Interactions between veterinary
pharmacotherapy, toxicology of residues, prevention of residues of
veterinary drugs and the evaluation of
veterinary drug files are discussed on the basis of a number of examples. Sulphadimidine is used to treat
atrophic rhinitis in medicated feeds which do not benefit the animal but are the cause of persistent sulphonamide residues in feed mills and husbandry.
Carbadox is a potentially effective prophylactic feed additive for the prevention of swine
dysentery, but is mostly used in high dosages which are almost toxic for the animals, and used during unnecessary prolonged periods. It is also prescribed as a therapeutic agent in which case a symptom of
poisoning, dry faeces, is mistaken for a sign of recovery.
Carbadox and/or its metabolites are carcinogenic and its use should be restricted to a bare minimum.
Furazolidone is an example of an effective
veterinary drug, the use of which should be limited by the fact that detoxification mechanisms of the animals, may result in the appearance of reactive metabolites which are available in the gastro-intestinal tract of the consumer. The central issue in a 'minimal residue' policy regarding the use of
veterinary drugs should be the selection of effective drugs. Such a selection could result in a significant reduction of the incidence of
veterinary drug residues. Second to this issue is the question of the extent to which residue toxicology should modulate the use of
veterinary drugs.