St. Equis Hospital first appeared in the Pilot episode, where Beth and Davin were seen performing surgery on a horse with the aide of Tom, who was reading the horse's heart rate. Jerry came into the ER, interrupting them while they were working, to try and convince Beth to put Rick in a nursing home. Beth argued with Jerry while working on the horse, and that caused the horse to get close to dying a couple of times. Every time the horse began flat-lining, Tom would inform them about it, which eventually drove Beth mad. Later in the episode, Beth was seen in her office, arguing with Jerry again. Davin then came in and started to talk to Beth about how passionate it was that they saved that horse's life together.In the episode Rick Potion #9, Beth had to go to the hospital because there was a seven horse collision and so she had to work with Davin. When Jerry heard that Davin was going to be there, he became extremely jealous and drove over there. After the surgery, Davin took Beth into his office with her. When he did, he turned out the lights and lit some candles, attempting to seduce and have sex with her, revealing that he truly does have feelings for Beth and also proving Jerry right. However, before Davin could go deep into his love for beth, the love potion and mantis DNA had spread through the air vents and infected him, causing him to start changing his sexual feelings and begin having lust for Morty. He then started to chase Beth around the room like a crazed rapist, only talking about Morty. Jerry then busted in and beat Davin to death with a crowbar. The events of this episode were then undone as Rick and Morty traveled to a different dimension, where Rick had found a cure for the cronenberg virus, meaning that things must have happened a little differently, undoing all of these events.
In the episode A Rickle in Time, Beth nursed a deer back to health in another Animal Hospital, claiming that she is a certified horse heart surgeon. Although the real St. Equis Hospital was not seen or directly mentioned, Beth's employment and experience with the hopsital had major significance in this episode.
- It is a running gag in the series for Jerry to criticize Beth for being a horse heart surgeon, using the argument that a horse heart surgeon is not a real surgeon.