Static upper respiratory tract Flashcards
Which meatus is used to pass stomach tubes and scopes?
Ventral meatus
- largest
- unlikely to hit ethomoids
- easier to enter guttural pouch
Endoscopy of nasal cavity
If you suspect sino-nasal disease
Inspect all nasal meatuses
○ Ventral
○ Common (middle)
○ Dorsal (if wide enough)
False nostril cyst/atheroma
Uncommon
Epidermoid cysts can develop in the false nostril lining -> facial swelling in the area of the naso-maxillary notch.
Soft fluctuant swelling 3-4cm diameter
Do not cause nasal airflow obstructions.
Treatment of false nostril cyst/atheroma
usually for cosmetic reasons
total surgical removal of the cyst in sedated horse
Needle drainage often leads to infection and recurrence
Equine nasal paralysis
Nostrils, nasopharynx and larynx need active muscle for dilation during fast work
Facial nerve paralysis -> nasal paralysis
○ injury at petrous temporal bone, caudal mandible, or buccal branches of VII
○ Tight headcollar, GA lat recumb, buckles damage nerve
Clinical signs of equine nasal paralysis
Muzzle twisted towards normal side if unilaterally affected
Droopy eyelid
Prognosis of Equine nasal paralysis
Following severe bruising nerves regrow at circa 1cm per month
Severed nerve unlikely to recover
Nostril wounds
Need accuarate apposition or can lead to large flap or healing with stenosis
Scrolled ethmoturbinates in a normal horse
Next to olfactory lobe of brain at dorso-caudal aspect
Variation in shapes of normal ethomoturbinates - endoscopic appearance
Incidence of progressive ethmoid haematome (PEH)
Common
Progressive Ethmoid Haematoma (PEH)
An ethmoid haematoma is a haemorrhagic polyp with the histological appearance of a haematoma.
Usually occur in adult horses
Can grow rostrally from the ethmoturbinates within the nasal cavity but also grow within the paranasal sinuses.
History of progressive ethmoid haematoma (PEH)
Their capsules release small amounts of blood over very long periods (even years) so the clinical history is of multiple small volumes of (usually) unilateral epistaxis.
Some cases are affected bilaterally.
They are the commonest cause of chronic unilateral low volume epistaxis in the resting horse i.e. DDx from EIPH which occurs after exercise.
What is the commonest cause of chronic unilateral low volume epistaxis in the resting horse
Progressive ethmoid haematoma
Possible sequelae of progressive ethmoid haematoma
Slow enlargement in the nasal cavity and sinuses causes secondary infection with mucopurulent as well as haemorrhagic nasal discharge, and possibly airflow obstruction, facial swelling and neurological signs as the lesion gets bigger.
Diagnosis of progressive ethmoid haematoma
Endoscopically, the PEH is a classic dark red or brown coloured mass seen at the ethmoturbinates or within the nasal cavity or sinuses.
Can be very large or small
See stream of blood from sinus drainage angle if PEH has grown within a sinus
Radiography may show lesions that are contained within the sinuses.
Sinuscopy shows PEH in sinuses
Treatment of progressive ethmoid haematoma
repeated, transendoscopic (non-invasive) intra-lesional formalin injections for small to mid-sized lesions in the nasal cavity.
In a standing sedated horse
Have to be repeated q2-3 weeks until lesion fully regressed
For large lesions or those within the sinuses, surgical excision via sinus flap surgery is indicated.
§ Standing sedated
§ Referral
§ Complications include haemorrhage ++
Recurrence is common after treatment (around 50%), but if lesions are found early, they can be injected with formalin and repeat surgery is not frequently required.
Care injecting lesions in sinuses - formalin that remains in sinus will cause damage!
Traumatic epistaxis
The nasal mucosa has a well-developed blood supply.
Spontaneous epistaxis does not occur in horses (cf humans)
Major cause of equine epistaxis is EIPH (during/post exercise)
Blunt or sharp trauma, or iatrogenic trauma from naso-gastric intubation or endoscopy (not passed in ventral meatus)can result in significant epistaxis.
