I'm sorry to hear that!! It is very tough at times to try and restrict their activity.
When I took Riley for his 1-year exam the vet told me he had a little bit of LP in both legs.... He said not to downplay it but that it is fairly common in small breeds and that a lot of them get along just fine without having to have anything done. I told him that I had never seen him limping or anything.... He didn't say what Grade and I didn't know enough then to ask.... but when we go for his check-up, this year I will be sure to have him check him out a little more.
Hoping that perhaps a little Cosequin and some TLC is all that Cooper will need!!