Inflammatory Airway Disease Flashcards
What is inflammatory airway disease?
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
What is the prevalence of IAD?
20-60% of racehorses
What % of coughing horses have IAD
805%
What is the definitive cause of IAD?
unknown, dust, etc low bacterial levels
What are the clinical signs of IAD?
- frequently subclinical
- poor athletic performance
- coughing
- usualy afebrile
+/- evidence of EIPH (blood in parenchyma may induce an inflam response)
What is seen on endoscopic exam with IAD?
exudate in nasopharynx and trache
What is seen on CBC/chemistry with IAD?
within normal limits
not a systemic response
What should you do on transtracheal wash with IAD?
low numbers of bacteria–treat for that?
What should you see on BAL? Why is it done
- Mast cells >2% or PMNs >5% or eosinophils >1%
(Havemeyer consensus)
Important for diagnosis!!!
What is treatment for IAD?
- environmental alterations (decrease exposure to dust, mold, allergens)–horses fed w/ round bales
- corticosteroids (R/O bacterial infection!)
- bronchodilators
- mast cell inhibitors: sodium cromoglycate
- decrease EIPH
What are mast cell inhibitors?
sodiuum cromoglycate
What is heaves?
Recurrent Airway Obstruction (RAO)
What horses get recurrent airway obstruction?
middle aged and older horses
What is RAO?
overwhelming inflammatory disease in the airway
usually not septic
What is RAO characterized n?
recurrent episodes (worse and better etc) doesn't occur with IAD--one time event
What is RAO associated with?
exposure to hay, straw, molds etc, older barns, etc
allergens and viruses, bacteria contribute to inflam
horses fed with round bales
What is the etiology of RAO?
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)
What fungi are common triggers of RAO?
aspergillus fumigatus
faenia rectivirgula
What is the etiopathogenesis of RAO?
- hypersensitivity
asymptomatic horses devleop clinical dz within 4-6hrs of exposure to allergens
neutrophilic influx to airwys coincides with clinical signs
immunologic basis unclear - Chronic bronchiolitis–mucopus, bronchospasm, peribronchial infiltration, increased goblet cells, viscous mucus
- nonspecific hyperresponsiveness (cold air, NH3, excercise)
What chronic changes occur with RAO?
- airway wall remodeling
- mucus metaplasaia, smooth muscle hypertrophy etc
- mucus accumulation (incrased production, viscoelasticity)–can’t clear
- bronchospasm
???
Why is it not uncommon to have bacterial infectio in RAO?
the clearance mechanisms are impaired, cannot clear the bacteria.
Why do horses get hypoxemia?
decreased lung compliance
increased lung resistance etc
What are the clinical signs of RAO?
- chronic spontaneous cough
- mucopurulent nasal discharge
- accentuated expiratory effory
- hypertrophy of external abdominal oblique and rectus abdominis muscles
- normal or increased RR +/- resp distress
- adventitious lung sounds (crackles, wheezes)
- exercise intolerance
- weight loss
- usually afebrile
What is heard on ausculatation with RAO?
- wheezes
2. crackles
