Does my wife have a case against her employer?

My wife was in the hospital all of last week, She had a doctors note to return on Saturday the 29th. But when she arrived to work, her supervisor said his boss was "not going to tolerate her being out all week". Then finds out that they had taken her off the schedule for all of next week. Her job is open every day and she usually only gets 1 day off a week, now they are acting like they want to terminate her employment. Is that legal? does she have a case?