Medical procedure in canada and visitor visa

Hi all,
I would love your advice on the issue of applying for a visitor visa for Canada to undergo a medical procedure. My father is in need of an important hernia surgery and he has arranged for the surgery to be performed at the Shouldice Hospital in Ontario - one of the best hospitals for this kind of surgery. This is an out of pocket expense and the Canadian social service system will not be burdened in any way. He is now applying for a visitor's visa to Canada in order to get the surgery and I got worried that he may be denied the visa if we tell the embassy that the main reason for his entering the country is a medical procedure. Does anyone have any experience with this kind of visa situation?

Another question is how long does it usually take to get the visa if he applies in person in the NY office? Is it likely that he would get the visa within the next few days? Any experience with wait times would be much appreciated as we are trying to decide to how proceed.

Thanks!