As your wife is employed, she may be able to claim this expense if her employer does not reimburse her...however the employer needs to complete and sign and then provide to your wife a T2200 (Declaration of Conditions of Employment) form stating that your wife is required to provide that service at her own expense. If your wife does not have this form, then she is unable to make the claim.
http://www.cra-arc.gc.ca/E/pbg/tf/t2200/README.html
