Can a heart problem in my cat be made worse by giving steroids?
Can an undetected heart problem in my cat be made worse by giving steroids?
Symptoms: lethargy and loss of appetite.
Editor's note: If your cat is exhibiting these symptoms, please call your vet and get some guidance.
Steroids are powerful drugs and not without side effects. I have heard of steroid use causing a reaction in cats that have heart problems.
Lethargy and loss of appetite can be some of the symptoms. In some cases, congestive heart failure can result, which needs immediate treatment.
Some cats, sometimes very young cats, have underlying heart problems but show no symptoms.
Other cats don't develop signs of heart problems until later in life. This was the case with my cat, Priscilla, who was diagnosed with hypertrophic cardiomyopathy at age 11.
Since echocardiograms aren't done unless either the cat shows symptoms, or a veterinarian detects a heart murmur (that's how Priscilla was diagnosed with HCM), there's no way to know that anything is wrong beforehand.
See Dr. Vicky Lamb's response to a cat parent with a 1 year old cat with an apparent reaction to a steroid shot.
"The reaction that your cat had to the shot is one we can see in cats that have underlying heart disease. The steroid shot did not cause the disease, it just made it evident to us by the side effects it causes. So, most likely, your cat had a diseased heart already, that was functioning pretty well prior to the shot. The shot then made his heart worse. Most cats will experience lethargy from the steroid shot for 24 hrs. However, if there is difficulty breathing or the lethargy does not resolve, I will start worrying about the heart. There are some cats whose hearts will sound completely normal on examination, but will have a bad reaction to the steroid shot, and there is no way to predict this unfortunately. These cats usually have hypertrophic cardiomyopathy."
Also see Dr. Elyse Kent on whether or not steroid use is dangerous in cats.
"A less common side effect of corticosteroid use is to uncover hidden congestive heart failure (CHF). If heart disease is undetected (occult), especially if a heart murmur is not heard, fluid can rapidly fill up the lungs causing labored breathing and distress after a steroid injection is given. If the patient is promptly seen by a vet on an emergency basis and CHF is diagnosed by a chest x-ray, oxygen therapy and diuretic injections generally cause the fluid to be urinated out and an echocardiogram can be performed to further define the heart condition."