What Physiology Lets Dogs Growl?by Betty Lewis
Though your pup's voice works similarly to yours, he can't speak. He can bark, whine and growl, however, thanks to his larynx. If you pay attention to when and how he growls, you'll get the gist of what he's saying. He may growl for help, out of fear or because he's frisky.
Larynx: Gatekeeper for Sound and Air
Buddy's growl -- and his bark and whine -- come from his larynx, more commonly known as the voice box. The larynx is at the top of his throat, in front of the trachea and esophagus. It's made of cartilage and soft tissue and has an oblong opening in the middle. The organ's muscles contract and relax to open and close the larynx, depending on whether your pup needs to breathe or swallow.
Anatomy of a Growl
When it's supper time and Buddy's enjoying his dinner, his larynx closes to allow his food and water to pass through his esophagus to his stomach, bypassing his lungs. If he's breathing, his larynx opens to allow air to pass through his trachea to his lungs. Because it's his voice box, it houses his vocal cords, which vibrate when they're stimulated by air. Just as you learned how to control what sound you make with your voice -- for example, how to speak or how to hum -- Buddy learned how to control his larynx to produce different sounds.
Growling for a Purpose
You can hear Buddy's bark or howl over a distance, but a growl is different; it's low and meant for close range. It's more intimate than a bark. A dog may growl for a very benign reason: he may want a potty break or be waiting for dinner. In other instances, such as if he's feeling fearful, a growl may serve as a warning, telling the object of his attention to back off. Buddy may growl if he's guarding his supper or favorite toy, or if he feels home is being threatened. You may catch him growling during play, a common response when a dog plays chase or tug of war.
Sometimes a dog's larynx will close when it should be open, resulting in difficulty breathing. Known as laryngeal paralysis, this condition can be caused by genetics for some breeds or disease for others. If Buddy develops laryngeal paralysis, he will likely have trouble breathing or barking, perhaps making a hoarse, raspy noise when he inhales. He might also gag and hack when eating and drinking or collapse when he's active. Labrador retrievers, dalmatians, Siberian huskies and Bouvier des Flandres are among the vulnerable breeds, as well as middle-aged to older large-breed dogs. Treatment can range from exercise restriction to oxygen therapy to surgery.