The Dog Lover‘s Guide to Choosing the Safest and Most Effective Heartworm Prevention

As a dog lover, there‘s nothing quite like the bond you share with your furry best friend. We want our canine companions by our sides for as many years as possible. That‘s why protecting them from deadly heartworm disease is one of the most important things we can do as pet parents.

Heartworm is a serious and potentially fatal condition caused by foot-long parasitic worms that live in the heart, lungs, and blood vessels of infected animals. It‘s transmitted through the bite of an infected mosquito. And while it‘s most commonly diagnosed in dogs, it can also affect cats, ferrets, and even wild mammals like foxes and coyotes.

According to the American Heartworm Society, heartworm disease has been diagnosed in all 50 states. And cases are on the rise, with the number of infected dogs increasing by 20% between 2013 and 2016 [1]. Some of the highest rates of infection are found in the Southeast and along the Mississippi River, where mosquitoes thrive in the warm, humid climate.

While heartworm disease is treatable, it‘s a complex and costly process that involves a series of injections of a arsenic-based drug called melarsomine, often alongside steroids and antibiotics. Treatment usually requires multiple vet visits and weeks of strict exercise restriction. Even then, there‘s a risk of serious complications like pulmonary thromboembolism.

That‘s why heartworm prevention is so critical. By giving your dog a safe and effective preventative medication, you can help them avoid ever having to go through the ordeal of heartworm treatment. Plus, you‘ll gain priceless peace of mind knowing that you‘re protecting your pup from a devastating disease.

Understanding Heartworm Preventatives

Most heartworm preventatives work by killing off the immature stages of heartworms, called microfilariae, that circulate in an infected dog‘s bloodstream. Many of these medications also have activity against other common intestinal parasites.

The most popular heartworm preventatives are given orally as monthly flavored tablets or chews. There are also topical liquids applied to the skin, typically between the shoulder blades where a dog can‘t lick it off. And more recently, a long-lasting injectable form of prevention called ProHeart has come on the market.

The active ingredients most commonly found in heartworm preventatives are:

• Ivermectin (Heartgard, Tri-Heart, Iverhart): A broad-spectrum antiparasitic that‘s highly effective against heartworm larvae at low doses. Also treats roundworms and hookworms. Known to cause neurological side effects in dogs with a genetic mutation of the MDR1 gene, found frequently in Collies and other herding breeds.

• Milbemycin oxime (Interceptor, Sentinel, Trifexis): Prevents heartworm disease and also controls hookworms, roundworms, and whipworms. Considered safe for use in Collies and other MDR1 breeds. Rarely, may trigger seizures or other neurological symptoms.

• Moxidectin (Advantage Multi, ProHeart): A potent macrocyclic lactone that prevents heartworm disease. Also effective against fleas, sarcoptic mange, and intestinal worms in certain formulations. Available as a topical solution or six- or twelve-month injectable. Generally well-tolerated but may not be suitable for very young puppies or MDR1 breeds.

• Selamectin (Revolution): A unique topical preventative that protects against heartworms, fleas, ear mites, and sarcoptic mange. Can be used in puppies as young as six weeks. Reported to be safe for both dogs and cats with few adverse effects. The only FDA-approved topical heartworm preventative currently on the market.

While generally quite safe when used appropriately, no medication is without potential side effects. Some dogs may experience gastrointestinal issues like vomiting or diarrhea, particularly if the preventative is given on an empty stomach. Others may seem lethargic or lose interest in food for a day or so after their dose.

More serious but rare adverse reactions have been reported, including seizures, tremors, incoordination, and even death. This is more likely in dogs with the MDR1 mutation who are exposed to high doses of ivermectin or other macrocyclic lactones [2]. It‘s important to report any concerning symptoms to your vet and the drug manufacturer right away.

