Recognizing Heart Trouble Early: Understanding Congestive Heart Failure in Dogs and Cats

A pet can live with a heart murmur for years and still look totally fine, right up until breathing becomes an emergency. We walk through what congestive heart failure really is in dogs and cats, why it often shows up as fluid in the lungs, and how that changes oxygen exchange so quickly. If you’ve ever wondered whether a cough is “just a cough” or something more serious, this conversation gives you clear, practical signals to watch for.

We break down the mechanics in plain language: the heart is a pump with one-way valves, and when a valve leaks, blood can move the wrong direction and raise pressure in the lungs. That pressure can cause pulmonary edema, leading to coughing in many small dogs and making cough suppressants the wrong tool when the root problem is fluid. We also explain why you can’t rely on what you hear alone a murmur doesn’t tell you whether congestion is present which is why chest x-rays and especially ultrasound can be so valuable in emergency veterinary medicine.

Then we get specific about treatment and next steps. In the ER, we use oxygen therapy to reduce the work of breathing and furosemide (Lasix) to pull fluid out so the lungs can dry out. We talk about common long-term medications, including pimobendan, and why earlier treatment in some dogs may delay the onset of congestive heart failure. For cats, we cover how hypertrophic cardiomyopathy can stay hidden, why cats often don’t cough, what open-mouth breathing can mean, and why clot prevention meds like clopidogrel (Plavix) may be part of the plan.

If this helps you think differently about your pet’s breathing, share it with another pet parent, subscribe for more emergency vet guidance, and leave a review so more families can find us when every second counts. What early sign do you want us to cover next?

To learn more about Frisco Emergency Pet Care visit:
https://www.FriscoEmergencyPetCare.com
Frisco Emergency Pet Care 
11201 Preston Road 
Frisco, Texas 75033 
469-287-6767 

Transcript

Welcome And What’s At Stake

SPEAKER_01 0:03

Welcome to the Frisco Emergency Pet Care Podcast, your trusted source for expert insight into emergency veterinary medicine. Hosted by Dr. Mike Lasasso, Chief of Staff at Frisco Emergency Pet Care, this podcast brings you essential information to help protect the health and safety of your dogs and cats. Serving North Dallas with 24-7 emergency and critical care, the team at Frisco Emergency Pet Care is here when every second counts. Now, let's begin.

SPEAKER_00 0:40

Heart disease in pets can be subtle until suddenly it isn't. Today we're breaking down what congestive heart failure really looks like, how it develops, and the early signs pet parents should never ignore. I'm Julie Schwenzer, co-host and producer with Dr. Mike Lasasso, Chief of Staff at Frisco Emergency Pet Care. Doctor, it's always awesome to chat with you. If you could please break down what is congestive heart failure, particularly in dogs and cats.

What Congestive Heart Failure Means

SPEAKER_02 1:10

Congestive heart failure is a condition that we see mostly in smaller dogs and occasionally in cats, that causes a fluid buildup in the lungs secondary to what's going on with the heart. So your heart is a two-sided pump. So for a second, we're going to ignore the right and left aspect, and we'll just talk about the top and bottom. When the top chambers squeeze, they push blood through what's supposed to be a one-way door. And then when the bottom chamber squeezes, it slams that one-way door shut. So it's a pump, and those valves make it one way so that when your heart pumps on the left side, it pumps blood to your body, it doesn't go backwards. But in dogs with congestive heart failure and in cats with congestion, we see valvular problems. It really is a valvular dysfunction. So a lot of times these dogs have got murmurs sometimes for years before they become actual heart failure patients. Because a murmur is not disease. Murmur is the sound the blood makes when it's going through that valve, and instead of being a true closure, instead of opening and then closing and making a good seal, it either overcloses or the leaflets are not shaped right, and you end up with blood that goes backwards. And it's that blood moving backwards, back up into the lungs from the left side that causes the murmur. A lot of dogs aren't symptomatic for that, they're not in congestive failure. But at some point, when that process gets advanced enough, you have the right side of the heart, which is pumping blood into the lungs because that's its job. And then you have the left side pumping blood into the lungs because it's going the wrong direction. That's a lot of blood in the lungs. And if you put blood under pressure in a vessel, it's going to start to leak fluid. And when that fluid leaks into the pulmonary tissue, into the lungs, then it affects how well that dog can oxygenate. It affects how well it can trade oxygen for carbon dioxide. Frequently, these dogs will start coughing. So classically, it's our smaller dogs. Typically, our congestive heart failure dogs are 20 pounds or less. That's not a hard and fast rule of any kind, but typically it's the little dogs, the traumas, the schnauzers, the dachshunds. Actually, the poster

Small-Dog Murmurs And The Cough

SPEAKER_02 3:45

child for congestive heart failure is actually the Cavalier King Charles. They are very well known for having left-sided heart disease, which is a tragedy because they are the sweetest creatures on the planet. But those dogs will start to cough a little bit. Sometimes we'll find that veterinarians will treat them with antitussives with cough suppressants. That doesn't help if your problem is not irritation. If it's actually fluid in the lungs, then it's very difficult. So, you know, how do you diagnose that? You definitely can look with x-ray. We actually find fairly frequently that uh I just look with ultrasound, ultrasound. I was taught back in the 1900s, you can't look at lungs with ultrasound because they're full of air and all you get is an artifact. And that is absolutely true if your lungs are dry, but if your lungs are full of fluid, actually I can see very distinctly and be able to grade those lungs with ultrasound. It's frequently a little bit cheaper, it's definitely less stressful on the dogs. They don't have to lay on their backs like they do for x-ray.

