Union representation for nurses by nurses is the gold standard, but there are so many places across the US where nurses aren't able to collectively organize in large enough numbers to lead to a nurses-only union. Those nurses determined enough to become unionized will seek out support from other, hopefully strong, unions like the United Auto Workers.
In all ten of Canada's provinces, registered nurses are represented by the provincial nurses' union; LPNs in some provinces are also members, while in others they're represented by the provincial public employees' union. (Under Canada's universal health care system, nurses fall under the heading of public employees along with police, fire, EMS, municipal and others.) In the three northern territories, all health care employees are covered by their public service unions.
Alberta's nurses only recently were given the right to strike after the Supreme Court ruled the province's legislation prohibiting strike action was unconstitutional. But in the absence of a negotiated essential services agreement, the ability to actually go on strike is in limbo. Basically, the employer has all the power in this kind of negotiation; they determine who and how many are "essential" (which usually puts more people on the floor than is the usual baseline number!). When the decision to strike is taken and notice provided to the employer, a "strike schedule" is drawn up and each nurse is expected to work the scheduled shifts. No repercussions ensue for the ones who work their published schedule, but anyone picking up overtime to take advantage of the strike will be censured. The nurses who are working are expected to adhere to only providing "nursing" services - no answering phones, passing trays, transcribing or activating orders, delivering specimens to the lab, picking up blood products, emptying garbage and linen bags, restocking, filing chart copies of labs, or any other task that falls under another non-nursing employee's job description. That's a bit of an eye-opener on most units, when they realize how much nurses do that isn't "nursing work", things we do because they need doing, not because they're OUR jobs.
Canada doesn't have the same level of agency/travel staff relief that the US does, and in the event of a strike, nursing care is provided by the usual personnel. Does patient care suffer? It probably does, to some extent, simply because nurses are only nursing, so trays will be late, specimens might sit, transfusions might be delayed, needed supplies might not be readily available. But if we don't stand up for ourselves and our coworkers, we get what we deserve.