Pour on application of growth promoters in veal calves: analytical and histological results†

Abstract

To investigate the possibilities for screening and confirmation methods when the ‘pour on’ method of application is used for administration of growth promoters, an animal experiment was performed using a cocktail of a combination of growth promoters derived from (illegal) practice. Two cocktails were used, cocktail A consisting of stanozolol and estradiol benzoate and cocktail B consisting of stanozolol, estradiol benzoate and beclomethasone dipropionate. The intended dose per animal was 110 mg stanozolol, 25 mg estradiol and 10 mg beclomethasone. The experiment was performed on 20 male veal calves, 16 treated and 4 vehicle treated controls and 3 female veal calves, 2 treated and 1 vehicle treated control. Half of the animals were shaven prior to the application of the drugs. The cocktails were administered using two types of vehicles: vehicle A; Miglyol 840 with butylated hydroxytoluene and vehicle B; di(ethyleneglycol) monobutylether. During a 28 day treatment period, one group of animals was treated once a week, another group of animals was treated once every two weeks and slaughtered. Preliminary results showed that pour on application of anabolic steroids markedly increased growth performance of veal calves, the animals treated with cocktail A performed better than the animals treated with cocktail B. Macroscopically, the thymus was reduced in weight and size in the B animals. The bulbo-urethral glands were enlarged in all treated animals. Histologically all treated animals showed squamous metaplasia in the prostate, bulbo-urethral gland and Bartholins glands. Moreover, a changed secretion pattern was observed in both the prostate and the bulbo-urethral gland. Severe cortical atrophy was observed in the thymus and to a lesser extent the adrenals of the beclomethasone treated animals. The recently discovered 16β-hydroxy-metabolite of stanozolol was detected in urine, in relatively high concentrations. This is the first report of the excretion of this metabolite in urine after pour on administration showing the prospect for detection of dermal treatment. Estradiol levels were remarkably elevated (up to 200 µg l^–1) exceeding the endogenous levels (<1 µg l^–1).