i just remembered a bit of luck i had with a dog that had atrophy of hind quarters of an increasing nature for several years after surgery. hypericum brought it back to normal function.

you mentioned that the panleuk. occurs in autumn.

might be worth looking therefore amongst the autunmal remedies. in boenn these are
aur3 bry2 chin4 colch3 merc3 nuxv2 rhus5 stram2 verat4