Dogs and Storms and Fireworks

Question
I have an eight year old gold shih-tzu.  He is realatively healthy and
weighs about 22 lbs. We got him when he was almost 3 years old and
discovered at that time that he had separation anxiety.  Since then he has
been very good staying at home by himself.  We can leave him up to 10
hours or so and he's ok.  That is up until now.  Storms and fireworks
never did bother him.  He never showed any reaction to them.  A few days
ago someone in the apt. bldg. set off one really loud firecracker.  He
shivered so bad I thought he was going to collapse.  He got over tht and
then we had to go to the doctors and had to leave him alone for about 2
hours.  When we got back he was a mess.  Raight back to where he was 5
years ago.  This weekend is our (Canadian) holiday weekend with firworks
all around and he's been really bad.  What happened?? Why now it's
bothering him?? We have no idea.  He's been fine for 5 years and then a
big drastic change.  

Answer
Hi Jaissa!  I just have to tell you, I have a little 2 year old Shih Tzu.  Aren't they just the cutest?  I just love my little Charlie to pieces!
As a dog ages, they do pick up certain behaviors.  This may be what is going on with your little guy.  Since this weekend, with the holiday, will be very stressful to him, you may want to take him to your veterinarian for a medication called Acepromazine (I am from the US...not sure what it may be called in Canada, as the names of medications change with different vendors).  Acepromazine is a very mild sedative that will work as a calming agent.  I have always found this to work with stressed animals.  It is an extremely slight sedative so it causes no harm; it will just make him a little more calm so he won't panic with the fireworks.
I hope this helps!
Please give that "smooshie face" (as I lovingly refer to them as) tons of kisses for me!
Hilary