Heartworms are a serious and potentially fatal condition for dogs, caused by parasitic worms that live in the heart and lungs. These worms can cause severe health problems, including heart failure, lung disease, and damage to other organs.
Thankfully, heartworm disease is entirely preventable, and the key to prevention lies in consistent use of heartworm medicine for dogs.
This article provides a comprehensive overview of heartworm disease, the role of heartworm medicine, and how to choose the right medication for your dog.
What Is Heartworm Disease in Dogs?
Heartworm disease is caused by Dirofilaria immitis, parasitic worms transmitted through the bite of an infected mosquito. These worms can grow up to a foot long and live in the heart, lungs, and blood vessels of an infected dog, causing inflammation, obstruction, and even damage to vital organs. The larvae that are transmitted by the mosquito grow into adult worms inside the dog’s body.
Dogs are the natural hosts for heartworms, which means they are ideal environments for these parasites to grow and reproduce. Without prevention, heartworm disease can lead to severe illness and death. Symptoms of heartworm disease in dogs include coughing, fatigue, weight loss, difficulty breathing, and even sudden collapse in extreme cases.
How Heartworm Medicine Works
Heartworm medicine works by preventing the transmission of heartworm larvae before they can mature into adults. The medicine kills the larvae as they enter the dog’s bloodstream, effectively stopping the development of heartworms before they become a problem.
Types of Heartworm Medicine for Dogs
There are two primary types of heartworm medications available for dogs: monthly preventatives and annual injections.
1. Monthly Preventative Medications
Most dog owners use monthly preventatives, which are typically either oral pills or topical treatments. These medications contain active ingredients that kill the heartworm larvae as they are introduced into the dog’s bloodstream by a mosquito bite.
By killing the larvae early in their development, monthly preventatives prevent heartworms from maturing and causing damage.
Some of the most common ingredients in monthly heartworm medications are:
Ivermectin: One of the most popular and well-known ingredients in heartworm preventatives, ivermectin is used in a number of widely recognized brands like Heartgard Plus.
Milbemycin oxime: This ingredient is used in brands such as Interceptor, which also provides protection against other parasites like roundworms and hookworms.
Selamectin: Used in products like Revolution, which are topical solutions that not only prevent heartworms but also protect against fleas, ticks, and other parasites.
Moxidectin: Found in products such as ProHeart, which is available as a monthly pill or as an injectable form.
2. Annual Injections
For dog owners who prefer a less frequent option, annual injections offer a solution. One injection of moxidectin can provide heartworm protection for an entire year. This method eliminates the need for monthly medication but requires a veterinarian’s administration.
The ProHeart 12 injection is the most common annual treatment, providing long-term protection for up to 12 months. While it’s a great option for owners who have trouble remembering to administer monthly doses, the injection does carry a slightly higher cost and requires a visit to the veterinarian.
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How to Choose the Right Heartworm Medicine
When selecting heartworm medicine for your dog, several factors should be taken into account. Here are a few considerations:
1. Age and Size of Your Dog
Different medications are formulated for dogs of different sizes and ages. Most heartworm preventatives are safe for puppies once they reach a certain age, typically around 8 weeks. It’s important to consult your veterinarian for the correct dosage based on your dog’s weight and age.
2. Type of Medicine
As discussed, heartworm preventatives come in various forms, including chewable tablets, topical solutions, and injections. The type of medication you choose will depend on your dog’s preferences, lifestyle, and any potential allergies. Some dogs may find it easier to take a chewable tablet, while others may require a topical solution or injection.
3. Additional Parasite Protection
Many heartworm preventatives also provide protection against other common parasites, such as fleas, ticks, and intestinal worms. If your dog is at risk for multiple parasites, a combination medication that protects against heartworms and other common parasites may be the best choice.
4. Health History
Your dog’s health history is crucial in determining the most appropriate heartworm preventive. Some dogs may have sensitivities or health conditions that make certain medications unsuitable. Your veterinarian can help you choose the safest and most effective product for your pet.
5. Cost and Convenience
While annual injections may be more expensive upfront, they offer the convenience of not having to remember to administer monthly doses. On the other hand, monthly preventatives are generally more affordable and offer more flexibility in case your dog misses a dose. The choice will depend on your budget and the level of convenience you require.
When Should You Start Heartworm Prevention?
It’s recommended that puppies start heartworm prevention as early as 8 weeks old. Early prevention helps ensure that they remain protected throughout their life. However, even adult dogs that have never been on heartworm prevention should begin treatment as soon as possible, with a heartworm test to ensure they are not already infected.
If you’re transitioning to a new heartworm preventative, consult your veterinarian to ensure you don’t inadvertently miss a dose. Some preventatives may require a test before beginning treatment, especially if your dog is switching from another type of medication.
What Happens If You Miss a Dose?
If you miss a dose of heartworm medication, it’s important to administer the dose as soon as you remember. If a month has passed, contact your veterinarian. They may recommend that you have your dog tested for heartworms to ensure no larvae have developed. In the case of injectable preventatives, missing a dose may require a new injection or other action from your vet.
Heartworm Treatment vs. Prevention
While heartworm prevention is simple and effective, treatment of an established heartworm infection is much more complicated and costly. If a dog becomes infected with heartworms, treatment involves a lengthy process that includes injections to kill adult heartworms, as well as other supportive treatments. This process can take several months, and recovery can be tough on the dog’s health. Preventing heartworm infection is far easier and less expensive than treating the disease after the fact.
FAQs
How often should I give my dog heartworm medicine?
Most heartworm medications are administered monthly, but it’s important to follow the specific instructions of the product you choose. Some products may require annual injections, which offer protection for up to 12 months.
Can I give my dog heartworm medication if they already have heartworms?
No, heartworm preventatives are not designed to treat existing infections. If you suspect your dog may already have heartworms, take them to the veterinarian for a test. If your dog is infected, your vet will recommend a treatment plan.
What happens if I forget to give my dog their heartworm medicine?
If you miss a dose, administer it as soon as you remember. If you’re unsure or have missed multiple doses, contact your vet. They may recommend a heartworm test and advise you on the next steps.
Are there side effects associated with heartworm medicine?
Most dogs tolerate heartworm preventatives well, but some dogs may experience mild side effects like vomiting, diarrhea, or lethargy. Serious side effects are rare but can include allergic reactions. If you notice any unusual symptoms, contact your veterinarian immediately.
Can heartworm preventatives protect my dog from other parasites?
Yes, many heartworm preventatives also protect against other parasites such as fleas, ticks, roundworms, and hookworms. Be sure to check the product label to confirm which parasites are covered.
How do I know which heartworm medicine is best for my dog?
Consult your veterinarian to determine which heartworm preventative is best based on your dog’s age, size, health, and lifestyle. Your vet can also help you choose a product that offers protection against other parasites if needed.
