Allergens, usually inhaled include a wide range of environmental agents such as dust, pollens and aerosolized infectious antigens (e.g. dust mites), trigger histamine release within brnchial epithelial cells, leading to bronchoconstriction and mucin production.
Affected dogs present with coughing, dysphagia, retching and in severe cases, weight loss.
Diagnosis is one of exclusion with supportive radiographic evidence of primary non-infectious pulmonary disease.
Radiographs frequently show mineralization and thickening of the bronchial walls ('doughnuts' and 'tramlines' inflammation.
Chronic bronchitis is an exclusion diagnosis. Thickened bronchial walls and their increased visibility are a reliable sign of chronic bronchitis in dogs. In severe cases the bronchi can be completely opacified by mucus and can be confounded with vessels or even small nodules.
Bronchiectasis of pulmonary parencyma may be seen in protracted cases.
Treatment is usually effective with prednisolone or antihistamines.
- Turner NC et al (1995) Eicosanoid release in allergen-induced bronchoconstriction in dogs. Its relationship to airways hyperreactivity and pulmonary inflammation. J Lipid Mediat Cell Signal 11(1):93-102