Horse Veterinary Questions? Ask an Equine Vet.
The shaking is most likely related to him being over at the knee. If he is ridden less now or more lightly it may be that his muscle tone has changed and he can no longer stand straight all of the time since he is over at the knee. It is unlikely that this is causing him any discomfort. Other things to check would be that he is not getting too much protein for his level of work and that his trimming/shoeing has not changed. Hope this helps! Dr. Rik