As I write this, my dog Finzi is lying in her bed across the room, resting after her morning walk.
Even if I stop typing, I cannot hear any sound at all from her. She is breathing so quietly that she is barely making any noise at all. This is normal: she's a healthy two year old dog, and her respiratory system is functioning exactly as it should do.
Many animals suffer from noisy breathing: it's so common in some breeds that it's almost regarded as normal. Loud breathing sounds are usually the result of air passing through narrowed passageways, meeting resistance, resulting in turbulent air flow. I often explain this to owners by making a comparison with the flow of water. If you are beside a wide, free-flowing river, you can barely hear the water moving. On the other hand, if you are close to a narrow stream, with water rushing over stones and rocks, the sound can be deafening. In animals, when airways are wide and open, like my dog Finzi, it's the equivalant of a wide river: there's almost no sound. In animals with noisy breathing, the airways are narrowed or obstructed, like a babbling brook.
The source of the noise depends on the part of the airway that's narrowed. It can be the nasal passages, the back of the nose (nasopharynx), the throat (pharynx), the voice box (larynx), or the windpipe (trachea). You don't need to be a vet or to use a stethoscope to hear the noise: it's clearly audible, but it can be surprisingly difficult to pinpoint exactly where it's coming from. You need a quiet room, no distractions, and plenty of time to listen and watch the animal.
The most common type of noisy breathing is the type seen in short-nosed ("brachycephalic") dog breds, such as pugs and bulldogs. It's seen as "normal" for these dogs to make a loud noise when breathing, especially when they get excited. This is because their upper airways have been narrowed, shortened and twisted by selective breeding, to give them that "cute" squashed face appearance. While there may be no serious harm caused by noisy breathing, in some cases the narrowing of the air passages is so severe that affected animals are unable to get enough air into their bodies to oxygenate their blood properly. I have seen some patients collapse when they get excited because they cannot breathe properly. I know some pugs that have had to have permanent tracheostomies, with a breathing hole half way down their throat, completely bypassing their larynx, mouth and nasal passages. After this radical surgery they are able to breathe quietly and comfortably, and they no longer collapse when excited. But it's a radical answer to a man-made problem. It would be far better if breeders stopped producing dogs that are innately unable to breathe. The problem is that these dogs often have an appealingly cute appearance, and there is always a ready market for pups of this type. Doting potential owners are unable to look into the future: if they realised the complications that their adorable new puppies were going to experience as adults, they might not get involved in the first place.
The second most common cause of noisy breathing is a problem known as laryngeal paralysis. The larynx - or voice box - is at the junction between the throat and the windpipe. All air has to pass through the larynx on the way in, and on the way out, of the lungs. In a healthy dog, the muscles of the larynx are active and effective. When a dog is relaxed and resting, the larynx remains half closed, because air flow is slow and easy. However when a dog exercises, or gets excited, the laryngeal muscles contract, opening up the larynx, and creating a much wider space for air to flow in and out. With laryngeal paralysis, these muscles stop working, so that the larynx remains permanently half-closed. Affected animals are comfortable at rest, but when airflow speeds up, during exercise or any other activity, the half-closed airway acts as an obstruction to the free flow of air. The result is difficult, noisy breathing.
Laryngeal paralysis is common in large breeds like Labradors, Golden Retrievers and Irish Setters. It develops in older dogs, usually over ten years of age. Exercise becomes more difficult, because the animal starts to struggle to breathe comfortably. The signs develop gradually and imperceptibly: owners often don't realise that there is a problem at first, and by the time affected animals are taken to the vet, the condition can be advanced and severe.
The answer to laryngeal paralysis is simple but radical: throat surgery to permanently fix the larynx in an open position. After the operation, most animals regain their normal, quiet, easy breathing. However because this condition usually happens in older pets - sometimes as old as thirteen or fourteen - owners may be understandably reluctant to put their pets through such a major operation. I often think that I should keep a video library of dogs before and after the surgery to help to convince such people: there is such a dramatic improvement in quality of life that it's very obvious that even for elderly pets, the operation is well worth doing.
Does your pet have noisy breathing? If so, listen carefully to find out where it's coming from, and talk to your vet about what might be done to help.