Hey Hansam I had one of those mastiff exceptions
he was a bullmastiff/boxer mix and worked fine, abit slow but I said he was thourough instead, I trusted him more than my fathers spitz because the spitz would go after the closest moose
My mastiff probably saved my and my fathers life when we were tracking a bear that had been hit by a car. we let the spitz go loose and I had the mastiff on a leash, we heard the spitz starting to bay and we start moving up but my mastiff starts to growl and isn't moving, then I see it in the corner of my eye about 20 meters into the woods on the side of the path we were walking.
luckily she wasn't charging, the spitz was treeing one of her cubs