Ask a Vet: How Can Cats Suddenly Develop Symptoms of Heart Failure?


Many months ago I worked on a case that will haunt me for a while. A cat was brought to my office with a two-hour history of respiratory distress. I could tell within moments that the cat was not going to make it.

The cat was an 11-year-old Maine Coon mix. She lived indoors and had not escaped recently. She had not been exposed to any toxins, and she had not suffered any known trauma. She had been to the vet two months prior to her crisis, and she received a clean bill of health at that time. Earlier in the evening the owner had noticed that her breathing was abnormal, and the symptoms had gotten worse since that time.

By the time I met her, she was in serious trouble. Her chest and abdomen heaved with every breath. She stood with her neck extended and her nose up, and she breathed through her mouth. Cats breathe through their mouths only in desperation. Her breathing was raspy, noisy, and wet — it sounded like there was fluid in her throat.

There are two common causes of such severe respiratory distress: asthma and heart failure. With time, as a veterinarian, one gains an intuition about which one to suspect. This case had heart failure written all over it.

Photo of Dr. Eric Barchas by Liz Acosta
Photo of Dr. Eric Barchas by Liz Acosta

We immediately began oxygen supplementation, and a technician administered an injection of furosemide, a diuretic medication that treats heart failure. To definitively differentiate between asthma and heart failure would require X-rays.

But there was a problem. To take X-rays we would have to violate rule No. 1 for cats with breathing difficulties: Do not stress them. X-rays require cats to be in certain positions, and changing position can be very stressful and dangerous for a cat who’s having trouble breathing. X-rays were out of the question.

There was, however, an alternative: I performed a quick ultrasound exam. This technique (called a VetBLUE, which is short for veterinary bedside lung ultrasound exam), which did not require the cat to change positions, confirmed my suspicions. Ultrasound artifacts called B-lines, which indicate fluid in the lungs, were prominent in all of the lung fields. Wet lungs are not compatible with asthma, but they are a hallmark of heart failure.

We redoubled our efforts with the diuretic. An additional, high dose was administered. The cat voided a large quantity of urine — the medication was working, but the situation was too advanced for it to save her. The wet breathing noises she made indicated that fluid had accumulated in her major airways, and it is a sign of a severe situation. Cats with such massive fluid accumulation almost never survive — they drown in the fluid their own bodies produce. Sadly, this cat was not an exception.

Intensive care pet unit by Shutterstock

The owner was beside herself. Was the heart failure the result of the lifestyle that the owner had provided? Had it been caused by diet? Could the crisis have been prevented at home? How could she have received a clean bill of health two months before the crisis? And how had things gotten so bad, so very fast?

The answers to the first three questions were no, no, and no.

Most heart disease in cats is caused by a condition called cardiomyopathy. Cardiomyopathy is a problem in which the muscle of the heart does not function properly. It is a hereditary condition, and Maine Coons are highly predisposed to it. Unlike human heart disease, it is not linked to exercise or lifestyle choices.

In the past, many cats died of cardiomyopathy because their diets contained insufficient quantities of an essential amino acid called taurine. Once the link between taurine and cardiomyopathy was discovered, all commercial cat foods were supplemented with taurine. Diet-related cardiomyopathy is very rare now as a result. The cat in question received a high quality commercial food. Diet had not caused her problems.

The crisis could not have been prevented at home — it came on fast, and it was not precipitated by anything that the owner or cat did. And I’m not surprised that the cat received a clean bill of health two months before the crisis. Cardiomyopathy does not consistently cause any irregularities (such as a heart murmur) that can be detected on a physical exam.

Food and other lifestyle factors play no role in many cases of feline heart failure. A Russian Blue cat eats food from a can by Shutterstock

However, although the cat’s previous physical exam was normal, it is certain that she was suffering with cardiomyopathy at the time of the exam. This brings us to the owner’s last question: How did everything happen so fast?

Many crises related to heart disease in cats occur as a result of decompensation. Cats’ bodies are remarkably good at adapting to disease. As a result, cats with chronic diseases often show no symptoms as the disease progresses. They may go months or years without any symptoms. Ultimately, the pathology reaches a point beyond which the body can no longer compensate. At that time, everything falls apart at once. The cat appears to get sick suddenly, when actually what is happening is the sudden manifestation of a long-standing problem.

