What is heartworm disease?

Note: We’d show you a picture of an actual heartworm diseased heart, but we didn’t think you’d want to see that rawness.

One of the most common dog ailments is heartworm disease, which is a severe lung disease that can cause heart failure and other damage to the dog’s organs. It is parasitic and is transmitted through a mosquito bite.

Related: Best food for dogs prone to allergies.

How does a dog get heartworms?

Much like malaria, heartworm is only spread by the bite of an infected mosquito. There is no other mode of transmission! Unfortunately, there is no way to tell if a mosquito is infected and that is why prevention is vital.

A simple bite from one mosquito which is infected with the heartworm larvae, may in-turn infect your dog with heartworm disease!

The incubation period

Once your dog has been bitten by an infected mosquito, it may take approximately seven months for the larvae to mature into adult heartworms. The worms then lodge themselves in various organs of your pet, such as the heart and lungs, where they begin reproducing.

The adult worm can grow up to a length of 12 inches, it has an average lifespan of around 5-7 years, and one dog can be host to as many as 250 adult worms.

Can my dog infect me?


Heartworms are only transmitted through the bite of an infected mosquito. It’s also species specific and only infects dogs, cats and some other mammals.

A human can be infected with the larvae, but it cannot complete its lifecycle in your system, and will die off after the larvae stage. (Phew!)

Can my dog infect my other pets?

Again, no. As this is only transmitted via the bite of a mosquito, your infected dog will not be able to pass it on to your other household pets. They too need to be bitten by a mosquito who is a carrier of the disease. (Another positive thing to hear.)

Symptoms of heartworms in dogs

There will be no obvious symptoms at the beginning of the worms’ life cycle. As more worms crowd the heart and lungs though, your dog will develop a cough. As the disease progresses, they will not be able to exert themselves as much as they were previously able to do.

In severe instances there will be abnormal lung sounds, dogs can faint due to loss of blood to the brain, and they will retain fluids. If the disease is not treated it will almost always prove to be fatal.

Keep a lookout for the following symptoms, and consult with your vet immediately; if you have reason to believe your dog’s been bit and notice any of these:

  • coughing and fainting
  • weakness or lethargy
  • loss of appetite and weight
  • labored or rapid breathing
  • a bulging chest (caused by fluid build-up)
  • asthma and other allergy symptoms.

Severe symptoms include:

  • high blood pressure
  • nosebleeds
  • excessive sleeping
  • blindness
  • lameness
  • seizures
  • secondary pneumonia

As an owner, it’s hard to keep an eye on everything, naturally. So the best you can do is be aware of the connection between mosquitoes and this horrible disease, and keep that in mind as you’re raising your pup and hanging out with your canine friend into their mature years.

How do heartworm prevention meds work?

The truth is, prevention of heartworms in your pets is very easy, and it definitely makes more sense than having to deal with a full-blown infection, that will be very expensive to treat and may not even guarantee 100% cure.

What the medication should do is to kill the heartworm larvae, before it has any chance of growing and maturing into an adult and cause damage to your pet. Most of these medications also contain powerful ingredients that can protect your dog against many other parasites such as hookworms and roundworms.

Best heartworm prevention for dogs

Unfortunately, love alone is not always enough to ensure the health of your pet. It’s important to protect them from potentially deadly mosquito-transmitted diseases such as the one in question.

Which is why we researched the best options for shielding dogs against heartworm disease. Check them out below.

Tri-Heart Plus

This is a preventative medication that is given once-a-month and should help in protecting your pet against parasitic worms such as roundworms, heartworms, and hookworms.

It is ideal for dogs that are older than six weeks. The Tri-heart plus tablet is chewable and filled with flavor for your dog, which makes it easy to administer as the dog thinks it is just a delicious treat they are receiving.

This medicine is solely intended to be a preventative measure against the parasitic worms listed above, and in case your dog is already infected, be sure to deworm him before administering this medication.

Possible side effects of the medication include: convulsions, diarrhea, anorexia, hypersalivation mydriases, vomiting and staggering.


