A COMPARISON OF A NEW COMPOUND VALNEMULIN (ECONOR® - NOVARTIS) AND TIAMULIN ADMINISTERED IN-FEED FOR THE PREVENTION AND TREATMENT OF EXPERIMENTALLY INDUCED SWINE DYSENTERY
M.R. Burrows, J.H. Morgan, D.G.S. Burch and P.H. Ripley

Abstract
Two trials were carried out to evaluate the efficacy of valnemulin, a new pleuromutilin antibiotic, for the prevention and the treatment of swine dysentery. In the prevention trial, groups of nine pigs were challenged with 2 x 1010 Brachyspira hyodysenteriae on 2 consecutive days and then allocated to one of the following treatment groups: valnemulin at 0, 5, 10, 20, 30 and 40ppm in the feed, and tiamulin at 30ppm. Medication was given for 21 days after infection and all pigs were autopsied at the end of this period. Valnemulin, at 10ppm and above, proved very effective in preventing clinical swine dysentery and the shedding of spirochaetes, except in one pig in the valnemulin 30ppm group, that also had a concurrent E. coli infection. Eighty-eight per cent (8/9) of the untreated pigs developed clinical swine dysentery and 22% (2/9) of the tiamulin 30ppm group. In the treatment study, pigs were challenged as before but were allocated to one of the treatment groups, valnemulin 0, 50. 75, 100, 150 and tiamulin 100ppm, when sufficient pigs showed clinical signs of the disease. The pigs were treated for 10 days and then observed for a further 14 days prior to the termination of the trial, and then autopsied. All of the untreated pigs and 37.5% (3/8) of the tiamulin 100ppm group developed severe swine dysentery and were removed from the trial. All of the valnemulin treated pigs responded quickly to treatment, but one relapsed in the 50ppm group. B. hyodysenteriae was isolated from 62.5% (5/8) of the 50ppm valnemulin group and 12.5% (1/8) of the 75ppm group at autopsy, but not from the 100 or 150ppm valnemulin groups.

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