I'd think purebred beagle based on looks, but 15 pounds at 3 months? Is pretty big for a beagle pup. Beagles usually top out at about 25-30 lbs and 13 or 15 inches tall at the shoulder. There's also something subtly... not-beagle in that adorable faceHe is adorable! If I didn't know any better ... I would think he was a purebred Beagle. I am not very familiar with Beagles though!