Buzz
Dog owners often become familiar with aspects of canine and feline anatomy, such as why a dog's paws sometimes smell like popcorn or why cats puff up their tails when stressed. Depending on the breed, a scratch behind the ears may prompt owners to question the purpose of the small pouch some dogs have at the edge of their ear.
This feature is called a cutaneous marginal pouch, or a Henry's pocket, and there are a few theories as to why your dog might have this curious trait.
One possibility is that the pocket aids in hearing. The pouch could help dogs detect higher frequencies by dampening lower ones. In other words, Henry's pocket might assist your dog in reacting when they hear a siren or similar sounds.
The pouch may also enhance a dog's overall hearing experience, possibly opening when the dog adjusts their ears or even blocking certain sounds as they move their ears.
Chihuahuas also possess a Henry's pocket. | Seregraff/iStock via Getty ImagesWith such precise control over their ears, dogs can effectively perform their predator role. Enhanced sound detection helps them locate prey, while the ability to move their ears independently of their body allows them to listen in one direction while heading in another.
Henry’s pocket may also serve a mechanical purpose, allowing dogs to more easily flatten their ears when needed.
The pocket is more prevalent in certain breeds, particularly those with short fur or upright ears. Chihuahuas, Boston terriers, pugs, and corgis are among the dogs that often have them.
Like any skin fold, Henry's pocket can accumulate bacteria and debris, so it’s a good idea to check it occasionally for signs of irritation, ticks, or fleas. While not all dogs have Henry’s pocket, most cats do, likely for similar reasons. This feature can also be found in foxes and bats.
The identity of the first person to discover and name the pocket remains a mystery, though it's believed that the name was given by someone named Henry.
