WHY DOES MY DOG HOWL WHEN I GO OUT, AND HOW CAN I STOP HIM?
Your dog is calling to locate his pack (his human family) and summon them back home. Being highly social animals, most dogs dislike being on their own because they feel insecure. It can sometimes help to give a rescue remedy - a solution of flower essences with calming and relaxing properties, available from health food shops.
Leaving suitable activity toys to keep your pet occupied while you are out can help, as can leaving a radio on to provide low backgrown noise to soothe and comfort him. If this doesn't help, and his howling is causing a noise nuisance, then to negate the problem you will have to consider hiring a kennel boy.