Cats are beautiful and mysterious creatures, and we love that about them. Visit YouTube and you'll find thousands of videos of cats being weird and adorable and well… mysterious. Unfortunately for veterinarians their mysterious nature extends to their ability to hide very serious illnesses from us for a long time, often until they're critically ill.
Heart disease is so very common in cats, and often we don't figure out that anything is amiss until it's quite advanced. Taking great care of your cat starts with being an observant pet parent at home. The first step to detecting that something might be wrong with your cat's heart is knowing what to look for. Read on to learn the most common signs of heart problems in cats.
Difficulty breathing and/or increased respiratory rate
Here are some “doctor words” for you. “Tachypnea” means having an increased respiratory rate. “Dyspnea” means having difficulty breathing. Cats with heart disease can have one or the other or both, and for different reasons. Here's why.
Having a heart problem doesn't necessarily mean that a cat will have symptoms. The most common heart disease cats get is something called hypertrophic cardiomyopathy, which is commonly abbreviated “HCM”. HCM happens for a number of reasons - it can be present from birth, it can be acquired as a result of aging, and it can be secondary to problems in the endocrine system, specifically with the thyroid gland. When a cat has HCM the heart gets bigger and bigger, and the walls of the heart, specifically the left side of the heart, get thicker and thicker. The result is that the interior chambers of the heart, which are supposed to fill with blood before getting pumped out to the body, get smaller and smaller.
It's the secondary effects of having HCM that cause problems for the cat. These secondary effects are called congestive heart failure, or CHF. In cats, congestive heart failure can produce fluid that backs up into the lungs (pulmonary edema) or fluid that occupies the chest cavity itself (pleural effusion). Either problem causes tachypnea and/or dyspnea.
What does a cat with tachypnea look like?
Tachypnea is probably the easiest symptom of early heart failure to look for at home. However, here's the catch: as I suggested above, a cat can have heart disease for a long time before he's symptomatic. So even with heart disease a cat can have a normal heart rate - it's when they go into congestive heart failure that we see the signs, like tachypnea.
Probably the easiest way to determine if a cat has an elevated respiratory rate is to measure sleeping respiratory rate. It should be less than 30 breaths per minute, and probably closer to the low twenties. The process is easy. For 60 seconds, count the number of times your sleeping kitty's abdomen moves outwards for a breath.
What does a cat with dyspnea look like?
Dyspnea can be difficult to recognize, and without knowing what to look for you might miss it. Cats with difficulty breathing can be observed doing something similar to what a dog does when it pants - although a cat never truly pants to cool itself, like a dog does. Open-mouthed breathing in a cat is a sign of respiratory distress, and should be treated as an emergency situation.
Subtler signs of respiratory difficulties include sticking the neck out (called “orthopnea”) and inability to get into a comfortable sleeping position. Cats with respiratory difficulties, especially those with fluid in their chests, will often maintain what's called a sternal posture. This means they'll sit up on their chests, as this keeps the fluid in the bottom of the chest cavity and allows them some room to expand their lungs in the upper chest cavity.
Lethargy or reduced activity
Lethargy in cats is one of those could-be-one-of-a-million-things signs. It's unfortunate that napping is the #1 hobby of most adult cats, especially as they get older, because it's often difficult to tell if a cat is becoming lethargic or just exhibiting normal napping behavior.
If we're really paying close attention, lethargy is probably the very first sign that something is amiss with a cat's cardiac system. That's because as HCM progresses, is makes the left side of the heart thicker, reducing the size of the interior chambers, resulting in less blood being pumped out to the extremities. This makes the cat relatively weak, and less interested in moving around.
You cat has a heart murmur
Clearly most of us aren't listening to our cat's hearts with a stethoscope on a regular basis. But a veterinarian is trained to listen to the heart for abnormalities, and can often pick up on abnormal heart sounds on routine physical examinations. A heart murmur is merely the sound of turbulent blood flow within the heart. Sometimes in cats we can hear a murmur long before there are actual clinical problems.
Unfortunately, some cats with heart disease, especially in the early stages, don't have murmurs. But it's still important to have a veterinarian listen to your cat's heart regularly, because putting all of the information together, including physical exam findings as well as information about what you've observed at home, can help us to diagnose a serious condition before it becomes life-or-death.
Sudden rear limb paralysis and/or pain
Sudden paralysis of one or both back legs is often observed in cats that have heart disease that is so severe it is causing blood clots to travel out from the heart and into the aorta. These clots eventually lodge in the part of the aorta closest to the rear legs, causing severe pain and loss of function. This is an extremely critical problem, and while sometimes we can restore some or all function with blood thinning medications, most of these cats never regain function and are euthanized due to our inability to do so and to control their pain.
The good news is that aortic thromboembolisms are extremely rare when heart disease is in its early stages. If you're watching for respiratory difficulties and increased lethargy, and taking your cat in for regular annual wellness exams, you'll detect heart disease long before it gets to this stage.
Your cat is a Maine Coon or a Ragdoll
Any cat can have heart disease, but Maine Coons and Ragdolls can actually have a genetic mutation that causes it. This is the most devastating form of the disease, as kittens that are affected often start to show signs of the disease as early as one year of age. The prognosis for these cats is bleak, with many only living a few weeks or months after diagnosis.
Reputable breeders will perform testing on their cats to ensure that the mutation that causes HCM isn't present in their breeding lines. If you have one of these cats and aren't sure if it's been tested, or if the breeder tested the parents, talk to your vet about testing your cat for the mutation. The diagnostic laboratory at North Carolina State University performs this test, and you can get more information and request forms at www.ncstatevets.org/genetics/submitdna