Some breeds have a propensity to suck or chew on blankets, but the behavior is thought to be associated with the dog’s experience as a puppy. Puppies are born with an instinct to nurse at mother.
As you relax on the couch with your pooch, you notice he seems quite focused on his favorite toy. In fact, he seems to be sucking on it. This otherwise puppy-like behavior doesn't necessarily signal any problems with your pup, unless it becomes overly obsessive.
Dogs That Refuse to Give Up Suckling by Rob Harris. or a favorite toy. Some dogs start sucking on themselves, often their sides near their hind legs, called their flanks. Why They Suckle. Several schools of thought regard why adult dogs suck on items or their flanks. Some scientists believe the behavior occurs in puppies who were weaned.
Object Sucking In Dogs. The image of a human infant clutching their comforter and sucking their thumb is a familiar one. Blanket, bed or toy sucking in canines seems to be the doggy equivalent, and the behaviour seems to occur at a time when they are getting ready to sleep as in human infants.