I think it depends alot on your area. Where I live, we really don't have to worry about fleas. When I talked to my vet about it, he said he's only seen 5 cases he can remember in 25 years he's been working here, and every one of them had been out of state recently, so I don't give flea medication. As for heartworm, again, I think it depends on where you live. While we do have heartworm in this area, it's pretty rare, and my vet has never seen a case of heartworm in a cat ever, so I don't give heartworm prevention either-Dogs yes, I keep them on heartworm prevention year round, but not the cats. It's a good idea if you can afford it, though. Personally, I've got 24 cats I take care, most of them feral, so it's just to expensive and difficult to give anything more then I have too. I've considered putting my house cats on Heartgard for cats, but I haven't. My vet hardly sells any cat heartworm prevention, and I trust him to give me good advice. If I lived in a warmer climate where heartworm and fleas where more prevalent, I probably would find a way to give the medications, but it's really not a problem here. Talk to you vet about it, and other pet owners in your area, and see what they say about it.