IAD Flashcards
What symptoms do horses with Heaves (Recurrent Airway Obstruction - RAO) and Summer Pasture-Associated RAO exhibit?
They exhibit marked lower airway inflammation and obstruction, frequent coughing, increased respiratory effort at rest, and exercise intolerance.
How can clinical signs and airway obstruction in horses with RAO be reversed?
By using corticosteroids, bronchodilators, or making environmental changes.
At what age does Recurrent Airway Obstruction (RAO) principally affect horses?
It principally affects horses over 7 years of age.
List the clinical signs of RAO.
Severe airway inflammation, frequent coughing, increased respiratory effort even at rest, and exercise intolerance.
What are the treatment options for RAO?
Administration of corticosteroids and bronchodilators, and environmental management to reduce allergens.
Which age group of horses is commonly affected by Inflammatory Airway Disease (IAD)?
Horses of all ages, but it is commonly reported in young horses.
What are the clinical signs of IAD?
Subtle signs including poor performance and occasional coughing, with normal breathing at rest.
Describe the nature of inflammation in IAD.
Mild inflammation with limited pulmonary dysfunction, requiring sensitive diagnostic methods for detection.
What diagnostic method reveals excess tracheobronchial mucus in both RAO and IAD?
Airway endoscopy.
What does BALF cytology show in both RAO and IAD?
Mild increases in neutrophils, eosinophils, and/or metachromatic cells.
How can pulmonary dysfunction be confirmed in both RAO and IAD?
By evidence of lower airway obstruction, airway hyperresponsiveness, or impaired blood gas exchange.
What systemic signs of infection exclude a diagnosis of RAO or IAD?
Anorexia, lethargy, fever, and hematologic abnormalities.
What respiratory effort at rest excludes a diagnosis of IAD?
Increased respiratory effort at rest.
What term is used to describe horses with airway disease ranging from mild (IAD) to severe (RAO)?
Equine asthma syndrome.
Name two similarities between equine asthma syndrome and human asthma.
Chronic airway inflammation and respiratory symptoms such as coughing, difficulty breathing, and expiratory airflow limitation.
Does IAD necessarily progress to RAO over time?
No, IAD does not necessarily progress to RAO over time.
Which age group is more commonly reported to be affected by IAD?
Young horses.
What clinical signs are associated with IAD?
Poor performance and chronic (>3 weeks) occasional coughing.
What should be ruled out if poor performance is the only complaint in IAD suspected horses?
Non-respiratory causes must be ruled out.
What diagnostic methods confirm IAD?
- Airway endoscopy revealing excess tracheobronchial mucus (score ≥2/5 for racehorses and ≥3/5 for sports/pleasure horses).
- Bronchoalveolar lavage fluid (BALF) cytology showing mild increases in neutrophils, eosinophils, and/or metachromatic cells.
- Documenting pulmonary dysfunction through lower airway obstruction, airway hyperresponsiveness, or impaired blood gas exchange.
What are the exclusion criteria for diagnosing IAD?
Evidence of systemic signs of infection such as anorexia, lethargy, fever, hematologic abnormalities, and increased respiratory effort at rest.
What are the general clinical signs of IAD in horses?
The signs are generally nonspecific and subtle.
How is decreased performance in horses with IAD characterized?
It is associated with excess tracheal mucus but not with tracheal wash neutrophilia, BALF neutrophilia in racehorses, delayed recovery of respiratory rate after exercise, exaggerated respiratory effort during work, and is limited by impaired pulmonary gas exchange.
What are the specific signs of decreased performance in IAD-affected horses during intense exercise?
Intensely exercising horses with IAD exhibit worsening of exercise-induced hypoxaemia, and lower speeds of exercise are obtained with a blood lactate concentration of 4mmol/l.
Describe the nature of the cough in horses with IAD.
It is a chronic, intermittent cough lasting more than 3 weeks, associated with increased neutrophil proportions in BALF, and can occur both at rest or during exercise. Occasional coughing can indicate an increased risk of developing RAO, and the absence of a cough does not rule out IAD.
How effective are questionnaires in identifying cases of severe airway inflammation like RAO compared to IAD?
Questionnaires are effective in identifying cases of severe airway inflammation like RAO, but their usefulness for distinguishing IAD-affected horses from controls based on owner-reported clinical history seems limited.
What does thoracic auscultation typically reveal in IAD-affected horses?
Thoracic auscultation usually does not reveal abnormalities, but some IAD-affected horses can exhibit increased breath sounds or subtle wheezes, particularly during rebreathing manoeuvres.
What is the significance of serous to mucopurulent nasal discharge in Thoroughbred racehorses in training?
It is commonly observed, with some indication of an association between increased nasal discharge and increased tracheal mucus in older racehorses. Nasal discharge can also indicate an increased risk of later developing RAO.
What does airway endoscopy reveal in horses with IAD?
It reveals excess tracheobronchial mucus.
What scoring system is used for airway endoscopy in racehorses and sports/pleasure horses?
A score of ≥2/5 for racehorses and ≥3/5 for sports/pleasure horses.
What does bronchoalveolar lavage fluid (BALF) cytology show in horses with IAD?
It shows mild increases in neutrophils, eosinophils, and/or metachromatic cells.
What is chronic cough associated with in BALF cytology?
Increased neutrophils in BALF.
How is impaired blood gas exchange assessed in horses with IAD?
Through blood gas analysis during and after exercise.
What does thoracic auscultation typically reveal in IAD-affected horses, and what can be observed in some cases?
Thoracic auscultation typically does not reveal abnormalities, but some IAD-affected horses may exhibit increased breath sounds or subtle wheezes, especially during rebreathing manoeuvres.
How is IAD pathogenesis defined?
It remains incompletely defined with multiple etiological agents potentially involved.
WWhat environmental factor is linked to IAD development in horses?
High levels of aerosolized particles and gases in stables.
What are the components of the respirable fraction contributing to IAD?
Organic particles (fungi, moulds, endotoxin, beta-D-glucan, microorganisms, mite debris, vegetative material), inorganic particles (ultrafine particles <100 nm, inorganic dusts), and noxious gases.
How do aerosolized allergens and endotoxins contribute to IAD?
They induce inflammation in the respiratory tract, with high eosinophil and mast cell counts in BALF, along with Th-2 cytokines (IL-4 and IL-5) indicating aeroallergens’ role.
What effect does dust exposure have on older horses?
Exposure to high levels of organic dust and endotoxin results in mild to moderate BALF neutrophilia.
How do environmental factors like cold, dry environments affect IAD?
They might contribute to BALF neutrophilia, but their role is likely limited.
What does dysregulation in inflammatory cell homeostasis lead to?
It leads to clinical signs of variable severity in IAD.
What are the specific inflammatory cells in BALF indicating different types of IAD?
Metachromatic cells (associated with airway hyperreactivity and subclinical pulmonary obstruction) and neutrophilic IAD (linked with cough and tracheal mucus presence).
What is the mucus scoring system used in endoscopy for horses with IAD?
Grade 0: No visible mucus.
Grade 1: Single to multiple small blobs of mucus.
Grade 2: Larger but non-confluent blobs.
Grade 3: Confluent or stream forming mucus.
Grade 4: Pool forming mucus.
Grade 5: Profuse amounts of mucus.
