Rat Terrier and Arthritis

Okay, so me and my family adopted a dog.. about 12 years ago when he was less than a year old. So as you know, he is a pretty old dog. All he ever does is sleep and when he is up you can hear his bones popping a lot and you can tell that he is uncomfortable when he walks. We’ve had dogs that had arthritis before, but this is probably the worse we have seen. It gets worse when the weather is cold or rainy. In my opinion, I would just rather get him euthanized so he doesn’t have to be in pain, but my mom and sister want to continue to give him medication which really doesn’t help. He has gotten to be a really grumpy dog from the friendly dog he used to be. If you bother him he growls at you, he can barely walk, and he doesn’t want to get up and eat really anymore, unless it’s a good day for him. What is everyone else’s opinions? I hate to see the dog suffer, but my mom and sister want to keep him around regardless.

I’m not trying to sound like I’m a mean pet owner or anything, but I think it’s the right thing to do since he can barely walk without hurting.