A portrait of a relaxed dog on the ground with heartworm preventative medicines nearby.

Best Heartworm Prevention Medicines for Dogs

As a dedicated dog owner, ensuring the health and well-being of your furry friend is likely one of your top priorities. Among the various health concerns dogs may face, heartworm disease is one of the most serious. This potentially fatal condition is transmitted by mosquitoes, putting virtually all dogs at risk. But the good news is that heartworm disease is preventable, and several effective medicines are available to safeguard your dog from this threat.

In this blog post, we will dive deep into the world of heartworm prevention medicines for dogs. We’ll discuss what they are and how they work and share some of the best options available today. So, whether you’re a new dog owner or a seasoned pet parent, stay with us as we navigate the essentials of safeguarding your pup against heartworms.

The Importance of Year-Round Heartworm Preventative Medicines

Year-round heartworm prevention plays a critical role in safeguarding your dog’s health. The disease, spread by Dirofilaria immitis, a parasitic worm, has been reported in all 50 U.S. states, reflecting its wide geographic spread and underscoring the need for consistent preventative measures. The unpredictability of mosquito season, the carriers of heartworm, adds another layer of complexity to the issue.

Traditionally, heartworm transmission has been associated with the warmer months when mosquitoes thrive. However, with shifting weather patterns and the presence of indoor mosquitoes, there’s no longer a clearly defined ‘safe’ season. This makes year-round prevention not just a recommendation but a necessity.

Furthermore, prevention is undeniably more straightforward and cost-effective than treatment. Treating heartworm disease is complex and expensive, often involving long-term medication, potential surgery, and a restrictive recovery period. Some dogs might not fully recover, living with the after-effects of the disease. Conversely, year-round preventative measures are affordable and easy to administer. A lapse in prevention, even briefly, leaves your dog vulnerable to infection and subsequent ccc. 

Additionally, many heartworm preventatives protect against common parasites like ticks, fleas, and roundworms, providing an all-in-one solution for your pet’s parasitic defenses. Consistent, year-round heartworm prevention is the best way to keep your pet safe, healthy, and heartworm-free.

Best Heartworm Preventatives for Dogs

 There are three main types of heartworm preventatives: oral medications, topical medications, and injectable medications. Choosing the best heartworm prevention medicine for your dog depends on age, lifestyle, and your vet’s recommendations.

Oral Heartworm Preventatives

Oral preventatives come in chewable tablets or soft chews that your dog ingests. Oral heartworm preventatives are generally easier to administer because they are designed to be palatable to dogs. They work by introducing a small dose of medication that circulates in the dog’s system and kills off heartworm larvae that may have been ingested through the bite of an infected mosquito.

  1. Simparica Trio
  2. Nexgard Plus
  3. Heartgard Plus
  4. Interceptor Plus
  5. Sentinel Spectrum
  6. Tri-Heart Plus
  7. Trifexis

Topical Heartworm Preventatives

Topical heartworm preventatives are applied directly on the skin, usually on the back of the neck or between the shoulder blades, where the dog can’t lick it off. They are easy to apply and do not require the pet to ingest anything, making them a good choice for dogs with difficulty taking oral medications. Many also offer protection against internal parasites (like heartworms and intestinal worms) and external parasites (like fleas and ticks).

  1. Revolution
  2. Advantage Multi

Injectable Heartworm Preventatives

Injectable heartworm preventatives provide long-term protection with a single dose, reducing the chance of missed doses. They also take the responsibility of remembering to administer monthly preventatives off the pet owner’s shoulders. As a vet administers these medications, it also ensures the full dose is given every time.

  1. ProHeart 6
  2. ProHeart 12

Injectable heartworm preventatives (containing moxidectin) offer an alternative to oral and topical treatments. ProHeart 6, for example, can be used in puppies as young as six months of age, while ProHeart 12 is suitable for dogs over one year. These injections protect for six or 12 months, depending on the chosen product. These injections also protect against hookworm intestinal parasites.

Choosing the Right Heartworm Preventative for Your Dog 

Please consult your veterinarian to find the best possible heartworm prevention method for your dog’s lifestyle and budget. If heartworm disease is prevalent in your area, using a product specifically targeting heartworms is vital. A monthly chewable tablet might be a more convenient option over topical applications, as it doesn’t require a messy application.

Common Side Effects of Heartworm Preventatives

Oral, topical, and injectable heartworm preventatives may have different side effects based on their mode of administration and active ingredients. Let’s discuss each one:

Oral Preventatives: Oral heartworm preventatives are typically well-tolerated by most dogs, but they may occasionally cause gastrointestinal upset, including

  • vomiting
  • diarrhea
  • loss of appetite

In some instances, dogs might experience lethargy or hypersalivation.

Topical Preventatives: Topical heartworm preventatives are applied to the dog’s skin. The most common side effect is skin irritation at the application site, which can include

  • redness
  • itching
  • hair loss.

Rarely, some dogs might experience vomiting, diarrhea, salivation, or nervous system disorders.

