food and Drug Administration’s reported acceptable level, 300 ppb.