If external trauma has occurred, radiography of the head is useful to check there are no significant skull fractures.
Horses can bleed into the sinuses and then experience low grade epistaxis for a few weeks afterwards.
DDx for epistaxis at rest
Guttural pouch mycosis
Progressive ethmoid haematoma
Head trauma
Sino/nasal tumours and infections
Treatment of traumatic epistaxis
Most traumatic nasal epistaxis in horses will cease spontaneously within a few minutes.
Packing the nasal cavity is possible but difficult!
Almost all are self limiting
○ May lose 5-10L
○ Keep head elevated (headstand)
Tear of rectus capitus muscle in the guttural pouch
Very rare
Caused by head trauma
Acute onset of bledding from guttural pouch
Nasal neoplasia
Rare
Equine nasal tumours are uncommon but often malignant, e.g. adenocarcinomas or osteogenic sarcomas and usually affect older animals.
Clinical signs of nasal neoplasia
initially reflect local inflammation and secondary infection on and around the tumour
i.e. chronic unilateral purulent nasal discharge, which may progress to a bilateral discharge, malodourous breath, unilateral submandibular lymph node enlargement, nasal airflow obstruction, facial swelling.
Diagnosis of nasal neoplasia
Endoscopy + biopsy + radiographs (either transendoscopic or via trephine hole/flap).
Treament of nasal neoplasia
Unless detected very early, most equine nasal tumours are very difficult to effectively treat surgically (nasal flap surgery).
Radiotherapy can be considered but often is cost prohibitive.
Euthanasia is indicated if the tumour is large/advanced.
Incidence of nasal mycosis
Mycotic rhinitis
rare in UK, more common in USA
Aetiology of nasal rhinitis
Equine mycotic rhinitis in USA is usually caused by Phycomycosis, Cryptococcosis or Coccidioidmycosis, which have regional distributions.
Clinical signs of nasal mycosis
Unilateral, malodorous, mucopurulent nasal discharge and unilateral lymphadenitis
Epistaxis occasionally present
Diagnosis of nasal mycosis
On endoscopy, mycotic rhinitis resembles a ‘mouldy cheese’-like white, yellow or black coloured fungal plaque on the nasal conchae (turbinates) or ethmoturbinates, with underlying deep red ulcers visible if the mycotic plaque is removed.
nasal swabs -> heavy pure growth of potentially pathogenic fungus.
However, fungi may be cultured from the nasal cavities of healthy horses.
Treatment of nasal mycosis
endoscopic removal if possible + topical therapy with natamycin or enilconazole solutions.
Rostral maxillary cheek tooth apical abscessation
Common
Usually younger horses
Infection of the first 2-3 maxillary cheek teeth usually results in external maxillary bone swelling
But most infections of 06/07 tooth drain laterally -> facial swelling +/- tract
Occasionally drain medially into nasal cavity
Oro-nasal fistula
Rare
Food and inspissated pus in nasal cavity after dental infection
Wry nose
In neonates
Nasal septum and facial bone deformity
If severe euthanase
Major surgery to correct
BUT many horses can survive fine - if mild and foal can suckle successfully
How many pairs of paranasal sinuses are there in the horse?
7
But can be considered as two compartments
What does the caudal paranasal sinus compartment contain?
the caudal 2-3 cheek teeth apices, and:
- caudal maxillary sinus
- dorsal conchal sinus
- frontal sinus
- ethmoidal sinus
- sphenopalatine sinus
What does the rostral paranasal sinus compartment contain?
Rostral maxillary sinus
Ventral conchal sinus
Apices of the two middle cheek teeth
Sphenopalatine sinus
Causo-medial extension of CMS via sphenopalatine foramen
What is the sphenopalatine sinus closely related to?