Injectable Preventatives: The injectable heartworm preventative ProHeart 6/12 is administered by a vet every six or twelve months. Potential side effects include

  • swelling or tenderness at the injection site
  • lethargy
  • decreased appetite or hyperactivity. Rare side effects may include seizures, vomiting, diarrhea, and allergic reactions.


To keep your dog healthy, ensure they are on a heartworm preventive recommended by your vet. Year-round heartworm prevention is crucial, so follow the recommended treatment schedule to protect your pet from this dangerous disease.

Frequently Asked Questions

The number one vet-recommended heartworm prevention is a class of medications called macrocyclic lactones, which includes ivermectin-based preventatives such as Heartgard and Sentinel and other options like Milbemax and Interceptor. These medications are highly effective in preventing heartworm disease when administered as directed by a veterinarian.

For heartworm treatment, veterinarians typically follow a comprehensive protocol that involves multiple steps. The specific treatment plan may vary depending on the severity of the infection and the individual dog’s health condition. Treatment often includes using melarsomine, an arsenic-based medication, and other medications to manage heartworm disease’s side effects and complications. It is crucial to consult a veterinarian to determine the most appropriate treatment plan for an infected dog.

Alternative medications are available if you want a heartworm prevention option without ivermectin. One option is using a product called moxidectin, another type of macrocyclic lactone that effectively prevents heartworm disease. Examples of moxidectin-based preventatives include ProHeart 6 and ProHeart 12, administered as a veterinarian’s injections. These products provide long-lasting protection against heartworms.

Apart from ivermectin-based preventatives, several heartworm preventatives that do not contain ivermectin are available. Some examples include milbemycin-based preventatives like Interceptor and Trifexis, which effectively prevent heartworm disease and protect against other parasites such as intestinal worms and fleas. It is important to consult a veterinarian to determine the most suitable heartworm prevention option for your dog.

An alternative to ivermectin for dogs is moxidectin. Moxidectin is a different type of macrocyclic lactone that is effective against heartworms. It is available in products such as ProHeart 6 and ProHeart 12, administered as a veterinarian’s injection. These products provide extended protection against heartworms and eliminate the need for monthly administration. It is important to consult a veterinarian to determine the most appropriate heartworm prevention option for your dog based on their needs and medical history.

The best heartworm prevention without ivermectin would depend on various factors such as the dog’s health status, age, breed, and individual needs. Some alternatives to ivermectin-based preventatives include milbemycin-based products like Interceptor and Trifexis, which are effective against heartworms and other parasites. Additionally, moxidectin-based preventatives like ProHeart 6 and ProHeart 12 provide long-lasting protection with a single injection. It is essential to consult with a veterinarian to determine the most suitable and effective heartworm prevention option for your dog.

Heartworm medicine should always be obtained with a prescription from a veterinarian. Over-the-counter options for heartworm prevention are generally not recommended as they may not be as reliable or effective as prescription medications. It is essential to consult with a veterinarian who can assess your dog’s health, consider its specific needs, and prescribe the most appropriate and safe heartworm medicine.

The survival rate for dogs undergoing heartworm treatment is generally high. However, the prognosis can vary depending on several factors, including the stage of the infection, the dog’s overall health, and any complications. With proper veterinary care and adherence to the treatment protocol, most dogs can successfully recover from heartworm disease. It is important to work closely with a veterinarian to ensure the best possible outcome for your dog.

While some natural or herbal products claim to offer heartworm prevention for dogs, it is essential to note that there is no scientifically proven natural alternative to prescription heartworm preventatives. These products may lack the efficacy and safety to protect dogs against heartworm disease effectively. To ensure the best protection for your dog, it is recommended to use veterinarian-prescribed heartworm preventatives that have been extensively tested and proven effective.

Heartworm medicines approved by veterinarians and obtained through a prescription are considered safe when used as directed. These medications undergo rigorous testing and are proven effective in preventing heartworm disease. The safety of a specific heartworm medicine can vary depending on the dog’s health, age, breed, and any potential drug interactions or underlying medical conditions. It is important to consult with a veterinarian to determine the most suitable and safest heartworm medicine for your dog.

Heartworm preventatives approved by veterinarians and obtained through a prescription are generally considered safe for dogs. These medications have undergone extensive testing and are proven effective in preventing heartworm disease. The safety of a particular heartworm prevention option can depend on various factors such as the dog’s health status, age, breed, and any potential drug interactions. It is crucial to consult with a veterinarian who can evaluate your dog’s specific needs and recommend the safest and most effective heartworm prevention option.

Yes, it is highly recommended that dogs take heartworm prevention medication. Heartworm disease is a serious and potentially life-threatening condition that can be prevented through regular use of heartworm preventatives. Even if your dog lives in an area with a low incidence of heartworm disease or spends most of their time indoors, they can still be at risk. Mosquitoes carry heartworm larvae and can transmit them to dogs.

Administering heartworm prevention medication as your veterinarian recommends helps protect your dog from infection and potential complications associated with heartworm disease. Prevention is always better and less costly than treatment. Discussing your dog’s most suitable heartworm prevention option with your veterinarian is important, considering factors such as your dog’s health, lifestyle, and geographical location.

