KEENE, N.H. (MyKeeneNow) Professional dog trainer Denise Mazzola tackled everything from aggressive dog behavior to puppy training and hot weather pet safety during Tuesday’s edition of Ask the Trainer on WKBK’s Good Morning with Dan Mitchell. Mazzola said dogs that bark or nip at guests often become overstimulated when people enter the home. Mazzola identified the behavior as resource guarding and said repeated bites during a single incident should be taken very seriously. The program also addressed puppy mouthing, with Mazzola explaining that young dogs naturally use their mouths while learning bite inhibition. Before taking listener calls, Mazzola and Mitchell also discussed the challenges of exercising dogs during extreme summer heat, drawing on her recent trip to the Phoenix area.