Factors to Consider When Choosing a Heartworm Preventative

With so many heartworm preventative options out there, how do you pick the right one for your precious pooch? Here are some key factors to consider:

1. Age: Most oral and topical preventatives are labeled for use in puppies eight weeks or older. Some products, like Interceptor Plus, can be given to pups as young as six weeks. There are also specially formulated puppy preventatives available.

2. Weight: Heartworm medication dosage is based on body weight, so an accurate measurement is essential for safety and efficacy. Growing puppies and dogs whose weight fluctuates may need to switch dosage levels over time. ProHeart injections are also weight-dependent.

3. Breed: Herding breeds and mixes like Collies, Australian Shepherds, Shelties, and Old English Sheepdogs frequently carry a genetic mutation of the MDR1 gene that makes them more sensitive to certain drugs, including high doses of ivermectin and other macrocyclic lactones [3]. For these dogs, products containing milbemycin oxime or selamectin are safer choices. Dosage adjustments may be required for very small or large breed dogs as well.

4. Lifestyle: If your dog is an avid swimmer, consider a water-resistant topical like Revolution or a long-lasting injectable like ProHeart 12. For picky eaters or dogs who may spit out pills, a flavored chew or tablet could be a better choice. Travel plans are another consideration, as you‘ll need to dose preventatives appropriately around trips and boarding.

5. Other Parasites: Multi-parasite preventatives like Trifexis, Advantage Multi, and Simparica Trio appeal to dog owners looking to control intestinal worms, fleas, mange mites, and ticks alongside heartworm protection. Just be sure your dog isn‘t getting a double dose of any active ingredients if combining preventatives.

6. Pre-existing Health Conditions: Dogs with a history of seizures or other neurological issues may need to avoid certain preventatives or use reduced dosages. If your dog takes other medications or supplements, check for potential drug interactions with your vet. Some preventatives shouldn‘t be used in pregnant or breeding animals.

The Importance of Annual Heartworm Testing

Even if your dog is on consistent heartworm prevention, annual testing is still a must. Here‘s why:

• Ensures Prevention Is Working: No preventative is 100% effective, especially if doses are missed, spit up, or given late. Regular screening helps catch any potential infection early before permanent heart and lung damage occurs.

• Detects Existing Infections: Many heartworm preventatives work by killing off immature larvae but aren‘t effective against adult worms. If started on prevention with an existing infection, a dog could experience a severe reaction. All dogs should be tested prior to starting heartworm prevention for the first time.

• Required for Dispensing Preventatives: Most U.S. states require a heartworm test within the past 12 months before a veterinarian can legally prescribe a preventative. This is also true for many online pet pharmacies.

• Monitors for Resistance: Though still rare, some strains of heartworm are showing early signs of resistance to macrocyclic lactone preventatives, particularly in the Mississippi Delta region [4]. Annual testing helps monitor for any potential loss of efficacy.

A heartworm test involves taking a small blood sample to screen for proteins released by the female heartworm into the dog‘s bloodstream, called antigens. Most vets use a simple in-house SNAP test that returns results within minutes. For dogs who spend a lot of time outdoors or live in high-risk areas, twice-yearly testing may be recommended.

Heartworm Prevention By the Numbers

To really grasp the importance of heartworm prevention, let‘s take a look at some important statistics:

• Prevalence: A recent American Heartworm Society survey found that 1 in 76 dogs tested positive for heartworm in 2016, a 20% increase from 2013. Higher prevalence was found in the Southeastern U.S., where 1 in 37 dogs tested positive [1].

• Cost of Treatment: According to the AHS, the average cost of heartworm treatment for a 40-pound dog is $1,200-$1,800, including diagnostics, injections, hospitalization, and follow-up. Complications can drive the cost much higher. Preventatives cost just $75-$200 per year, depending on a dog‘s size [5].

• Risk Factors: The mosquito species known to transmit heartworm are found in all 50 states. Factors that increase heartworm risk include living in a warm, humid climate; spending a lot of time outdoors; and visiting high-prevalence areas without adequate prevention [6].

