This disease affects middle-aged dogs of both sexes. It is characterized by an acute inflammatory reaction of the interior of the smaller airways. Chronic bronchitis should be considered whenever a cough persists for more than two months.
In most cases the cause is unknown. Although some cases are preceded by kennel cough, infectious agents usually do not play a role except as secondary invaders. House dust, cigarette smoke, and other atmospheric irritants contribute to bronchial inflammation.
The hallmark of chronic bronchitis is a harsh, dry cough that may or may not be productive. Coughing is triggered by exercise and excitement. Episodes often end with gagging, retching, and the expectoration of foamy saliva. This can be mistaken for vomiting. The dog's appetite and weight are well maintained.
Unchecked chronic bronchitis damages the airways and leads to the accumulation of infected mucus and pus in dilated bronchi. This is called bronchiectasis. Chronic coughing can also lead to enlargement of the alveoli (lung air sacs), a condition called emphysema. These two diseases are not reversible and gradually progress to chronic lung disease and congestive heart failure.
The diagnostic work-up for bronchitis is the same as that described in Diagnosing a Cough.
Treatment: General measures include eliminating atmospheric pollutants such as dust and cigarette smoke. Minimize stress, fatigue, and excitement. Overweight dogs should be put on a weight-loss diet. Walking on a leash is good exercise, but don't overdo it. To avoid pressure on the larynx, switch from a collar to a chest harness or head halter.
Medical management is directed toward reducing bronchial inflammation. Your veterinarian may prescribe a course of corticosteroids for 10 to 14 days. If this is beneficial, the dog may be placed on a maintenance dose given daily or every other day. Bronchodilators such as theophylline or albuterol relax the breathing passages and reduce respiratory fatigue. They are beneficial for dogs with associated wheezing and airway spasms.
If the cough gets worse there is probably a secondary bacterial infection. Seek veterinary attention, because antibiotics will be required. Cough suppressants are beneficial for episodes of exhaustive coughing, but should be used only for short periods, as they interfere with host defenses and prevent the elimination of purulent secretions. Expectorants can be used as often as needed.
The response to treatment varies. Some dogs make a near-normal recovery, while others require frequent medication adjustments.
This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc