Dog leg

I saw a man walking along with a three legged dog today. The dog was hobbling along in typical three-legged dog fashion. A woman also walking a dog (with four legs) went over to him and pointed to the dog and said something. The man stopped and got the dog to lie down. As I walked past him he was checking the dog's single front paw looking concerned. I wanted to say to him "I don't think that's the leg you should be worried about."

I didn't though, just in case the guy already knew.