In fact, the first sign of heart disease in cats may be a crisis like the one I have described. Other cats may experience an incredibly painful blood clot in their hind legs as the first symptoms. For some cats, sudden death is the very first sign of heart disease.

I felt truly sorry for the cat’s owner. I look forward to the day when medical science gets the better of cardiomyopathy.

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23 thoughts on “Ask a Vet: How Can Cats Suddenly Develop Symptoms of Heart Failure?”

  1. I lost my beloved 13 years old boy two month a go, it started with coughing and I went through the hairball, but it wasn't. I brought him to ER and they did X-RAY, he got enlarged heart and fluid in his lung but not too much. they said it's heart failure They gave all medication that they knew! antibiotic, asthma pumps and Frusemide for his heart. He didn't get better and despite frusemide and in last 3 days I could hear the fluid sound in his breathing and his tongue got blue and had breathing issue. I hat to put him down. I wish I could do something for him. My heart is so broken. He was the love of my life. He was my best friend. I still can not believe how it happened one day suddenly and how fast it got worse!

  2. Trying to find some closure as my healthy handsome brown/white male short hair was out 2 days coming back with his ribs looking like he was starving. Rushed him to the vet who charged $500 telling me he had fluid in his lungs. They wanted $5000 to tell me the possible cause? He died 2 days later unable to breathe. What could have happened as he showed no signs before going outside?

  3. I lost my beautiful Maine coon mix Benji suddenly on Tuesday nite to acute Right side heart failure.
    He was 8, I adopted him just 3 months ago.
    He was perfect. Everyone loved him.
    He seemed fine until monday when he went into resp distress. The first vet appt said asthma and treated accordingly.
    The next morning was worse and the diagnosis was heart failure.
    He was euthanized at the ER vet that nite.
    I am haunted and beside myself at the suddenness.
    If I had known the first day I could have saved him the suffering he experienced those last hours.
    I’ve had many beloved cats and this is the worst thing I’ve experienced. My thoughts and sympathy to anyone experiencing this.

  4. On a bitterly cold night in February of 2013, my husband rescued a beautiful, but emaciated, stray Maine Coon. As my husband was leaving the library, the cat unsteadily walked right up to him, obviously crying out for help. My husband put him in the car by the heater and brought him home. We could not get him to eat or drink, and he had a difficult time walking, so we rushed him to the ER Vet. X-ray’s were taken that showed he had been so hungry that he had swallowed a plastic tie bag with a bird in it. This was lodged between his tummy and colon. It would require surgery to remove the bag and bird. He was estimated at being only about 1 year old at the time. We just couldn’t let this beautiful boy, who had obviously lived a horrible life so far, be euthanized. So, we decided that we would adopt him and pay for his surgery. He had only a 50% chance of surviving, due to his emaciated condition. Then, one surgery became two surgeries because everything could not be removed with the first. Weeks later, our boy (now named Leo) was healing well, but had developed a terrible cough. He was diagnosed with asthma and put on steroids. I always wondered about this diagnosis, mainly because with good nutrition, he never developed to the size that male Maine Coons should be. But, he was checked over well, and we were told that he was fine. The Vet could never detect a heart murmur, so heart conditions were ruled out. We got a second opinion, and asthma was again confirmed. He was such a happy guy – always walking around our house “chirping”, as if to say “thank you for giving me a home”. He developed a strong friendship with our other cat, who had also been a stray. Almost five years to the day later, my husband and I woke up and could not find Leo. I finally found him hiding under our bed. When we got him out, we could tell that he was in obvious respiratory distress. We called our Vet and she got him right in. He had never had so much as a heart murmur, but X-ray’s showed that our boy was in severe Congestive Heart Failure. We were told that even with extensive treatment, he would only live a possible 6 to 8 months. We ended up putting our little Leo down that day while I held his little face in my hands and lovingly looked into his eyes. He had just turned 5 years old two days before, and had been so happy at all of the attention and new toys he was getting, not to mention his favorite foods.
    We are now convinced that Leo never had asthma. We think that he always had a heart condition that went undiagnosed. On top of that, the steroids that he was being given for his asthma diagnosis had probably further damaged his little heart.
    Through my tears, my heart goes out to each one of you who have gone through this horrible disease.