Diagnosis With X-Ray Or Ultrasound

SPEAKER_02 4:55

Uh, we want to do whatever we can. Sometimes I'll actually, if the dog's cooperative enough, then I can actually just stick my hand in through our through the door of our oxygen cage and not even have anybody holding them and be able to look at those lungs with ultrasound and see how wet they are. Treatment for congestive heart failure, I mean acute treatment when they come into us, is uh an oxygen cage. We effectively double the oxygen that they're breathing. So you and I right now are breathing about 20% oxygen. Technically, I think it's 19, but we'll call it 20. We can get our oxygen cage up to about 40. So we double the oxygen that's available to try to make it a little bit easier for them. The reality is if they have a physical problem trading oxygen for carbon dioxide, while that makes it a little bit easier for them, it doesn't come anywhere close to solving the problem. What we have to do is dry those lungs out. So we give them a kidney drug called Lasix or Furosamide, and that helps pull water from the body. And the first place we notice that happening is in the lungs, because as they dry out, breathing gets much easier, respiratory rate drops,

Emergency Treatment And Home Meds

SPEAKER_02 6:10

and then if we can you know successfully treat them with furosomide and keep them in oxygen, eventually we can wean them out of oxygen, and when they go home, they're typically on oral ferrosamide to help keep their lungs dry, and then a couple of heart medications. So it's a pretty involved process. But if I had an older dog with a murmur, I'd sure talk to my veterinarian about maybe starting one of those heart medications prophylactically. Dogs with murmurs that go on to pimobendon, a lot of the studies have shown that that actually delays the onset of congestion and may in fact prevent it completely. The real struggle we have is with those cavaliers, because we we all know that they're going into heart failure at seven or eight years of age. Occasionally we'll see some that live longer, but uh it's pretty frequent that we see them as what we would normally consider middle-aged dogs with a very old dog problem. They've got very old dog hearts even when they're young.

SPEAKER_00 7:10

What can pet parents understand? Like if they're starting to see symptoms that they suspect could be congestive heart failure, what should they do? And then how advanced could it be by that time when symptoms start to show?

SPEAKER_02 7:25

It's pretty well down the line by the time they start to have enough breathing trouble that people bring them to me. Now, before that, they're like, Yeah, he's been coughing for a couple of months. I would be very concerned about a persistent cough in a small breed dog, especially if you're talking about 12, 13, 14 years of age, because that could very well be heart disease. And I would definitely get that checked out, either with x-rays or with ultrasound. I don't know that a lot of the GPs in our area use ultrasound, but they certainly could to look at those lungs and determine if they're, you know, if they're wet or not. You can't just go by the murmur. The the murmur doesn't tell you if there's congestion or not, the murmur just says there's inappropriate blood flow. Dogs in congestive heart failure almost always have a very significant murmur, but you can have a very significant murmur and not have heart disease. So

Cats, Silent Signs, And Clot Risk

SPEAKER_02 8:22

you can't rely on what you hear. You have to you have to look a little farther, either with x-rays or with ultrasound.

SPEAKER_00 8:28

Can you please touch on cats and uh more expand on that? And I know before we jumped on this recording, you were mentioning that treating cats is quite challenging.

SPEAKER_02 8:39

Treating cats is really difficult. Um so occasionally we'll see a cat that comes in in congestive heart failure. They generally have something we call hypertrophic cardiomyopathy, but that's probably not that important. They're in congestion. We treat them with LASIKs and with oxygen, just like we do dogs. And then if we can get them out of oxygen, then they need to be treated with generally with a combination of pimobendon, and actually we put them on plavex because those cats are very prone to clot formation and have some trouble. So they're actually put on a drug that prevents platelets from aggregating and causing clots. The challenge with cats is that most people either don't want to or are not capable of treating their cats with oral medications twice a day. It's a real challenge for cat owners, and a lot of cats are not treated for nearly as long as dogs are, strictly due to the difficulty and the logistics of trying to give oral meds to cats. It's tough. You know, and if if when you get the pill bottle out, you can't find your cat because he's hiding under the bed. I mean, it can be a real struggle and it really, really changes the relationship. It's really challenging in cats.

SPEAKER_00 10:01

Are cat symptoms similar to dogs?

SPEAKER_02 10:05

No, well, they generally don't cough like dogs do. You don't know they are really in trouble until they're not moving around very much, their open-mouth breathing, their respiratory rate is really high. Uh, so it it catches a lot of people off guard. And heart disease in cats in general is a silent killer. We see cats are actually born with that same hypertrophic cardiomyopathy that are simply either found dead or have a clot event when they're two or three years old. Something they were born with, they don't have a murmur, there's no indication that they've got any problems whatsoever until you find them, either struggling with a clot or passed away. It's uh very suddenly. It's tough.

How Common It Is And Closing

SPEAKER_00 10:52

How often do you see this?

SPEAKER_02 10:54

Is this one of the most common I I haven't seen it actually in a few weeks? So I would say that on average we we see probably one congestive heart failure dog every couple of weeks. But I I mean I say that I've also had all four of my oxygen cages full of congestive heart failure dogs at the same time. So it really depends. But I would say, yeah, 40 to 50 times a year, maybe.

SPEAKER_00 11:17

Oh wow. So yeah, so still a lot. Well, thank you so much for breaking this down clearly. We appreciate you and everything you're doing for our fur babies.

SPEAKER_02 11:26

Yes, ma'am. Thank you.

SPEAKER_01 11:32

Thank you for listening to the Frisco Emergency Pet Care Podcast. To learn more, visit FriscoPetER.com. Call 469-287-6767. Or stop by 11201 Preston Road, Frisco, Texas, 75033. Open 24 hours a day, seven days a week. Frisco Emergency Pet Care is always here when your pet needs us most. Until next time, take care of your pets, and they'll take care of you.