Brain
Pituitary gland
Optic chiasm
Cranial nerves II and V
Clinical signs of disease in sphenopalatine sinus
As for sinusitis +
Blindness
Trigeminal neuritis
Exophthalmus
Meningitis
Head shaking
Maxillaty sinus septum
Separates rostral maxillary sinus and caudal maxillary sinus
From lateral aspect of maxilla -> plate of bone beneath infra-orbital canal
Extends dorsally and medially as maxillary sinus Bulla (MSSB)
Maxillary sinus bulla
A continuation of the maxillary sinus septum
the easiest part to break through surgically to make the rostral and caudal compartments communicate
Incidence of sinusitis
(paranasal sinus empyaema)
Very common
The most common cause of unilateral discharge in the horse
Secondayr bacterial infection can occur with any other primary intra-sinus lesion
Aetiology of sinusitis (in order of frequency)
- Primary (bacterial) sinusitis
- Dental infection
- Maxillary (sinus) cysts
- Intra-sinus ethmoidal haematoma
- Sinus neoplasia
- Mycotic sinusitis
- other rare lesions
Clinical signs of sinusitis
usually unilateral and often non-specific for the type of sinusitis present
Muco-purulent nasal discharge (can be malodorous)
Submandibular lymph node enlargement
No coughing
Facial swelling (maxilla or frontal regions)
Epiphora
Nasal airflow obstruction and stertorous breathing
Unilateral epistaxis (ethmoidal heamatoma)
Diagnosis of sinusitis
Oral exam
Nasal endoscopy may show discharge emanating from the sino-nasal ostium at the caudal aspect of the middle meatus (“sinus drainage angle”).
- cannot pass the scope into the sinuses in a normal horse
Radiographs of the sinuses and teeth are then indicated
CT if more info needed
Treatment of sinusitis
Obviour space occupying lesion?
- biopsy/bone flap
Dental disease?
- treat that
Primary sinusitis?
- likely to resolve with sinus lavage
Direct sinoscopy (endocopy of sinuses)
Visualisation of the caudal compartment is possible through a small trephine hole made in the frontal (or maxillary) bone made under local anaesthesia, through which the scope is passed.
Technique of making a trephine hole into the caudal sinus compartment
Sedation
Skin is clipped and prepped
Portal sites infiltrated with 1-2ml of LA
Incision 1.5x diameter of trephine
How can you access the rostral sinus compartment for treatment
removal of part of the maxillary sinus septal bulla with a narrow forceps, under endoscopic guidance.
Normal sinus drainage
Slit like ostia
RMS and CMS drain separately
- paths converge just before they enter the nasal cavity
Easily occluded
Diagnosis of obstructed middle meatus
Endoscope - you won’t be able to see the Y shape or pass the scope if something is blocking the passage
Primary sinusitis incidence
Very common
Aetiopathogenesis of primary sinusitis
Presence of bacteria in sinus cavity +
Obstructed ostium (mucosal oedema
Blockage of outflow
Failure of mucociliary clearance
Accumulation of secretions -> bacterial growth
Diagnosis of primary sinusitis
radiography +/- CT +/- sinoscopy to rule out other causes of sinusitis.
Treatment of primary sinusitis
May clear spontaneously
Remove purulent material
- liquid
- insippated
Re-establish sinus drainage
Feed from ground
Antibiotics, NSAIDs
Continuing exercise
Which antibiotics should be used for primary sinusitis?
Normal sinus microbiota includes aerobic bacteria and fungus
Sinusitis: anaerobic bacteria common
Penicillin i/m
Doxycycline p/o
When are antibiotics likely to be efficaious in sinusitis?
Facial swelling
Epiphora
Significant dental abnormality
Chronic duration of nasal discharge
Bloody nasal discharge
Multi-resistant bacteria in primary sinusitis
Pseudomonas, Bacteroides, E. coli spp
Surgical site infection
- trephine hole
- sinus flap site
Persistent sinusitis
Treatment for chronic sinusitis
surgical lavage via a trephine opening (usually into the frontal sinus), followed by irrigation for several days with large volumes (2-3L BID or TID) of lukewarm water or very dilute antiseptics using an indwelling tube/foley catheter.
