Equine asthma syndrome Flashcards
IAD = ?
RAO = ?
SPAORD = ?
And what do all of the above have in common?
IAD = inflammatory airway disease
RAO = recurrent airway obstruction
SPAORD = summer pasture-associated obstructive respiratory disease
They all belong under the same “asthma” umbrella.
Etiology of mild asthma.
- Multifactorial and not 100% clear.
- Non-infectious agents like particles < 100nm, mite debris.
- Immune system dysfunction involving hypersensitivity to pollens, molds, etc. other things.
- Infectious agents like bacterial infection, viral infection.
- EIPH (Exercise-Induced Pulmonary Hemorrhage) and Equine asthma are connected?
Clinical signs of mild asthma in horses.
- Poor performance
- Increased respiratory effort during exercise
- Prolonged recovery after exercise
- ± coughing
- ± nasal discharge
- No increased respiratory effort at rest.
- No sign of systemic infection
Etiology of severe asthma.
- Exposure to organic dust e.g. during stabling, feeding.
- Inflammatory response to inhaled molds,
endotoxins etc. - Some genetic susceptibility is involved.
SPAORD = summer pasture-associated obstructive respiratory disease or equine pasture asthma seems to be
* a hypersensitivity to environmental allergens
* seasonal: late spring → early autumn
Clinical signs of severe asthma.
- Exercise intolerance
- Respiratory distress at rest
- Abdominal expiratory phase
- „Heave“ line
- Nostril flaring
- Coughing Regularly and Frequently
- Nasal discharge
- Weight loss if condition is severe.
More in mature horses.
Diagnosis of equine asthma involves: (7)
- History
- Clinical signs
- Hematology and serum biochemistry
- Endoscopy
- BAL cytology
- Exclusion of severe equine asthma and
infectious causes/other respiratory diseases.
Tx trial with
* Short-acting bronchodilator systemically e.g. Atropine, butylscopolamine
* Does the horse respond or not?
What are thoracic radiographs for when suspecting equine asthma?
Useful to rule out other pulmonary diseases
What are blood gases for when suspecting equine asthma?
- Abnormal gas exchange at rest with severe asthma
- Hypoxemia and sometimes hypercapnia
- But with mild clinical signs you should have normal blood gases
Tx of equine asthma.
Environmental changes to decrease environmental irritants to airways:
* Horses out 24/7, better ventilation than stabled.
* No dry hay (soak it or use cubes)
Medical therapy:
* Reduce bronchoconstriction
* Control airway inflammation both systemically (side effects, longer elimination) and aerosolized (easy, safe, expensive).
Bronchodilators alone aren’t enough as they don’t reduce inflammation. Should be administered prior to inhalation therapy with corticosteroids.
Describe Aerosol therapy for equine asthma.
Salbutamol 360 – 720 mcg/450 kg horse MDI (metered dose inhaler) or nebulised
* Short acting (30 – 60 min)
* Most useful in treatment of acute bronchoconstriction.
Salmeterol 210 mcg/450 kg horse via MDI q6-12h
* Effective in 30-60min
* Lasts for 2-8h
Salmeterol + fluticasone
Fluticasone 1000 – 2500 mcg/450 kg horse via MDI or nebuliser q12-24h
* Most potent
* Less systemic effects
Systemic corticosteroids for equine asthma.
Dexamethasone
* Time of onset 2hrs
* 0,02 – 0,2 mg/kg IM q24h
* 0,02 – 0,2 mg/kg PO q12 –24h
* 0,05 – 0,2 mg/kg IV q12 –24h
Prednisolone
* 0,2 – 1 mg/kg PO q12 –24h
* Dose of 1 mg/kg is antiinflammatory
* Higher doses (0,2 – 4,4 mg/kg) are immunosuppressive.
Triamcinolone acetonide
* Long-acting (2 – 4 weeks)
* 0,02 – 0,05 mg/kg IM
What is Sodium cromoglycate (cromolyn)?
Mast cell stabilizer drug used in hte the ts of equine asthma.
- Decreases bronchial hyperresponsiveness if there is high mast cell count in BAL fluid.
Prognosis for equine asthma.
Mild asthma:
* good chance of returning to previous level of performance
* In some cases the disease can occur though.
Severe asthma:
* these horses are likely to develop acute
exacerbations.
* Permanent environmental changes needed.
* Weather conditions dependent?
* More difficult to manage as the horse ages.
* People fail in MANAGEMENT usually.
