Personally, I prefer to travel with mine in a sturdy travel bag. I use a sturdi-bag belted into the car for safety.
If you had an accident and were unconscious and the dog was scared or hurt, you have no idea how they would react, they might get very snappy. If a policeman, emergency worker, or anyone can easily lift them out of the car bag and all, you have the best chance of them getting to a place of safety.
__________________
 Armani & Chloe |