Dog1 gets very worked up when Dog2 runs. Help!

[StupidTuftyTailedFucknut]

In July I adopted a second dog. Dog1 and Dog2 are different breeds but a similar size and age and do get on very well the majority of the time. There have been no fights or agression or anything like that in the house.

They are walked 3 times a day, 2 together and 1 separate. They get on perfectly fine if they are both on the lead or if Dog1 is off and Dog2 is on. If I let Dog2 off and he starts running Dog1 goes absolutely bonkers. Snarling, barking, snapping and just working himself in to a frenzy, even when he's on the lead and being distracted with treats, toys etc. It's awful and terrifying for both Dog2 and me. Obviously now I only let Dog2 off when he is alone but I want to work through this issue. It's unfair that Dog2 should often be on the lead when he is not the problem.

Dog1 happily runs around with other dogs with no issues and always has. When introductions were made between Dog1 and Dog2 originally they played really well together several times.

I'm waiting to hear back from a dog trainer but was wondering if anyone had any advice in the mean time?

[Shriek]

i sometimes get this issue when working one ddog and another getting very excited wanting to do that work.

I do less exciting things instead whilst one on lead, and take it in turns so that they get to realise its simply not their turn and that all the noise doesnt make any difffierence nothing will havppen till its their turn and then reward for waiting quietly. you might need two of you to do this as it can be tricky depending what activity you choose. like one off and one on-lead in the house/garden, before taking it totally outdoors on a larger /faster scale.

[RaveclawZia13]

Some dogs have dog aggression when they are on the lead as they can't display the appropriate body language. If you can have someone walking them with you one can be with the second dog whilst you work on training with the first.