I've switched all my dogs to Proheart, a six month shot which runs about $5.00 per month. Heartworm is really bad here in Texas. Two of my babies that I adopted from a shelter were heartworm positive. Both dogs were not highly infected so my vet suggested the "slow kill" method which is just putting them on a heart worm medicine for six months and retesting. Both got the Proheart shot and in six months they were negative. The really harsh treatment is now only done for highly infected dogs.
I don't have a flea problem, thank God, so don't use any flea meds. Their backyard is gravel and my house has wood floors with throw rugs which are washing regularly thus no fleas.
Nikki, I've never added up what my dogs vet bills cost me annually (Proheart, flu, kennel cough, rabies, etc) it would probably give me a heart attack. I'm using the money I used to spend on traveling for them and that's okay with me. They're worth every penny. I only give rabies once every THREE years. Most vets want to do it every year but they only make a THREE year rabies vaccine so you're over medicating if you give annually. Its because most cities want it given every year and if you license your dogs (which I never do) then the vets will suggest it annually. Ask your vet if he uses the much more expensive yearly vaccine or the three year one.