Unit 1 - Athsma Flashcards
What is Severe Asthma (SA) also known as? What about Mild to Moderate Asthma?
Heaves (Recurrent Airway Obstruction (RAO), Small Airway Disease, COPD, Broken Wind, Hay Sickness, SPAOPD)
Mild to moderate: Inflammatory Airway Disease (IAD)
Describe the character of inflammatory respiratory conditions of the horse.
- Excessive Airway Mucus Production
- Airway Neutrophilia
- Bronchial Hyperreactivity
- Reversible Bronchospasm (usually)
What geographic locations are high prevalence of equine asthma? What feeding forms are risk factors?
Environment - Regions of cool and wet weather like the northeast and midwest.
Stabling and hay feeding, especially round bales in round bale feeders.
Following exposure to inhaled triggers, ______ ________ have upregulated gene expression of TNF-a, IL-1B, and IL-8, among other cytokines and factors.
alveolar macrophages
______ production, which attenuates neutrophil chemotaxis, is reduced in RAE affected horses and suggests an absence of an inflammatory braking system.
secretoglobin
True or false: Th17 cells are increased in equine RAO in addition to increased IL-17 at IL-8.
true - the roles of lymphocytes are unclear at this time
What do mast cells and histamine do in RAO? Do antihistamines provide therapeutic relief to RAO horses?
They increase vascular permeability and bronchoconstriction.
They do not provide relief to RAO horses.
Are NSAIDs and COX inhibitors effective in providing bronchodilation and bronchoconstriction to give relief to RAO horses?
Nope - there’s a lack of therapeutic response in RAO horses even though these treat prostaglandin inflammatory mediators.
True or false: Miniature horses and standardbreds are predisposed to RAO.
False - There is no gender or breed predisposition, but the average age of horses with RAO is 7 years old. There is a genetic component - horses are more likely to get it if at least one parent has RAO.
What seasons increase severity of asthma?
winter (stabling time) and summer due to the increase in airborne pollen and molds
What are some of the common clinical signs of equine asthma?
Coughing
Nasal discharge (after exercise or head lowering)
Exercise intolerance
Abnormal breathing effort/difficulty
With increased severity, tachypnea, nasal flaring, and heaving may be noted.
What heart condition may occur in horses with long standing RAO?
Cor pulmonale (RV dysfunction) with jugular distension, pulsation, ventral edema, and tachycardia. PA enlargement is likely in these cases.
How does pulmonary fibrosis or interstitial disease differ from RAO?
Cases of severe pulmonary fibrosis or interstitial disease result in restrictive pulmonary disease while RAO causes increased expiratory effort, characterized by marked inspiratory distress (obstructive).
What will BAL cytology find in a horse with severe asthma? What about mild asthma?
Severe (RAO): >20-25% neutrophils, Mild: >5% neutrophils
Normal or RAO-remission BAL should reveal >90% macrophages and lymphocytes.
Microscopic inspissated airway mucus and cellular debris is often identified and known as _____ _____.
Curschmann’s spirals
What might you see on CBC/Chem and Arterial blood gas in a horse with severe asthma?
CBC/biochem: stress leukogram +/- acute phase proteins
ABG: hypoxemia and hypercapnia (<85% PaO2)
True or false: intradermal skin testing has been extensively researched and allows for the identification of RAO-susceptible or affected horses.
FALSE
What are the four measurements and findings in RAO affected horses in which you perform pulmonary function testing?
- ) Dynamic lung compliance (Cdyn): Decreased (reflects changes in peripheral airways)
- ) Pulmonary resistance (RL): Increased (reflects changes in central/large airways)
- ) Maximal pleural pressure changes((delta)Pplmax): Increased (>15 cm H2O)
- ) Peak inspiratory and expiratory flow rates: Increased
Are pulmonary artery pressure and pulmonary vascular resistance increased or decreased in RAO cases?
Significantly increased - Airways that are narrowed, obstructed, or both result in increased pulmonary resistance and fail to participate in efficient gas exchange.
How do clinical RAO lungs appear on gross pathology?
On gross pathology, clinical RAO lungs fail to collapse and may have rib impressions (hyperinflation), however animals in remission may have normal appearing lungs.