[The occurrence of dapsone residues following a one-time oral, intramuscular and intramammary application in healthy dairy cows].

Dapsone is frequently used as a bacteriostatic drug in the treatment of mastitis, endometritis and footrot (necrotic pododermatitis). The farmer usually obtains this drug by 'non-ethical' channels. A regular scheme of checking the milk for residues of sulphonamides will be introduced in 1986. The sensitivity of the test is approximately 25 ppb for Dapsone. This will result in lower milk price in the case of positive tests. In healthy animals, it is shown that intramuscular treatment with 35 grammes (+/- 70 mg/kg-1 body weight) of Dapsone results in residues of Dapsone and its metabolite monoacetyldapsone above this detection level for more than 6 1/2 days. Within 5 days after oral treatment with 48.75 grammes (+/- 100 mg/kg-1 body weight) and 2 1/2 days after single intramammary treatment with 0.8 grammes, the concentrations of residues detected dropped below 25 ppb. The other well-known metabolite diacetyldapsone was only present in detectable quantities in the first milkings after oral treatment.