I'd agree a lot of competitive fighting dogs are basically of the veantre type- bks, tosas, presas, perhaps even ovcharkas to a degree, so it is obviously a rather effective type for dog/dog combat. 

I'm currently reading - researches into the history of british dogs (from ancient laws, charters and historical records) from 1866 (and containing much older passages), which I have read parts of here and there but I'm just now noticing something I haven't before. And that is the people who were employed to walk dogs on lead were called "veltrars" "vaultres" "veatrers", pretty much anything along those lines (such was the nature of very early english- very inconsistent and random) and I think this is really the last clue I need to suggest the alaunt veantre was a lead in bandog type, named after this very fact.  

The book also distinctly mentions multiple times that ALL alaunts are hunting hounds, and specifically strong hunting hounds used to hold game. The veantre MAY have been influenced by shepherd's mastiffs for size, but the 3 alaunt types were definitely not sheep guarding dogs, or guard dogs of any kind. Definitely dogs of the hunt and definitely western european/medieval, rather than ancient caucasian or persian or whatever.