i have 3 dogs 2 sister mastiffs and a spaniel they to get on very well but ive learnt that female dogs like to be dominant and will become very agressive over food , i to had a fight brake out with the 2 sisters which thankful was stopped but it couldve been very bad even though 1 needed vet treatment , i now feed them separate there never close and a gate is between them ,ive also got them use to a strict rule now noone touches anyone elses bowl , this has worked wonders