You can't teach an old dog
There is an English saying that says:
In Japanese, it means:
「老いたる犬に新しい芸を教えることはできない」
This is like the Japan ese saying:
「老い木は曲がらぬ」
But I suggest you try to teach your dog English too! The next time you take your dog for a walk, try using English. Keep that up for a while and see if your dog learns the English phrase:
Let's go for a walk!
I bet your dog can!