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Ask a Vet: What Are the Risks of Steroid Injection in Cats?

Steroids are risky as well as beneficial; giving them to certain cats can cause serious trouble.

Dr. Eric Barchas  |  Mar 29th 2016


A few weeks ago I saw a cat who was having trouble breathing.

Breathing difficulties are the most serious and urgent condition that any vet ever treats. It’s all over after a few minutes without air. It was a busy night, but the cat jumped the line and immediately became my top priority. For the record, if you are at an emergency hospital with your pet, you want to be the one kept waiting. You never want to be the one to jump the line.

In cats (as in all species), stress increases the need for oxygen. Cats who have difficulty breathing are at risk for a catastrophic cycle. They can’t breathe well, so they become stressed. The stress increases their need for oxygen, which in turn can’t be met because of the underlying respiratory problem. That leads to more stress, and more need for oxygen, and so on.

The cat in question was panicked when she got to the office. She did not want to be handled. She was gasping for air. She was on the brink. Any handling of her could push her over the edge. She received a tranquilizing injection and she was placed in an oxygen therapy unit. As her stress level improved her breathing got better, but it was still far from normal.

Photo of Dr. Eric Barchas by Liz Acosta

Photo of Dr. Eric Barchas by Liz Acosta

Some clients whose dog had an ear infection very graciously vacated an exam room so that I could speak with the cat’s owners. An assessment of medical and lifestyle histories often yields insight into cats with breathing difficulties. Outdoor cats might suffer trauma or infections in the chest that can lead to breathing difficulties. Cats with histories of heart murmurs might have heart disease that can lead to congestive heart failure and respiratory distress. Cats who have a history of coughing might have feline asthma, which can progress to severe respiratory distress.

The cat in question lived exclusively indoors. She had been completely healthy, with no concerns except for an occasional skin rash. In fact, she had been to the vet a couple of days earlier because of a rash. She was found to be otherwise healthy at that time.

She went to the vet and she started having trouble breathing a short time later. I began to develop an idea of what was wrong.

I asked the owners whether the cat had received any medications or injections at her previous veterinary visit. I was advised that she had received an antibiotic injection and had been sent home with a steroid cream.

Antibiotics almost never lead to breathing problems. Steroids, on the other hand, can. The steroids in creams, however, usually aren’t well enough absorbed to cause as severe of a crisis as this cat was suffering. I had a hunch. I asked whether, by any chance, the owners had a receipt from the visit two days earlier.

Indeed they did. Like many organized folks, they kept a file of veterinary information for their pet. Cleverly, they had brought the file with them. The receipt listed three items: Exam, Depo-Medrol injection, and hydrocortisone cream.

Deep-Medrol is not an antibiotic. It is a long lasting steroid. And with this information I knew exactly what had happened.

Deep-Medrol is not a muscle building steroid. It is related to cortisone, and it fights inflammation in the body. Most skin rashes involve a significant component of inflammation. Cats generally react well to Depo-Medrol unless it is given repeatedly (which might trigger diabetes). However, one group of cats does not tolerate the medication well at all: cats with weak hearts.

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A cat at the vet by Shutterstock

As I discussed in a recent column, cats with heart problems often have no detectable symptoms or physical-exam abnormalities until a crisis occurs. Depo-Medrol has the potential to precipitate such a crisis. It alters the way that the body stores, uses, and distributes water, and it can trigger heart failure in a cat with a weak heart. Heart failure causes fluid to build up in the lungs. Fluid in the lungs causes respiratory distress.

I asked the technicians to administer a diuretic to the cat. Diuretics cause the body to excrete water in the form of urine. This reduces the heart’s workload and helps fluid clear from the lungs. The cat’s breathing improved to the point that it was deemed safe to take X-rays. The X-rays showed abnormal patches of white throughout the lungs. It was a pattern compatible with heart failure.

Over the next 24 hours the cat received a continuous intravenous infusion of diuretics. Her breathing steadily improved. After 12 hours she no longer required supplemental oxygen. After a day, she was able to go home with oral diuretics.

The incident served as a reminder to me. The steroid injection had not caused the cat’s heart failure. She had a weak heart to begin, and the injection merely pushed her over the edge. But steroids are risky as well as beneficial. They are simultaneously the best and worst medicines ever invented. They should be used judiciously, and only with the full understanding and consent of the cat’s owner.