Bronchitis is a condition caused by inflammation of the airways deep within the lung.
The job of the lung is to absorb oxygen from the air, pass it into the bloodstream and vent carbon dioxide from the blood into the lung to be breathed out.
The air passes backward and forward through a branching network of tubes called bronchi and bronchioles, which become progressively narrower; if these tubes become thickened or inflamed, pushing air into and out of the lungs becomes much harder.
Bronchitis tends to occur in middle-aged or older animals. It is much more common in dogs than in cats, and in cats there is a considerable overlap in symptoms between bronchitis and feline asthma.
The condition can be treated, but the more well established it is, the less impact treatment makes at reversing inflammatory damage.
One of the characteristics of bronchitis is a long-term cough. These animals have often been coughing for 2 months or more, and are otherwise well except for this persistent, irritating cough.
As the condition worsens, the pet can be prone to shortness of breath, and mild exercise can provoke coughing episodes. Occasionally, if the coughing is severe enough, the animal may collapse.
Considering that so much is known about bronchitis in people, there is relatively little known about the condition in dogs and cats. There may be a genetic predisposition because some breeds, such as West Highland white terriers, are more likely to get bronchitis than others.
What is more certain is that long-term airway irritation provokes bronchitis. Exposure to cigarette smoke, allergies and cold air are all factors that cause inflammation in the lining of the bronchi.
Hand in hand with the inflammation is poor clearance of mucus and muck in the lungs, which causes plugs to form in the tubes, trapping air and ultimately causing the tiny sacs, or alveoli, in the lung to pop. A bit like popping bubble wrap, this then renders that part useless for its proper function.
Poor air circulation and stagnant secretions also make a great breeding ground for bacteria, so secondary infections and even pneumonia is a common complication of bronchitis.
Your veterinarian learns a lot by carefully listening to the chest and lung sounds.
Animals with bronchitis have harsh-sounding lung noises, which are noisier as the dog or cat tries to breathe out and force air through the narrowed tubes. If the alveoli have popped, then the chest may sound more resonant, like a drum, when tapped with fingers.
A diagnosis is made with a combination of tests such as radiography, endoscopy of the airways and washes to obtain cell samples from the lungs.
Pets with bronchitis are prone to chest infections, and a course of antibiotics is commonly prescribed. Once the infection is cleared, drugs may be required to decrease inflammation and open up the airways.
Corticosteroids are potent anti-inflammatories that can provide quick relief for an animal with distressed breathing. Another family of drugs called bronchodilators can help facilitate air to flow in and out of the lungs.
There is a strong link between bronchitis and long-term irritation of the lungs, so never smoke near a dog and avoid the use of potentially irritating sprays such as air fresheners or deodorants.
- “Diagnosis and treatment of canine chronic bronchitis.” McKiernan. Vet Clin North Am Small Anim Pract, 30(6): 1267–1278.
- “Canine chronic bronchitis.” Padrid, Hornot, Kurpeshoeu & Cross. JVIM, 4: 172–180.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 13, 2018.