Hunting with dogs, whether its lamping, earthwork or hunting pigs all carry some risk I would think the only danger your bullmastiff would be in from bowling over a leonberger would be collision injury from such a large useless lump
It's a good point, Lamping, earthwork etc. has been done for years in this country so you don't notice the risks as much. I think it's the unknown factor of boar hunting that gets you nevous!
And it's more bulldozer than Bullmastiff! ran straight into in head first, knocked it over then scruffed it, their best mates now, go walking together most weekends