Yeah , it’s shows your love & concern towards those pretty poor faces ( stray dogs) , if it’s unable to touch the ground with the foot at least for once, it should be taken to near by veterinary doctor they will rule out the cause , as it’s stray dog some one might have thrown an stick or some object on it . Some times it becomes normal after couple of days but if it’s still been the same even after couple of days it must be taken to a near by veterinary doctor.
Next Steps
Wait for one or two days to see its doing better or not & if the condition is being the same they should visit the near by veterinary hospital
Health Tips
Be cautious as it’s stray dog