Hello. I have a 10 year old Brittney Spaniel and within the last couple of days i've noticed that when he gets up from lying or sitting he will not put any weight on his left hind leg. Now once he has been up for a while he runs and jumps on it with no problem, but I mostly notice the trouble early in the morning and in the evening time. While he is outside during the day he's fine. Could it be arthritis or has he pulled a muscle? I have an appointment with the vet in 1 week. He still has a healthy appetite though. We live in Chicago and the temperature has dropped, so could the cooler weather affect it. Thank you for your time.

