The A-Z of Heartworm Medicine for Dogs

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Heartworm medicine for dogs is so important. Heartworms can cause several uncomfortable and even debilitating symptoms in your beloved pooch. If left untreated, a heartworm infestation can be fatal. Read on for more information about the various treatment options.

A Quick Look at the Dangers of Heartworm in Dogs

Heartworm (Dirofilaria immitis) is a blood-borne parasite that can affect any dog despite their size, age, or breed. It normally takes a few years for your pet to show clinical signs of a heartworm infestation. This means, unfortunately, that by the time that your dog is showing symptoms of heartworm disease, the disease is far advanced.

Adult heartworms move to the heart and lung tissues of a dog. They cause illness by clogging the heart chambers, preventing valves from functioning correctly, and blocking blood vessels.

By clogging the main blood vessels leaving the heart, they slow down blood flow to the lungs and to other organs in the body. This can cause breathlessness, and liver and kidney failure.
Signs of heartworm disease (dirofilariasis) in dogs include the following:

  • A soft, dry cough.
  • Weakness, listlessness, and loss of stamina.
  • Shortness of breath.
  • Poor circulation can lead to fluid build-up in the legs.
  • Anemia, weight loss, pale gums.

doggo looking at bottle of dog heartworm medicine

Bloodsuckers Through and Through: The Dog Heartworm Life Cycle

The heartworm parasite requires the mosquito as an intermediate host. The heartworm’s life cycle begins when a female mosquito bites a dog infected with heartworm. As the mosquito sucks up blood, she ingests microfilariae (juvenile heartworms). Over the next 10 – 30 days, the microfilariae develop further and enter the mosquito’s mouthparts.

When next the mosquito bites a dog, the infected larvae enter the dog’s bloodstream Here they mature to adult heartworms. Within 6-7 months they can mate and produce microfilariae. Thus, completing the dog heartworm life cycle.

The Most Common Active Ingredients in Heartworm Medicine for Dogs

The most common active ingredients in heartworm medicine for dogs are ivermectin and milbemycin.In the past, heartworm infestations were treated with arsenic.This is a very poisonous substance and had some negative side effects.

Since the 1980s, ivermectin has been used to prevent heartworm disease in dogs. If given at the correct dosage, there are rarely any side-effects. Some dogs may experience symptoms such as diarrhea, vomiting, or incoordination. Allergic reactions include itching, swelling of the face, hives, and seizures.

Dog breeds such as the Collies, Sheepdogs, Whippets, and Australian Shepherds are at risk of reacting to ivermectin or milbemycin treatment.

This adverse response is as a result of a genetic mutation. Due to this mutation, the drug is able to pass through the dog’s blood-brain barrier. The drug enters the central nervous system and can have fatal consequences.

The Best Heartworm Prevention for Dogs: How it Works

Ivermectin works to kill the heartworm parasites by causing neurological damage. The drug is thought to paralyze the parasite or inactivate the parasite’s gut. This, in turn, will result in the heartworm dying.

Milbemycin oxime also acts by blocking the transmission of nerve signals within the parasites, resulting in paralysis and/or starvation.

From Chewables to Heartworm Pills for Dogs

There are many different products available for the prevention of heartworm infection in dogs. Injectables, chewables, and topical treatments. Topical and chewable drugs are usually administered monthly. Injections are administered by veterinarians, strictly, every six months. When given regularly in the correct doses, preventives are effective.

Heartgard Plus Chewables

Heartgard Plus Chewables come in a variety of sizes/doses according to your dog’s weight. This beef-flavored chewy treat is easy to administer. Most dogs like the taste and eagerly gobble it up! This medication is a combination of ivermectin and pyrantel. Monthly treatment of Heartgard Plus protects your dog from heartworm, hookworms, and roundworm.

Tri-heart Plus Chewable Tablets

You give this medicine to dogs orally. Tri-heart Plus is a chewable treat. It is a combination of heartworm preventive and intestinal de-wormer. It kills the heartworm microfilariae. Tri-heart Plus can treat and control hookworm and roundworm infestations too.

Revolution Topical Solution

In dogs, Revolution protects against heartworm, as well as several other parasites. These include ear mites, the mites that can cause sarcoptic mange, fleas and American dog ticks. Revolution topical solution is a once-a-month treatment that you apply directly onto your dog’s skin.

Trifexis Chewable Tablets

Trifexis chewable tablets are also a monthly chewable for dogs to aid in the prevention of heartworm. This medication can prevent heartworm disease and kill fleas. It also helps to control adult hookworm, roundworm and whipworm infections.

