Lecture 27 11/21/24 Flashcards
How does the airway epithelium respond to stimuli?
-hypertrophy
-metaplastic change
-erosion/ulceration
How do airway goblet cells and submucosal glands respond to stimulI?
-hypertrophy
-production of excessive amounts of viscous mucous
What can cause injury to the airways?
-hypoxia-induced effects
-fibrotic destruction of vascular beds
-mechanical stress
How do the bronchial mucosa and submucosa respond to stimuli?
-become infiltrated with variable number and type of inflammatory cells
-become edematous
What are the possible responses of bronchial smooth muscle to stimuli?
-unaffected
-hypertrophy
-spasm
What are the characteristics of feline bronchitis?
-inflammation of the bronchi
-underlying causes include insult to epithelium or parasites
-airway hyper-reactivity is NOT part of this disease
-no extreme resp. distress
What are the characteristics of feline asthma?
-airway obstruction caused by heightened reactivity of tracheobronchial tree
-aeroallergens drive disease
-life long
How does feline bronchitis compare to feline asthma?
-both are inflammatory diseases
-asthma may have more eosinophils in an ETW
-asthma has acute, severe bronchoconstriction
-asthma presents with resp. distress and airway hyperreactivity
Which functions of the airway/lung anatomy contribute to asthma?
-bronchial smooth muscle hypertrophy
-inflammation and edema of the airway
-epithelial cell/mucociliary dysfunction
-intraluminal exudate and mucous plugs
What are the steps of an asthmatic response?
-allergen is inhaled
-dendritic cells present allergens via MHCII to naive CD4 T cells
-polarized Th2-mediated immunity results in cytokine production and IgE activation
-IgE binds to FcEpsilonRI receptors on mast cells and basophils
-re-exposure to allergen results in IgE crosslinking, mast cell degranulation, and inflammatory cascade
What is the role of the sympathetic nervous system in feline asthma?
-beta-2 activation increases cAMP
-causes bronchodilation and decreased mucous production
What is the role of the parasympathetic nervous system in feline asthma?
-muscarinic activation increases cGMP
-stimulates glandular secretion, smooth muscle contraction, and vasodilation
What is the role of vasointestinal peptide?
causes bronchodilation
What is the role of substance P?
causes bronchoconstriction
What is the pathophysiology of histamine?
-released during mast cell degranulation
-triggers bronchoconstriction, mucus secretion, increased capillary permeability, and granulocyte chemotaxis
-variable response to antihistamine treatment
What is the pathophysiology of serotonin?
-released from mast cells
-mediator of smooth muscle contractility
-possible mediator in feline asthma
What are the potential triggers of feline asthma?
-viruses
-mycoplasma
-litter
-dust
-smoke
-perfume
-exercise
-emotion
What are the characteristics of airway resistance?
-affected by radius of airway
-small changes in radius make significant changes is resistance (4 fold)
What affects the radius of the airway?
-bronchoconstriction and bronchodilation
-material in the lumen of the airway
What are important questions to ask when trying to determine if a cat has asthma?
signalment; typically younger at first presentation
-determine severity of clinical signs
-determine if clinical signs are daily or intermittent
What are the clinical signs of asthma in cats?
-coughing
-wheezing
-sneezing
-wretching/vomiting
-resp. distress
-cyanosis
What are the clinical signs and signalment of feline bronchitis?
-occurs in middle aged to older cats
-cough persisting 2 months or longer
-not usually associated with severe resp. distress
What are the characteristics of the physical exam in cats presenting for asthma or bronchitis?
-may appear normal at rest
-tracheal palpation may induce cough
-possible to auscult crackles and wheezes
-expiratory “push”/increased effort on expiration
-dyspnea, open-mouthed breathing, and cyanosis in asthmatic cats only
what must be ruled out when assessing a cat for respiratory signs?
heart failure
How is heart failure diagnosed?
-history
-physical exam
-radiographs
-NT-proBNP
What are the characteristics of radiographs in cats with lower airway disease?
-may be normal
-bronchial disease prominent
-interstitial to patchy alveolar infiltrate
-lung lobe collapse
-hyperlucent lung fields that may look hyperinflated
What are the diagnostic steps for feline lower airway disease after taking radiographs?
-CBC
-heartworm AG/AB
-fecal exam
-serum chem.
-ETW/BAL for cytology and culture
What are the long term treatment goals for feline lower airway disease?
-educate the owner that there may not be a cure
-exclude underlying disease that could be treated specifically
-achieve good quality of life for the cat
-avoid exposure to trigger situations
-reverse and prevent bronchoconstriction
-suppress ongoing airway inflammation
-treat secondary or concurrent infections
What are the emergency treatment steps for cats with lower airway disease?
-oxygen
-cage rest to calm animal
-terbutaline SQ or inhaled albuterol
-corticosteroids
-sedation if severe
-anesthesia/intubation if really severe
What are the characteristics of bronchodilators?
-reduce bronchoconstriction in acute asthma attacks
-should not be used for monotherapy; exacerbate airway hyper-responsiveness and fail to control airway inflammation
-include methylxanthines and beta-2 agonists
What are the characteristics of methylxanthines?
-include theophylline and aminophylline
-inhibit PDE related breakdown of cAMP to increase relaxation
-intracellular Ca conc. increase and increase diaphragmatic muscle contraction
-end result of use in bronchodilation, CNS and cardiac stimulation
What are the characteristics of terbutaline?
-selective beta2 agonist
-administered SQ, IM, IV, PO. elixir
-indicated in acute exacerbations
-reduces resp. rate by 50% in short time frame
-can be repeated
-duration of action of 6-8 hrs
What are the characteristics of albuterol sulfate?
-selective beta2 agonist
-used in dogs, cats, and horses
-administered parenteral, oral, and inhalation
-duration of action of 4 hrs
-not for long term use
What are the characteristics of systemic corticosteroids?
-decrease inflammation in the airway
-permissive effect on beta2 receptors
-many side effects
What are the characteristics of inhaled nebulization/aerosol corticosteroids?
-fluticasone or flunisolide
-local action leads to less side effects
-less systemic immunologic effects
-not for emergency use; needs 7-10 days to work
What are the characteristics of cough suppressant use in cats?
-not commonly done
-want to allow productive coughs to continue
-cats do not often cough continuously
What are the characteristics of antibiotic use in feline lower airway disease?
-lungs are not sterile have a normal pop. of bacteria
-treatment is based on # and type of bacteria on culture
-Mycoplasma spp. may have a pathogenic role; can treat with doxy
What are the potential treatments for feline lower airway disease?
-diet change
-probiotics
-omega 3s/antioxidants
