Feline bronchial disease Flashcards
What is the difference between feline asthma and chronic bronchitis
Asthma is characterized by reversible bronchoconstriction
Chronic bronchitis is characterized by permanent airway inflammation and excessive mucus production that result in largely irreversible narrowing of the airways
What would be your main differentials for feline bronchial disease
Feline bronchial disease
- asthma
- chronic bronchitis
Lungworm infection
Heartworm infection
Infectious bronchitis
- e.g., mycoplasma
What would be your investigation plan to narrow down your main differentials
Fecal analysis including use of the Baermann technique to assess for Aelurostrongylus abstrusus
- a nested PCR on pharyngeal swabs can also be done
Heartworm antibody and antigen testing to assess for feline heartworm disease
Analysis of fluid samples obtained from the lower airways
What is the traditional therapy for non-infectious feline bronchial disease
Traditionally, therapy for non-infectious feline bronchial disease has relied on the use of:
- oral anti-inflammatory agents (glucocorticoids)
- bronchodalitors such as the methylxanthines (e.g, theophylline) or B2-agonists such as terbutaline
Why glucocorticoids are important in the treatment of feline bronchial disease
Glucocorticoids are the main therapeutic agents
They act to reduce the underlying inflammation in the airways and promote bronchodilation by sensitizing B2 receptors (increasing their number and their affinity)
What are the advantages of inhalant steroids versus oral medications
This method of administration has the benefit of reducing the systemic side effects of glucocorticoids, and delivery of the agent directly to the required site of action
What are the difference between chronic bronchitis and asthma on BAL cytology
Feline allergic asthma is primarily characterized by the presence of eosinophilic inflammation
- there should be a predominance of eosinophils (> 17%) identified in the BALF
Chronic bronchitis should result in primarily nondegenerate neutrophilic inflammation in BALF
Explain why bronchodilators should not be used as a monotherapy
Bronchodilators are critical to reduce bronchoconstriction in acute asthma attacks BUT they should not be used for monotherapy because they fail to control the airway inflammation that exacerbates airway hyperresponsiveness
Inhalant salbutamol is a racemic mixture consisting of the R-enantiomer, which possesses bronchodilatory properties, and the S-enantiomer, which promotes bronchospasm and is pro-inflammatory
- with repeated use, the S-enantiomer preferentially accumulates in the lung because of slower clearance, enhancing bronchoconstrictive and proinflammatory effects
Explain why the right middle lobe is the most frequently collapsed one on thoracic X-ray
The right middle lung lobe is most frequently collapsed because the main bronchus of this lobe has a dorsoventral orientation within the bronchial tree, making the accumulated mucus subject to the effects of gravity
Even if there are highly variable nucleated cell counts in BAL fluid and variation in the proportion of cell types, what findings can help in diagnosis inflammatory airway disease
Cats with inflammatory airway disease have higher cell count in BAL fluid compared with healthy cats
- cell counts from normal cats are typically 200 to 300 nucleated cells/µL (can be as high as 600 cells/µL)
- cell counts can exceed 1500 cells/µL in cats with airway inflammation
