Treating a yard for ticks?

Ok I am not sure if anyone has had this problem but hopefully I can get some good ideas. Is there anyway to treat our yard for tics? I am worried that poor English Mastiff will finally be off his meds after a month a he will get bitten again and this will become a vicious cycle. We have a very large back yard with a ton of trees. I would hate to spend a bunch of money and have it not work. And of course the health of our pup is the most important thing. Thanks!!