can you tell me why my 8 year old red cocker spaniel is fighting with my new gsd cross of 1 year old.my cocker used to live with my other large dog until he died 2 and a half years ago.
They do not fight until my little one gets verbal, if he doesn't growl the big one is perfectly happy and just wants to play

My partner's mum has a german shepherd dog (in her senior years now, but still top dog!) who had lived happily with a little german spitz. When a younger German Shepherd puppy was introduced, the older GSD took it fine (generally by ignoring it), and would occasionally snap at the puppy as a reprimand (nothing aggressive, but what you would expect from a parent!) When the younger GSD got older however, and they started to play, playtime could quickly degenerate into actual fighting, which was extremely frightening to witness. Play would be fine until the younger dog overstepped the mark by growling aggressively, and then the older GSD would defend her superiority. This only went on for a brief period, perhaps a few weeks, and we quickly worked out the pattern which ked to this (usually going into the sandschool where the horses trained, for some reason triggered this behaviour of play beginning in a nice way and then becoming nasty and serious). Now they play together just fine, and have never shown any aggression towards each other since. I think the fighting in this case was the older dog guarding her status and making sure the younger knew not to challenge her. I am only a novice when it comes to dogs, and use this site to learn as much as I can, but perhaps your older dog is just establishing himself (and his status) with what to him is a 'newcomer'. In our case, we noticed the pattern that triggered the behaviour, and stopped that pattern, which may or may not have helped to calm everything down, but I would suggest (as in our case) to try and control their playtime a little better until things sort themselves out.

How long have you had the new dog? It could well be that, although he was perfect friends with his old pal, the spaniel resents the presence of this interloper on 'his' space.