  5. I want to just send out a hug to all those who lost their best friends to this awful disease. We lost ours to this too, just 10 days ago. Life is miserable without our cat and in the manner they are taken away is both sudden and cruel.
    Take care of yourselves. x

    1. I think my cat may have this, I was told at ER it was asthma, but he has a murmur and is not responding to treatment. It has been 24 hrs, I think I will have to put him to sleep. I am at my wits end. I am so sorry for your loss.

  6. This article is truly helpful. I hope that one day our fur babies can have as much treatment options as humans do. After all, they are also family.

  7. I lost my 10 year old orange tabby to heart failure. The day before he started breathing rapidly and stopped eating, but drank lots of water. I got him to the vet to find out he had an enlarged heart and fluid around his heart and lungs but very little fluid was drained from his lungs. He seemed so healthy all his life. He jumped and played a few days before. He always did well at his checkups. I really thought he was going to last longer than 10 years with me. I wonder if blood tests and xrays at his checkups would have detected his condition. I’ll never know. I miss him so much. I had to put my baby to sleep. He became acidotic, had a very low blood pressure, and developed arrhythmias. His last meows were painful to hear. Worst day of my life. I lost my soulmate.

    1. I lost my 11 year old black cat Raven to acute heart failure. She seemed fine one day, the next she was critically I’ll. My vet thinks she developed a ruptured chordae tendinae. The thought of something in her heart rupturing sounds so horrible. What are chordae tendinae? What causes them to rupture? Did I do something wrong with her?

  8. I just lost my sweet Himalayan cat Clementine to this exact disease. She got sick last Saturday, breathing heavy and labored, cold to the touch. Took her to emergency vet Saturday evening. Body temp was 90 (cats should be 180), couldn’t get a blood pressure to register on her. Vet said heart disease, congestive heart failure, cardiomyopathy, nothing they can do to save her. I had her euthanized so she wouldn’t suffer. She was only seven. Just devastating. I had no clue she was sick. This article definitely gave me peace of mind that I didn’t do anything wrong. You think to yourself, “How could I have missed this?” ????

    1. This happened with my 7 and a half year old, Booboo. He was a mixed breed, mostly likely mixed with Maine Coon, large (19 pounds but the vet said he was normal weight for his structure), long haired, black, and biggest green eyes you’ve ever seen.
      Yesterday morning, I had just gotten home at around 2:00am (I work late and go to visit my mother who’s currently in the ICU). I went to feed my babies and Booboo cake out from under the bed, but just sat at his food dish breathing through his mouth. I looked at him and knew something was wrong. I screamed for my husband to get the carrier and during this time Booboo peed all over the bed and started meowing these terrible meows.
      We got him to the vet and she just told me he was in heart failure and I begged for her to tell me there was something we could do. I didn’t care how much it would cost I’d figure it out… but while I sat there crying and holding my baby, my husband was talking to the vet who explained he was in really bad shape and would probably not survive treatment. She also explained that even if he did survive the treatment that it wouldn’t cure his condition, only give him a small amount of time before he was back in the same amount of pain and if we weren’t there to find him he would die in excruciating pain.
      My husband explained there was nothing we could do and we had to say goodbye to our baby boy. My heart is so broken. He was the love of my life. He was my best friend and he was there for all of the biggest moments in my life. He will forever be in my heart, but I don’t know how to stop this pain.
      I’m glad to know there truly wasn’t anything I could have done and that I didn’t take the “easy” way. My poor baby boy. I just wish I could have stopped him from feeling any pain at all, he didn’t deserve to feel pain after all the years of joy and love he gave me and my family.

      1. Thank you for sharing,
        I fully relate to the painful experiences
        My 2 year old male orange tabby mix, just suddenly fell very ill .
        the ER vet said the right decision would be euthanasia , she said my cat was suffering from fluid in lungs and enlarged heart
        diagnosis was congestive heart failure
        .She said would be a process ,to even start a treatment plan ,with testing and all needed
        meds and possible surgery would not likely save him .if life was extended ,he would not have the normal activity of a healthy cat and would eventually be back in critical condition, all in a short time period. She also said he could be under stress ,
        of having to administer meds, leave him not a happy ,healthy pet anymore

        I understand the suffering your experiencing or already experienced .
        Having a tragic experience, with sudden illness and loss of my mother 3 months ago , in which you adapt to living with the pain of that loss
        3 months later this death of my cat , is adding a high impact of pain and anguish
        You immediately think and try figure out when and where things start going wrong
        There is regret , along with this painful loss making decisions in these moments horrific

        These beautiful pets are sensitive to their owners, the owner /pet relationship you develop, is unexpected , they have so much to offer to your family, so loving .

