Lower respiratory disease in individuals (Yr 4) Flashcards
what are the two names for the different severities of equine asthma?
mild… inflammatory airway disease
severe… recurrent airway obstruction (heaves)
what can cause asthma?
inhalation of allergens (mild, bacteria, dust, gas…)
how horse responds to allergens
what is happens once allergens are inhaled to cause asthma?
triggers inflammatory mediator release…
mucus production
increased blood flow and vascular permeability
cell accumulation/activation
neural reflex mechanism (parasympathetic)
increased airway smooth muscle tone (bronchoconstriction)
what causes the respiratory noise heard with asthma?
bronchoconstriction (creates a wheeze)
what contributes to the narrowing airways associated with equine asthma?
mucosal hyperplasia, inflammation, oedema
increased inflammatory cells
decreased mucociliary escalator and mucous production
(fibrosis in chronic cases)
when do horses typically present with mild asthma?
young horses
signs of poor performance, coughing at exercise
often improve/resolve with treatment
what are the factors of chronic asthma that lead to airway remodelling?
smooth muscle hypertrophy
peribronchiolar fibrosis
epithelial cell hyperplasia
mucus plugging
what are the clinical signs of asthma?
exercise intolerance
cough, nostril flare, nasal discharge, tachypnoea
heave lines (forced expiration)
very severe - respiratory distress and weight loss
does asthma cause an inspiratory or expiratory noise?
expiratory wheeze (respiratory tract collapses when breathing out)
how can suspected equine asthma be diagnosed?
endoscopy of upper airway (increased mucous)
BAL - airway cytology (mild increase in neutrophils/eosinophils)
how can the mucous be graded on endoscopy of equine asthma?
0-5
0 - no mucous
5 - river of mucous
is tracheal aspirate or bronchoalveolar lavage better for asthma diagnosis?
BAL
what result on tracheal aspirate would be associated with the horse having asthma?
neutrophils >40%
what is done on bronchoalveolar lavage to diagnose equine asthma?
count cells, if >25% are neutrophils it indicates asthma (the severity of the increase correlates with grade of asthma)
what are the three main treatment options for equine asthma?
environmental control
corticosteroids
bronchodilators
what is the best treatment for asthma flares (short term treatment)?
bronchodilator
what is the environmental control used for asthma?
reduce respirable particles (dust, mould, fungi, grass…)
ventilation and time outside
feed - soak hay, turn out to pasture, pelleted feeds
low dust bedding - paper, rubber mats, cardboard
turn out during/around mucking out
what is the main treatment used for inflammation associated with equine asthma?
corticosteroids
how do corticosteroids help to control asthma?
reduce cell accumulation/activation
reduce vascular changes
reduce bronchoconstriction (inhibit cytokines, histamine, prostaglandin release)
how can corticosteroids be given for asthma?
systemic
inhaled
what systemic corticosteroids are available for asthma?
prednisolone
dexamethasone (stronger)
what inhaled corticosteroids are available for asthma treatment?
ciclesonide
beclomethasone dipropionate
nebulised dexamethasone
what is the benefit of inhaled corticosteroid for asthma treatment?
targets specific area so there are less side affects associated with their use
what are the two types of bronchodilators available for asthma treatment?
beta2 adrenergic agonists (sympathetic)
muscarinic antagonists (parasympathetic)
what are the indications for using bronchodilators in equine asthma cases?
emergency therapy in flare ups
before other inhaled medications
before exercise
(don’t use a sole therapy)
what is the most common bronchodilator used?
clenbuterol
(salbutamol)
what is the mode of action of clenbuterol?
beta2 adrenergic agonist
why can’t beta2 agonists be used long term as bronchodilators?
the receptors become down-regulated and tolerance is built up against them
what are muscarinic antagonists used for bronchodilation in asthma cases?
atropine
buscopan
ipratropium bromide (inhaled)
what are some extra therapies that might be useful in equine asthma cases?
mucolytics
rest
disodium cromoglycate
antioxidants
what causes bronchopneumonia/pleuropneumonia?
secondary infections from opportunistic pathogens
what factors predispose horses to bronchopneumonia/pleuropneumonia?
transport
inhalation (anaesthesia, reflux, choke, dysphagia…)
viral URT disease
exercise induced pulmonary haemorrhage
what is the main site for bronchopneumonia/pleuropneumonia in the lungs?
right ventral lung lobes
how are bronchopneumonias diagnosed?
clinical signs - dyspnoea, tachypnoea, pyrexia, dull, increase HR
adventitious lung sounds
tracheal aspirate - degenerative neutrophils and culture
how are pleuropneumonias diagnosed?
clinical signs
reduced lung sounds ventrally
very painful (abducted elbows, short shallow breaths)
thoracocentesis
what are the three stages of pleuropneumonia?
acute exudative - inflammation of lung/pleura
fibrinopurulent - bacteria invade, fibrin deposits
organisational
what is done to treat bronchopneumonia/pleuropneumonia?
broad spectrum antibiotics (penicillin, gentamicin)
anti-inflammatory (meloxicam)
drain/support drainage
supportive therapy
what is a specific part of the history in equine lungworm?
they have to graze with donkeys
how is equine lungworm treated?
ivermectin
what causes equine multinodular pulmonary fibrosis?
equine herpes virus 5 (EHV-5)
what is the prognosis for equine multinodular pulmonary fibrosis?
guarded/poor
