In case this happens to your cat: the cat did not seem in pain, he had a bruised leg. However, vet gave him this injection. The cat came home and sat upright and stared for hours then he was hyper active moving from one place to another looking out the window, sometimes rolling around on the floor as if on a hallucinagenic drug. He did NOT sleep for 68 hours. I know this sounds crazy (we stayed up with him around the clock as we were so worried about him). He did not defecate for 3 1/2 days. He ate pretty normally. He used the litter (urine) twice in 3 1/2 days. The vet didn’t offer feedback. Eyes were largely dilated the whole time. The cat came back to normal 68 hours after the injection (started sleeping, woke up a few hours later). This is a cat that usually sleeps six hours straight twice a day. He is 6 years old and healthy, perfect weight. Just FYI if this happens to your cat. We love this cat so much!