My cat is having a hard time breathing, so I took him to the vet hospital. I called out of work, then my boss blows up my phone saying I still have to come in anyway. What do I say?

My cat is in pretty serious condition at the vet hospital, and I have no one to stay with him. My boss said I can leave him there for the day and still come into work. They want me there in 2 hours and to call when I’m on the way in. What can I say so they’ll let me stay with my cat?