Heartworm medicine for dogs can be divided roughly into two types: those that prevent heartworm, and those that treat (or cure) heartworm. Obviously, prevention is simpler to deal with but they aren’t always 100% effective, unfortunately.

Preventive medicines have been around for quite some time and even though they aren’t 100% effective, they indeed do a remarkable job at keeping our pets safe, especially in areas known for high levels of infected mosquito infestations. Monthly treatments involve topical ointments that are usually rubbed onto the back of your dog’s neck where he can’t lick it off, and/or pills that can be taken daily or monthly.

Most medicines are multi-functional, meaning, they work on more than just heartworms. Depending on the medicine it could also be used to prevent roundworms, hookworms, and/or tapeworms, along with being able to kill eggs and larvae and perhaps even ticks.

Don’t reckon that keeping your dog indoors is preventive medicine! Mosquitoes are notorious for going where they aren’t welcome, and our homes aren’t immune from harboring at least one or two of these pesky critters. And that’s all you need to get your dog infected.

Depending on your vet, he may also recommend giving your dogs pills in addition to using the topical ointments. In areas that are near water – where mosquitoes thrive – he may want your dog to be doubly protected. Do as he suggests, but make certain you don’t overmedicate or buy substitute prescriptions that may be cheaper without checking with your vet first.

If your dog has been diagnosed with heartworm, you will now need to give him the heartworm medications that are to cure/treat, rather than prevent. Once your dog has been diagnosed with heartworm, he’s already very sick, and these medications can make him worse. Some dogs have no side effects, others succumb to the side effects. Much like chemotherapy in human cancer patients, these medicines are poisons meant to kill the invading worms and larvae, frequently making the patient sicker before things get better.

It’s hard to get a right reading on how effective these drugs can be because frequently the deaths caused by the drugs are recorded as “death by heartworm” instead of the real culprit. If your vet suggests that you start an aggressive treatment schedule, you need to have a serious discussion with him about possible side effects – especially in your pet – vs. What would happen with no medical intervention.