What You Need To Know About Heart Disease In Dogs

And how to keep that sweet little heart healthy ❤️

heart disease in dogs

A dog’s big heart is what makes him so easy to love, which is why you want it to stay nice and strong.

Heart disease in dogs is scary to think about, but the more you know about it, the better you’ll be able to keep your BFF healthy — even if he does end up developing a heart problem.

The Dodo spoke with Dr. Zach Marteney, a veterinarian and medical director at Meadowlands Veterinary Hospital in New Jersey, and Dr. Claire Walther, the parasiticides medical affairs lead at Zoetis Petcare, to find out all you need to know about heart disease in dogs.

How your dog’s heart works

In order to understand why heart disease is so serious in dogs, you should know how your pup’s heart works in the first place.

“The heart has four chambers. I like to think of them as rooms,” Dr. Walther told The Dodo. “In between those rooms there are four valves, which are like doors. And then the veins and the arteries that bring blood in and out and throughout the body, I think of them as like the hallways leading in and leading out of the room.”

So, the blood travels through your dog’s heart in a specific direction and then out to other parts of his body, like his lungs.

The heart pumps blood into two areas: the lungs (pulmonary circulation) and the body (systemic circulation),” Dr. Marteney told The Dodo.

What happens when your dog has heart disease

There are actually several types of heart disease that affect dogs in different ways, but the more common ones result in the same major issue.

“For the more common types of heart disease, the heart is unable to pump blood to the body (systemic circulation) as effectively as normal,” Dr. Marteney said.

A heart that can’t pump blood effectively is never a good thing (that’s its job, after all). And without treatment, things can get pretty bad pretty quickly.

“As a result, blood can start to back up in the blood vessels of the lungs,” Dr. Marteney added.

When heart disease causes that blood to back up into the lungs, it makes it tough for your pup to get enough oxygen in his blood (and ultimately get that oxygen to the other parts of his body).

“As the disease progresses, more of the blood starts to fill the blood vessels of the lungs until it starts to leak out into the microscopic airways,” Dr. Marteney explained. “This fluid accumulation in the airways prevents proper exchange of oxygen and carbon dioxide into the bloodstream, forcing pets to breathe harder and more quickly to get enough oxygen into their blood.”

Common types of heart disease in dogs

Common types of heart disease result in an inability of the heart to pump blood correctly because there’s an issue in certain parts (or even all) of the heart.

“Depending on which one of those components isn't functioning properly ... you're going to see different types of heart disease,” Dr. Walther explained.

Here are some of the most common types of heart disease in dogs.

Degenerative mitral valve disease

According to Dr. Marteney, degenerative mitral valve disease is the most common form of heart disease in dogs.

This is a degenerative change in the valve between the top and bottom chambers in the left side of the heart that causes the valve to leak,” Dr. Marteney said. “As a result, each time the heart contracts, some of the blood is pumped backward into the atrium (the top chamber), rather than forward into the systemic circulation.”

Dilated cardiomyopathy

You want your dog to have a strong, healthy heart, but dilated cardiomyopathy can make it thinner and weaker.

In this disease, the heart muscle becomes weaker over time, so it is less able to effectively pump blood out to the body,” Dr. Marteney said. “As the heart muscle weakens, the heart enlarges, much like a balloon inflating.”

Heartworm disease

Heartworm disease happens when a dog gets infected by parasitic larvae that grow into big worms inside his chest.

The good news is that dogs can’t give heartworms to other dogs. The bad news is that heartworm larvae are spread through mosquito bites, and mosquitoes seem to be almost everywhere.

Heartworms are transmitted by mosquitoes and live in the large vessel between the heart and the lungs, where they damage the vessel and block blood flow to the lungs,” Dr. Marteney explained.

The scariest part? These worms can grow to be a foot long inside your dog, so they can really damage all parts of his heart.

“Not only do they affect the chambers, but because they go through the chambers, in through the valves, they can affect the valves,” Dr. Walther said. “They also tend to wiggle their way into the arteries and veins, and so they can cause damage not only to the heart, but also to the lungs, as well.”

Heart murmur

A heart murmur is when your dog’s heart is making abnormal sounds due to a disturbance in his blood flow.

