Is your pet on the pill? Or do you apply an oily liquid to their skin every month? Differentiating between the many oral and topical heart worm preventives available to select the medication appropriate for your pet may be confusing. Similarly, few pet owners have the opportunities to thoroughly understand the differences between heartworm preventives. In this article, I will outline the differences between each heartworm preventive and discuss the importance of monthly heartworm preventives.
Heartworm disease is caused by a parasitic worm that colonizes the large vessels leading from the heart to the lungs. Mosquitos spread heartworms and any dog that is exposed to mosquitos is at risk of developing the disease. The disease has been identified in every state in the United States and dogs living in the Southeast are at particularly high risk. The American Heartworm Society recommends year-round treatment with a heartworm preventative regardless of the geographical location.
Heartworm preventives are insecticides that kill heartworm larvae. These medications are given on a monthly basis and can be given orally or topically. It is recommended to give heartworm medication year-round despite the observation that mosquitos are less active during the winter and your dog is less likely to become infected. However by providing your dog with year round preventives, the total number of heartworms present in a community is reduced. Fewer numbers of heartworm present in a community provides an additionally source of protection to all of the pets in the community.
- Heartgard, Heartgard Plus (by Merial)
- Iverhart Plus, Iverhart Max (by Virbac)
- Tri-Heart Plus (by Schering Plough
These heartworm medications are given orally once per-month. Although the amount of drug present in the mediation is effective at killing heartworm larvae, it is not sufficient to eliminate other types of parasites. Medications with a “plus” refer to the addition of another parasite medication called pyrantel pamoate that kills common intestinal parasites hookworms and roundworms. The “max” indicates the addition of praziquantel that targets tapeworms in addition to pyrantel pamoate and ivermectin. Although these drugs are considered to be very safe- they do cause neurological side affects in dogs such as Collies and Shetland Sheepdogs that are considered to be genetically sensitive to the drug.
-Targets just heartworm. If additional drugs are added (Plus) targets hookworms and roundworms. If another drug is added (Max) targets tapeworms.
- Safe in most dogs except Collies and Shetland Sheepdogs
These heartworm medications are also given orally once per-month. They target heartworms, roundworms, hookworms and whipworms and include another drug to prevent flea infestation. These drugs are very safe and adverse effects such as tremors and wobbly gait are rarely seen. Similarly, no specific dog breeds have been reported to be sensitive to milbemycin.
-Target heartworm, roundworms, hookworms, whipworms and prevent flea infestation
- Safe for most dogs
- Revolution (by Pfizer)
Selamectin is applied topically once per-month. In addition to heartworm larvae, it kills hookworms, roundworms fleas and ear mites. Because selamectin is absorbed through the skin, it must be applied directly to the skin, commonly between the should blades to be effective. Most dogs tolerate selamectin well, however some dogs do have adverse reactions such as loss of appetite, excessive drooling, vomiting, diarrhea, muscle tremors, fever and rapid breathing.
- Targets heart worm larvae, hookworms, roundworms, fleas and ear mites
- Some adverse reactions
Moxidectin kills heartworms, hookworms, roundworms whipworms and fleas. Advantage Multi is administered topically directly onto the skin. This drug rarely causes side affects such as lethargy, itching and hyperactivity. Proheart 6 is an injectable drug given every six months. The drug is released slowly into the bloodstream allowing it last for six months. Unfortunately severe adverse reactions and death has been reported following the administration of this drug resulting in the FDA withdrawing the drug from the market in 2004. The drug was reintroduced in 2008 with additional warnings, precautions and adverse reactions. Veterinarians who have completed the company’s certification can only give this drug. It is not for dogs with allergic diseases such as food, skin or flea allergies or those that are sick, debilitated or underweight. Similarly this drug cannot be given within a month of vaccinations.
- Targets heartworm, heartworms, hookworms, roundworms and whipworms. Proheart 6 can be given every 6 months.
- Proheart 6 can cause severe side effects including death and cannot be given to every dog
Having options and understanding your options improves your decision making process. With over twelve heartworm preventive products available, deciding on the right product for your pet may be difficult. If flea control is important to you, then select those that also target fleas. Similarly, if you cannot give your pet a pill every month, a topical medication may fit your needs. If price is a concern, ask your veterinarian about special promotions from these companies, as rebates are often available. The most important aspect of heartworm preventives is that they are given regularly every month.