Equine Respiratory Diseases Flashcards
what are the overarching types of respiratory disease?
URT
LRT
are horses always systemically unwell when they have respiratory diseases?
no
what are disorders of the respiratory system second only in importance to in limiting athletic performance?
musculoskeletal
what issues would you expect to present at birth?
congential
what respiratory issues would you expect to present at 1-6 months?
Rhondococcus infection
what respiratory issues would you expect to see in weanlings/yearlings?
viral and bacterial URT infections
what respiratory issues would you expect to see in performance horses?
exercise induced pulmonary haemorrhage (EIPH)
inflammatory airway disease (IAD)
what respiratory issues would you expect to see in middle aged horses?
asthma
what about a horses environment or the environment it was exposed to help may be useful when looking at history?
mixing with new horses
local endemic infections
vaccination history (if so and when)
exposure to dust (bedding, feed or that of their neighbor)
what about prior medical issues may help to diagnose current respiratory issues?
may be related to current complaint e.g. viral disease may precede bacterial
what questions should be asked when gaining history about the presenting respiratory problem?
last normal
slow or quick onset
signs
did signs come on after strenuous exercise or following long distance travel
are there any new arrivals on the yard who have not been quarantined
signs seen at rest or only at exercise
what elements must be assessed in the physical exam of a patient with suspected respiratory disease?
demenour stance nasal discharge SM lymph nodes RR respiratory effort heave line
what will the horses stance be like if they are finding it difficult or painful to breathe?
head and neck extended with elbows abducted
what is normal RR in horses?
8-10 brpm
what should respiratory effort be like in a healthy horse?
difficult to see breathing occurring - if visible there is probably an issue
what is rectus abdominus hypertrophy?
increased definition of rectus abdominus due to chronically increased respiratory effort
when auscultating the lungs may the horse appear normal at rest even if unwell?
yes
what should be done if a horse isn’t showing increased respiratory effort and sounds normal at rest?
rebreathing
describe the process of rebreathing to assess horses respiratory function
cover nose with a bag to increase CO2 levels and cause them to breathe harder and more deeply
auscultate throughout and then as bag is removed
what is the purpose of rebreathing during auscultation?
patient will breathe more deeply which will enable you to hear any crackles more clearly
why should you continue to auscultate the chest after bag is removed during rebreathing?
there will be a large breath after rebreathing ends which is useful to hear any lung sounds
what sampling techniques are available when testing for respiratory disease?
nasal swab
naso-pharyngeal swab
tracheal wash
brochoalveolar lavage
what imaging techniques are available to test for respiratory diseases in horses?
endoscopy
x-ray (head, thorax)
CT (head)
ultrasound (larynx, thorax)
when is endoscopy useful?
for all respiratory diseases
where should the endoscope be passed through the nose?
up ventral meatus
what can be examined by endoscopy?
URT down to tracheal bifercation
gutteral pouches
URT during exercize
what is the function of gutteral pouches?
unknown - special adaption of horses
what happens during sinoscopy?
sinuses are scoped via a trephine or a flap
how many views of the head need to be taken if using radiographs to diagnose respiratory disease?
many views
what views of the thorax may be taken by radiographs?
lateral to lateral thorax
how many plates are needed to fit the entire equine chest on x-ray?
around 5
what is the best imaging modality for the head in the standing, sedated horse?
CT
what can be imaged with CT in the horse?
nasal turbinates para-nasal sinuses teeth nasopharynx gutteral pouches skull
what is the issue with MRI for horses?
they are mostly to big to fit their head into a scanner
what level of sedation is required for equine CT?
standing sedation
what are the main methods of sampling respiratory secretions?
nasopharyngeal or nasal swab
washes
what can samples of the respiratory tract gained by swabs be used for?
bacterial culture
viral tests
PCR
what sample tubes are needed to collect washes?