  • Protects against different types of worms
  • Chewable
  • Palatable
  • Easy to administer


  • Not to be given to pups younger than six weeks
  • Has numerous potential side effects

Customer’s feedback

With a 4.5 out of 5-star rating, this is a product that has been very well received by most clients, and most of them highly recommend. They also mentioned that although there was a warning placed for potential side effects, their dogs did not experience any.

See it on PetCareRx

Heartgard Plus Chewable for Dogs

Heartgard is one of the most trusted, and top-rated heartworm medications for dogs. It has an excellent 5 out of 5-star rating from customers, and with good reason. In terms of keeping your dog free from heartworms, roundworms, and hookworms, it does a marvelous job, according to verified Amazon reviews.

These chewable tablets will protect pets that are six weeks old and above. One dose alone provides 30 days of protection. With a delicious beef flavor, your dog should not even realize they are taking any medication, making it very easy to administer.

Before administering the Heartgard tablets, ensure that your dog has been tested and dewormed appropriately.


  • Delicious beefy flavor
  • Chewable and easy to administer


  • Pricier than other medications

Customers feedback

As stated above, this medication has a 5 out of 5-star rating, which means that almost all feedback friendly customers that used the product gave it raving reviews. In terms of protecting their dogs against different types of worms, this product is the best, and they gave it a big thumbs up, with perfect recommendations.

See it on PetCareRx

Sentinel Spectrum

Sentinel spectrum should be ideal in protecting your pet against heartworms and other types of worms. It has a chewy beef flavor that is great for dogs, as it makes it easy to administer. It is given on a monthly basis, and each tablet should protect against hookworms, tapeworms, roundworms, heartworms, and whipworms.


  • Beef flavored
  • Chewable
  • Prevents and controls heartworms
  • Simple one-a-month administration


  • Can only be used in older puppies

Customers feedback

This product has received a rating of 4.4 out of 5 stars and great reviews from customers. Most of the customers claimed that it saved their dog’s lives, and as a result, they recommended it to loving dog owner everywhere.

See it on 1800PetMed


This is a multi-purpose chewable tablet, which will protect against infestations of fleas, parasites, heartworms, roundworms, hookworms, and whipworms.

It has a tasty beefy flavor that your dog should love, and even not realize that they are being medicated. It should be used monthly on dogs eight weeks and older, but it does require a prescription from your local veterinarian.


  • Multi-purpose medication
  • Guard against heartworm disease
  • Beef flavored
  • Chewable
  • Easy one-month administration


  • Only ideal for dogs over eight weeks of age

Customers feedback

With a 4.1 out of 5-star rating, this is a well-received product, that is affordable and can handle many different parasites at the same time. Most customers were happy with the results after administering it, and one customer actually called it a “miracle drug.”

See it on 1800PetMeds


This is a easy-to-use non-greasy topical treatment which can be used on both cats and dogs and claims to be able to eliminate ear mites, flea eggs, scabies and other types of fleas, as well as worm infestations, including heartworms.

Other than that, it should also guard against roundworms and hookworms. It is FDA certified and is administered on a monthly basis. It is non-greasy, quick drying and is released quickly into the dog’s system.


  • Protects against heartworms and other parasites
  • FDA certified
  • Safe for dogs
  • Quick acting


  • Has possible side effects
  • Must have a prescription

Customers feedback

This medication earned a rating of 4.5 out of 5 stars and most customers were extremely happy with the fact that it was easy to administer and that is was a multi-purpose ointment which eliminated worms and other forms of parasites, such as fleas.

See it on PetCareRx

Final thoughts on preventing dog heartworms

Heartworm is a frightening illness that could threaten your dog’s life expectancy. Additionally, treatment is expensive and rough on your dog’s system. Prevention is really the best way to cut out all the worry, and you need to do this by killing the mosquito larvae before they develop into adult worms and cause heartworm symptoms.

Consult with your veterinarian and decide upon the best prophylactic treatment suitable for your precious pooch, and keep her healthy and her heart strong!