Sometimes, Benadryl or Melatonin is tried for anxiety...so may be worth a try at some point. Could also look into pheromone anti-anxiety products for dogs (collars, sprays etc). There are also prescription meds too.
Also try putting treats in the bag and praise like crazy if he goes and gets them. Treat him when he goes in the bag.
Otherwise, what about a car seat?
__________________ ~ A friend told me I was delusional. I nearly fell off my unicorn. ~ °¨¨¨°ºOº°¨¨¨° Ann | Pfeiffer | Marcel Verdel Purcell | Wylie | Artie °¨¨¨°ºOº°¨¨¨° |