Eosinophilic bronchopneumopathy

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Endoscopic image of the right caudal and accessory lung lobes in a dog with eosinophilic bronchopneumopathy. Partially to fully obstructive yellow-green mucopurulent material is evident in both lobar bronchi. Mild diffuse mucosal hyperemia is also evident[1]

Eosinophilic bronchopneumopathy (eosinophilic bronchitis) is a relatively uncommon respiratory disease of dogs characterized by eosinophilic infiltration of the lung and bronchial mucosa and bronchiectasis[2] and closely resembled human asthma[3].

A predisposition to this disease has been noted in the Cavalier King Charles Spaniel[4][5].

The cause of this condition is thought to be a hypersensitivity to inhaled allergens is suspected, particularly fungi, drugs, bacteria and parasites that triggers CD4+ helper cell release of cytokines[6].

Persistent antigenic exposure is thought to result in chronic irritation of the tracheal and bronchial mucous membranes and inflammation, with eventual epithelial desquamation, hyperplasia of the mucous glands, and airway obstruction. These changes impair mucociliary clearance and predispose to secondary bacterial infections, ultimately resulting in bronchiectasis[7].

Affected dogs usually present with chronic progressive coughing unresponsive to conservative palliative treatment. A cough can easily be elicited by palpation of the trachea. Thoracic auscultation reveals severe crackles and expiratory wheezes over all lung fields. As the condition worsens, dyspnea and cyanosis may develop and in rare cases, hemoptysis. A seasonality to the condition may be noted in some dogs, that makes it difficult, clinically, to distinguish from chronic pulmonary interstitial fibrosis.

Complete blood (cell) count, serum chemistry panel, and urinalysis are usually unrewarding.

Chest radiographs usually reveal multiple rounded bullae-like structures, predominantly found in the ventral lung fields, consistent with diffuse, severe, cylindrical bronchiectasis.

Diagnosis is by demonstration of an eosinophilic inflammatory cell infiltrate within respiratory tract cytological specimens (tracheal wash or bronchoalveolar lavage fluid)[8].

A differential diagnosis would include tracheal collapse, chronic bronchitis, heartworm disease, pulmonary interstitial fibrosis, pulmonary parasite infection (e.g. heartworm disease, Aspergillus spp, Histoplasma spp), bronchopneumonia, and pulmonary blastomycosis[9].

Most dogs are responsive to immunosuppressive dose of oral, parenteral or inhaled prednisolone[10], beclomethasone, azathioprine[11] and cyclosporine.

References

  1. Meler E et al (2010) Diffuse cylindrical bronchiectasis due to eosinophilic bronchopneumopathy in a dog. Can Vet J 51(7):753-756
  2. Clercx C & Peeters D (2007) Canine eosinophilic bronchopneumopathy. Vet Clin North Am Small Anim Pract 37(5):917-935
  3. Peeters D et al (2005) Distribution of leucocyte subsets in bronchial mucosa from dogs with eosinophilic bronchopneumopathy. J Comp Pathol 133(2-3):128-135
  4. German AJ et al (2002) Eosinophilic diseases in two Cavalier King Charles spaniels. J Small Anim Pract 43(12):533-538
  5. Joffe DJ & Allen AL (1995) Ulcerative eosinophilic stomatitis in three Cavalier King Charles spaniels. J Am Anim Hosp Assoc 31(1):34-37
  6. Clercx C et al (2002) An immunologic investigation of canine eosinophilic bronchopneumopathy. J Vet Intern Med 16(3):229-237
  7. Clercx C et al (2000) Eosinophilic bronchopneumopathy in dogs. J Vet Internal Med 14:282–291
  8. Clercx C & Peeters D (2007) Canine eosinophilic bronchopneumopathy. Vet Clin North Am Small Anim Pract 37:917–935
  9. Heikkilä HP et al (2012) Procollagen type III amino terminal propeptide concentrations in dogs with idiopathic pulmonary fibrosis compared with chronic bronchitis and eosinophilic bronchopneumopathy. Vet J Aug 18
  10. Bexfield NH et al (2006) Management of 13 cases of canine respiratory disease using inhaled corticosteroids. J Small Anim Pract 47(7):377-382
  11. Katajavuori P et al (2013) Eosinophilic pulmonary granulomatosis in a young dog with prolonged remission after treatment. J Small Anim Pract 54(1):40-43