your terriers are twice the size of mine lol ,but yes its good stuff alright .i got the ivomec super for cattle fmwtc and have had no problems with that either and works the same . other good stuff is this mate couldnt get it for a few year but its back on the market ,no more mites at all now mate this is very good stuff
http://cgi.ebay.co.uk/HARKAMITEX-Duramitex-replacement-from-Harkers_W0QQitemZ390172584657QQcmdZViewItemQQptZUK_Pet_Supplies_Birds?hash=item5ad8192ad1
its called dektermax now good stuf kills everyhtin