        I am seeking help with coping .
        This is a very hard loss, you don’t know how you will get over the pain it brings on
        I hope there are support groups of other pet owners that can help with coping
        Also , some organizations have pet loss counseling over the phone I believe.
        Will be seeking these , the loss was 2 days ago
        Thank you for sharing your experiences .
        may God give comfort and peace through his son the savior

  9. Our precious child, Jay Jones, died instantly today of this I suspect. We got him to the ER vet in probably 10 minutes but we knew he was gone. He was a 7 yr old male DSH cat. No warning signs and he had a good check up this Summer. Also he had an ear wax issue, probably bacteria they said last month and saw a vet twice in December. We are in complete shock and devestation. I am sorry for all of your losses here and was looking for an article to kind of confirm what I thought happened to him since ER said heart or embolism likely
    and was worried if it was something I did too. Thank you for this article sir. May the animal medicine advancements find a good screening for this heart condition in the near future. God Bless.

  10. My snowshoe, 3 years old, who saw the vet on 11/2/18, died yesterday (11/18/18) of cardiomyopathy. It was painful and sudden onset of symptoms.

  11. My 3 year old cat died 2 days ago of hear failure. We had only adopted him 10 days prior and had just visited the vet and gotten a clean bill of health FOUR days before his heart failed. Everything happened very fast for him too. It was such a heart breaking experience.

  12. I just lost my sensitive, adoring Vito last night to this. He received a clean bill of health 2 weeks ago from the vet. He just turned 8 and was breathing weird. It was after midnight so the nearest hospital was a drive. I thankfully had a family member drive us as I held him and tried to console him. He bit me all over and cried for a long time (which he would never do normally). He did the standing up with head back thing that you mentioned. He eventually died in my arms before we made it and I tried chest compressions to no avail. I’m heartbroken. My other cat is his brother from the same litter. He suffers from epileptic seizures so now I’m afraid he has the heart condition as well.

  13. Thank you for posting this. I just experienced this with my beautiful Persian. I asked the same questions your client asked and I still feel helpless and guilty that I didn’t know. Angus was given a clean bill of health just two weeks before this episode that ended in tradgedy. He was up and down the stairs, eating and drinking when all of the sudden he was breathing wrong. By the time we reached the vet it was too late. I appreciate your honesty as a vet as we often believe you have all the answers. Please keep researching so we can make sure this doesn’t happen anymore. Is there a research foundation you recommend for this illness?

  14. Chanelle De Beer

    Hi Dr Barchas,

    My Russian Blue was diagnosed with HCM after two congestive heart failure episodes (the first was believed to be poisoning) in the space of a week and is currently on 4 medications, twice a day – which he truly hates. I’ve done a lot of research and found that the likelihood of him developing an ATE is almost certain. As a result, I’m very seriously considering planned home euthanasia before he gets an embolism and suffers or dies afraid or alone. Yes, it may cut his life short, but is it not worth saving him an inevitably painful death? To be clear, I want what’s best for him. I don’t want him to suffer so I may have more time with him. In your opinion, is this a reasonable thing to do or am I taking it too far?

    I’d appreciate any advice you may have,

    1. Hi Chanelle,

      Thanks for reaching out. We suggest contacting your vet with these questions. Much love to you and your kitty.

  15. I have 3 kitties, all litter mates, and one just suddenly died from what I think is cardiomyopathy. She was only 8 years old. She had no symptoms up to her passing other than coughing 2 times over the course of 2 days prior. She was a long haired cat though so I thought she had a hairball and it didn’t alarm me. From what I have read though, the coughing was a sign…the ONLY sign I got. We found her dead in our front lawn. I’m utterly devastated. She was my little buddy, followed me everywhere and was a fixture in my daily routine. The other 2 I have left I love dearly but their personalities are different and they are way more independent. However, I am worried since they were all litter mates that these 2 may also have cardiomyopathy. I’m planning on taking them to the vet for exams but what is the likelihood they have it too? I can’t loose another so tragically.

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