A dry, hacking cough that sounds like your dog is gagging, almost like something is stuck in his throat, followed by the appearance of frothy white mucus (known as phlegm) from his mouth are signs of tracheal irritation. The trachea (or windpipe) is the tube that connects your dog’s throat to his lungs and through which air passes. Tracheal irritation may be a normal physiologic response or it may be a sign of disease. Understanding how the windpipe works can help you recognize what a cough and phlegm appearance requires a visit to the vet.
How the trachea works
The inside of your dog’s windpipe is lined with microscopic hairs called cilia. These cilia are covered by a thin layer of mucus. The cilia beat rhythmically in an upward direction, moving the layer of mucus away from the lungs and toward the throat. This is called the mucociliary escalator.
When your dog inhales bacteria, viruses, dust, or anything else the body doesn’t want reaching the lungs, these particles get trapped in the mucus layer. The cilia strike and move the mucus containing these particles towards the throat, where they can be coughed up or swallowed. Inhaled irritants, such as dirt, dust, or even air pollutants, naturally become trapped in the mucociliary escalator and travel up to the throat, where they can be coughed up or swallowed.
Think of this smart gadget like the escalator at the mall. Like the person who gets on the escalator, you are like a particle that gets stuck in the mucus. When you get on the escalator, you have no choice but to go up to the next floor. Even if you try to run up the escalator to go back to the previous floor, the escalator is still moving you up. And you can’t get off the escalator until you’re on the next floor!
Inhaled irritants, such as dirt, dust, or even air pollutants, naturally become trapped in the mucociliary escalator and travel up to the throat, where they can be coughed up or swallowed. If your dog coughs up phlegm once or twice and then doesn’t cough up any more, your dog’s mucociliary escalator is doing its job. But if your dog is coughing up phlegm every few minutes, there is a problem that needs to be diagnosed and addressed by your vet.
kennel cough
The most common cause of coughing up phlegm is infectious tracheobronchitis, also known as kennel cough. the bacteria Bordetella bronchiseptic is a common pathogen that causes kennel cough. Bordetella it has two properties that help it wreak havoc on your dog’s windpipe. This bacterium is capable of binding to the cilia on the mucociliary escalator and immobilizing them, ceasing the upward movement of mucus. The mucus accumulates in the trachea and has to be coughed up. This is what causes dry, dry cough followed by coughing up phlegm.
Also, as mucus builds up, Bordetella the bacteria deactivate the immune cells lining the trachea so they can no longer engulf and destroy pathogens. This is like sending out invitations to other bacteria or viruses to join the party and create a bigger infection. Most healthy young dogs can clear the infection before it gets worse. But sometimes a simple case of kennel cough can turn into pneumonia.
Other causes of cough
External pressure on the trachea can cause a dog to cough up phlegm. Usually this is caused by a dog pulling on the leash. If your dog pulls on the leash to the point of coughing, get help from a trainer, or at the very least have your dog wear a front clip harness or halter. These control devices take the dog’s pressure away from his throat and prevent him from pulling as hard.
The cough associated with tracheal irritation sounds like your dog has something stuck in his throat. In most cases, he’s just coughing up mucus. The exception is when your dog has He swallowed something that got stuck in his esophagus. Esophageal foreign bodies can exert external pressure on the trachea and trigger a cough of phlegm.
If your dog is coughing up yellow or pink-tinged discharge or blood, or is having difficulty breathing, your dog may be experiencing a life-threatening emergency. Take your dog to your nearest primary care veterinarian or emergency veterinary hospital immediately.
