Consensus Statements Flashcards
With reference to asthma, what is the typical age distribution for mild (IAD) versus severe (RAO)?
RAO 7 yrs plus
IAD any age
Is equine asthma a disease continuum in which horse with IAD should be expected to progress to RAO?
No, although they may be at higher risk.
What are the typical characteristics of racehorses with IAD?
Coughing, increased tracheal mucous and high bacterial counts
List features of the IAD phenotype of asthma that can be used for diagnosis of this condition.
- Poor performance with or without chronic coughing
- Airway mucous grade >2/5 for racehorses >3/5 for sports horses
- BALF neutrophilia, eosinophils and or metachromatic cells
- If PFT available evidence of pulmonary dysfunction seen as lower airway obstruction, hyperresponsiveness, or impaired blood gas exchange
- Exclusion of systemic diseases that could result in these signs.
Are abnormalities on thoracic auscultation expected in horses with IAD?
Usually not but subtle wheezes and increased breath sounds may be heard, particularly with rebreathing examinations.
Which features indicate and increased risk of later development of RAO?
- Occasional cough
- Nasal discharge
List potential contents of the respirable fraction in a stable
- Organic and inorganic particles including
- Fungi
-Moulds - Endotoxins
- Beta-D-Glucan
- Ultrafine particles
- Microorganisms
- Vegetative material
- Inorganic dusts
- Noxious gases
What does the presence of increased eosinophils and mast cells along with Th-2 cytokines such as IL-4 and IL-5 in BALF suggest?
A role for aero allergens
True or false: predominance of metachromatic cells indicates airway hyperreactivity and presence of increased neutrophils has been associated with cough and tracheal mucous?
True
True or false: BALF neutrophilia occurs more commonly in young horses whereas airway eosinophilia has been associated with Coughing?
False. Eosinophilia is more common in young horses (<5yrs) whereas neutrophilia is more often in older horses and associated with coughing.
Which inflammatory mediators are associated with an innate immune response and BALF neutrophilia compared with those suggesting involvement of the adaptive immune system and mast cells?
Increased expression of genes encoding for TNF-a, IL-1B and IFN-y have been linked to luminal neutrophilia and suggest activation of the innate immune response and Th-1 polarisation may be involved in the pathognesis. Likewise mRNA expression of IL-17 and IL-23 have been linked with increased neutrophils while increased IL-4 and IL-5 with the matocytic form supporting implication of the adaptive immune response including Th-2 polarisation.
True or false: there is no conclusive evidence about the relationship between bacterial and viral infections and IAD.
True
What volume of fluid is administered for BAL and what cut off values are proposed for diagnosis of IAD versus RAO?
250-500mL 0.9% NaCl
IAD: neut <5%, eosinophils <1%, metachromatics <2%.
Total nucleated cell count <530 cells/uL
RAO: >25% neutrophils.
True or false: Tracheal mucous score was positively associated with neutrophil percentage but negatively correlated with mast cell percentage
True, by some authors.
True or false: doubling the infusate volume (ie using 500ml instead of the more commonly used 250mL) requires doubling the cut off values?
True. If using 500mL infusate the cut off for IAD neutrophil percent becomes 10% instead of 5%.
True or false: tracheal wash cytology has been correlated well to poor performance.
False. There is a lack of association between TW cytology and poor performance.
Gas exchange is impaired during exercise in horses with IAD, and more sensitive lung function tests such as forced expiration and impulse oscillometry indicate that horses with IAD have detectable airway obstruction. Airway hyperresponsiveness is a prominent feature of IAD, in particular with which cell types?
Increased eosinophils and mast cells.
The development of bronchoconstriction, airway hyperresponsiveness and cough are likely the airways response to what?
Inhaled irritants
How might IAD be differentiated from RAO?
- Severity of exercise intolerance
- Evidence of increased respiratory effort at rest in RAO only
- Severity of airway neutrophilia and mucous.
There is weaker evidence for a role of bacterial bronchitis (Strep zoo, S. pneumoniae) as an aetiological factor in IAD in which horses more commonly?
Typically young horses and those that have recently entered training.
Differentiate IAD from parasitic infections and EIPH from IAD?
The eosinophilic inflammation in BALF from horses with parasitic pneumonitis or eosinophilic pneumonia is usually more severe.
EIPH usually causes macrophagiv bronchiolitis and fibrosis and the haemorrhage is almost exclusively from the caudodorsal lung fields.
True or false: some studies have shown an additive effect on clinical signs, airway neutrophilia and inflammatory cytokines in horses with RAO when combining corticosteroid Tx with measures to improve air quality.
True
List medications for systemic and inhaled treatment of asthma
Systemic:
- Dex 0.05mg/kg SID
- Pred 1.2-2.2mg/kg SID
- Aminophylline 6-12mg/kg BID
- Clenbuterol 0.8-3.2ug/kg BID
- Pentoxifylline 35mg/kg BID
- Omega 3 fatty acids 1.5g DHA SID
Inhaled puffers:
- Beclomethasone 1-8ug/kg BID
- Fluticasone 1-6ug/kg BID
- Albuterol 1-2ug/kg q1-3h
- Ipratropium bromide 0.2-0.4ug/kg q812h
- Dex nebuliser 5mg diluted 1:1 in saline q12-24h
Inhaled nanoparticles of cytosine phosphate-guanosine oligonucleotides have been shown to decreased neutrophil percentage in TW and mucous secretions as well as improve lung function and clinical signs in horses with RAO - what is the mechanism behind this response?
Inducing a Th-2/Th-1 shift.