CT for imaging of sinusitis
Useful for:
Ruling in/out dental infection
Outlining extent of space occupying lesions for pre-op planning
Cases with dental dysplasia
Evaluating trauma cases with skull fractures
Post surgical complications
Potential pitfalls of CT for sinusitis
Sometimes cannot differentiate between different soft tissue masses or fluid material
PEH/Cyst/pus/inspissated pus
Indications for sinus osteotomy
No response to lavage (or recurs)
No/poor drainage from nostril when lavaging (blocked nasomaxillary ostium)
Inspissated pus seen on sinoscopy
Ventral conchal sinus involvement
Mass/other specific lesion suspected
Requirements for standing sinus surgery
(referral)
Flunixin
Penicillin/doxycycline
- or based on culture
Alpha 2 + butorphanol/morphine
Local infiltration lidocaine
- nasal cavity
- skin
- intrasinus
Maxillary nn block
Surgically creating a sino-nasal fistula
Improves drainage if natural ostium is blocked
Caudodorsal aspect of ventral concha
Close to natural ostium
Causes haemorrhage ++++ so do last
Complications of sinus flap surgery
HAEMORRHAGE
Premature loss of nasal packing
‘Dirty surgery’ (gross infection present)
Dental sinusitis incidence
Very common
Aetiopathogenesis of dental sinusitis
Maxillary 08-11 periapical infection
Clinical signs of dental sinusitis
Infection will cause purulent sinusitis
Unilateral nasal discharge
Unilateral submandibular LN swellings
Possibly unilateral epiphora
Facial swellings rare
DIignosis of dental sinusitis
Oral exam
Radiography – oblique lateral
If unsure –
CT/scintigraphy
Sinus cyst
Common
Fluid filled cysts of varying size often with areas of bony material within their lining
- respiratory mucosa and bright yellow fluid inside
If enlarge sufficiently, they can cause occlusion of normal sinus drainage, pressure changes in the surrounding bones, inflammation, secondary sinus infection and obstruction of the nasal cavity.
Can occur in all age groups, including foals
Clinical signs of maxillary sinus cysts
Very marked facial swelling and epiphora is a feature of many cases.
Nasal discharge is usually less purulent than with other types of sinusitis and there is minimal smell.
Complete nasal obstruction including contralateral side
Massive remodelling of nasal conchae - extension into SPS and calvarium
Diagnosis of maxillary sinus cysts
radiography, CT sinoscopy or direct sinus centesis (needle through bone) which may yield bright yellow cyst fluid.
Treatment of maxillary sinus cysts
Surgically remove the cyst using a bone flap surgery.
Excellent prognosis
Incidence of sinus neoplasia
Infrequent
usually affect older animals
Sinus neoplasia
usually very malignant growths, most commonly SCC
Tumour types and signs almost identical to nasal neoplasia
Malignant carcinomas causing extensive invasion and tissue damage
Poor prognosis except with benign tumours
Even these often recur as difficult to get complete excision
Radiation therapy in valuable horses
Clinical signs of sinus neoplasia
nasal discharge, facial swelling, epiphora, SMLN.
Intra-sinus ethmoidal haematomas
Haemorrhagic polyps
Start small -> slow enlargement
Can be single or in multiple sites/bilateral
Can cause complete nasal obstruction
Treatment of Intra-sinus ethmoidal haematomas
Formalin injection not advised
- retention of large amount in sinus -> necrosis of mucosa
Increased risk of haemorrhage at surgery
Incidence of mycotic sinusitis
Infrequent
Aetiopathogenesis of mycotic sinusitis
Common post-sinus osteotomy
Can occur as a primary lesion
Often lots of secondary inspissated pus
Diagnosis of mycotic sinusitis
usually on sinoscopy, (radiography and CT often not that useful for this)
Treatment of mycotic sinusitis
Physical removal of the plaque (sinoscopy or sinus flap surgery) + local irrigation of the affected sinus with enilconazole, immaverol, or natamycin using an indwelling catheter is usually successful.
