Employee absences are tough for any company in which each person's role is essential to operations. The reason for the absence doesn't matter; you're going to be short a key player. The easy response is to hire a temporary employee, but there's a better way to deal with the situation: Use the challenge to strengthen your culture.
Let's say one of your employees is taking maternity leave. Maybe she'd prefer to work from home for part of that time or after her leave is over. Whenever one of our expectant mothers at CitiStorage wanted one or both of those options, we bent over backward to accommodate her. The message was clear: You're important, and we care about you.
Regardless of the reason for the absence, we respond the same way. We meet with the other employees, explain the situation, and note that the person's absence will temporarily mean some extra work for everybody. We say, "We'll need you to put in some overtime. Some of you may have to learn new skills. We can train you. But these things happen, and we just have to adjust. Next time, it will be someone else. We'll pull together for you when that time comes."
In other words, we'd use the problem of being short-handed to generate esprit de corps and to show that we were looking out for everybody--not only the absent employees but also those who'd be covering for them. The overtime, after all, was a way to put more money in their pockets, and most of them welcomed the chance to broaden their skills with extra training.
Thorough preparation for employee absences is important, but remember that they offer a chance to implement a key rule of business: Never miss an opportunity to turn a negative into a positive.