be very careful with ivomec it has a reputation for killing jrt's an collies with the blue eye gene, an all other dogs it seems to work really well. The very best stuff is aludex. I empty a full bottle 100ml into a 45 gall plastic drum the fill it 3/4 with water. I dip every dog in the kennels, affected or not then do the affected dogs again 10 days later. Then put the remaining solution in a knapsack sprayer and soak the kennels and runs transport box/ trailer etc.
Seleen shampoo is quite good as well but is not quite as heavy duty, but it can be bought without prescription.