What You Need to Know About Murmurs and Heart Disease in Senior Dogs

As well as in cats.

Originally published in the August 2015 issue of Veterinary Practice News. Subscribe today

A loud murmur may not indicate heart disease in a dog, and conversely, a dog with heart disease may not necessarily have a loud heart murmur.

That was the top piece of advice to general practitioners offered up by Pamela M. Lee, DVM, Dipl. ACVIM (Cardiology), an assistant professor in veterinary clinical sciences at Washington State University College of Veterinary Medicine.

In older, small- to medium-size breed dogs, the most common heart diseases are degenerative issues, such as endocardiosis, also called chronic degenerative-valve disease or acquired valvular heart disease, Dr. Lee said.

For large-breed dogs, the most common heart disease is dilated cardiomyopathy, where heart muscle contracts poorly, Lee said.

When checking for endocardiosis, it’s the type of heart murmur, not the loudness, that a practitioner should listen for.

“One of the big things to know, at least with endocardiosis: The severity of the heart disease does not correlate with a loud heart murmur,” Lee said.

This may be important to keep in mind, because experts spoken with, including Lee, pointed to degenerative-valve disease as the most common heart disease in older dogs.

Chloe Thorn, DVM, with the Ryan Hospital at University of Pennsylvania School of Veterinary Medicine, sees a lot of degenerative-valve disease in older dogs.

“The mitral and tricuspid valves separate the atria from the ventricles,” Dr. Thorn explained. “In a normal dog, the valve leaflets are thin and close with a tight seal, preventing any blood from going backward in the heart with each heartbeat. As some dogs age, the valve leaflets become thickened and cannot seal properly, which causes blood to leak backward in the heart and results in a heart murmur, which a veterinarian can detect by listening to the chest with a stethoscope.”

This valve disease may be mild, and cause no symptoms in a dog’s lifetime, but in other dogs, the leaks in the valves can be severe and can cause the heart to enlarge. This can ultimately result in fluid build-up in the lungs, she said.

“This fluid is by definition congestive heart failure, and results in symptoms at home, including cough and trouble breathing,” Thorn said.

Sandra Tou, DVM, Dipl. ACVIM (Cardiology and Internal Medicine), clinical assistant professor of cardiology at North Carolina State University College of Veterinary Medicine, also said that the culprit behind the majority of older dogs she sees with heart problems is chronic valvular heart disease.

However, many dogs show no symptoms, Dr. Tou said.

“Thankfully, many affected dogs will remain asymptomatic in their lifetime, but severely affected dogs can develop complications, including congestive heart failure,” Tou said. “The earliest sign of the disease is often the detection of a left-sided systolic heart murmur, which stresses the importance of a complete annual health exam. Detection of such a murmur warrants further diagnostic testing to best assess the stage of disease.”

Treatments for Canine Heart Issues

If a worst-case scenario like congestive heart failure develops, Thorn said the fluid in the lungs can be cleared with diuretic medications.

“Once an animal develops heart failure, they must be on lifelong medications,” Thorn said.

Most dogs with congestive heart failure can be managed with medications and have great quality of life and be symptom-free for several months.

“Over time, heart failure can become difficult to control due to development of resistance to treatment or side effects of the medications,” Thorn said.

To treat severe heart disease, Lee uses Pimobendan, Enalapril or ACE inhibitors.

“The need for medication depends on the severity of the heart disease,” Lee said.

Different mediations have varying reports of success, and Lee noted that she’s waiting on an ongoing study on Pimobendan.

The drug has already showed promise in prolonging an affected dog’s life.


An early study from 2012 on the medication, “Efficacy of Pimobendan in the prevention of congestive heart failure or sudden death in Doberman Pinschers with preclinical dilated cardiomyopathy,” was conducted on 76 dogs in the U.S. and U.K.

The results, published by the American College of Veterinary Internal Medicine, was nearly 200 more days of life.

“The administration of Pimobendan to Dobermans with preclinical DCM prolongs the time to the onset of clinical signs and extends survival,” the study’s conclusion states. “Treatment of dogs in the preclinical phase of this common cardiovascular disorder with Pimobendan can lead to improved outcome.”

No drugs can cure heart disease in dogs, but Lee said the drugs she prescribes can help with the goal of slowing down its progression.

“At this time, it’s not 100 percent successful,” Lee added.

While some experts said asymptomatic dogs do not need to be treated, Tou with NCSU said that even dogs with enlarged hearts, but no symptoms, may benefit from medical therapy.

“Dogs with congestive heart failure warrant additional medical therapy to prevent pulmonary edema and optimize cardiac function,” Tou said.

Lee was optimistic about ongoing research to better treat dogs with heart disease. Beside studies on Pimobendan, there are also experts examining the benefit of surgical valve replacement, she noted.

Of course, preventing congestive heart failure is priority number one, Lee said.

“A big concern with the heart disease is that [it can] become severe enough to cause complications,” she said. 

However, endocardiosis, though a big concern, doesn’t always result in death.

Sometimes, this disease progresses slowly, and a dog may die from something else. The primary indicator of whether a dog will develop congestion heart failure depends on how fast the disease progresses, Lee said.

“One thing I think veterinarians should be aware of is not all dogs with endocardiosis develop congestive heart failure,” Lee added.

What You Need to Know About Cats and Heart Disease

The most common heart disease in cats is hypertrophic cardiomyopathy, Thorn said.

“This is a disease of the heart muscle which causes it to become thickened and stiff,” Dr. Thorn said. “This limits the ability of the heart to fill properly, and can also, ultimately, result in congestive heart failure.”

Tou noted that hypertrophic cardiomyopathy results in hypertrophy of the myocardium. 

“Middle-age cats are most commonly affected by HCM, although the disease does affect a wide age range,” Dr. Tou said. 

