Now that I look back, he DOES bark only at other big dogs! Today, he kept barking at this big dog and that dog got annoyed so he scared him. Carmel freaked out and started yelping REALLY LOUD like he got hurt. The dog didn't attack him so he couldn't have possibly gotten hurt, he just got scared. Then, he kept barking at that dog. We were so embarrassed...he was so noisy...believe it or not, he rarely barks at home!! He used to never bark too!!
Maybe he IS trying to be alpha over those big dogs.
How can I train him to stop this behavior??