All dogs are good dogs, but not all dogs are well-trained pets. There are dogs that bark when the doorbell rings. Dogs that pull while on walks. Dogs that chase the family cat. Some pet owners chalk up their pets’ behavior to mere doggy antics, but sometimes bad behavior requires professional help.

Take Ginger, a rescue puppy that would poop when someone picked her up. When strangers came near, she’d hide under the porch or tremble. This was how she expressed her fear of the world around her — a fear that made training her difficult, said Kim Kavin, Ginger’s owner and author of “The Dog Merchants: Inside the Big Business of Breeders, Pet Stores, and Rescuers.” At a loss, Ms. Kavin sought the help of a dog trainer (well, five different trainers) when Ginger turned 1 year old.

“It was trial and error,” Ms. Kavin said, who also noted that methodologies vary among professionals. “You need to find someone willing to work with you. We had to adapt to Ginger’s peculiarities, which not a lot of trainers will allow you to do.”

Dog trainers can be helpful for dogs of different ages with different issues, from fear to aggression to problems mastering basic commands. And hiring one shouldn’t be considered a reflection of an owner’s failure. Sassafras Lowrey, a certified trick dog instructor, said, “Working with a trainer isn’t a sign that something went wrong or that someone is failing at properly managing their dog. Rather, it’s a sign that you deeply love and value your dog and want to have a better relationship.”