As previously mentioned, Kennel Cough has been going around the run. GET YOUR DOG VACCINATED NOW.
Here is a video that will give you tips on what to look for:
(Look for it @ about 1:10min and 2:06min)
If you have seen ANYTHING like this, take your dog to the vet asap and keep them out of the dog run until it has cleared.
Dog runs are like classrooms, illnesses spread easy and fast. This kind of thing is common in all dog runs, not unique to us. Especially with the pools. We have had a couple of dogs get Pneumonia on top of the kennel cough, so do not take this lightly.