1. Dept. of Veterinary Medicine and Animal Productions; Federico II Univ. of Naples; Via Delpino 1 80137 Naples Italy
2. Experimental Zooprophylactic Inst. of Southern Italy; Via Salute 2; 80055 Portici (Naples) Italy
3. Univ. of Messina; Viale Annunziata; 98168 Messina Italy
4. Dept. of Pharmacy; Federico II University of Naples; Via Montesano 49 80131 Naples Italy