We don't worry to much about fleas or heartworm here. Apparently it's too cold here even for those critters
Tapeworms are another story though. Just about every spring my cat gets one. She is an outside cat in the summer and eats birds. Every spring we go to the vet and get pills and she gets one in the spring, one in the middle of summer and one right after the first snowfall. They aren't fun to pick up off the rug or pick out of a butt!!
