Asma Felino

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Proceedings of the World Small Animal Veterinary Association Mexico City, Mexico – 2005

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Reprinted in the IVIS website with the permission of the WSAVA

Published in IVIS with the permission of the WSAVA

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Feline Medicina Laboratory Medicina

FELINE ASTHMA
Gardner SY North Carolina StateUniversity College of Veterinary Medicine 4700 Hillsborough Street Raleigh, NC 27606

Feline asthma has been referred to in the literature by a variey of terms including eosinophilic bronchitis, allergic bronchitis, feline bronchitis, feline bronchial asthma, and feline chronic obstructive pulmonary disease.1,2 Cats of all ages may be affected.3 There is an increased incidence in Siamese cats, andthey may have a more chronic form of bronchial disease.4

PATHOLOGY

Histopathological lesions of feline asthma include: bronchial smooth muscle hypertrophy and bronchoconstriction; inflammation and edema of airway mucosa and submucosa; epithelial cell desquamation, intraluminal inflammatory exudate, and airway mucus plugs; and emphysema, submucosal gland hyperplasia, and increased airway gobletcells.1

CLINICAL SIGNS

Clinical signs may be mild and chronic or acute and severe with cough and/or dyspnea and may be exacerbated by environmental changes.5 The cat may have a history of a recent upper respiratory tract infection and sneezing or oculonasal discharge may be present.5,6 On physical examination the cat may appear normal at rest but exhibit increased tracheal sensitivity withauscultable post-tussive crackles.5 A more severely affected cat may have harsh lung sounds, crackles, or wheezes on expiration with a prolonged expiratory phase or decreased lung sounds with a barrel-shaped thorax and increased resonance on percussion.1,5 An abdominal component to respiration may be present.5 A severely affected cat may present with extreme respiratory distress, cyanosis, and open-mouthbreathing.5

DIAGNOSIS

Differential diagnoses for cough and/or dyspnea in the cat include: (1) feline asthma; (2) pulmonary infection (bacterial, fungal, parasitic, viral, protozoan); (3) pleural effusion (chylothorax, pyothorax, hydrothorax, hemothorax); (4) pneumothorax; (4) pulmonary thromboembolism; (5) cardiac failure; (6) upper airway obstruction (nasal, laryngeal, tracheal); (7) bronchialforeign body; (8) neoplasia (upper airway, lower airway); and (9) heartworm disease.1,7 Diagnostics should

Proceedings of the WSAVA Congress, Mexico City, Mexico 2005

Published in IVIS with the permission of the WSAVA

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include: (1) complete blood count; (2) fecal examination; (3) thoracic radiographs; (4) heartworm test; (5) biochemical profile; (6)urinalysis; (7) feline leukemia virus and feline immunodeficiency virus test; (8) airway sampling; and (9) pulmonary function testing if available.1 A complete blood count may reveal neutrophilia, eosinophilia, and hyperproteinemia.3 Thoracic radiography may be normal or abnormalities may be present including: peribronchial cuffing; alveolar or interstitial infiltrates; flattening of thediaphragm; air trapping or hyperlucency; and atelectasis of the right middle lung lobe.5 Cytology of airway samples reveals inflammation.3 Bacterial culture of airway samples is positive in 24 – 42% of cats but may only represent bacterial colonization and not actual infection.3,4 Isolation of Mycoplasma may be an exception, though, as it is not normally isolated from the lungs of normal cats.8,9 Pulmonaryfunction testing may reveal increased airway resistance, airway hyperreactivity, and abnormalities in tidal breathing flowvolume loops.3,10

PATHOGENESIS

In an attempt to better understand the pathogenesis of feline asthma, studies have been performed in a feline model induced by antigen sensitization and challenge with Ascaris suum.11 In this model cats develop airway hyperreactivity and...