Thanks for all the help. The doggy day care did divide them into 2 very large groups based on size. I'm not exactly sure what education the staff received...I admit I didn't do my research. I was a little shocked when told they spray citronella at the dogs when they misbehave (although they didn't say what they defined as misbehaving). Is this common? I saw a dog get sprayed for barking. I will say that Barkley did come home with yellow stains on his white fur. He is doing better today. Pretty sure he won't stay there in the future.
I've never heard of spraying citronella at a dog for misbehaving, and at the kennel where I worked no dog would be reprimanded for simple barking.
At the kennel where I worked, everything was run like a Swiss watch. The managers were so particular that we took absolute 100% care in everything that was done. We "lodging attendants" weren't even allowed to FEED the dogs without proper training. We were trained to clean and do laundry and dishes the first day, and that's what we did until we completed our six week training course. We had to be trained before we could feed, before we could even TOUCH a dog, and we certainly weren't allowed to run day care groups at first. The training we received was so extensive that it seemed ridiculous, but you know what, we very very very rarely had fights. Our play groups were initially divided up by size and temperament. Each dog that came into daycare had an index card with a list of dogs he or she got along with. This was used only as a starting point, and we were trained to treat each group of dogs as though they had never met before. They had to be introduced on leash, one at a time, and could only be allowed off-leash once they demonstrated proper body language such as play-bowing. Additionally, once the dogs were playing, the group was not allowed to be out of our sight.
Our group size limit was 5 dogs, although they rarely got that big. Typically the groups were 2-4 dogs in size. Occasionally, we had to have dogs play by themselves. These were usually the dogs that the owners had been told repeatedly that their dogs caused problems, but they continued to bring them anyway. And YES, by all means we told owners that their dogs caused problems. We would put it politely, but when we took the dog up to the owner at the end of the day we had to give them a "report" of how they did, who they played with, etc. A bad report would go something like, "Well, Toby didn't have such a good day today. We tried him with Scruffy, Fluffy, and Spot and he didn't get along with any of them. When we introduced him to the last dog, Spot, he tried to bite her, so he immediately had a time out and then he had to play by himself the rest of the day." A lot of times it was just a dog having a bad day, but we did once or twice tell somebody they weren't welcome to bring their dog back, but those were cases where we couldn't even put the dog out by itself because it tried to bite US.
As for how we broke up fights, we never really HAD to because of the care we took. If the dogs were going to cause problems together, 98% of the time it showed up in their behavior when being introduced and they were never allowed to play together in the first place. If dogs did start to get sick of each other while they were playing, they could be immediately separated because they were all under direct supervision at all times and the early signs could be caught right away. If things started to get out of hand and they started to play too rough, a sharp "HEY!" or "AH-AH!" was usually all it took to break it up. I never had to break up an all-out brawl because things were never allowed to escalate to that point.
If I were you, the next time you take that dog to a kennel where there are play groups involved, ask them about the training the employees receive and what precautions are taken to make sure no dogs are picked on. Find out how they establish play groups (we discussed this with owners when we took them on tours of the facility), and what they do to break up fights if they do occur. If something sounds fishy to you, or just not right, it's probably not. Go with your gut.