Experimental infection of sheep with ovine and bovine Dichelobacter nodosus isolates

The aim of this study was, under experimental conditions, to investigate infection of Nor-wegian White sheep with ovine and bovine isolates of Dichelobacter nodosus of varyingvirulence. In addition, the efficacy of gamithromycin as a treatment for the experimentallyinduced infections was examined. The study was performed as a single foot inoculationusing a boot. Four groups, each with six lambs, were inoculated with four different chal-lenge strains (Group 1: benign bovine strain; Group 2: virulent bovine strain; Group 3:benign ovine strain; Group 4: virulent ovine strain). The main criterion to determine thatinfection was transferred was that D. nodosus isolate was obtained by culture. After the trialall lambs were treated with gamithromycin. Clinical symptoms of footrot developed in allgroups, and when removing the boots two weeks after challenge, D. nodosus was isolatedfrom 5 of 24 experimental lambs. All lambs tested negative for D. nodosus by PCR within sixweeks after treatment with gamithromycin. This study strongly indicates that D. nodosusisolates from both sheep and cattle can be transferred to sheep under experimental con-ditions. The study also indicates that gamithromycin may be effective against D. nodosus.