Percentages of flea-free primary dogs at Weeks 4 , 8 , and 12 were 91.1 % , 95.4 % , and 95.3 % for the fluralaner group ; and 44.7 % , 88.2 % , and 84.4 % for the controls ; the differences were significant at Weeks 4 ( P < 0.0001 ) and 12 ( P = 0.0370 ) .