Termination and Top Surgery

so i’m currently in the process of trying to get top surgery, but i’m worried about losing my job because of it.

for reference i live in Ohio and work at a small business with just under 40 employees. i’ve been working at said business for almost 3 years now and i hold a more valuable position than the standard.

i haven’t brought it up with my boss, but they said they want me there to grow with the company.

one of my other employees also had to get a major surgery done, but someone told them that they can’t promise that their position will be there when they get back (although it is a lower level position.

what can i do to make sure that i won’t get fired? the job really means a lot to me. FMLA doesn’t apply since the company is too small.