After suddenly losing our previous dog (adopted as a 4 mo old pup) at 4 years old (septic shock), we adopted a rescue (about 1½ yo now) from the Dominican Repub

After suddenly losing our previous dog (adopted as a 4 mo old pup) at 4 years old (septic shock), we adopted a rescue (about 1½ yo now) from the Dominican Republic. After several months of trying to calm him with the various ways we know through decades of rescue dog ownership and multiple training sessions with different dogs, we currently have him on prozac. He arrived in Canada on a flight with ~90 other rescue animals and went to a foster house that already had 3 other dogs (one of whom passed not long after his arrival, AIUI). We do not want him to be on prozac long-term. But our vet has suggested that if he learns what it is to be calm, we should eventually wean him off and he should be in a better place as he understands that this house is safe for him. The behaviours we worry about are not the barking, but the shaking in terror. We know he will always be a somewhat more nervous dog than the last one (the last one was a 90 pound king shepherd cross; this one is a 23 pound terrier mix known as a potcake or coconut hound). But he’ll get there.