Protecting Your Dog from Heartworm

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For the most part, being a dog mom or dad is a walk in the park, literally. Before you get a dog, you envision a rousing game of fetch followed by the dog bringing you your slippers and curling up at your feet. All of that is true but being a dog parent is also about being responsible for your pup’s health and well-being. Heartworm is something that happens to many dogs.

Many pet owners don’t take it as seriously as they should because they don’t think their dogs are at risk, perhaps because they live in a drier or colder climate or they think heartworm prevention is something veterinarians push on pet owners for higher vet bills.

Unfortunately, heartworm is a very serious disease that every dog is susceptible to, regardless of climate. The good news is heartworm is preventable. Here are a few tips to keep your dog safe from heartworm.

What is Heartworm?

Heartworms (Dirofilaria immitis) are parasitic roundworms that can infest the dog’s internal organs. The dog’s muscles, blood vessels, pulmonary artery, and heart can all be adversely affected by the worms.

The worms often reproduce inside your dog, leading to more health problems. Adult heartworms can survive for up to 7 years inside your dog, during which time they could potentially go through many reproductive cycles.

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How is Heartworm Transmitted?

Heartworms are transmitted only one way – through a mosquito bite from an infected mosquito. Cats, ferrets and other mammals are also at risk of contracting heartworm from mosquitoes. Unfortunately, there’s no way to tell if a mosquito is infected with heartworm.

Luckily, heartworms aren’t a death sentence for dogs if treatment is sought immediately and continued under the care of a vet. The high price tag of repeated treatments prevent many owners from fulfilling their responsibility to their dog and instead, abandon the dog at already overcrowded and underfunded shelters.

Heartworm Treatment & Prevention

The fact that heartworm is a completely preventable disease and the high cost of treatment is the reason so many veterinarians encourage heartworm preventative medications, even in the mosquito “off-season” that some areas see as the seasons change.

Once a dog has been diagnosed with heartworms and began treatment, the owners are under strict orders to keep the dog as calm as possible, meaning no exercise or other rambunctious behavior that can cause pulmonary blockage from the particles of the heartworms. Pulmonary blockage is the main cause of death in heartworm-positive dogs, not the treatment itself.

Signs of Heartworm

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A dog who survives heartworms can still potentially get bitten again by another infected mosquito, which is why all dogs are recommended to be on preventative medicine, regardless. But how do you tell if your dog might have heartworm? It’s not easy, but here are some signs to watch out for in your pooch.

There are no visible symptoms at the beginning stages of the disease, when the larvae mature into adult heartworms. As the worms multiply, they will surround the heart and lungs, crowding in the small area. The first warning sign of heartworms is your dog developing a cough that is worse during exertion, such as exercise.

A dog who survives heartworms can still potentially get bitten again by another infected mosquito, which is why all dogs are recommended to be on preventative medicine, regardless. But how do you tell if your dog might have heartworm? It’s not easy, but here are some signs to watch out for in your pooch.

There are no visible symptoms at the beginning stages of the disease, when the larvae mature into adult heartworms. As the worms multiply, they will surround the heart and lungs, crowding in the small area. The first warning sign of heartworms is your dog developing a cough that is worse during exertion, such as exercise.

Heartworm Symptoms

If left untreated, a dog will eventually die from heart failure or a buildup of fluids in their system. An advanced stage of heartworm disease can be diagnosed easily by a Vet. But the early warning signs can be caused by other conditions. If your dog exhibits one or more of the following signs of heartworm, contact your Vet immediately:

  • Cough
  • Bloody or brown urine
  • Low energy levels or lethargy
  • Decreased appetite
  • Pale gums
  • Sudden, unexplained weight loss
  • Difficulty breathing, especially after exercising
  • Collapsing or fainting

Your veterinarian will use blood tests and examinations to determine if your dog has heartworms or another, less severe ailment. Once the results are back, your vet will advise you on your treatment options and help you develop a treatment plan.

More severe cases of heartworm may require immediate, emergency surgery to remove any worm blockages that may be fatal without medical intervention.

5 Ways To Protect Your Dog From Heartworm

It’s impossible to protect your dog from ever getting bitten by a mosquito. And since there’s no indication of whether a mosquito has heartworm until your dog is already infected, prevention is the best way to protect your pup from a harmless, completely preventable disease.

