I'm just getting ready to take Sam for his morning romp in the desert. I spray him with a mixture of lemongrass and eucalyptus oils. It REALLY helps with the ticks. There are several commercial mixes available (Amazon among others) and I also have the raw oil to mix (with water) myself.

Let the record show that Sam doesn't like being sprayed. He doesn't understand the benefits after we are out of the house, but I know that it works. Sam's other Dad used it on him the last summer he spent in Wisconsin. Erv dropped the ticks he plucked off Sam into a pop bottle with water in it and kept it for the whole season. The last summer there were notably less ticks in the bottle-the difference being using the spray.