Are Heartworm Pills Bad for Dogs?

Because pets are so often cherished family members, dog owners are careful about what medications they put into their pet's bodies. In order to determine if heartworm pills are bad for dogs, it is first necessary to understand what heartworms are, why they are harmful and why chemicals that prevent them may be more beneficial than chemicals that treat them after the fact. Once the severity of the heartworm problem is understood, it is easy to see that heartworm pills are not considered to be bad for dogs.

  1. Heartworms Defined

    • Heartworms are parasites that live inside of a dog's heart and pulmonary artery where they have access to a constant supply of oxygen rich blood. Adult heartworms look like spaghetti and are usually about 6 inches long. Mature heartworms can live for 7 years inside a dog. Throughout this time they reproduce and release baby heartworms, called microfilaria, into the dog's blood stream. The micorfialria are then transmitted from one dog to another through mosquito bites.

    Why Heartworms Are a Problem

    • Heartworms damage the arteries they live in by causing them to become inflamed and narrow. Small arteries may become completely blocked by heartworms. The dog's body responds to damage and blockages by rerouting blood through arteries that do not have worms living in them. Unfortunately, this increases the stress on the dog's healthy arteries. Eventually this process results in blood clots, aneurysms and a building up of fluid in the blood vessels of the lungs. This fluid forces the lungs and the heart to work much harder to deliver oxygen to the body. If left untreated, heartworm will ultimately end in death due to heart failure.

    Symptoms and Diagnosis

    • Heartworms begin to cause the dog physical problems almost immediately upon entering the body. Unfortunately, all of these problems occur internally and go unnoticed by the dog owner's. These problems include inflammation of the arteries, arterial blockage, increased blood pressure and stretching of the heart muscle. Outward signs of heartworm infection usually do not occur until the heartworms have been present in the dog for at least 6 months. Noticeable symptoms of heartworm include lethargy, a dull coat, coughing, fainting and difficulty breathing.

    Treatment

    • During treatment, antibiotics are prescribed to eliminate the bacteria caused by heartworm infections. Steroids may be prescribed to reduce arterial inflammation and heartworm prevention pills are given to the dog to kill any microfilaria present in the bloodstream. To kill the adult heartworms, the dogs are given an injection of a heartworm-killing drugs known as adulticides. Unfortunately, adulticides contain arsenic which can cause damage to the dog's body. Adulticide injections can be painful, so medications for pain management may also be required. After treatment the dog cannot engage in exercise and must be monitored for 1 to 2 months to make sure that the worms are gone.

    Dogs and Heartworm Pills

    • Heartworm prevention pills work very well, but they can have side effects, including nausea, vomiting, tiredness, loss of appetite and diarrhea. Usually these effects are mild but they can be severe in some dogs. Because heartworm pills are given weekly or monthly, dogs who experience a severe reaction to the pills may be sick quite often, leading owners to wonder if the heartworm pills may be bad for the dogs. Although the side effects of heartworm pills are unpleasant, they are not deadly like a heartworm infestation can be. The medications given to a dog to treat heartworm are much harder on the animal than the heartworm prevention pill. Because heartworm is so deadly and widespread, vets agree that heartworm pills are worth the risk of side effects. If your dog has a negative reaction to heartworm pills, talk to your vet about trying a different type of pill.