The size and shape of a dog's chest depends on factors such as its breed, gender, age and health. Some dog breeds have larger breasts as adults, but not all breeds do. Female dogs usually have larger breasts than male dogs because their bodies need to prepare for nursing puppies.
However, even female dogs, if they have not been bred or neutered, will not have breasts. Will become fuller during puberty like human females. In short, whether a dog has plump breasts depends on a variety of factors rather than a simple answer. If you have any concerns about your dog's health, please consult your veterinarian.