I adopted a 14 year old dog today, small cute 15 pound lil thing, and I have two dogs at home: Ozzy the 85 pound Golden and Felix the 30 pound terrier. They were all hanging out fine until I have the new lad, Frank, a toy. He became so possessive and weird, and wouldn't let me pick him up. I could tell my other dogs were scared. Did I do something wrong? Can I fix it? Or is this normal? Or should I give the dog back?