Tou’s advice to veterinarians who encounter cats with heart murmurs or gallop sounds is to have them evaluated for underlying cardiac and metabolic disease.

However, changes in a cat’s heart can be due to other factors, Lee said.

Diseases like high blood pressure (systemic hypertension), or hyperthyroidism, can cause heart changes as well.

Detecting heart disease in cats isn’t as easily as finding it in their canine cousins.

“Cats hide heat disease much more easily,” Dr. Lee said.

Cats can have normal auscultation of heart and still have heart disease, but in some cats, a loud murmur may not indicate heart disease, Lee said.

There are a variety of medications to treat the disease, Pimobendan being one of the preferred.

A 2014 study, “Case-control study of the effects of Pimobendan on survival time in cats with hypertrophic cardiomyopathy and congestive heart failure,” looked at seven cats receiving treatment with Pimobendan and 27 cats receiving treatment without Pimobendan.

“Cats receiving Pimobendan had a significant benefit in survival time,” the study concluded. “Median survival time of case cats receiving Pimobendan was 626 days, whereas median survival time for control cats not receiving Pimobendan was 103 days.” 

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6 thoughts on “What You Need to Know About Murmurs and Heart Disease in Senior Dogs

  1. My 13 yr old Pom has a #4 heart murmur. The Cardiologist does not feel using Vetmenden will help . SHe does not have CHF. Will meds help a murmur?

  2. My 13 year old dog has an extremely hard time breathing she has lots of mucus in her nose and drainage down her throat. However it is taking up the whole passage of her nose. She has recently been diagnosed with a heart murmur. Could these two complications be related?

    1. My 10 year old has same problem have you found out if there Related I am very confused I feel like my dog has asthma along with stage five heart murmur if you have any information can you let me know

      1. I’m not a vet but I would strongly ask about Pimobendan, but as a compound medication. I had to mail order the drug but I know the difference in my dog before he started taking it and now. Please read my post on 10 year old Havernese. The Vet who prescribed this for a grade 5-6 heart murmur had a dog that had a heart issue. Her dad was a Vet too. With prescribing this medication, one that none of the rescues vets, and city shelters would prescribe just due to cost. Interestingly enough it’s not as expensive as regular Rimadyl. Not many places do compounding of medications, but there are some.
        I can also tell you it tastes horrible. So I got some empty capsules via Amazon and I can put the tablets in them. He could always find the drug in every type of pill pocket and food I tried to hide it in. He was a gentleman and would just calmly place the pill on the floor next to his bowl, or spit out the whole pill pocket. Now that I hide them inside these vegetable based capsules, he is getting his medications and I’m not having panic attacks that he won’t take them.

        No one thought my dog would see 12/1/19. That was only two weeks after I brought him home. I’m not sure how long he has now, but he really is doing great for a dog with a grade 5-6 heart murmur and diagnosed with congested heart failure. Good luck to both your dog and yourself. Prayers for both.

  3. I rescued an 10 year old male Havernese. At the time of first fostering him it didn’t look like he would last long, maybe a few weeks. He only weighed 8 lbs and had a terrible grade 5-6 heart murmur. He was only taking Enalapril and Salix Furosemide. I knew that I was actually going to hospice him.

    I got really, really lucky and found the most amazing Vet. She just happened to be the Vet working the day I went into a new Vet location. This Vet had a childhood dog with similar issues, plus a father who was also a Vet. Immediately she put him on Pemibenden Flex. She also added, on an added needed basis hydrocodone/homatrop 5-1.5mg for his cough. Originally to be given every 8 hours, but with her ok I made it just at night, unless his coughing got out of hand. I didn’t want him to get it too much before needing it more later. Bottomline, I really thought this dog would not make it longer then one week. He barely was eating, and moving took so much energy.

    I read the above article and wanted to say that Pemibenden made a huge difference for my little guy. It was 11/14/19 when I brought him home. He is truly thriving and it’s 7/19/20. He weighs a normal weight for a Havernese at 15.2lbs. He is eating and drinking like a normal dog. I’m still only having to give him the cough medication once a day at night.

    About two weeks after bringing this dog home to hospice, I decided to adopt him. I knew it would it would allow the rescue group the ability to save the money for his meds etc. I also knew that I wanted to show him that he could have a better life. He actually has even tried to play with my other digs a few times. He tires out quickly.

    The rescue group whom I adopted him from got him from a kill shelter. He was considered nothing. He was a senior dog, who couldn’t see too well due to terrible cataracts. He was also thought to be be deaf or hard of hearing. But that wasn’t true. His ears were so caked in a black debris that it took about a month before they stopped giving off the black when his ears were cleaned. It was also evident that he had been abused by his eyes and ears, so he would get really angry and upset if you tried to touch his ears and eyes. Again, this outstanding Vet got it on the first day, she prescribed a mild relaxation drug so he could get a proper exam. I give it to him 2 hours prior to a vet visit. I do believe without it he would still have his ears in bad shape.

    The vet clinic I took this dog too did not end up treating their employees very well. The vet who I know saved my dog had to leave just to get health insurance. I don’t know where she went, but she could tell you that giving Pemibenden should be mandatory. I am ever so thankful for my time with my little dog. I named him Paw Paw. It’s a type of fruit and just seemed to fit him. He is black with some white. And has big feet.
    He truly is a loved dog. His heart doesn’t scare me as much any more all because of an amazing Vet. Thank you to all the Vets and Vet tech’s our there helping all our animals during the Covid-19 situation. You are amazing.

    1. Thank you for your useful comments. My dog was just diagnosed with a grade 4 holosystolic heart murmur. I wanted to share that when I found out my vet had left the clinic after I tried to make an appointment, I was able to locate and contact her through Linkedin.com.