Heartworms are a type of worm, commonly known as a foot-long worm, that lives inside the heart, lungs, and blood vessels near these organs. Dogs are natural hosts for heartworms. The heartworms inside the pet grow into adult worms, and once they mate and reproduce, your pooch may be infected with several hundred.


Cats, on the other hand, aren't natural carriers, meaning it's rare for a cat to have adult heartworms. They tend to have far fewer worms, sometimes just one or two. Cats with heartworms still have serious complications due to the immature parasites. For instance, they can develop heartworm-associated respiratory disease, referred to by the acronym, HARD.


Fortunately, there are preventive measures against heartworms, and our pet care experts at Normandale Vet Hospital will discuss some of them below. But before we do that, let’s look at how heartworms are transmitted.

How Are Heartworms Transmitted?

Mosquitos spread heartworms from pet to pet. First, they bite a pet with heartworms, and when they do, they ingest microfilaria, better known as baby worms. The baby worms are carried inside the mosquito anywhere from 10 to 14 days. During this time, the next victim the mosquito bites will be infected.


When a heartworm-infected mosquito bites a dog, what are the symptoms? Let’s check them out below.

Dog Heartworm Symptoms

The severity of dog heartworm symptoms depends on how many worms live inside the dog, and how long the dog has been infected. Because of the longevity of the heartworms, it might be difficult to notice the presence of heartworms in your dog on time.


Depending on how healthy your dog is, it may be difficult to detect the presence of heartworm at first. However, the following symptoms will help you determine whether or not your dog has heartworm.

Heartworm Symptoms by Stages

Stage 1: No symptoms or mild symptoms such as an occasional cough.


Stage 2: Mild to moderate symptoms such as intermittent cough and constant tiredness after moderate activity.


Stage 3: Symptoms that are more severe include a sickly appearance, a persistent cough, and exhaustion after light exertion. Breathing difficulties and indications of heart failure are prevalent.

To keep your pet on a safer side, reach out to a reliable Veterinary services provider near you to conduct a chest X-ray on the dog when you sense early symptoms.


Stage 4: At this stage, there is such a heavy worm burden that blood flowing back to the heart is physically blocked by a large mass of worms. This leads to Caval syndrome, which is very deadly. When dog heartworm symptoms reach this stage, it will require veterinary medical and surgical care for quick surgical removal of the heartworms. 


Specific Signs of the Condition

●        Mild, persistent cough

●        Reluctance to exercise

●        Weight loss

●        Decrease in appetite

●        Exercise-related fatigue

More Advanced Cases May Have the Following Symptoms

●        Fluid retention in the abdomen

●        Heart failure

●        Pale gums

●        Cardiovascular collapse

●        Dark, bloody, coffee-colored urine

●        Labored breathing

Symptoms Exclusive to Cats

●        Difficulty walking

●        Fainting

●        Seizures

●        Asthma-like attacks

●        Periodic vomiting

Prevention & Treatment

Prevention in dogs is the most successful method to protect against heartworms. However, it's the only way to protect cats against heartworm damage. A vet will prescribe a medication that's best suited for cases where there are no or mild signs of heartworms. Severe cases can be treated, but complications are more likely in these instances.


Remember that even dogs with numerous worms may have no or mild symptoms. Cats can't take treatment for heartworms, so they must be kept stabilized. In some instances, it's possible to operate to remove the parasites in cats and dogs, but more so in canines.

Check Your Pet for Heartworm at Our Edina Veterinarian Care Center

Taking care of your pets goes beyond feeding and bathing them. It also involves paying close attention to their health. Taking up this responsibility demands you invite your pet care professional to check your pet occasionally.


At Normandale Veterinary Hospital, our veterinary experts love getting to know your pets and helping you live long lives together. We can't wait to meet your sweet furry family members and give them the best health care we can offer.


Schedule your annual check-up by calling us at 952-831-8272 or send us a message on our contact page to find out more.