EDTA - cytology
plain - culture
where does tracheal wash sample cells from?
the level of the tracheal pull
what cells are sampled during tracheal wash?
respiratory secretions and cells that accumulate in the trachea and are a collection from the entire respiratory tract
where does bronchoalveolar lavage happen?
at the level of the lungs
what cells are sampled by bronchoalveolar lavage?
specific peripheral lung segment
where is the tracheal pull?
level of the neck where the trachea slopes less and so secretions collect
what is the most common wash used in practice?
tracheal wash
what are the benefits of tracheal wash?
general sample
less invasive
what is the disadvantage of tracheal wash?
cells have degenerated so less accurate
what is the advantage of bronchoalveolar lavage?
more accurate
what are the disadvantages of bronchoalveolar lavage?
more invasive
sedation and LA required
only samples a specific area so may miss disease
what equipment is needed for bronchoalveolar lavage?
long scope or a BAL tube
what signs will the horse show during a BAL?
will cough a lot
how far should the tube/scope be advanced for BAL?
should be as far into the lung as possible and stuck
what must be done once BAL tube/scope is stuck in the lung?
keep pressure (scope) or inflate the cuff (tube)
how much fluid needs to be instilled into the lung during BAL?
300-500ml
how much of the fluid should be drawn back to be sampled during BAL?
50-80%
what indicates a BAL sample is good?
froth (is surfactant)
what is ultrasound used for in respiratory medicine?
peripheral lung disorders
what may ultrasound need to be combined with in order to gain full picture when diagnosing respiratory disease?
x ray
what is the most common presenting complaint for horses with disorders of the nasopharynx and larynx?
abnormal respiratory noise during exercise
how can respiratory noise during exercise be heard?
audible stood near the horse while exercising without stetheoscope
depending on the severity of the disorder and the sue of the horse what are disorders of the larynx and pharynx likely to cause?
poor athletic performance
exercise tolerance
what is DDSP?
dorsal displacement of the soft palate
what happens during DDSP?
soft palate comes over the top of the epiglottis
when does DDSP most commonly occur?
racehorses during strenuous exercise but can be seen in sport or pleasure horses
what signs is DDSP associated with?
poor performance
abnormal expiratory noise (gurgle)
why is DDSP associated with poor performance?
reduced air supply as size of larynx is reduced
how is DDSP diagnosed?
exercising endoscopy
what causes DDSP?
not understood
what treatment is available for DDSP?
conservative treatment such as rest
surgery
what surgical options are available for DDSP?
soft palate cautery
laryngeal tie forward
what is the aim with soft palate cautery to treat DDSP?
idea is to stiffen soft palate so it can’t flap about and displace
what occurs during a laryngeal tie forward?
larynx is pulled forwards
what is the benefit of a laryngeal tie forwards?
if the larynx is further forwards then it is harder for the palate to displace
what is arytenoid cartilage collapse also known as?
recurrent laryngeal neuropathy (RLN)
laryngeal hemiplegia (LH)
laryngeal paralysis
what is arytenoid cartilage collapse thought to be caused by?
recurrent laryngeal neurophathy
how does arytenoid cartilage collapse occur?
recurrent laryngeal nerve innervates cricoarytenoideus dorsalis muscle which abducts the arytenoid cartilages and so opens the larynx
left nerve is really long so the end dies off leading to affected left side of larynx as muscle can no longer abduct cartilage
what are the clinical signs of arytenoid cartilage collapse?
inspiratory noise (whistling, roaring) exercise intolerance
how is arytenoid cartilage collapse diagnosed?
resting endoscopy may give some indication
exercise endoscopy is best
what is the treatment available for arytenoid cartilage collapse?
ventricolochodectomy (Hobday) - removes noise prosthetic laryngoplasty (tie back) - holds open arytenoid cartilage
what is the risk associated with prosthetic laryngoplasty?
aspiration pneumonia as can’t close of the airway when swallowing food
what is sinusitis?
accumulation of exudate within sinus cavities
what is the primary cause of sinusitis?
follows bacterial or viral URT disease
what is sinusitis usually secondary to?
