Hello and welcome to Marco Polo.
This jack russel has suffered the common issue of luxating patella for most of his years. But in the last few weeks something has happened and caused it to get worse.
As dogs age maintaining muscle can be difficult. This can be the same in some people. As a result sometimes ailments that have been there for the whole life time, can become worse as they dont have the muscle support anymore.
He is however, in incredible condition. At 12 years old statistically we expect to see some signs of arthritis somewhere. But he has none. Hes Australian so his mum thinks its good genes. His sister who we saw a few months ago also has inpressive joints. No matter what the reason, it is impressive.
So we have set him up with a few home excercises to gain some hind limb muscle. No massage for this patient as we dont want to stretch the muscle supporting the knee.
Good luck Marco Polo and mum.