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Heartworm Symptoms: Signs to Watch for in Colorado Dogs

October 2nd, 2017 by Cherished Companions Animal Clinic

James strokes his dog's ears after learning that his dog's heartworm symptoms were actually a sign of something else.

Do you suspect your dog has heartworm disease?

Our Castle Rock veterinarians have put together this article on heartworm symptoms to help you keep your dog safe and healthy.

The good news is heartworm disease is not as common in Colorado as it is in the Midwest or the South.

But yes, your dog can still get it here, particularly if you and your dog visit rural areas or travel to states like Kansas or Oklahoma.

Colorado families also are awesome about adopting out-of-state dogs.

Some of these dogs have heartworm, bringing it in from parts of the country where it’s more common.

So, with that in mind…

Here are the heartworm symptoms to look out for in your dog:

  • Coughing
  • Avoiding exercise (you may notice a big change in your dog’s activity level)
  • Having trouble breathing (due to an increased respiratory rate)
  • Swelling in your dog’s abdomen and legs
  • Passing out and then waking up

When you bring your dog into our Castle Rock veterinary clinic, we can run a heartworm test to look for signs of adult worms.

If your dog’s initial test is positive, we’ll send your dog’s test to a specialty lab for deeper analysis, so you can get a better picture.

(With this test, false positives do happen.)

How long does it take for dogs to show heartworm symptoms?

Dogs get heartworm through mosquito bites, but heartworm symptoms don’t appear right away.

Rather, the heartworm larvae go through a lifecycle in your furry friend.

Most dogs begin to show clinical signs of heartworm disease within six to eight months of the mosquito bite.

Some dogs can live for several years before the disease becomes life threatening.

Heartworms can grow long enough to cross your dog’s heart valves and cause heart failure.

They also can cause severe damage to your dog’s lungs and arteries.

That’s why prevention is so important!

 Keep your dog safe

If you’ve noticed any heartworm symptoms or you just want to make sure your dog is protected, call us today at 303-688-3757 or:

Book your visit here 

Are heartworms contagious?

Not directly.

But if you have a heartworm-positive dog, your dog may be putting other dogs at risk through mosquito bite transmission.

Can humans get heartworms from their dogs? Can cats get them from dogs?

No, people can’t get heartworm from an infected dog.

While cats can get heartworm, it’s more rare and it wouldn’t be directly from your dog. They’d get it through a mosquito bite.

Adult cats are not the ideal hosts for heartworms, so their bodies typically take care of the worms.

If you have a kitten, there are some preventive measures that can be taken to protect your kitty.

What if I don’t give my dog heartworm prevention meds?

You may be fortunate, and your dog may never have an issue. Your dog is at risk, though.

How do I prevent heartworm disease in my dog?

You have several options, including:

  • A monthly, chewable medication that kills the immature larvae that are migrating through your dog’s body. Most dogs like the taste of these chewable tablets.
  • Topical medications you can apply to your dog as a mosquito repellant. They’re a good secondary prevention method, and they may be worth looking into if your dog is traveling to the South or the Midwest. However, we don’t recommend using them as the only form of protection.

If you’re on the fence, consider that heartworm prevention meds:

  • Are much less expensive than heartworm treatment.
  • Aren’t as strong as the drugs used to treat heartworm disease.
  • Help protect your dog’s arteries, lungs and heart from severe damage.

Typically, our veterinarians recommend keeping your dog on heartworm prevention year-round.

It protects your dog, particularly when mosquitoes hatch on those warm winter days above 60 degrees.

It makes it easier to remember.

And there are often financial rebates for buying more at one time.

The companies that make heartworm prevention medicine suggest having your dog tested for heartworm every two years to make sure the medicine is working properly.

If you don’t give your dog heartworm prevention year-round, we’ll run a heartworm test during your dog’s annual exam to make sure he or she didn’t pick up the worm during the off-months.

We want to help you keep your pup happy and healthy!


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Cherished Companions Animal Clinic is a veterinary clinic in Castle Rock, Colorado. Specializing in the care of cats and dogs, our goal is to help you and your pet feel more comfortable, keeping your stress to a minimum.

This article is intended to provide general guidance on heartworm symptoms in Colorado dogs. If you have specific questions or concerns, please contact your local veterinarian. (If you live in or around Castle Rock, we welcome your call: 303-688-3757.)

© 2017, Cherished Companions Animal Clinic

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