Dogs often hide all but sudden or acute pain, such as right when an injury occurs and then after that will do their very best to mask their pain. In the wild, an obviously injured or hurting(weakened) dog can become the object of an attack so they do their best to hide such a condition.
__________________  Jeanie and Tibbe One must do the best one can. You may get some marks for a very imperfect answer: you will certainly get none for leaving the question alone. C. S. Lewis |