Heartworm Awareness Month: The Dog Who Lived Because His Owner Said Yes

Heartworm Awareness Month: Signs, Prevention, and Treatment in Dogs and Cats

There are some patients you never forget.

One of mine was a dog whose life may have changed because of one conversation.

He had come to Pennsylvania from South Carolina.

It was February, and for many people, “winter” feels like a season when mosquitoes and heartworm do not need to be top of mind. But where he came from, the weather had been warmer. The risk had not disappeared just because the calendar said winter.

I spoke with his owner about heartworm testing and prevention. She listened. She agreed.

We tested him.

He was positive.

And when we looked closer at the blood slide, there they were, swimming in the blood.

It is one of those moments that stays with you.

The good news is that he was treated. He survived. And he went on to live for many more years. He was about 10 when we first met him, and if I remember correctly, he lived to be around 16 or 17.

That is why Heartworm Awareness Month matters.

Not because fear is helpful. It is not.

But because awareness saves lives.

What is heartworm disease?

Heartworm disease is caused by parasitic worms that are spread through the bite of an infected mosquito. When a mosquito carrying immature heartworm larvae bites a dog, cat, or other susceptible animal, those larvae enter the body and begin developing.

Over time, the worms mature and begin living mainly in the heart, lungs, and associated blood vessels. This can lead to inflammation, damage to the lungs, strain on the heart, breathing problems, and serious complications throughout the body.

Heartworm is not spread directly from pet to pet. Mosquitoes are the vector, meaning the transmission vehicle, which means the environment plays a huge role in the risk.

How is heartworm transmitted?

The cycle begins when a mosquito bites an infected animal and takes in microscopic baby heartworms called microfilariae. Those microfilariae develop inside the mosquito into an infective stage. When that mosquito bites another animal, it deposits the larvae into the skin, and the infection begins.

This is why heartworm prevention is so important. Once adult worms are present, the disease is much more serious, and treatment becomes far more difficult, especially in cats.

What environmental conditions increase risk?

Many people associate heartworm only with hot southern climates, but the truth is more complicated.

Mosquitoes thrive in warm, humid conditions, standing water, and areas where temperatures allow them to remain active longer. That means risk may be higher in some regions, but it is not limited to them. Pets who travel, pets adopted from other states, and pets living through unusually warm seasons may all face exposure.

Even one infected mosquito bite can matter.

That is why prevention should be discussed year-round, not just in summer.

Can cats get heartworm, too?

Yes, cats can get heartworm.

This is something many pet parents do not realize.

Cats are not the natural host the way dogs are, so the disease behaves differently in them. They usually carry fewer worms, and in some cases, only one or two worms can cause significant illness. Sometimes immature worms alone can trigger inflammation and damage in the lungs.

Because of this, heartworm in cats can be harder to diagnose and can look very different from heartworm in dogs.

Signs of heartworm disease in dogs

Some dogs show no obvious signs early on. Others develop symptoms gradually as the worms cause more damage.

Signs in dogs may include:

• coughing

• exercise intolerance

• tiring easily

• breathing difficulty

• decreased appetite

• weight loss

• lethargy

• in severe cases, collapse or signs of heart failure

  
  

The severity often depends on how many worms are present, how long the dog has been infected, and how much damage has already occurred.

Signs of heartworm disease in cats

Heartworm disease in cats can be subtle, confusing, and sometimes sudden.

Signs may include:

• coughing

• rapid or labored breathing

• wheezing

• vomiting

• decreased appetite

• weight loss

• lethargy

• episodes that resemble asthma

• sudden collapse

• in some tragic cases, sudden death

  
  

Because cats often do not carry many adult worms, diagnosis can be more challenging. Their symptoms may come and go, or they may be mistaken for another respiratory problem.

How is heartworm treated in dogs?

Dogs with heartworm disease can often be treated, but treatment is serious and must be managed carefully by a veterinarian.

Treatment generally involves confirming the diagnosis, evaluating the severity of the disease, restricting exercise, and following a veterinarian-directed treatment plan. In many cases, this includes medications to address different stages of the parasite and adulticide treatment to kill the adult worms. Strict rest during treatment is critical because, as worms die, they can create dangerous complications inside the blood vessels and lungs.

This is one reason prevention is so much easier, safer, and kinder than treatment.

How is heartworm treated in cats?

Cats are different.

There is no approved medication that safely eliminates adult heartworms in cats the way treatment is done in dogs. Management in cats is usually supportive and based on the symptoms and complications present. Some cats may need medications to reduce inflammation or help with breathing, and every case should be handled closely by a veterinarian.

Because treatment options are limited, prevention in cats is especially important.

How can heartworm be prevented in dogs and cats?

Prevention is one of the best gifts we can give our pets.

Heartworm prevention for both dogs and cats usually involves routine veterinary care, testing when recommended, and staying consistent with veterinarian-prescribed preventives. Dogs should be tested according to veterinary guidance, even when they have been on prevention, because early detection matters.

Cats, too, benefit from prevention, even if they live indoors, because mosquitoes can and do get inside homes.

A few important reminders:

• indoor cats are not risk-free

• adopted or relocated pets may bring exposure history from another region

• missed doses matter

• prevention is far easier than treatment

  
  

A gentle reminder for pet parents

Heartworm disease can sound frightening, but awareness is not about panic. It is about paying attention.

It is about remembering that weather, geography, travel history, and mosquito exposure all matter.

It is about asking questions.

It is about catching something early enough to make a difference.

I still think about that dog from South Carolina. His owner said yes to the conversation, yes to the testing, and yes to the care he needed. Because of that, he had years ahead of him.

That matters.

And if this month’s reminder helps even one more pet parent ask the right question at the right time, it matters again.

With love and care,

DawnParadise

Pawsome Pet Care