• Market Share: According to market research firm Packaged Facts, the top-selling heartworm preventative brands in 2019 were Heartgard Plus (ivermectin/pyrantel), Simparica Trio (sarolaner/moxidectin/pyrantel), and Interceptor Plus (milbemycin oxime/praziquantel) [7].

So based on the latest data, heartworm is a serious and costly threat to our canine companions – but also a highly preventable one with the consistent use of a safe and effective preventative medication.

The Benefits of Heartworm Prevention Go Beyond Physical Health

Any dog lover who‘s seen their formerly active pet struggle through the pain and distress of heartworm treatment will tell you: an ounce of prevention is worth a pound of cure. But did you know that protecting your dog from heartworm can also have emotional benefits?

Knowing your best friend is shielded from a potentially deadly disease brings tremendous peace of mind. No more worrying about every mosquito bite or stressing over missed doses. You can relax and enjoy your time together, secure in the knowledge that you‘re being a responsible pet parent.

Plus, heartworm prevention can strengthen the bond you share with your dog. That moment of praise and a tasty treat after your pup takes their monthly medication becomes a special ritual between the two of you. Your dog learns to trust you to keep them safe and healthy.

At the end of the day, heartworm prevention is so much more than just a pill or a spot-on liquid. It‘s an act of love. It‘s a promise to your loyal companion that you‘ll do everything in your power to keep them by your side for years to come. And for a devoted dog lover, there‘s no greater gift than that.

Conclusion and Product Recommendations

We‘ve covered a lot of information in this guide, but here are the key takeaways:

• Heartworm disease is serious, costly, and potentially fatal – but also highly preventable with the right medication given consistently
• The best heartworm preventative for your dog will depend on factors like age, weight, breed, lifestyle, and overall health
• Annual testing is essential to ensure preventatives are working and catch any early signs of infection or resistance
• Protecting your dog from heartworms has emotional benefits and strengthens your bond

As a devoted dog lover and veterinarian, I know firsthand the peace of mind that comes with knowing your furry friend is protected against heartworm. While no single product is perfect for every dog, some of the ones I recommend most often include:

• Heartgard Plus: Still one of the most widely-used preventatives on the market with a proven track record of safety and efficacy. Kills immature heartworms and treats hookworms and roundworms.

• Interceptor Plus: A great choice for dogs with the MDR1 mutation and off-label use in pregnancy. Also protects against roundworms, hookworms, whipworms, and tapeworms. Scored tabs for precise dosing.

• Simparica Trio: One of the newest combination products on the market. A tasty monthly chew that prevents heartworm disease, kills adult fleas, and treats roundworms and hookworms.

• ProHeart 12: The only FDA-approved injectable heartworm preventative currently available. Offers a full 12 months of protection with one dose for dogs 12 months of age and older. Highly convenient for owners who struggle to remember monthly dosing.

When in doubt, your veterinarian is always the best resource for selecting a safe and appropriate heartworm preventative tailored to your dog‘s individual needs. Don‘t hesitate to voice any questions or concerns you may have.

Armed with knowledge and a commitment to prevention, you can give your beloved companion the healthiest, happiest life possible. As a fellow dog lover, I‘m grateful for dedicated pet parents like you who go the extra mile to safeguard your dog against heartworm disease. Together, we can keep more tails wagging for many years to come.

Sources:

1. American Heartworm Society | Heartworm Incidence Maps
2. PLoS One | Frequency of the mutant MDR1 allele associated with multidrug sensitivity in dogs
3. VCA Hospitals | Multidrug Resistance Gene (MDR1) Genetic Testing
4. FDA | Keep The Worms Out Of Your Pet‘s Heart! The Facts About Heartworm Disease
5. American Heartworm Society | Current Canine Guidelines for the Prevention, Diagnosis, and Management of Heartworm Infection in Dogs
6. Companion Animal Parasite Council | Heartworm Disease
7. Packaged Facts | Pet Medications in the U.S., 7th Edition