For the most part, an employer is entitled to terminate an employee for any (or no) reason, as long as the employer provides proper notice or pay in lieu of notice (i.e., severance).
However, if an employee’s termination is because of (or influenced by) the person’s disability, the employer may be liable for human rights damages. Discrimination based on disability is prohibited under Ontario’s Human Rights Code.
In certain circumstances, the employer may also be liable for additional monetary damages which can compensate an employee for the emotional harm caused by the “manner” of the termination (i.e., moral damages).
Further, sometimes (though it is relatively rare), an employer can suffer “punitive” damages, which is the court's way of punishing heavy-handed, reprehensible conduct.
You should always consult an employment and long-term disability lawyer if you have been terminated from your employment for any reason, regardless of whether you applied for LTD benefits or were receiving long-term disability benefits around the time of your termination or not. Putting aside possible human rights violations based on disability, many employees are wrongfully terminated by not receiving the notice or pay in lieu of notice they are legally entitled to upon termination.