The best way to keep the Maine Coon from bringing ticks inside is to remove all the ticks before you go in. You just have to check him all over. The ticks take longer to attach to a cat with thick fur, so you should be able to find them before they do any damage. Watch for the tiny, newly hatched "seed ticks" in the spring though. I don't think any of the flea/tick treatments actually repel ticks.