All About Heartworms In Dogs


Heartworms are parasites (worms) that pose a much more serious risk to your pet's health than intestinal worms.

They are transmitted into your puppy or dog's bloodstream through the bite of a mosquito who is carrying the microfilaria in it's blood (*microfiliaria are very immature heartworm larvae) 

This is the ONLY way that heartworm disease can be transmitted to your puppy or dog.

It isn't a condition that's contagious or that can be transmitted to another dog (or cat, ferret or other mammal -  including humans) without the 'middle-man' (ie the mosquito).

Quick Links:


Where & When Are Heartworms The Biggest Problem?

Because they're are spread by mosquitoes, it's most prevalent in warmer, central and southern states and during the Spring, Summer and early Fall season.

Rural locations tend to have more mosquitoes than cities do, but it just takes one infected insect to cause trouble.

Because it tends to be a seasonal problem (although depending on where you live, the 'season' could be 4 months long, or 9, or even year-round) and the incubation period before symptoms show up is fairly long, it's important to protect your pup or dog from being mosquito bitten.

It's also vital that you give him a heartworm preventative to will make sure that, IF he does get any larvae in his bloodstream, they won't be able to survive.

Although symptoms can take up to 6 months to show up, the earlier the problem is detected the better your pet's chance of survival.


Heartworm Symptoms

Unfortunately by the time symptoms of a heartworm infestation appear, a dog is usually pretty sick - so it's very important to act right away if you think your dog could be infected.

Because heartworms invade the heart, they cause problems with blood circulation, either in the heart itself or in major/minor blood vessels in other organs such as the lungs. Many of the signs of a heartworm problem are directly related to reduced bloodflow.

Heartworm Symptoms can include :

  • Loss or energy, or persistent lethargy

  • Coughing or hacking

  • Difficulty breathing

  • Swollen belly due to retained fluid

  • Heart rhythm changes, such as a heart murmur

  • Eventually, collapse or death

Usually generalized weight loss and lethargy will accompany these symptoms.

If you're worried that your dog may have heartworms, your vet can do some diagnostic tests for you.......

The most common one is a simple blood-test called the Heartwormantigen Test.

Other diagnostic procedures include a test to determine the concentration of microfilaria in the bloodstream, and X-rays. Ultrasounds or ECG's.


Heartworm Treatment For Dogs

A dog with heartworm disease needs to be carefully examined by a vet to make sure his organs are healthy enough to withstand the treatment/drugs.

If your pet is diagnosed with a mild-moderate case of heartworm infestation, he will likely be given a powerful drugs to kill off the heartworms - both in their larvae and adult stages.

He will also need complete rest and IV fluids, possibly corticosteroids as well, and all of this usually means an extended stay at the animal hospital initially.

Overall it usually takes about 6-7 months to treat canine heartworms and make sure they're fully removed from your dog's body.

There can be complications as the dead parasites are eliminated from his body and both your veterinarian and yourself will need to monitor your pet's condition very closely for several months.

It's vitally important that a dog who is being treated for this condition is kept very still and quite for several months, as exercise (even mild exercise) can cause the worms to block major blood vessels or arteries, or result in other complications, any/all of which could cause sudden death.

In severe cases, heart surgery may be needed. This involves the veterinarian surgically removing the worms from a dogs' heart. Of course, this is as dangerous and as costly as it sounds!

BUT the good news is that there's really no need for your pup/dog to ever have to go through this ordeal because there are reliable heartworm preventatives that will protect him from ever being infected.

IMPORTANT...... IMPORTANT...... IMPORTANT

Never give a dog a preventative if he's over 3 months old without getting a heartworm test done by your vet first.

Giving this type of medication to a dog who is already infected can be fatal!



Prevention Is The Key!

A heartworm infestation is terrible for your dog and often fatal.

Even if you're lucky enough to catch the problem while it's still treatable the treatment itself is painful, expensive and complicated.

So why risk putting yourself (and your precious pup) in that position?

Especially when it's so simple to prevent the problem in the first place! 

Check out my Heartworm Prevention page for everything you need to know to keep your pet safe.


› Heartworms In Dogs

› Heartworms In Dogs


Back To Top Of Page