I have a dog who had torn his front knee ligament. Currently he is not limping anymore. But you can see he is not always putting full pressure on the leg. He also has practically no muscles on that leg left. I took him in to the vet for control 2 months after the injury occurred, we made a photo and there was no osteoarthritis? so he made the conclusion it had not been completely torn and with some luck and if i kept walking him he would be ok again. We also gave him some nandrelone to support. The problem is he is so intense, and when he sees another animal that he is only making things worse.

Its a valuable dog for me and as a matter of fact he's hooked for autumn. I would hate to put him into retirement, i dont even have space for brood dogs.

So right now im over thinking my options to try to recover him.

1 option i think of is to put an electric mill in my house. When he trots at a certain pace he makes good use of both of his legs. When i walk him outside it goes to slow and he will not always use/bend his left knee.

Another option is to place a water tank in my shed. there is no possibility to put it outside since i live in an urban area where 20 different people could look in my yard. The problem is, my door opening is 89x 180.

I have found 2 tanks. 1 is 140cm x100 cm x 80cm(deep) the other is 1,20x80x100(deep)
I have no experience trying to let a dog swim in a tank, the first thing i would like to know is what are the minimum measurements it should have for a 46lbs dog?

If these are not long or deep enough does anyone have a plan for building one easy?
I think the first is not long enough and i don't know if 80 cm is deep enough so he cant touch the ground.

Any other options on the problem for my dog are very welcome.