Here are a few simple steps you can take to protect your dog from heartworm:

1. Adopt dogs from reputable breeders and shelters, not puppy mills.

Puppy mills are morally problematic to begin with, but the unsanitary conditions of many puppy mills are a breeding ground for mosquitoes infected with heartworm. Remember – it only takes one bite for a mosquito to pass the heartworm larvae to puppy and the larvae eventually turn into adult heartworms that reproduced inside the dog, creating possibly hundreds of more worms.

Even if you adopt from a shelter, there’s a chance that the puppy you adopt has heartworm, unbeknownst to the shelter. Since the symptoms of heartworm can take up to seven months to present themselves and shelters don’t have the extra funds to test the blood of every puppy they acquire, be aware that a shelter pup could have heartworm.

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If you have your heart set on a purebred dog and not a shelter dog, seek out reputable breeders in your area. Reputable breeders keep their dogs in pristine conditions. However, that’s still no guarantee that a rogue mosquito hasn’t made contact with one of the puppies.

2. Use preventative medication.

As the saying goes, an ounce of prevention is worth a pound of cure.  Heartworm prevention costs less than $20 a month, while treatment for a heartworm-positive dog will set you back hundreds of dollars and your dog, unfortunately, might not survive the treatment.

You may have qualms about whether your dog needs the medicine during the months when mosquitoes aren’t active. Before the cold sets in, mosquitos can potentially migrate indoors and live out the cold months in close proximity to you and your pup. That’s why heartworm prevention is necessary for twelve months out of the year, not just the few months of warm weather.

Heartworm prevention comes in the form of monthly pills, topicals or an injection that lasts for up to six months. Another reason it is encouraged to continue to give your pup medication year-round is because if you forget one month, your dog will likely still be protected. However, if you miss more than one month of prevention medication, your dog won’t be protected.

The heartworm prevention medicines kill the heartworms while they are still in the early larvae stages. As the worm grows through the larval cycles, it becomes immune to the heartworm prevention medicine. Many preventive medicines on the market today also work against other intestinal parasites, such as roundworm and tapeworm.

Giving your pup a heartworm prevention medicine every month is a simple and easy way to save your pet’s life. Consult with your Vet for a heartworm prevention plan tailored for your pet. (Remember – cats and other mammals are also at risk for heartworm.)

3. Take your dog to the vet for regular checkups.

Delilah North Branch Animal HospitalBefore your dog can start taking heartworm prevention medicines, the vet needs to run a test to make sure they aren’t already infected. Giving an infected dog heartworm prevention medicine can adversely affect the dog and have no effect on the heartworms.

Puppies less than 7-months-old do not need a heartworm test before starting heartworm prevention. If infected, it typically takes at least 6-months for dogs to test positive.

An annual checkup at your preferred veterinary clinic has many benefits for your pup. They can be given the required vaccines, tested for heartworms and your vet can recommend the best heartworm prevention medicine for your dog.

Regular visits to your vet also give them an idea of your dog’s general demeanor. Making it easier for your Vet to know when your dog isn’t feeling well. Giving them a better chance to notice any subtle changes in your dog.

4. Mosquito-proof your yard.

While it’s impossible to keep every mosquito away from your dog, you can take steps to drastically reduce the population around your home and yard.

If your dog spends a lot of time outside, using a pet-friendly insecticide spray can help keep the pests away from your dog.

5. Feed your dog a healthy diet.

Prevention with medicine is the main step in keeping your pup heartworm-free. However, keeping your dog healthy can give them the tools they need to stay strong if they do get contract it.

Your dog’s diet is paramount in keeping them healthy. The right food can give your pup the proper nutrients while keeping them at their ideal weight. However, dogs who survive heartworms can be severely underweight. They will need food and supplements to gain weight after treatment. Consult with your vet for suggestions on which dog foods are best for your dog’s specific needs.

Bottom Line

Protecting your dog from heartworms is much easier and cheaper than treating your dogs for an infestation. It’s important to note that a dog that has survived heartworm treatment CAN get get them again in the future. Remember, prevention is the best way to keep your dog safe and healthy.


Thank you to guest author Leo Wilson. Leo graduated from a university major in animal health and behavior. Leo has over a decade of experience in the pet industry. And has contributed many dogs and pet-related articles to several websites before starting his own blog. When he isn’t busy working, he loves spending time at home with his wife, their 3 dogs and 2 cats.
Guest Authoer: Leo Wilson

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