My understanding is sick leave is used specifically for these purposes. That's why they accumulate sick leave that way, if they have to go out for some type of treatment. If they're away for treatment for a medical condition, sick leave can be advanced if no credits are available, up to 15 days and, if needed, employees can also ask for a payout of annual leave, experiencing financial hardship with being on sick leave without pay.
Robert C. McLeod on Question 45-18(3): Employment Family Assistance Program
In the Legislative Assembly on October 20th, 2017. See this statement in context.
Question 45-18(3): Employment Family Assistance Program
Oral Questions
October 19th, 2017
See context to find out what was said next.