Severe equine asthma, recurrent airway obstruction Flashcards by Silje Mørk

RAO or heaves definition

recurrent airway obstruction that is reversed by a change in environemtn or use of bronchodilators

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What are the different RAO phenotypes?

Airway neutrophilia

Airway obstruction - bronchospasm

Mucus accumulation in airways

Bronchial accumulation in airways

Bronchial hyperactivity

poor performance, exercise intolerance

airway remodelling

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Breeds predisposed to RAO

thoroughbred, arabian, morgan and standardbred

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aetiology of RAO

complex genetics

(RAO and IL-4 receptor gene

RAO and decreased strongyle egg sheding

RAO and increased risk of allergic skin disease)

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What are some environmental factors causing RAO?

moulds

endotoxins

mites and their faeces

plant material

inorganic dust ingredients

gases -ammonia

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Wat moulds/fungi can be causative to RAO

aspergillus fumigatus

faeni rectivirgula

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What is meant by summer.pasture associated RAO? (SPARAO)

time when the clinical signs gets worse due to

warm and humid weather

high fungal spore concentration

high pollen concentration

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RAO has many different pathogenesis, mention some of them

complex immune-mediated hypersensitivity
probably type IV allergic reaction is the most important
Oxidative stress
matrix metalloproteinase
release of inflammatory mediators
bronchospasma
increased mucus production
airway remoddeling

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Describe the lung function in RAO

airway is obstructed leading to inceased pulmonary resistance and decreased compliance. The hor has to increase the respiratory effort to acheve the necessary todal volume.

this will lead to a ventilation-perffuison mismatch and hypocaemia

increased respiratory drive + airway obstruction will give hives

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what kind of dyspnoea will a RAO horse have

expiratory

abdomnial respiratory component - not synchronized ith outflow, increased oxygen and energy consumption contributing to cahexia

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When diagnosing RAO how does the x-rays look?

normal and concave diaphragm

increased interstitial pattern

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Diagnosing RAO - what are the cytological procedures?

tracheal wash and BALF

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How can RAO be diagnosed with BALF?

neutrophils persistent in the lungs after corticosteroid therapy

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differential diagnosis to RAO

SPARAO

IAD

Pneumonia

Pleuritis

pulmonary fibrosis

thoracic neoplasia

lungworm infection

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What are the environemntal managemet measures taken - known as air hygiene, to treat RAO?

pasture turnout

external stable for the sick horse

good ventilation

separte air-space from hay and straw

alternative beddings

alternate roughage instead of dry hay

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GGC given orally to RAO patients

prednisolone

dexamethasone

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GGC given IM to RAO patients

dexamethasone, triamcinolone

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Drug categories of bronchodilators

B2- adrenergic agents

Anticholinergic agents

MEthyl xanthine derivatives

B2-adrenergic agents given to RAO patients

celbuterol

salbutamol/albuterol

salmetrol

anticholinergic agents given to RAO patients

atropine sulphate - IV

glycopyrrolate

ipratropium bromide - inhaled

methyl xanthine derivatives

aminophylline

pentroxifyline

mucolytics goven to RAO patients

dembrexine

acetylcystein

bromhexine

Exercise induced pulmonary hemorrhage (EIHP) definition

rupture of microbronchial and alveolar capillaries in the caudodorsal lung segment during exercise - often in exhausting competitions, racehorses, three-day-eventers - showjumpers

What are the cuases and pathogenesis of EIPH?

unknown origin

lesions of the capillary wall

genetic predispostion

small airway disease

environemtnal

RAI, IAD,resp infection

How can mechanicla forces cause EIPH?

pressure of the diaphragm and forelimb locomotory impact forces the capillary pressure forces open the pareital connection of the endothelial and epithelial cells

Clinical signs of EIPH

foamy, light red nasal discharge

How can EIPH be treated?

With furosemide it should be given before the competition it will improve the state of the capillary walls also vitamin C, flavenoids and conjugated estrogens

Causative agents of pneumonia - pleuropneumonia

secondary to viral infections, aspiration, bacteremia immunosuprresion, alterations in mucociliar clearance

predisposing factors of pneumonia

strenous exercise transportation faults of stable managementgeneral anesthesia

Aetiological agents for pneumonia

streptococcus equi staphylocccus aureus E.coli klebsiella pneumoniae bordetella bronchisepica pasteruelle, bacteroides, clostridium Actinobacillus equuli, suis

hy do an ultrsound when suspecting pneumonia?

check quantity and quality of fluid check for gas echos and help with the positioning for sampling

What is the prognosis if anaerob bacteria are found during thoracocentesis?

poor

What is the course of treatment for pneumonia?

* first: AB therpay * drainage * long term antibiotics therpay * NSAIDS * bronchidilator, muoltics inhalation * fluid and electrolyte therapy, energy supply * stall rest

In what case will rhodococcus equi cause pneumonia?

during specific weather conditions when the maternal immunity is decreasing if there is a EHV-2 infection or a extrapulmonary ongoing disease

How can a horse be infected with rhodococcus equi?

aerogen route from soil or other foals

Clinical signs of rhodococcus equi

resp symptoms growth retardation, weaker, poor haircoat fibrinogen level will increase neutrophil granulocytes

How is r.equi infection seen on X-ray?

nodular increase in radiodensity so we can see nodular interstitial pattern and air bronchograms

How is R.equi diagnosed with ultrasound?

cna see abscess in the peripheral lung field

What treatment is the best choice for R.equi?

clarithromycin with rifampin

What should you be aware of when giving macrolides to foals (rifampin)

hyperthermia can occur

How can R.equi be prevented?

Separation Cleaning of pastures and stables Avoidance of overcrowded conditions Vaccination against EHV-2 Vaccination against Rh. Equi Supportive therapy