Harvest Mites

[Boto]

Last summer my rescue lab picked up harvest mites. He was really bothered by them. I don't know if it was a particularly bad year for harvest mites as most of my previous dogs were not bothered by them. A trip to the vets sorted him out at vast expense! As I have now another rescue lab as well who may be allergic to the mites I was wondering if there is anything to perhaps spray on them so that they don't get them in the first place. Anyone know of anything? Thanks.