So we’ve established that we don’t want our pets to be infected with heartworms. My friend Dr. Melissa McFarland commented on my last blog post via Facebook, reminding me that we vets are facing a shortage of the drug used to treat heartworm infection. As of the end of last year, the FDA has allowed the drug manufacturer to import limited quantities of drug into the U.S. from Europe, to augment the small amount being produced domestically. This will hopefully allow dogs with the most severe infections to be treated. Dr. McFarland also commented that she personally treated SEVEN cases of heartworm in southcentral Pennsylvania last year. This highlights how the heartworm has become more prevalent in areas where it once was considered rare. In contrast, during my first year in veterinary practice 15 years ago, the entire clinic (with four vets) had only a couple of cases.
Heartworm prevention products are available as pills, liquid applied to the skin, or as an injection. The drugs used in all of these products are part of a broad class called macrocyclic lactones, and the specific drug names are ivermectin, milbemycin oxime, moxidectin, and selamectin. The pill and topical forms are given every 30 days, whereas the injection is a slow-release product providing 6 months of protection. What I’d like to do next is to list all the marketed heartworm products with their trademark names, along with a description of what each one covers.
- Heartgard Plus for Dogs: beefy chew given once a month to dogs 6 weeks and older. Contains Ivermectin and pyrantel. Also covers round- and hookworms.
- Heartgard for Cats: chewable once-a-month tablet for cats 6 weeks and older. Contains ivermectin. Also covers hookworms.
- Tri-Heart Plus for Dogs: chewable once-a-month tablet for dogs 6 weeks and older. Contains ivermectin and pyrantel. Also covers round- and hookworms.
- Iverhart Max for Dogs: chewable once-a-month tablet for dogs 8 weeks and older. Contains Ivermectin, pyrantel, and praziquantel. Also covers round-, hook-, and tapeworms
- Sentinel for Dogs: chewable once-a-month tablet for dogs at least 4 weeks old and 2 lbs in weight. Contains Milbemycin oxime and lufenuron. Also covers round-, whip-, and hookworms, as well as flea eggs.
- Sentinel Spectrum for Dogs: chewable once-a-month tablet for dogs at least 6 weeks old and 2 lbs in weight. Contains milbemycin oxime, lufenuron, and praziquantel. Also covers round-, whip-, hook-, and tapeworms, as well as flea eggs.
- Revolution for Dogs: applied on skin once monthly in dogs at least 6 weeks old. Contains selamectin. Also controls fleas, flea eggs, ear mites, sarcoptic mange, and American dog tick.
- Revolution for Cats: applied on skin once monthly in cats at least 8 weeks old. Contains selamectin. Also controls fleas, flea eggs, ear mites, round- and hookworms.
- Advantage Multi for Dogs: applied on skin once monthly in dogs at least 7 weeks and 3 lb. Contains moxidectin and imidacloprid. Also controls fleas, round-, hook-, and whipworms.
- Advantage Multi for Cats: applied on skin once monthly in cats at least 9 weeks and 2 lb. Contains moxidectin and imidacloprid. Also controls fleas, ear mites, and round- and hookworms.
- Trifexis for Dogs: chewable once-a-month tablet for dogs at least 8 weeks and 5 lb. Contains milbemycin oxime and spinosad. Also covers fleas, round-, hook- and whipworms.
- Proheart-6: injection given under the skin every 6 months in dogs at least 6 months of age. Contains moxidectin. Also covers hookworm infection.
Whew. That’s a long list. How can you make a good choice for your pet? The first consideration is are you going to give a tablet monthly or apply a topical? I’ve worked with dogs that have some stomach upset from pill forms and do better with topical treatment. Perhaps you would like to also have flea and intestinal worm coverage. Maybe cost is your primary concern. If so, Iverhart Max and Tri-Heart Plus are typically priced lower than the other choices.
What do I usually recommend? In south-central Pennsylvania, where we are dealing with fleas, ticks, heartworms, and intestinal worms, and the cost of managing all of these parasites can add up, I have found a combination of Iverhart Max and Advantix (topical flea/tick) to be effective and safe. In certain cases, Revolution and Advantage Multi have been better choices, especially for cats. I have not prescribed Trifexis or Proheart-6. I want to specifically address these two medications, because there is a lot of mixed information about them on-line, and that’s where I will pick up next time.
If you have questions about any of the drugs I’ve written about here, please ask me! Post a comment here or on Facebook or Twitter!