I'm going to be the voice of dissent here and say that I would definitely protect against heartworms
Although some of the chemicals used to treat a dog after it has contracted heartworms are the same as those used in the preventative drugs, they tend to be at a higher doseage. Some of the other drugs used to treat heartworms are much more harsh on the body. A dog already infected with heartworms also runs the risk of blood clots, congestive heart failure, and even the dead worms blocking the flow of blood during treatment. The treatment is not just take a pill and go on your way, like the maintenance drugs. Heartworm treatment involves keeping your dog quiet 24 hours a day and watching him/her like non-stop. The treatment is also quite expensive and many dogs require more than one round.
Thank you People Whisperer for your comments - I agree.
I do not disagree with East Jenn here - but want to clarify that we are making distinctions here as well. East Jenn is referring to full blown heartworm - active worms - and the traditional treatment to address it. It is in fact a harsh treatment, not regarded as healthy and runs the risk because it is so aggressive, of killing the worms so fast that the body can not expel them fast enough - hence the side effects that East Jenn refers to.
I have seen dogs test positive for heartworm - at the stage 1 level - and be treated with safe, slow methods as People Whisperer references whereby the dog does NOT have to be confined or kept still and the risk of over-aggressive expulsion is not present. I have never seen a problem with this method and know without a doubt it is safer on the body. This of course presumes that it is caught early and we are treating larvae.
So I still want to emphasize that the safe, more effective treatment for heartworm is to keep your dog protected, test your dog as often as your geographic area necessitates, and treat naturally, slowly for optimal health - the harsh, aggressive drugs aren't necessary then as a result.
And again, heartworm is still a great example of many illnesses - the harsh aggressive drug protocol often employed in western medicine is also often not the most successful protocol. Distemper is another great example. Vets scare people into vaccinating for this one even when the risk of it is nil - simply because of the horrific results of the traditional treatment for distemper. Neurological damage often results and dogs often don't make it as a result, but what most people do not understand is the neurological damage is not the distemper virus - it is the aggressive drug interaction that causes it. I have seen distemper treated completely differently, and the dogs have fully recovered, without any neurological damage. It will always depend on the strength of the individual dog, but I know the effective treatment exists.