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What Are Heartworm Pills?

Caitlynn Lowe
Caitlynn Lowe

Heartworm pills are one of the most common forms of preventative pet medication against the heartworm parasite. Dogs get heartworm disease more than other pets, but cats and other mammals are also at risk, especially if they spend time outdoors. Since heartworm disease is difficult to treat once it develops, veterinarians typically recommend taking measures to prevent it. Heartworm pills are both inexpensive and effective, making them a common preventative treatment, but other preventative treatments do exist.

Dirofilaria immitis, more commonly known as heartworms, transfer to household pets when an infected mosquito bites them. These parasites attack the heart and bloodstream of an infected animal. In 6 months or less, heartworms cause organ damage and failure, particularly in the lungs and heart. This damage occurs whether a pet is infected by several worms or several hundred.

Heartworms can be transmitted through mosquito bites.
Heartworms can be transmitted through mosquito bites.

Since heartworm disease is transmitted through mosquito bites, pets who spend time outdoors have the greatest risk of getting infested. Pets who live in warm, humid climates are especially prone to heartworm disease. Most heartworm infestations are found in dogs, but cats and ferrets are also susceptible. Those who own any of these pets should consult their veterinarians about a prescription for heartworm pills or another preventative treatment.

A prescription from a veterinarian is needed to obtain heartworm pills.
A prescription from a veterinarian is needed to obtain heartworm pills.

Obtaining heartworm pills requires a prescription from a veterinarian. The right dosage for a pet depends on the type of pet — dog, cat, or ferret — as well as the size or weight of the pet. A lighter weight dog must not take a prescription meant for a heavier dog, since this dosage will be too high and may cause health problems. Most brands are administered on a monthly basis. A veterinarian may suggest administering heartworm pills only during peak mosquito season, but many veterinarians will recommend administering the pill year-round to provide the ultimate level of protection.

Veterinarians recommend giving animals heartworm pills to prevent a heartworm infection, which can be expensive and difficult to treat.
Veterinarians recommend giving animals heartworm pills to prevent a heartworm infection, which can be expensive and difficult to treat.

Each brand uses a different drug to destroy heartworm larvae before it has a chance to mature and breed, but the most common drugs used in these medications are ivermectin and milbemycin oxime. Some dogs have a genetic sensitivity to ivermectin, however. A veterinarian may recommend testing a dog for this sensitivity if it has certain breeds in its bloodline, including but not limited to Collie, Shetland Sheepdog, and Australian Shepherd. If a dog tests positive, milbemycin oxime or another drug should be administered, instead.

While all heartworm pills prevent the heartworm parasite, some also prevent other parasites, such as hookworms, whipworms, and roundworms. Other factors that pet owners should consider include cost and reputation. All reputable brands should come with a manufacturer's or veterinarian's guarantee for safety and effectiveness.

Topical heartworm medication is a safe, effective alternative to heartworm pills. Most brands of topical heartworm medication use a drug called selamectin. In addition to medication, pet owners should consider taking measures to prevent or reduce the risk of mosquito bites. Individuals should keep their pets indoors throughout most of the late afternoon and evening, when mosquitoes are the most active. Removing sources of standing water and spraying mosquito repellent around the yard can also help reduce the mosquito population, reducing the overall threat to pets.

Frequently Asked Questions

What are heartworm pills and how do they work?

Heartworm pills are a form of medication designed to prevent heartworm disease in pets, primarily dogs and cats. They contain active ingredients like ivermectin or milbemycin oxime that eliminate the larval stages of the heartworm parasite, preventing them from maturing into adults that can cause serious health issues. These pills are typically administered monthly and work by disrupting the nerve transmission in parasites, leading to their death.

How effective are heartworm pills in preventing heartworm disease?

When administered correctly and on a regular schedule, heartworm pills are highly effective, with efficacy rates nearing 100%. According to the American Heartworm Society, consistent use of preventatives is the key to ensuring pets remain heartworm-free. It's crucial to follow the prescribed regimen without missing doses to maintain this level of protection.

Can all pets take heartworm pills, and are there any side effects?

Most pets can safely take heartworm pills, but a veterinarian should always be consulted first, especially for animals with existing health conditions. Side effects are rare but can include vomiting, diarrhea, and lethargy. In some cases, pets with a pre-existing heartworm infection may experience more severe reactions, which is why a heartworm test is recommended before starting prevention.

How often should my pet take heartworm pills?

Heartworm pills are generally administered once a month, year-round. This consistent dosing schedule is crucial for ongoing protection against heartworm disease. Some veterinarians may adjust the frequency based on local climate and mosquito activity, but the trend is towards year-round prevention due to changing weather patterns and the potential for indoor mosquito exposure.

Do indoor pets need heartworm pills as well?

Yes, indoor pets should also receive heartworm pills. Mosquitoes, which transmit heartworm larvae, can easily enter homes, putting indoor pets at risk. The American Veterinary Medical Association recommends that all dogs and cats, regardless of their living situation, be placed on heartworm prevention to safeguard against this potentially fatal disease.

Are heartworm pills the only way to prevent heartworm disease?

While heartworm pills are a popular and effective method, there are other forms of prevention, including topical applications and injectable products that provide multi-month protection. Each type has its advantages, and a veterinarian can help determine the best option for an individual pet's lifestyle, health status, and the owner's preferences for administration.

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    • Heartworms can be transmitted through mosquito bites.
      By: hjschneider
      Heartworms can be transmitted through mosquito bites.
    • A prescription from a veterinarian is needed to obtain heartworm pills.
      By: Steve Cukrov
      A prescription from a veterinarian is needed to obtain heartworm pills.
    • Veterinarians recommend giving animals heartworm pills to prevent a heartworm infection, which can be expensive and difficult to treat.
      By: Gabriel Blaj
      Veterinarians recommend giving animals heartworm pills to prevent a heartworm infection, which can be expensive and difficult to treat.