Trifexis is a combination of two active ingredients: Milbemycin oxime and spinosad. The milbemycin oxime kills the immature heartworms as well as the adult hookworms, whipworms, and roundworms. The spinosad kills adult fleas, thus controlling flea infestations.

Advantage Multi Topical Solution for Dogs

Advantage Multi Topical Solution comprises imidacloprid and moxidectin. This prescription medication for dogs prevents heartworm infection, controls fleas, and kills intestinal parasites. Apply Advantage Multi topically once a month.

Pro-Heart 6 Injectable Heartworm Preventive 

In 2001, an injectable moxidectin product was developed. This preventive is administered by injection, strictly by a veterinarian. Only veterinarians that are registered with the manufacturer are allowed to prescribe and administer this medication. Its protective effects last up to six months.

What About Natural or Home Remedies?

Some people are concerned about the long-term use of heartworm preventives on their dogs. Others are concerned that consistent use of these medications might lead to drug-resistance of the parasites. The adverse side effects of some of the medications can be off-putting too.

There are natural alternatives to prevent heartworm infection in dogs. These medications consist of a combination of herbs that maintain your dog’s blood health. They also act against mosquito bites.

Do Natural Remedies Work to Prevent or Treat Heartworms?

Natural heartworm remedies are usually a combination of tinctures and herbs. Some contain essential oils, and/or diatomaceous earth and black walnut. These ingredients can help to repel pests such as mosquitoes. It’s not certain how well these remedies work though.

These treatments need to be used as part of a complex protection plan against both mosquitoes and heartworms. If you would prefer to follow a natural treatment/prevention plan, be sure to do so with the guidance of a homeopath veterinarian.

Veterinary Heartworm Medication for Dogs May Be the Safest Option!

There is no science to back up the efficacy of natural heartworm. Some may even be dangerous to your pet’s health.

The only effective medication that can kill heartworm larvae before they become adult worms is a macrocyclic lactone. Examples of drugs in this class include ivermectin, milbemycin, moxidectin, and selamectin. These are the active ingredients that form part of prescribed heartworm medicines.

At the end of the day, one must weigh up the risks. A full-blown heartworm infection can cause terrible damage to your pet’s heart, lungs, liver, and kidneys. Treatment is extensive, of long duration, and expensive. Most would agree that the risk of putting their beloved pooch through all that is simply not worth it.

Where to Buy Dog Heartworm Medicine?

You can buy your heartworm medicine online. Or, you can purchase it from your local vet or vet shop. Always make sure that you are buying the medicine prescribed by your vet. Also check that the medication is at the correct dosage for your dog.

Can You Get Heartworm Medicine Without a Vet Script?

In short, no, you cannot get heartworm medicine without a prescription.
The FDA places a ‘prescription-only status’ on medication considered to be unsafe without proper veterinary follow-up or monitoring.

In the case of heartworm preventives, there is the danger that the medication is given to dogs that are heartworm positive or that have the mutant MDR-1 gene.

A Note on Generic Heartworm Treatment for Dogs!

Most generic heartworm treatments will be just as efficacious as the originals. If the ingredient/s are the same and present in the same concentrations, the results should be the same. Always check in with your veterinarian before administering a new/different medication to your pet.

What About Heartworm Prevention for Cats?

Heartworm can spread from infected mosquitoes to cats too. Cats, however, are more resistant to heartworm infection. They are abnormal hosts.

An infected cat might have only two or three worms. However, the immune response elicited in response to these worms is what causes health disturbances. Clinical signs such as coughing, or vomiting could indicate a heartworm infestation. 

There is no cure for heartworm disease in cats. So, prevention is your best option. Both topical and oral applications are available. Most cat heartworm preventives contain ivermectin or milbemycin.

Heartworm Meds for Dogs are a Must if Your Doggo is at Risk!

Cases of heartworm infection in dogs occur throughout the U.S. Heartworms in dogs are easy to prevent, not so easy to cure. If you have mosquitoes and you have mammals, it is highly likely that you will have heartworms.

Some areas are at lower risk than others. However, it is better to exercise caution and follow a regular heartworm preventive treatment schedule.

3 Common Questions About Heartworm Medicine for Dogs

Do Dogs Really Need Heartworm Pills?

What is the Best Heartworm Medicine for Dog?

Do Natural Remedies Work to Kill Heartworms in Dogs?

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