Bronchitis in dogs is the inflammation of one or more of the respiratory airways, which are called bronchi and which take air to and from the lungs. When the condition often also affects the trachea (or "wind pipe"), it is called tracheobronchitis. Another name that is sometimes used for chronic bronchitis is chronic obstructive pulmonary disease (COPD).
Causes of Canine Bronchitis
Bronchitis in dogs can be either an acute (sudden-onset) or a chronic (slow onset) condition. Acute canine bronchitis often comes at the tail end of a respiratory tract infection, which can be either bacterial or, more commonly, viral in nature. Other contributors to bronchitis in dogs can include physical or chemical inhaled atmospheric irritants, such as powdered feed products, chemical fumes, room deodorizers, irritating cleaning products and household dust, among others. However, a definitive cause of chronic bronchitis in canine companions has not yet been identified. This is a non-reversible, slowly progressive condition. When the sensitive lining of the respiratory tract becomes inflamed and irritated, it causes coughing and accompanying pathologic changes to the structure of the airways. They become thickened and narrowed, reducing the dog's ability to inhale and exhale air properly and adversely affecting the normal transport and exchange of oxygen, carbon dioxide and other substances.
Prevention of Bronchitis
Keeping the household environment free from airborne fumes, chemicals and other irritants will help to prevent some cases of bronchitis in dogs. Otherwise, since the actual causes of chronic canine bronchitis are not well understood, it is not meaningful to speculate on what might be appropriate preventative measures.
Long-term bronchitis, which necessarily involves development of a chronic cough, can actually lead to broken ribs in especially severe cases.
The hallmark of chronic bronchitis in domestic dogs is a cough of unknown origin that persists for two or more months.
Symptoms of Bronchitis
A dog with bronchitis will typically have the following symptoms:
Cough – dry and hacking (very common; usually can be induced by applying pressure to the trachea; may be productive due to excessive production of mucus by damaged tracheal and bronchial tissues)
Fever (+/-; can be fluctuating)
Retching, gagging and passing foamy saliva at the end of a coughing fit (this is called the "terminal retch" and is frequently mistaken by owners for vomiting)
Difficulty breathing (dyspnea)
Rapid breathing (tachypnea)
A harsh, dry cough that may or may not be productive is the classic sign of bronchitis. Dogs with chronic bronchitis have a cough that lasts more than two months and is not attributable to any identifiable source or cause. The cough usually is not more or less prevalent during the day or at night and often is triggered by exercise, activity, stress or physical pressure on the trachea (sometimes called the "wind pipe"), such as from straining against a collar and leash. In most cases, it is better to transition a dog with bronchitis to a chest harness or a head halter rather than a neck collar, to prevent undue irritation of the trachea.
Dogs at Increased Risk
Obesity is a common and complicating factor in dogs with chronic bronchitis.
Small and toy breeds seem to be affected more frequently by chronic bronchitis than are larger dogs, although any dog is at risk. West Highland White Terriers, Cocker Spaniels and older or aging dogs are predisposed.
Chronic bronchitis is a slowly progressive disease in domestic dogs that unfortunately is almost never reversible or curable. However, in most cases, it can be well-managed with medication and environmental modification.
How Canine Bronchitis is Diagnosed
When presented with a dog whose primary clinical sign is coughing, a veterinarian will take a complete history from the owner and conduct a thorough physical examination. She usually will be able to elicit a cough on palpation of the trachea and may hear characteristic lung sounds, such as crackles and wheezes at the end of inspiration, when listening to the chest through a stethoscope. The veterinarian also will probably recommend thoracic radiographs (chest X-rays), which can be quite helpful in arriving at a diagnosis. Unfortunately, normal chest films do not necessarily rule out chronic as the cause of the dog's condition. The results of routine blood work (complete blood count and serum biochemistry profile) and urinalysis are typically normal or inconclusive in dogs with bronchitis. Tests can easily be run to identify or eliminate lungworms and heartworms as the cause of the cough.
The veterinarian can obtain samples of cells from the dog's airways through several different processes, known as bronchoalveolar lavage and transtracheal wash. Both of these procedures involve flushing the trachea and respiratory airways with a sterile solution and then aspirating the fluid out of the airways through a tube and syringe for submission to a diagnostic laboratory. Although bacterial infection is not commonly associated with bronchitis in dogs, it can happen, and the veterinarian may recommend culturing the airway sample to identify any abnormal microorganisms that are present. Bronchoscopy is another diagnostic tool. This involves inserting a wand-like instrument with a camera at its tip (an endoscope) down the dog's throat and into its airways. This lets the doctor actually visualize the lining of the upper respiratory tract in real-time, and to take additional fluid or tissue samples if necessary. An echocardiogram may be used to rule in or out congestive heart failure as a cause of the dog's cough.
Diagnosis of chronic bronchitis is made by eliminating other potential causes of the dog's cough. It is called a diagnosis of exclusion.
The goals of treating canine bronchitis are to relieve inflammation of the sensitive lining of the airways, remove any physical airway obstructions, alleviate the frequency and severity of the dog's cough and cure any secondary respiratory tract infections.
The attending veterinarian has a number of pharmaceutical medications at her disposal to manage dogs with bronchitis. In acute cases, antibiotics, bronchodilators, anti-inflammatory drugs and/or cough suppressants may be appropriate. Cough suppressants should not be used if the dog's cough is productive (in other words, if the dog can successfully expel mucus, pus or phlegm by coughing), or if an underlying viral or bacterial infection is present. Dogs that are having significant difficulty breathing (dyspnea) may need to be hospitalized for administration of oxygen therapy until their breathing can be stabilized.
Dogs with chronic bronchitis are more difficult to treat successfully than are dogs with acute-onset of the disease. Obviously, any identifiable sources of airway irritation should be eliminated from the dog's living environment – including dust, airborne fumes, perfumes, carpet cleaners, air deodorizers, fertilizers, pesticides, cigarette smoke and smoke from fireplaces or wood-burning stoves. Anti-inflammatory medication (such as oral or inhaled prednisone or other corticosteroids), oral cough suppressants and/or bronchodialators (either oral or inhaled) can be quite helpful in relieving the dog's discomfort by reducing the frequency and severity of its coughing bouts. Antibiotics are available if an underlying bacterial infection is identified. Weight loss is extremely important if the affected dog is obese.
While most cases of bronchitis are considered treatable, it is rarely possible to completely eliminate the dog's cough. Chronic bronchitis is a progressive disease that causes physical and physiological changes in the dog's airways. Thankfully, it rarely is fatal or life-threatening. Most affected dogs can be well-managed medically and go on to enjoy excellent qualities of life with normal life spans.