Does this sound like heart failure? An accident occurred last night and one of my free ranging roosters got in the main pen where BJ is the cock. They must have fought. I removed the instigator and inspected BJ and found no injuries, not even on the comb...but he wouldn't stand up. I removed him to a cage for the night and this morning I found him unable to even keep his legs under himself. I've brought him inside and he is too weak to even try to stand. Every once in a while I heard gurgling as he breaths, and he occasionally coughs, but his eyes and nostrils are clear and dry. He was recently treated with Ivermectin and Valbazen, and he was mounting the ladies yesterday, with no signs of weakness or illness.
His sire did die of some wasting disease but it did not come on suddenly like this.