Heartworm preventatives approved by veterinarians and obtained through a prescription are generally considered safe when used as directed. However, like any medication, there is a potential for side effects or adverse reactions, although they are rare. Some dogs may experience mild gastrointestinal upset, such as vomiting or diarrhea, after taking heartworm preventatives.

Serious adverse reactions are extremely rare but can occur in a small number of cases. It is important to closely follow the dosing instructions provided by your veterinarian and contact them if you notice any concerning symptoms or changes in your dog’s behavior.

Adverse reactions to heartworm medicine in dogs are rare but can sometimes occur. The most common adverse reactions are mild and may include gastrointestinal upset, vomiting, or diarrhea. These symptoms are usually transient and resolve on their own. However, more serious adverse reactions, such as allergic reactions or neurological symptoms, can occur in rare instances. It is important to administer the medication as your veterinarian directs and closely monitor your dog after administration. If you notice any concerning symptoms or changes in your dog’s behavior, it is recommended to contact your veterinarian promptly.

No, attempting to get rid of heartworms without veterinary involvement is not recommended. Heartworm disease is a complex and potentially life-threatening condition that requires professional veterinary care. The heartworm treatment involves a multi-step process that includes medications to kill the adult worms, manage the symptoms, and prevent further infection. Additionally, treatment requires strict exercise restrictions and careful monitoring to minimize complications. Only a veterinarian has the knowledge, expertise, and access to appropriate medications to safely and effectively treat heartworm disease. It is crucial to consult with a veterinarian if you suspect your dog has heartworms or if you are seeking heartworm treatment options.

Dogs get heartworms through the bite of an infected mosquito. When a mosquito carrying heartworm larvae bites a dog, it transmits the larvae into the dog’s bloodstream. The larvae then mature and migrate to the heart and nearby blood vessels, where they grow into adult heartworms. These worms can cause serious damage to the heart, lungs, and other organs. It is important to note that heartworm disease is not directly transmitted from dog to dog. Mosquitoes serve as intermediate hosts, carrying the larvae from infected to healthy dogs.

Ticks and fleas have various survival strategies to endure the winter months. While some ticks and fleas die off during colder temperatures, others can survive by seeking shelter in protected areas. For example, ticks can hide in leaf litter, tree bark, or burrow into the ground, while fleas may find refuge in warm indoor environments, such as heated homes or the fur of infected animals. Additionally, certain life stages of ticks and fleas can enter a dormant state called diapause, where their development slows down until more favorable conditions arise. It is important to continue flea and tick prevention year-round to protect your pets from these parasites, as they can still pose a threat even in colder seasons.

Dogs with heartworms may exhibit a range of symptoms, although some infected dogs may show no signs, especially in the early stages of the disease. As the infection progresses, dogs may display symptoms such as coughing, exercise intolerance, lethargy, weight loss, difficulty breathing, or a decreased appetite. In severe cases, dogs may develop a swollen belly and show signs of heart failure due to fluid accumulation.

It is important to note that the severity and range of symptoms can vary depending on the number of adult worms present, the duration of the infection, and the individual dog’s immune response. If you suspect that your dog may have heartworms, it is crucial to consult with a veterinarian for proper diagnosis and treatment.

The cost of a heartworm injection can vary depending on the veterinary clinic’s location, the dog’s size, and other associated services or medications provided during the treatment. Generally, heartworm injections are administered as part of a comprehensive heartworm treatment protocol, which includes multiple injections, diagnostic tests, medications, and follow-up visits. The cost can range from a few hundred to a few thousand dollars. It is recommended to consult with your veterinarian to obtain a more accurate cost estimate based on your dog’s specific needs and the local pricing in your area.

Yes, heartworm disease can be dangerous for dogs if left untreated. As heartworms mature and multiply in a dog’s heart and blood vessels, they can cause severe damage to the cardiovascular system. This can result in heart failure, lung disease, and other complications that can be life-threatening. In the advanced stages of the disease, dogs may experience difficulty breathing, exercise intolerance, weight loss, and a decreased quality of life. Early detection and treatment are crucial to minimize the risks associated with heartworm disease and increase the chances of a successful outcome.

While a dog can go without heartworm medication for a short period without contracting heartworm disease, it is not recommended to go without it for an extended period. Heartworm disease is transmitted through the bite of infected mosquitoes, and even a single mosquito bite can potentially transmit the disease. Therefore, consistent and year-round prevention is necessary to protect dogs from heartworm infection.

Skipping or delaying heartworm medication increases the risk of dogs becoming infected with heartworm larvae and developing heartworm disease. Following your veterinarian’s recommendations and administering heartworm prevention medication regularly is important to ensure continuous protection against this potentially life-threatening disease.

Disclaimer: The information provided on this veterinary website is intended for general educational purposes only and should not be considered as a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a licensed veterinarian for any concerns or questions regarding the health and well-being of your pet. This website does not claim to cover every possible situation or provide exhaustive knowledge on the subjects presented. The owners and contributors of this website are not responsible for any harm or loss that may result from the use or misuse of the information provided herein.

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