Guttural pouch anatomy
Mucosa lined outpouchings of the auditory (eustachian) tubes
Connect to nasopharynx rostrally
Naso-pharyngeal entrance to eustachian tubes are under cartilaginous flaps - the guttural pouch ostia
- ostia dilate during swallowing
Clinical examination of guttural pouch
Palpation
- immediately caudal to mandible
Endoscopy!!
Radiography
Examine other systems than may be affected as a result
- nares (discharge)
- neuro exam (cranial nerves)
- cardiovascular status
Endoscopy of the guttural pouch
Swallowing induced by flushing the endoscope in the nasopharynx will make the guttural pouch ostia transiently open and discharge may then be seen flowing from the ostia.
GP endoscopy can be aided by using a guide wire or biopsy forceps inserted through its biopsy channel, inserted into the auditory tube to act as a ‘leader’ for the scope.
Guttural pouch mycosis incidence
uncommon BUT important to know as potentially life-threatening
Aetiology of guttural pouch mycosis
Aspergillus fumigatus is an opportunist pathogen present in the URT (including the GPs) that can occasionally colonise the guttural pouch mucosa
tends to grow on the roof of the pouch often overlying the internal carotid artery (ICA) and associated 9th,10th and 11th cranial nerves
As the fungal plaque spreads, it can also cover and erode the cranial sympathetic nerve, 7th +12th cranial nerves, and large blood vessels in the lateral compartment
Clinical signs of guttural pouch mycosis
Unilateral muco-purulent (often malodorous) nasal discharge followed by a couple of small volume epistaxis episodes that precede a major haemorrhage, plus dysphagia +/- other neurological signs.
Cause of haemorrhage in guttural pouch mycosis
Erosion of wall of internal carotid artery -> epistaxis
Often 1 or 2 smaller bleeds precede massive (often fatal) haemorrhage
Clinical signs caused by haemorrhage
> 5L = significant blood loss
High HR
Pale MM
weak/ataxic
Neurological signs in guttural pouch mycosis
Dysphagia
- pharyngeal paralysis (IX, X, XI)
Recurrent laryngeal neuropathy
- left or right sided
- recurrent laryngeal branch of X
Horners syndrome
- cranial sympathetic trunk
Persistent DDSP
- pharyngeal branch of X
Facial paralysis
- VII
Tongue paralysis
- XII
Diagnosis of guttural pouch mycosis
Endoscopically, blood or mucopurulent material may be seen flowing from the GP ostium.
Within the guttural pouch see classic fungal plaques, usually in the dorsal aspect of the medial compartment.
Treatment of guttural pouch mycosus
If haemorrhage has occurred, the internal carotid artery should be surgically ligated/occluded with a balloon catheter or embolization coil.
Local antimycotic treatment with natamycin or enilconazole, sprayed onto the roof of the pouch can also help resolve the plaque if repeated on several occasions.
Prognosis of guttural pouch mycosis
If the artery is not surgically occluded in cases with epistaxis, 50% of horses will experience a fatal haemorrhage.
Prognosis post-op often depends on the degree and severity of nerve damage.
Cases with severe pharyngeal dysphagia have the poorest prognosis.
DDx for blood in the guttural pouch if no fungal plaque seen
rupture of the rectus capitus muscle (on medial wall of pouch - occurs after horse has reared and fallen over backwards. (rare).
Supportive treatment for dysphagia
Poor prognosis if severey dysphagic
IV fluids
Nasogastric feeding of slurry pr parenteral (drip) feeding
Antibiotics + anti-inflammatories to tx aspiration pneumonia
Guttural pouch empyaema/chondroids
common
Nearly always a sequel to strangles
Clinical signs of acute guttural pouch empyema/chrondroids
in the acute phase, liquid pus in the pouch drains -> nasal discharge.
