Pathology and residues in veal calves treated experimentally with clenbuterol.

Six veal calves were medicated with clenbuterol at 20 micrograms kg bodyweight-1 day-1 for 42 days before they were slaughtered, to evaluate the lesions and residues in target organs. Compared with six unmedicated calves the most noticeable changes were tracheal dilatation, decreased uterine weight, slight mucous hypersecretion in the uterus and vagina and depletion of liver glycogen. The highest concentrations of clenbuterol (62 to 128 ng/g-1) were recorded in the choroid/retina, and the aqueous humour had the lowest concentration (0.5 to 2.4 ng ml-1). The residue concentrations were higher than the maximum residue level set for clenbuterol (0.5 ng g-1).