Use Caution when Prescribing Entyce (capromorelin oral solution) for Feline Use

Our cat, Tabatha, should be quite familiar to those reading this blog. Tabatha has been part of our family for nearly 16 years and, as such, she has grown quite attached to us. Because she’s elderly and seems more comfortable with us than with a pet sitter, we decided to take her with us on a lengthy car trip over spring break this past March. This was a bit of an experiment because, prior to this, Tabatha had typically been in the car only to and from the vet. This would be, by far, the longest car trip she had ever taken.

Tabatha seemed to be doing well on the trip and seemed to be relaxed and happy. However, much to our alarm, halfway through our road trip Tabatha suddenly stopped eating. All attempts to bribe her with various foods failed. After she had fasted for 36 hours we became quite concerned. (Cats do not tolerate periods of fasting very well. It’s very easy for cats who have not eaten to suffer from a potentially fatal condition known as feline hepatic lipdosis, which is caused when the liver’s function is compromised by a buildup of fat cells.)

Alarmed by her continued fasting, we sought help from an emergency vet clinic that we found on our route. The wonderful folks at the clinic ran a bunch of tests and decided that Tabatha had stopped eating due to stress from the road trip. Because we had another day’s travel, we had to do something to compel Tabatha to eat. The veterinarian suggested that we try treating Tabatha with a relatively new medication, Entyce (capromorelin oral solution). Entyce is a medication that has been FDA approved only for use in stimulating appetite in dogs, typically for dogs whose appetite has been suppressed by other therapies, such as chemotherapy. Entyce stimulates appetite by binding to certain receptors in the brain. The veterinarian’s thinking was that prescribing Entyce for Tabatha might effectively stimulate her appetite as it does in dogs. (While Entyce has been approved only for use in dogs, it’s not uncommon for medications to be prescribed “off label,” for various other uses. This is true for human medications, as well.)

The Entyce worked like a charm. Within hours Tabatha was eating like a lumberjack. We gave her one dose a day for three days, just as prescribed. The rest of the vacation was uneventful, even the long drive home. We were very relieved that Tabatha tolerated the trip home and we figured that her stress on the outbound trip was solely because she hadn’t traveled that far before.

Fast forward five months and it was time for another road trip. This time just as long, but in an entirely different direction. Because Tabatha had done so well on the return trip during spring break, we decided to take her with us again. We explained her history to our local vet and obtained another prescription for Entyce to take with us, just in case she stopped eating again.

As it turns out, Tabatha did stop eating again, just as we reached our destination. Fortunately, we had the Entyce with us and we gave her the first daily dose, shortly after dinnertime. We were relieved to see her eat some dinner a few hours later.

The following morning we didn’t see Tabatha up and around so we went searching for her to offer her breakfast. To our horror, we found her on her side, under a bed, staring unblinkingly as she lay motionless. We picked her up and examined her and she was completely limp. She was alive but it appeared that she had suffered a massive stroke and was completely unaware of her surroundings. We quickly got online, found the nearest emergency vet, and whisked her there. Their initial diagnosis was that she had suffered a massive stroke. The only way to be sure, they said, was to perform an MRI. The challenge, however, was that a cat of Tabatha’s age (especially one with a heart murmur, which Tabatha had developed in recent years) needed full cardiac workup before they would feel comfortable administering the general anesthesia necessary to perform an MRI on a cat. The cardiac workup, including an EKG and consult from the cardiologist, took a few hours, with us agonizing all the while over Tabatha’s unresponsive form.

By late morning, it appeared that Tabatha was a little more responsive. She was raising her head and seemed to recognize us. One possible explanation, the vet said, was that she was stabilizing a bit after her stroke. As we continued to wait or the report from the cardiologist we noticed that Tabatha continued to improve. By early afternoon she was attempting to stand.

At this point, because she was showing steady improvement, we decided to watch her overnight instead of subjecting her to the risk of the general anesthesia and the MRI. We decided to take her home to watch her so that she wasn’t in an unfamiliar place all night. We told ourselves that if she took a turn for the worse we could zoom back to the emergency vet.

To our incredible amazement, by early evening Tabatha was 90% better and the following morning she was perfectly fine.

This was no stroke. Nobody, human or animal, is perfectly fine 24 hours after a massive stroke. This had to be something else. But what?

We think it was the Entyce.

Even though Tabatha tolerated Entyce perfectly in March, we think that this time Entyce caused a reaction that mimicked a stroke.

Remember, this is a medication that was created for dogs and has been officially approved only for dogs, so there’s not much history with the off label use of Entyce with cats.

I researched the issue and only found one other person who reported this same result; however, based upon her comments, it appears that neither she nor her vet made the connection between the Entyce and the stroke-like result.

I offer this story as a caution against the off-label use of Entyce in cats. Entyce may work wonders in dogs that need their appetite stimulated, but it doesn’t appear to be suited for use in felines.