- May also be pyrexic and dull
- swelling of parotid region
- submandibular lymphadenopathy
- dyspnoea and dysphagia
Diagnosis of Guttural pouch empyema/chrondroids
Guttural pouch endoscopy will show, pus or chondroids in its lumen.
Enlarged LNs within pouch
Treatment of Guttural pouch empyema/chrondroids
For empyema only, medical treatment (lavage and antibiotics) is effective.
For chondroids, transendoscopic removal or surgical removal using a ventral (modified Whitehouse) approach to the GP (sx usually done standing now). Stenosis of the auditory tube can cause reduced drainage in some cases.
Clinical signs of chronic guttural pouch empyema/chrondroids
Chronic cases -> unilateral or bilateral chronic low grade purulent nasal discharge or sometimes no nasal discharge in long term carriers with chondroids and no liquid pus
Guttural pouch tympany
rare
Congenital condition where air can enter but not freely exit one or both guttural pouches.
Young foals <6 weeks
Fillys>colts
Clinical signs of guttural pouch tympany
The affected pouch (in foals and yearlings) becomes very distended, and a resonant, drum-like swelling develops caudal and caudo-ventral to the mandible.
The swollen pouch can cause dysphagia and stridor (nasopharyngeal collapse)
Secondary empyema is also common due to restricted drainage.
Diagnosis of guttural pouch tympany
Radiography shows enlarged, air-filled pouch +/- fluid line
Treatment of guttural pouch tympany
transendoscopic laser fenestration of the midline septum in unilateral cases (so air can drain via the normal pouch) or laser creation of a salipingo-pharyngeal fistula for bilateral cases.
GUttural pouch melanosis
Melanosis of the internal GP wall is very common in older grey horses – often an extension of melanomas from the parotid region- rarely the tumours can cause dysphagia and stridor.
No specific tx indicated.
Guttural pouch neoplasia
Melanomas - common
Other tumours - rare
- lymphosarcoma
- SCC
Clinical signs of guttural opuch neoplasia
Swelling of parotid region
Nasal discharge
Dyspnoea/dysphagia
Neurological signs
Prognosis of guttural pouch neoplasia
Poor
Inaccessibility of the site for surgery
Need to preserve vital structures contained in GP
Rupture of rectus/longus capitus mms
Rare
Flexor muscles of the head
Damaged when horse rears over backwards
Present with epistaxis + neurological signs
Prognosis guarded if neuro signs present
Cleft palate/palatal hypoplasia
rare
Cleft palate - minimal tissue missing, just cleft in midline
Hypoplasia = tissue defect (more common in horses)
Can involve soft palate only or soft and hard palates
Aetiology of Cleft palate/palatal hypoplasia
failure of closure of embryonic palatal folds
Severity related to size of defect
Clinical signs of Cleft palate/palatal hypoplasia
Foals; usually caudal aspect of the soft palate, occasionally hard palate too.
CS = nasal discharge containing food (milk), cough immediately after suckling +/- signs of aspiration pneumonia - can commonly be fatal.
CS in adults (if they survive into adulthood): intermittent coughing/dysphagia, nasal return of food (usually mild), noise when exercising
Diagnosis of Cleft palate/palatal hypoplasia
endoscopy (small diameter scope)
-> defect in caudal soft palate.
If hard palate involved, see during oral examination.
Radiography: check lungs for changes associated with pneumonia
Treatment of Cleft palate/palatal hypoplasia
if foal is coping and no significant pneumonia, tx conservatively (abios as required).
If pneumonia present, can attempt surgical correction (v. difficult, often unsuccessful) or euthanasia = other option.
Permanently dorsally displaced soft palate (pDDSP)
Permanent DDSP = very rare compared to intermittent DDSP that occurs at exercise
Often 2ry to other disease e.g. epiglottic entrapment, sub-epiglottic fibrosis/ulceration, sub-epiglottic cyst, palatal cyst, epiglottitis.
