Being Ethical

In today's society ethics can mean many things. It really depends on what country you are in. Here in the U.S., basically put someone in jail for stealing. In Iran they cut off your dominant hand and make you eat, write, and worse off use the bathroom with your undominant hand which is messy. I tried it once and peeed all over the wall. But back to the subject matter here. My question is when is it ethical to put down your dog? For about 2 weeks now, Buck (my retarded bloodhound) has had a limp in his front leg. When he stands for a while he picks his paw up in the air. I checked his leg and tugged around on it and he never hollered so I figured it might be in his paw. His pulled away when I touched his paw but didn't see any visual wounds. Could be a cut, I'm not sure. I'm not positive but I may have to put him down soon. I'm not much on watching animals suffer. At the cabin this past year, when those two nasty dogs came up with the mange, lice, hepatitis B, HIV, and whatever else they had, I would have put thim down had Derek and Noel not fell in love with them. Those dogs were 3 feet from deaths door probably ready for the misery to end when Noel gave them a false hope that someone was about to take them to a new home where they would bowls and bowls of Pedigree and visit PetSmart every weekend. Only to find out that death was teasing them. Had it been me and Smith and Wesson, there would have been no deception. Back to Buck. At what point does Buck's leg warrant Dr. Kevorkian type initiative? Is it when he never puts any weight on the leg at all and hobbles around or is when he can't walk at all? These are questions that we animal lovers have to answer sometimes. But is there another option? Would it be better for me to cut a custom 2 by 4 board in the shape of a leg and duct take his injured leg to it? I could even paint it dark brown and put sand paper on the bottom of it for traction. Then I could screw a bracket to it to hold his leash. For now, we'll give it a few more days and observe his motorization skills and go from there. If anyone has any suggestions please post them below.

PS- A vet is out of the question, unless you are paying.