Although corticosteroids remain the treatment of choice for chronic bronchitis in dogs, a variety of alternative options can be used in conjunction with these drugs.

Chronic bronchitis is one of the most common causes of cough in dogs, along with airway collapse and eosinophilic lung disease. Combinations of these disorders also occur, such that the inflammatory and mechanical insults to the lower airways continue and perpetuate the cough cycle. They are irreversible, progressive, and have a guarded prognosis. Confirmed diagnosis of these inflammatory airway diseases often requires costly bronchoscopy along with bronchoalveolar lavage cytology and microbial culture. Corticosteroids remain the primary successful treatment, although alternative options are available and have been used in conjunction with steroids or apart from them. These management and treatment strategies do not cure the problem but are aimed at minimizing the severity of cough, thereby improving the quality of life for dogs and their caregivers, and hopefully limiting the progression of inflammatory airway injury.

DEFINING CHRONIC BRONCHITIS

Unlike acute bronchitis, which has bacterial and viral causes, chronic bronchitis is not contagious, and neither form is zoonotic. Chronic bronchitis may be difficult to diagnose and is often reached by excluding other diseases. Bronchitis is considered chronic if it’s present on most days, with a minimum duration of two months, in the absence of other underlying diseases. Regardless, any form of bronchitis can be aggravated by stress, extreme or prolonged environmental temperature changes, and a weakened or compromised immune system due to ongoing disease or metabolic and/or gastrointestinal dysbiosis (e.g. gut-brain, gut-bowel, gut-lung axis imbalance and disruption).

POTENTIAL CAUSES OF CHRONIC COUGH

There are many possible causes of chronic cough in dogs, of which chronic bronchitis is only one:

• Bacterial pneumonia
• Breed predisposition — e.g. Cocker Spaniel; Poodles; northern breeds with eosinophilic lung diseases such as Siberian Husky, Alaskan Malamute and sled dogs; small and toy breeds; brachycephalic breeds, especially French Bulldog, Pug, Pekingese and Shih Tzu with chronic obstructive airway disease/syndrome; and West Highland White Terriers with pulmonary fibrosis
• Canine infectious respiratory disease complex — e.g. Bordetella bronchiseptica, canine influenza
• Chronic bronchitis
• Congestive heart failure
• Fungal pneumonia — secondary to histoplasmosis, blastomycosis, coccidiomycosis, leishmaniasis
• Interstitial lung disease
• Lung tumors
• Parasitic pneumonia — e.g. lungworm, heartworm, neospora
• Pleural effusion
• Protozoal infections, coccidiosis, giardiasis
• Tracheal collapse (isolated)
• Upper airway dysfunction, including anatomically incomplete tracheal rings

DIAGNOSING CHRONIC BRONCHITIS

Dogs with chronic bronchitis have more than 12% neutrophils based upon bronchoalveolar lavage, whereas dogs with eosinophilic lung disease have more 14% eosinophils. Bacterial infection is typically absent from their microbial cultures.

Laboratory testing:

• Complete blood count and serum biochemical profile
• Thyroid profile
• Urinalysis, cystocentesis preferred
• Heartworm antigen testing
• Fecal analysis with oocyte numbers
• NT pro-BNP, to rule out cardiac-related disorders

Diagnostic imaging:

• Chest radiographs
• Fluoroscopy, for concurrent tracheal collapse Ultrasound, if isolated lesion or pleural effusion is found
• Computed tomography (CAT scan)
• Bronchoscopy (requires anesthesia so caution may be needed)

Airway sampling: cytology and culture (anesthesia required)

• Tracheal wash (transtracheal or endotracheal)
• Blind bronchoalveolar lavage
• Bronchoscopic bronchoalveolar lavage preferred

Lung function testing

• Arterial blood gas samples and/or pulse oximetry
• Six-minute walk test (dog should walk at least 400 meters)

TREATMENT OPTIONS FOR CHRONIC BRONCHITIS

A variety of alternative approaches and therapies can be used in conjunction with conventional treatment for dogs with chronic bronchitis.

1. Limit exposure to airborne pollutants (e.g. cigarette and cigar smoke, dust, grass, aerosols, strong odors and perfumes) and sick animals.
2. Install a humidifier.
3. Treat obesity aggressively and/or prevent it.
4. Limit exercise and barking; harnesses should be used instead of collars
5. Minimize leash time.
6. Avoid situations where the dog gets overexcited
7. Use natural approaches:

• • Medicinal mushrooms such as Reishi improve oxygen utilization and are adaptogenic; Cordyceps, Coriolus, Agaricus are anti-inflammatory and bronchodilatory.
  • Teas such as green tea and mullein tea are helpful. Brew to boiling and steep, then add to food or drinking water, or give by syringe without needle.
  • Lemon, ginger, raw honey, licorice root, eucalyptus oil and mustard can be used.
  • Additional therapies include steam diffusing, rest, lifestyle changes as needed, warm water, and sunlight for vitamin D.

8. Two classes of medications are commonly prescribed for chronic bronchitis: bronchodilators (theophylline, aminophylline, pentoxifylline and terbutaline) and corticosteroids (prednisolone, prednisone, methylprednisolone and fluticasone). Bronchodilators should help dilate or open the airways by relaxing the muscles around the airway walls. Inhaled corticosteroids (e.g. AeroDawg spacing chamber™) have been used successfully to help control cough in chronic bronchitis, and in some dogs with eosinophilic lung disease.

• • The chronic use of glucocorticoids predisposes the dog to fungal and urinary tract infections and iatrogenic Cushing’s disease.
  • Antibiotics and cough suppressants may also be used.

CLINICAL SIGNS OF CHRONIC COUGH DISORDERS

• Wheezing
• Gagging
• Dyspnea with shortness of breath
• Tachypnea
• Fainting, gasping for air
• Bluish gums from poor oxygenation
• Coughing up mucus and saliva
• Exercise intolerance
• Restlessness
• Pneumothorax
• Weight loss or gain
• Anorexia
• Weakness, lethargy

Chronic bronchitis is a common disorder in dogs for which there is no cure, but alternative therapies used alongside, or sometimes even in place of, conventional medications can help effectively manage the problem and improve quality of life.