For funzies I did a little digging. It seems that in the wild encounters between polars and grizzlies arent that uncommon. From what's been observed polsrs are more likely to walk away from a fight and cede prey or territory to a grizzly. Some scientists seem to think though that that may be due to where the overlaps in turf take place. It's more likely that a pillar may find itself further forth than it's ideal climate/habitat than a grizzly wandering too far into the frozen north. When observed actually fighting the polars trend to get the upper hand... after all they are bigger and stronger. So the short answer is if your pet polar decided to help you you probably are ok.