Muffy, the thirteen year old Russian Blue cat was laying on the exam table visibly struggling to breathe. Clearly this was a cat in trouble. An x-ray of her chest showed fluid in her lungs, but the source of the problem was not entirely clear. We needed to figure out whether she was having a lung problem like asthma or a heart problem because choosing the wrong treatment would make the other condition worse.
Heart disease is a common problem in both cats and dogs. They can be born with structural abnormalities that cause the heart to wear out over time, or they can acquire problems in which valves cease to function normally or heart muscle undergoes changes that cause it to be unable to pump blood strongly enough to supply blood as needed. With the exception of birds in the parrot family, however, most domestic animals are not susceptible to the artery hardening and plaque buildup that plagues people and causes much of the heart disease and heart attacks seen in the human population.
Symptoms of heart problems in dogs depend on what part of the heart is affected, but often include coughing that tends to be worse when the dog is at rest and which persists for weeks or months, exercise intolerance, fainting, and sometimes fluid filling the abdomen. Cats are much sneakier about their heart disease. They very well may have exercise intolerance, but that can be hard to judge in an animal that spends 23 hours a day in a coma anyway. Occasionally they will develop respiratory distress, but they can look exactly the same if they are having asthma problems too. Unfortunately for many cats the first apparent sign of heart disease is sudden death.
We can often identify the problem by listening to the heart, performing an ECG to look at the electrical activity of the heart, taking x-rays to see if the heart is normally shaped or if it is enlarging due to heart disease, and most definitively by performing an echocardiogram with an ultrasound. Echocardiograms are great for getting to the bottom of the problem, but they require specialized equipment and lots of training to perform, which means that most general practitioners will need to refer those patients to a specialist for that procedure. Some patients, especially cats, with significant heart disease may not have any apparent abnormalities when we listen to their hearts or look at them on x-ray.
Within the past few years a blood test has been developed for cats and dogs that not only identifies the presence of heart disease, but gives an idea of the magnitude of the problem as well. It can be particularly useful to quickly identify the source of the problem in cases like Muffy’s, and it is also an excellent screening tool to use for asymptomatic patients that may be at risk for surprise cardiac complications before an anesthetic procedure, or as part of a routine geriatric screen. If we could catch some of those apparently normal cats and dogs before they suddenly die of hidden heart disease we could start treatment that could extend their lives for years.
The blood test told us that Muffy’s problem was cardiac in nature. We had more strongly suspected asthma, but if we had treated her for that we could have fatally destabilized her already weakened cardiovascular system. Now she is on medication that is helping her heart work more efficiently and things are going well for her.