Severe equine asthma, recurrent airway obstruction Flashcards
RAO or heaves definition
recurrent airway obstruction that is reversed by a change in environemtn or use of bronchodilators
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
Breeds predisposed to RAO
thoroughbred, arabian, morgan and standardbred
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)
What are some environmental factors causing RAO?
moulds
endotoxins
mites and their faeces
plant material
inorganic dust ingredients
gases -ammonia
Wat moulds/fungi can be causative to RAO
aspergillus fumigatus
faeni rectivirgula
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
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
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
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
When diagnosing RAO how does the x-rays look?
normal and concave diaphragm
increased interstitial pattern
Diagnosing RAO - what are the cytological procedures?
tracheal wash and BALF
How can RAO be diagnosed with BALF?
neutrophils persistent in the lungs after corticosteroid therapy
differential diagnosis to RAO
SPARAO
IAD
Pneumonia
Pleuritis
pulmonary fibrosis
thoracic neoplasia
lungworm infection
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
GGC given orally to RAO patients
prednisolone
dexamethasone
GGC given IM to RAO patients
dexamethasone, triamcinolone
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