“This is a problem of the valves of the heart,” Dr. Walther explained. “Think about valves as like saloon doors. They're attached on the side, but then they're really swinging in the middle. In a normal heart, they swing open and shut together. With a heart murmur, one of those doors lags behind the other.”

So basically, heart murmurs happen when there’s a structural issue with your pup’s heart, which can actually occur at any point in your dog’s life.

“It happens in pets of all ages,” Dr. Walther said. “They can be born with it or they can develop it later in life.”

Signs of heart disease in dogs

The most common signs of heart disease in dogs are:

  • Coughing
  • Higher respiratory rate
  • Lower energy level
  • Loss of appetite

According to Dr. Marteney, coughing is the first sign of heart disease that pet parents will notice.

Sometimes the cough is a loud hacking cough, and sometimes it’s a more soft, subtle cough,” Dr. Marteney said. “Occasionally the cough has a wet sound to it, as if they are coughing up fluid. This is a sign of more severe disease.”

You’ll be able to tell that your dog’s respiratory rate is higher than normal (which is a common sign of heart disease) if he’s breathing quicker or harder than he usually does.

“An increase in respiratory rate and/or effort — especially while resting or sleeping — is a sign that they are working too hard to get oxygen into their body, resulting in the faster or deeper breathing pattern,” Dr. Marteney explained.

Having less energy or loss of appetite are actually signs of a bunch of different ailments, not exclusively heart disease, but are especially telling when paired with any of the signs mentioned above.

If your pup is showing any of these signs, you’re going to want a vet to check it out ASAP, so your BFF can be treated for the underlying cause, whether it has to do with his heart or not.

When to be really worried

There are some symptoms of heart disease in dogs that are actually signs of a medical emergency.

“If the pet is suddenly breathing much more heavily or coughing more than normal — especially if their gums are pale or blue-tinted — this is an emergency and should be evaluated by a veterinarian immediately,” Dr. Marteney explained. “Knowing where the nearest emergency veterinary hospital is can be lifesaving for a pet with heart disease.”

Grain-free dog food and heart disease

“Most types of heart disease cannot be prevented,” Dr. Marteney said. “The diseases likely have a genetic cause, as we see them more commonly in certain breeds and certain families of dogs.”

While it isn’t a guaranteed way to prevent heart disease, avoiding grain-free dog food could actually be a good move for your pup’s heart.

“A link between grain-free diets and dilated cardiomyopathy has been identified in recent years,” Dr. Marteney explained.

An exact cause hasn’t been pinpointed, but, to be safe, stick to brands you trust and companies that have research to back up their formulas (recipes that have been signed off on or even formulated by vets are always a good idea).

You should also try to avoid exotic proteins, like kangaroo, rabbit and venison.

Treatment for heart disease in dogs

You may not be able to totally prevent heart disease from developing in your dog, but you can treat it.

If your vet does catch a heart disease developing in your dog, they’ll be able to help you figure out which treatment plan would work best for him.

“This will likely include several medications to help improve the function of the heart and control fluid accumulation in the lungs,” Dr. Marteney explained. “It’s important that these medications are given according to the directions on the label.”

From there, you should stay on top of follow-up visits, so your vet can check how the meds are working and how your dog is handling them.

Your vet can also use bloodwork and X-rays to note how your pup’s system is reacting to the medication.

“Heart disease is often progressive, meaning it will get more severe over time,” Dr. Marteney said. “Regular checkups will help ensure that medications can be adjusted according to the severity of the disease.”

So, if your dog is diagnosed with heart disease, you don’t always have to panic. Your vet is here to help.

Plus, you could always reach out to a specialist if you’re super concerned.

“A board-certified veterinary cardiologist can help identify the cause and severity of the disease,” Dr. Marteney said. “A specialist’s opinion can be invaluable in forming a treatment plan and guiding it as the disease progresses. Your veterinarian will be able to recommend a cardiologist.”

Preventing heart disease in dogs

Doing things like avoiding grain-free (and exotic protein) food options, managing your pup’s weight and making sure he gets enough exercise are all great ways to keep his heart healthy. But keep in mind that you can’t change his genetics, which will still have a huge effect on whether or not your dog develops heart disease during his life.

In any case, annual vet visits are super important.

“A veterinarian will be able to listen to their heart and detect early signs of heart disease that a pet parent may not be able to see at home, or even be able to, you know, prevent with diet and exercise,” Dr. Walther explained.

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