Lower respiratory tract disease in the individual horse Flashcards
What are clinical signs of lower respiratory diseases?
- Increased respiratory rate/effort
- Coughing
- Pyrexia
- Nasal discharge
- Lethargy
- Poor performance
- Weight loss
What are Ddx for lower respiratory tract diseases?
- Asthma
- Pleuropneumonia
- Exercise Induced Pulmonary Haemorrhage (EIPH)*
- Trauma
- Lungworm
- Tracheal stenosis/collapse
- Equine multinodular pulmonary fibrosis (EMPF)
- Interstitial pneumonia
- Pulmonary abscess
- Neoplasia (Primary/Metastatic)
- African horse sickness
- Other exotic diseases
What does asthma include?
- Inflammatory airway disease
- Recurrent airway obstruction
- Summer pasture associated recurrent airway obstruction
What is inflammatory airway disease?
- Any age
- e.g. Young horses entering training
- Performance limiting
- Can improve spontaneously - low risk of reoccurence
- Minimal signs at rest
What is recurrent airway obstruction?
- > 5yo (7yo+)
- Cough/Heave line at rest
- Recurrence - cannot be cured but managed
- Allergic
- +/- Genetic
What does asthma result in?
- Bronchoconstriction
* + cholinergic mediated bronchoconstriction
* - adrenergic mediated bronchodilation - Airway inflammation - cytokine mediated (neutrophils)
- Airway remodelling - increased smooth muscle, peri-bronchial fibrosis, epithelial cell hyperplasia
- Mucus accumulation - increased secretion + viscoelasticity + loss of mucocilliary escalator
= airway narrowing
What are environmental triggers for asthma?
- Moulds
- Bacteria / endotoxin
- Mites
- Plant debris / pollens
- Inorganic dust
- Noxious gases
How is asthma diagnosed?
- Auscultation (+/- wheezes + expiratory crackles)
- Endoscopy to assess mucus score
- Tracheal wash / aspirate
- Bronchoalveolar lavage
What increased are seen in neutrophils with IAD / RAO?
- Normal = <5% neutrophils
- IAD = >5% neutrophils
- RAO = >25% neutrophils
How is asthma treated?
- Environment
- Medication to get there (Bronchodilators + Corticosteroids)
- recurrence if poor environmental control
What is environmental control of asthma?
- turn out is best if housed - low dust bedding, cardboard, dust extracted shavings
- Feed from floor + wet concentrates - pasture / completed pelleted feed (Dry hay = bad)
- Avoid deep litter
What does corticosteroid used do with asthma?
- Reduce cell accumulation and activation
- Reduce vascular changes
- Reduce bronchoconstriction
- Prednisolone / Dexmethasone (systemic)
- Ciclesonide, budesonide (Inhaled)
- Best drug for controlling asthma
What do bronchodilators do?
- B2-adrenergic agonists - Clenbuterol / Salbutamol
- Muscarinic antagonists - Atropine / N-Butylscopolammonium bromide (Buscopan)
- Reduce bronchospasm
- Can cause paradoxical bronchoconstriction after long term use + systemic side effects at higher doses (Sweating, tachycardia, muscle fasciculations)
What agents can cause pleuropneumonia?
– Commensals/environmental organisms
* Strep equi subsp. zooepidemicus = most common
* Mixed infections common
* Aerobic & anaerobic infection
– Strep zoo,
E.Coli,
Actinobacillus sp.’s,
Pasteurella sp.’s,
Bacterioides,
Clostridium,
Fusobacterium
What are inciting causes of pleuropneumonia?
- Aspiration
-Choke/reflux/dysphagia - General anaesthesia
- URT viral infection (EI/EHV)
- Long distance travel (with head elevated)
->500miles or >12hours - Immunosuppression
- High intensity exercise
