Recently, my 5yr old Bichoon has become anxious. While walking in our park, we heard gun shots of someone behind the park who killed a snake. Now, every loud noise bothers him to the point of where he is struggling to run & makes himself sick pulling on the leash. This is our favorite walking trail & now he doesn't want to walk there. He remembers. If I can get him around the trail - he wants to run the last 300-400 yards of it. It is almost as if he were having a panic attack. Other noises now seem to bother him. Car door, workers with hammers, etc. I don't know how to handle. The park has always been his happy place...but no more. It makes me sad. Any advice would be appreciated.
This question hits very close to home, and I wish I had a simple answer. I have a 5 year old dog that has reacted like this since very young puppyhood. I have tried desensitization recording and counter-conditioning, and these might be the simplest things to start with. But it sounds like your dog might be like mine: he will have no interest in treats when you get to a frightening situation, and so counter-conditioning doesn't help. When a dog panics, the thinking part of their brain shuts down, and so he cannot learn or reason during that time.
I very recently took my dog to a veterinarian who is a behavioral specialist. I decided to answer this question because of one advice she stressed: You need to manage the situations as best as you can because each incident damages neurons. We have started my dog on some prescription medications that are designed to reduce the panic response and allow her to think when confronted with something frightening. After we get the dosages right, we will be working on coping skills and counter-conditioning. But it looks to be a long road ahead, with slow improvements. (I was reluctant to start prescription meds because I didn't want a doped-out zombie dog. So far I don't see any change to her personality, so that fear was unwarranted).
So my advice is to not force your dog into fearful situations (my dog is the same as yours with remembering bad experiences, BTW; we have had to abandon some walking routes because she remembers bad experiences on them). Try counter-conditioning: Go to a point along that route that approaches where the dog becomes frightened but is before where he gets anxious, and then feed lots of treats, play with a toy, etc. -- you want to create a positive experience with that place. After a short time, turn around and go back the way you came, avoiding the frightening place. Very slowly (over the course of days or weeks) move farther along the route, feeding at new places. You can do the same with sound: get a recording of something that is frightening, and play it at a barely perceptible volume while treating. Slowly (days and weeks) increase the volume.
If you find that you cannot make progress moving along the route or increasing volume, then seek professional help. Here is a place for more information on fear in dogs: http://www.patriciamcconnell.com/fear (Dr. McConnell is an animal behavioral specialist). Finally, if you want to try drugs, check with your veterinarian. I started there, but my general practice vet was not comfortable in combining drugs because she did not have the expertise. So I sought out a veterinarian who specializes in behavior.