Week 9- Equine Lower Respiratory Tract Disorders Flashcards
What are the three main signs of an airway disease in horses?
- Cough
- Nasal Discharge
- Abnormal breathing patterns/ Sounds
What is a normal breathing pattern in horses?
- 8-16 bpm
- minimal chest or abdominal wall movement
What is an abnormal breathing pattern in horses
- Increased rate/ depth
- any changed breathing pattern should be noted
- any abnormal sounds associated with breathing
What is expiratory dyspnoea?
exaggeration of the biphasic expiratory phase with
increased incorporation of the abdominal muscles →
producing an obvious biphasic or double expiratory
lift: ‘heave
typical of small airway obstruction
What is inspiratory dyspnoea?
associated with a stertorous or stridorous noise
during inspiration
Indicative of upper airway obstruction
Occasionally, inspiratory dyspnoea may occur with
severe restrictive lung diseases (e.g. pneumonia,
interstitial disease, pneumothorax, rib fracture)
What is combined inspiratory and expiratory dyspnoea?
Suggestive of severe upper or lower airway
obstruction, diffuse pulmonary disease or pleural
disease
What may cause a ‘crackling’ sound?
‘popping’ open of airways that were
closed during expiration;
= ‘bubbling and crackling’ sounds caused
by air bubbling through excessive mucus
in the airway
What may cause a ‘wheezing’ sound?
musical notes produced by air flowing
through narrowed airways
What does pleural friction sound like?
‘crunching/creaking’ sounds due to the
rubbing together of inflamed pleural
surfaces
What is mild and severe asthma in horses also known as?
- Mild = inflammatory airway disease
- Severe= recurrent airway obstruction
What does mild Equine Asthma look like clinically?
- Common in young performance horses
- Intermittent coughing (38% of cases)
- Nasal discharge
- Lung auscultation- usually normal sounds
What causes mild equine asthma?
- Poor ventilation
- Dusty hay/ bedding
- Infectious agents
What does severe equine asthma look like clinically?
Common in mature horses and ponies
→ (usually > 7 years old)
* Subacute-chronic presentation
* Abdominal effort/nostril flaring
* Coughing
* “Wheezes and crackles
What causes severe equine asthma?
- Poor ventilation:
→ Dusty hay/straw bedding (moulds)
→ NH3, H2S,…. - Seasonal environmental allergens
What is the pathophysiology of severe equine asthma?
- Airway hyperesponsiveness
- Inflammation
1. Increased mucus prodcution
2. Bronchospasm
3. Airway remodelling
How would you treat severe equine asthma medically?
- Glucocorticoids
- B2 adrenergic agonists
- Muscarinic antagonists
- Furosemide
How would you treat severe equine asthma environmentally?
- Manage from the pasture
- minimise dust levels in the stable
- avoid overhead lofts
- feed complete diets
- consider using a dust extractor
What does RDC stand for?
respirable dust
concentration
= defined as the portion that is
of a sufficiently small
aerodynamic size (usually with
a diameter of <5 μm) to allow
penetration of the peripheral
(= smaller) airways
What may cause an infectious airway disease?
- Viral: EHV, EIV, ERV, (EVA)
- Bacterial: Streptococci,
Actinobacillus,
Rhodococcus etc. - Parasitic: Dictyocaulus
What are the two most common types of equine herpes virus?
- EHV-1
- EHV-4
When is Equine Influenza Virus most common?
Most common in horses commingled under stressful conditions
* Viral spread: through aerosolization of viral particles + fomites
* short incubation period (1 to 3 days)
* high fever, depression, paroxysmal and persistent coughing, nasal discharge (serous →
mucopurulent), submandibular lymphadenopathy, myositis, anorexia
* Horses with influenza = at risk of secondary bacterial infection that may progress to
bronchopneumonia and/or pleuropneumonia
How might you treat bacterial pneumonia?
Broad-spectrum antibiotic + general
supportive care
→ When disease is severe or chronic or involves marked
immunosuppression: guarded prognosis!
What is rhodococcus equi?
Gram-positive, intracellular bacteria → causes chronic suppurative
bronchopneumonia with abscessation
* Foals: 1–5 months of age
What are the clinical signs of rhodococcus equi?
mild and nonspecific early in the course of disease
* become more pronounced as pneumonia progresses
* cough, fever, lethargy, and increased respiratory effort – respiratory
distress.