dental disease
what is the main clinical sign of sinusitis?
nasal discharge
how is sinusitis diagnosed?
endoscopy (check for other causes)
x ray
CT
sinoscopy
what will often be performed at the same time as sinoscopy?
treatment for sinusitis
how is sinusitis treated?
lavage
open and ensure better drainage
treat underlying cause if secondary
what is found within the gutteral pouch?
lots of important structures
what is the issue with gutteral pouches?
don’t always drain well
what is gutteral pouch mycosis?
life threatening fungal infection of gutteral pouch
what vessel may be affected by gutteral pouch mycosis?
carotid artery - lies very close to gutteral pouch and my be eroded
what are the signs of gutteral pouch mycosis?
epistaxis
some may have cranial nerve dysfunction
why may cranial nerves be affected by gutteral pouch mycosis?
located in gutteral pouch so may be invaded by fungus
how many horses will die following repeated epistaxis caused by gutteral pouch mycosis?
50%
how is gutteral pouch mycosis diagnosed?
gutteral pouch endoscopy
how is gutteral pouch mycosis treated?
surgical occlusion of vessels
topical antifungal
will patients all recover from any cranial nerve deficits caused by gutteral pouch mycosis?
no and may take up to 9 months
may have such a severe impact on function that it is unethical to wait and see (e.g. unable to eat)
what is strangles caused by?
streptococcus equi bacteria
what is strangles?
URT bacterial infection
where are strangles ulcers often seen?
near SML nodes
what are the clinical signs of strangles?
dull fever purulent nasal discharge enlarged, absecessing SML nodes enlarged, abscessing retropharyngeal lymph nodes (seen on GP endoscopy
what element of the strangles infection is hugely contagious?
the pus
what are the complications of strangles?
difficulty breathing
abscesses may be seen around body
immune mediated complication
what must happen to strangles patients and any close contacts?
must be isolated
how is strangles diagnosed?
culture or PCR from abscess
endoscope and GP lavage for culture
how is strangles treated?
penicillin in some
drain abscessed lymph nodes
how does influenza spread?
inhalation in common airspaces
where does influenza replicate?
URT and LRT
what are the signs of influenza?
coughing pyrexia serous nasal discharge submandibular lymphadenopathy inappetance depression
how is influenza diagnosed?
virus detection (PCR or ELISA on nasal or nasopharyngeal swab) virus isolation (nasal or nasopharyngeal swab) serology (rising titre of antibodies)
how is influenza treated?
rest
NSAIDs
how can influenza be prevented?
vaccination - strict competition and import rules
what are the various types of equine herpes virus?
different signs:
respiratory
neurological
abortive
what are the most concerning types of EHV?
neurological and abortive
what types of EHV is there a vaccine for?
EHV 1 and 4
what is pleuropneumonia also known as?
shipping fever
which horses are at risk of pleuropneumonia?
horses travelling long distances
what is pleuropneumonia caused by?
opportunistic infection from the pharynx to the lungs by bacteria
what opportunistic bacteria often cause pleuropneumonia?
streptococcus zooepidemicus
what are the signs of pleuropneumonia?
history of long distance travel fever dull nasal discharge difficulty breathing weight loss
what tests are used to diagnose pleuropneumonia?
clinical exam chest x ray chest ultrasound tracheal wash sample pleural fluid sample (cytology and culture)
how are pleuropneumonia patients treated?
aggressive treatment
penicillin
chest drains
what is asthma also known as in horses?
RAO or COPD
what is asthma?
allergic airway disease
what is asthma usually caused by?
dust in stables, straw or hay
what are the signs of asthma?
increased mucous bronchoconstriction coughing and wheezing increased respiratory effort heave line
how is asthma diagnosed?
endoscopy
tracheal lavage
bronchoalveolar lavage
what are the white blood cell findings in equine asthma?
neutrophillia
how is asthma treated?
environmental management
inhaled or nebulised steroid and bronchodilator
