Can Preventive Tablet Wormers Cure a Dog Infected With Worms?

Heartworm medication is essential to keeping your dog free of the potentially fatal pest.
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Heartworms are a type of roundworm that can be fatal to Fido. Since most dogs are at risk of contracting heartworms, veterinarians usually advise pet owners to take proactive steps to reduce the risk. Some heartworm medications are effective for treating intestinal worms, but not adult heartworms. Make sure you seek your veterinarian's advice on the best method to protect the heart of the one you love.

The Life Cycle of the Heartworm

Dogs acquire heartworms via the bite of infected mosquitoes, so the parasites are more common in places with high mosquito populations. When a mosquito bites an infected animal, it ingests numerous heartworm larvae, termed microfilariae. When the mosquito bites your dog, some of these microfilariae travel into Fido's bloodstream. The microfilariae then develop into mature worms, which typically reside in your dog’s heart or lungs. These adult worms can cause a number of potentially fatal health problems, including cardiac failure.

Treating Heartworm “Preventively”

Treating a dog who is infected with adult heartworms is expensive, difficult and complicated. There is only one medication approved for treating adult heartworms, and even with its use, infected dogs may be forced into lengthy hospital stays and repeated tests. However, several medications will kill the immature microfilariae before they become adults. By taking one of these medications on a recurring basis, the microfilariae die before they mature. However, these medications do not prevent the heartworm larvae from infecting Fido; they merely kill the larvae before they become large enough to cause problems. No dog wormers truly prevent worms from infecting Fido -- they only eradicate worms once they are present.

Prescription Only

Heartworm medications are only available by prescription. It is important to ensure that Fido does not have an active adult infestation prior to giving him the medication. If Fido has adult worms in his heart, he's likely to have many microfilariae in his bloodstream, courtesy of the adult worms. If the microfilariae-killing medications are administered, most of the larvae will die in a short time. This can be overwhelming, causing him to become very ill. Sometimes it is still possible to treat Fido with the medication, but your veterinarian may prescribe additional medications or alternative treatments.

Useful Side Effects

Preventative heartworm medications often kill adult hookworms, roundworms and whipworms. Some are effective against tapeworms as well. Many preventive heartworm medications also contain other compounds, which broaden their efficacy. For example, some heartworm medications also treat fleas and ticks. For Fido's sake, it's best to consult your veterinarian before administering medication to treat intestinal worms.