English Mastiff Swollen Elbow
I just noticed yesterday that my mastiff has the exact same swelling on his front left leg, and started search online today to see if there was anything posted for it. I've seen hot compresses, and that's about all. My dog's leg looks exactly as your photo. It doesn't hurt him--I've massaged and pressed it, and it doesn't bother him, but it feels as if there's fluid on it. I thought it may have been a wasp bite or insect bite, but I know he flops down on the floor all the time.