Gazette Vet: Heart or Lungs?
By John Andersen, DVM
Patches is an 18-year old cat that has been alive about five years longer than she should be. I can recall when she came into the office about five years ago because she wasn’t eating well and started having some difficulty breathing.
Because they don’t really exercise, cats can have significant heart and/or lung disease with very little obvious clinical signs to their owners—until they just can’t compensate any longer. This was the case for Patches. Her owners actually told me that for several months she was having some wheezing when she was breathing, but they thought it was just her purring. She was eating fine and social, so really how could she be sick?
But there is nothing like a car ride to the vet to really make a cat with difficulty breathing decompensate. When I came into the exam room, here was Patches, open-mouth breathing, in critical condition. I almost had to convince her mom that she was critical because she had seemed so normal just hours before.
Despite her labored breathing, I heard very little noise when I listened to her lungs. Not good. We took some quick chest X-rays and then put her in the oxygen cage so she could breathe more easily. I was fairly shocked to see on the X-ray that she had only about 25 percent of her lung function because her chest was so full of fluid.
Working up a cat with difficulty breathing poses a challenging for veterinarians. Cats are actually very similar to humans in that the lungs are a very reactive organ system, and are referred to as the “shock” organ—i.e., sometimes when there is a lot of inflammation or trauma elsewhere in the body, the lungs can start to suffer from “inflammatory lung disease” and start filling up with fluid. Thus, when we see cats with fluid in their lungs or in their chest, we have to consider the whole cat.
Heart disease is an obvious cause of difficulty breathing and fluid buildup in the lungs. Dogs and cats don’t get coronary artery disease (aka, heart attacks) like people—they tend to get congestive heart failure due to chronic heart disease. Dogs are pretty predictable—they almost always have an audible heart murmur for a long period of time before the heart muscle actually starts to fail. Cats, however, can surprise the heck out of us because they can often have significant heart disease without a hint of a murmur or arrhythmia (abnormal heart rhythm). When cats like Patches present to us with fluid in their chest, heart failure is always possible, even without a murmur or history of heart disease.
Chronic allergic bronchitis, also known as “feline asthma,” is one of the most common causes of lung disease in cats. Cats are very prone to allergic lung disease. These cats almost always have a history of coughing, whereas cats with heart disease usually never cough.
Many people initially blow off the significance of their cat’s coughing spells because they assume they are just “coughing up a hairball.” I have no idea where the term “coughing of a hairball” came from because that is simply not possible. Hairballs come from undigested hair in the stomach; they are never coughed up, they are puked up! Okay, sometimes it can be hard to tell a cat that is puking from a cat that is coughing—but puking cats produce puke, while a coughing cat may crouch down in the puking position, but will cough, just like a smoker, and never produce any vomit (or hairballs).
Cats with chronic allergic bronchitis usually start with just occasional coughing, but over time this coughing becomes more and more frequent until the cats are actually starting to leak some fluid into their lungs and airways from the allergic inflammation.
There are certainly other causes of difficulty breathing in cats, but most cases will fall under the categories of heart disease or lung disease.
Ideally, we would love to get a chest CT scan and an echocardiogram by a board-certified cardiologist. However, the majority of cat owners are not going to take their cat to a specialist for these tests. I don’t think it’s that they don’t love their cats, but it just seems like people generally are a bit more limited in what they will do for their cats vs. their dogs. Sorry cats, but it’s a real thing.
So, the burden of figuring it all out usually comes to us, the general practitioner, trying to get the diagnosis without any of the expensive and referral-only tests.
So here in my oxygen cage is Patches, tons of fluid both in and around her lungs, looking like she wants to die. What to do?
These cases come down to judgment. Based upon the history, I thought that Patches probably had some pretty bad allergic lung disease that had recently just gotten a lot worse. However, I knew that I couldn’t rule out heart failure either as she is an older cat. So I empirically treated for both. We started a healthy dose of steroids to address allergic/inflammatory lung disease and also started her on a diuretic in case she did indeed have heart failure.
Patches worried me sick for about 12 hours, but then she made a pretty stunning recovery. In two days, she was back to breathing normally and eating just fine. Was it the steroids or the heart medication? Five years later, I still don’t know! We experimented with stopping both drugs at separate times, and she really seems to need both or she starts getting worse again. I wish we could get the cardiologist work up, but since she’s been doing so well for the past five years, why the heck would the owners want to drag their stressed-out cat to the specialist? I can’t blame them.
Many times in veterinary medicine, we are struggling to give owners a specific diagnosis. Even if our treatments have made the pet’s illness disappear, we are usually still “guessing” by using our power of deduction and clinical reasoning skills.
Patches is one who I just could never quite figure out, however the fact that she is still alive at the ripe age of 18 tells me we are doing something right.
So, if you ever see your cat coughing a lot, or having difficulty breathing, don’t delay, take him/her to the vet for a checkup. Normally, cats take about 15-25 breaths per minute, but you have to count this while they are sleeping. If they have a respiratory rate within this range, their heart and lungs are probably working just fine. However, if they have a respiratory rate of close to 40 or more, there is likely a problem with their heart or lungs and I would get them checked out asap. Sometimes the answer may elude us, but with some critical thinking, we are usually able to get them better and hopefully give them many more years of good spoiled life.