Idiopathic pDDSP presumably due to acquired neuromuscular dysfunction of the soft palate or epiglottic muscles.
Cinical signs of Permanently dorsally displaced soft palate (pDDSP)
loud and continuous gurgling noises at rest or at low level of exercise.
May be mildly dysphagic.
Diagnosis of Permanently dorsally displaced soft palate (pDDSP)
endoscopy -> soft palate is permanently displaced above the epiglottis.
Oropharyngeal endoscopy should be performed to examine sub-epiglottic area.
Treatment of Permanently dorsally displaced soft palate (pDDSP)
if no obvious predisposing lesion = tie- forward +/- laser staphylectomy –successful in 80% of cases
Epiglottic entrapment
Seen particularly in Standardbreds (high incidence epiglottic hypoplasia) and occasionally in TB.
Rostral (free) aspect of the epiglottis becomes trapped in a pouch of mucosa that develops from the mobile sub-epiglottic mucosa.
Entrapment is usually evident at rest, particularly after a swallow.
○ Rarely entrapment is only induced by exercise.
If permanent, entrapping membrane +/- epiglottic cartilage can become swollen and ulcerated over time -> longer healing time post-op.
Permanent or intermittent DDSP is seen as secondary disorder to EE.
Clinical signs of epiglottic entrapment
airflow obstruction and abnormal expiratory noises as air fills the entrapment during expiration.
Sometimes coughing when eating if entrapment very swollen.
Diagnosis of epiglottic entrapment
endoscopy: entrapped epiglottis loses normal flat, serrated appearance and become rounded, thickened +/- hyperaemic or ulcerated.
Additionally, the normally prominent blood vessels on its dorsal aspect of epiglottic cartilage -> not visible.
If pDDSP present -> endoscopy per os under sedation.
Treatment of epiglottin entrapment
Section entrapping membrane using hooked bistoury (long curved hook knife) per nasum or per os or using transendoscopic laser.
Most surgery performed standing.
Alternatively, resection or axial division of entrapping membrane via laryngotomy under GA (this tx -> higher incidence of permanent DDSP after).
Subepiglottic cysts
Rare congenital structures, usually obvious on endoscopy as discrete rounded mucosa-covered mass under the epiglottis.
They can deviate epiglottis dorsally -> airflow obstruction +/- dysphagia, depending on the degree of epiglottic distortion.
Secondary epiglottic entrapment +DDSP = common.
Diagnosis of subepiglottic cysts
endoscopy: see cyst, occasionally cyst may be hidden under soft palate – induce multiple swallows to make it appear.
Oral endoscopy may be required to confirm the diagnosis.
Treatment of subepiglottic cysts
Surgical excision - many options available but commonly using diode laser (standing) or via laryngotomy under GA
Tracheal collapse
Often small pony breeds with CS worsening in hot weather.
Caused by a cartilage deformity and/or degeneration of dorsal trachealis ligament and tracheal cartilage degeneration.
Intracervical location -> inspiratory obstruction (inspiratory ‘honk’), intrathoracic location -> expiratory obstruction.
Clinical signs of tracheal collapse
stridor, dyspnoea, exercise intolerance or may be undiagnosed due to the low workload of these animals.
Intracervical location -> inspiratory obstruction (inspiratory ‘honk’),
intrathoracic location -> expiratory obstruction
Diagnosis of tracheal collapse
classic honking respiratory noise in small pony + endoscopic observation of collapse.
Radiography during inspiration can be useful but sometimes the trachea is also rotated -> rad not useful.
Treatment of tracheal collapse
Tracheal collapse is worse with LRT disease so improve environment first.
Tracheal stenting – intra or extra-luminal
§ V. complicated surgery with major complications
§ Only possible for cervical trachea, not intra-thoracic
May be unnecessary if pony has sedentary lifestyle
§ Manage medically
Treat concurrent LRT disease
