Inflammatory Airway Disease

Question 1

What is inflammatory airway disease?

Answer 1

excessive mucoid or mucopurulent exudate in nasopharynx, trachea and bronchial bifurcation
nonseptic
mostly young performance horse
rarely ausculable
+/- cough and decreased performance
May be related to RAO (first stage) in mature horses

Question 2

What is the prevalence of IAD?

Answer 2

20-60% of racehorses

Question 3

What % of coughing horses have IAD

Answer 3

805%

Question 4

What is the definitive cause of IAD?

Answer 4

unknown, dust, etc low bacterial levels

Question 5

What are the clinical signs of IAD?

Answer 5

1. frequently subclinical
2. poor athletic performance
3. coughing
4. usualy afebrile
   +/- evidence of EIPH (blood in parenchyma may induce an inflam response)

Question 6

What is seen on endoscopic exam with IAD?

Answer 6

exudate in nasopharynx and trache

Question 7

What is seen on CBC/chemistry with IAD?

Answer 7

within normal limits

not a systemic response

Question 8

What should you do on transtracheal wash with IAD?

Answer 8

low numbers of bacteria–treat for that?

Question 9

What should you see on BAL? Why is it done

Answer 9

1. Mast cells >2% or PMNs >5% or eosinophils >1%
   (Havemeyer consensus)
   Important for diagnosis!!!

Question 10

What is treatment for IAD?

Answer 10

1. environmental alterations (decrease exposure to dust, mold, allergens)–horses fed w/ round bales
2. corticosteroids (R/O bacterial infection!)
3. bronchodilators
4. mast cell inhibitors: sodium cromoglycate
5. decrease EIPH

Question 11

What are mast cell inhibitors?

Answer 11

sodiuum cromoglycate

Question 12

What is heaves?

Answer 12

Recurrent Airway Obstruction (RAO)

Question 13

What horses get recurrent airway obstruction?

Answer 13

middle aged and older horses

Question 14

What is RAO?

Answer 14

overwhelming inflammatory disease in the airway

usually not septic

Question 15

What is RAO characterized n?

Answer 15

recurrent episodes (worse and better etc)
doesn't occur with IAD--one time event

Question 16

What is RAO associated with?

Answer 16

exposure to hay, straw, molds etc, older barns, etc
allergens and viruses, bacteria contribute to inflam
horses fed with round bales

Question 17

What is the etiology of RAO?

Answer 17

respirable organic dust, classicall hay and bedding
hypersensitivity reaction to organic dust or molds in poorly cured hay
pollens in some areas (summer pasture associated obstructive pulmonary disease)

Question 18

What fungi are common triggers of RAO?

Answer 18

aspergillus fumigatus

faenia rectivirgula

Question 19

What is the etiopathogenesis of RAO?

Answer 19

1. hypersensitivity
   asymptomatic horses devleop clinical dz within 4-6hrs of exposure to allergens
   neutrophilic influx to airwys coincides with clinical signs
   immunologic basis unclear
2. Chronic bronchiolitis–mucopus, bronchospasm, peribronchial infiltration, increased goblet cells, viscous mucus
3. nonspecific hyperresponsiveness (cold air, NH3, excercise)

Question 20

What chronic changes occur with RAO?

Answer 20

1. airway wall remodeling
2. mucus metaplasaia, smooth muscle hypertrophy etc
3. mucus accumulation (incrased production, viscoelasticity)–can’t clear
4. bronchospasm
   ???

Question 21

Why is it not uncommon to have bacterial infectio in RAO?

Answer 21

the clearance mechanisms are impaired, cannot clear the bacteria.

Question 22

Why do horses get hypoxemia?

Answer 22

decreased lung compliance

increased lung resistance etc

Question 23

What are the clinical signs of RAO?

Answer 23

1. chronic spontaneous cough
2. mucopurulent nasal discharge
3. accentuated expiratory effory
4. hypertrophy of external abdominal oblique and rectus abdominis muscles
5. normal or increased RR +/- resp distress
6. adventitious lung sounds (crackles, wheezes)
7. exercise intolerance
8. weight loss
9. usually afebrile

Question 24

What is heard on ausculatation with RAO?

Answer 24

1. wheezes

2. crackles

Question 25

What is heard on percussion with RAO?

Answer 25

normal or expanded lung field

Question 26

What is seen on thoracic radiography?

Answer 26

interstitial and bronchial pattern (diffuse)–differentiate from bacterial pneumonia

Question 27

What is seen with endoscopy and Trans endoscopic wash with RAO?

Answer 27

excessive mucus etc

Question 28

What is seen on BAL? (IMPORTANT!!!)

Answer 28

nonseptic inflam reaction
increase in mucus and nondegenerate neutrophils
neutrophils are usually

Question 29

How is RAO diagnosed?

Answer 29

1. arterial blood gas
2. atropine/glycopyrrolate (fewer GI effects) test
3. CBC
4. blood chemistry
5. intradermal skin testing (get many +)
6. serum allergen testing

Question 30

How is RAO treated?

Answer 30

1. environmental management
2. drugs
3. hyposensitization?

Question 31

What is the most important part of RAO treatment?

Answer 31

environmental changes

Question 32

What are environmental changes that can be do to reduce RAO?

Answer 32

1. keep on pasture
2. eliminate mold/dust
3. soak hay
4. good ventilation

Question 33

What is medical management of RAO?

Answer 33

1. corticosteroids
   a. systemic: (dex, pred)
   b. inhaled: fluticasone, beclomethasone
   nebulizers, aeromask (not made any more), metered dose inhalers

Question 34

What are too inhaltation devices?

Answer 34

1. aerohippus
2. equine haler
   decreases systemic effect of steroids because goes directly to lung but more expensive

Question 35

What are bronchodilators used?

Answer 35

beta adrenergics etc

Question 36

What are mucolytic and mucokinetic drugs that can be used?

Answer 36

dembrexine hydrochlorie, acetylcystine

Question 37

WHat are components of drug treatment in treating RAO?

Answer 37

corticosteroids
bronchodilators
mast cell inhibitors
maybe mucolytics, mucokinetics
antibiotcs if bacterial infection