If you have a cat who loves to snuggle under the covers, dont fit him with a flea and tick collar containing medicine designed to last six months or more. There are no studies out there, but logically, if a pet wearing such a collar snuggles under the covers, the person can be in contact with that topical insecticide during the entire night of sleep. Why take that risk? Penny says. However, if your cat sleeps at the foot of your bed on top of your bedspread, that is fine.