Our boxer is nearly 9 years old now and suffers from arthritis which would get worse after play as well. She also tends to re-injure an old muscle tear regularly. We took her to the vet when she started having difficulty climbing stairs. The vet recommended Ubavet glucosamine with omega 3 fatty acids. It comes in a liquid that goes on her food. She's been on it for over 2 years now and has shown great improvement. I used to have to help her to stand up and carry her up the stairs. She still gets a little stiff and sore sometimes after some aggressive play but it doesn't last as long and I don't have to help her up or carry her anymore. A bottle at $80 sounds expensive but it lasts about 6 months.
