Surgical respiratory tract diseases - Equine 1 & 2 Flashcards
List some primary problems of the equine URT - 6
- nasal discharge
- exercise intolerance/poor athletic performance
- abnormal respiratory noise (stridor and stertor)
- epistaxis
- abnormal swelling of head/neck
- cough
Outline the workup for equine URT disease
- signalment
- hx (past and current)
- PE and URT exam
- examination at work
- special examinations
- (examination of LRT depending on ultimate diagnosis)
What should you examine on the URT?
- nasal discharge
- facial symmetry
- airflow (symmetry)
What should you palpate when examining the URT?
- nostrils
- nasal septum
- sinuses
- GP
- regional LNs
- larynx
- trachea
What should you percuss when examining the URT?
Paranasal sinuses (frontal and maxillary)
What should you look for when examining a horse at work? 4
- onset and character of abnormal noise
- exercise tolerance
- soundness
- respiratory pattern and recovery
What special examinations can be performed on the URT? 5
- endoscopy (common, easy)
- radiography, CT scan
- sinoscopy
- bacterial culture/ sensitivity (relatively unhelpful)
- biopsy for cytology/ histopatholgoy
What dynamic exams can be done when examining a horse URT? 5
- endoscopy at high speeds
- (measurement of airway pressures)
- exercising ECG
- lameness assessment
- standardised exercise trial (fitness and myopathy assessment)
How should nasal discharge be defined? 3
CHARACTER - serous, mucoid, purulent, necrotic
LATERALITY - unilateral (sinuses, nasal passage, GP), bilateral (lungs, pharynx)
ODOUR - none (LRT disease, sinusitis, pharyngitis, pouch empyema) or foul odour (dental disease, neoplasia, necrotising LRT disease)
List 5 possible sources of nasal discharge
- nasal passages
- paranasal sinuses
- GPs
- pharynx/larynx
- LRT
How do you determine the source of a discharge? 3
Follow the trail of a discharge:
- PE
- Endoscopy - paranasal sinuses, GPs, LRT
- Radiography - sinuses, GP
How common is primary nasal passage disease?
Uncommon (in UK)
Causes of primary nasal passage disease - 4
- Bacterial infection of septum or turbinates
- Fungal infection of septum or turbinates
- neoplasia
- FBs
What findings might suggest nasal discharge is due to sinusitis? 5
- PE: decreased resonance on percussion
- ENDOSCOPY: drainage from nasomaxillary opening
- RADIOGRAPH (oblique): fluid lines, mass
- CT
- SINUS CENTESIS: rule out S.equi
Causes - nasal discharge due to sinusitis - 4
- Dental disease * (09-11, M1, M2 M3)
- Bacterial infection
- Fungal infection
- Neoplasia
What might be concurrent findings with nasal discharge due to sinusitis? 3
- decreased airflow
- facial swelling
- dullness on percussion
Tx - sinusitis
MEDICAL - lavage and ABs
SURGERY - sinoscopy (including fenestration of the ventral conchal bulla, VCB), removal of inciting cause (e.g. tooth), flap sinusotomy
What is the most common way to access to sinus for sinoscopy?
Concho frontal sinus approach in most cases and fenestrate the VCB if necessary to access the rostral compartments.
T/F: sinoscopy can be performed in the standing horse
True
What are the causes of nasal discharge due to GP disease? 4
- GP empyema * bacterial infection of GP, often S.equi
- GP catarrah = excessive mucous production by pouch due to inflammation
- (GP mycosis)
- (GP neoplasia)
What are possible concurrent signs of nasal discharge due to GP disease? 2
- swelling at Viborg’s triangle
- other signs of GP mycosis
What are the 3 borders of Viborg’s triangle?
between tendon mandibularis, linguofacial vein and back of the mandible. Viborg’s triangle sits directly over the GP. Becomes swollen in GP empyema.
Dx - GP empyema - 4
- ENDOSCOPY (discharge or fluid accumulation in the pouch)
- RADIOGRAPHY (fluid line)
- chondroids (inspissated pus)
- culture
Tx - GP empyema - 2
MEDICAL - pouch lavage, AB, removal of chondroids (before lavage)
SURGERY - viborg’s triangle approach for drainage, ventral paramedian approach for chondroid removal, dyspnoeic horses may require tracheostomy
What are the main causes of abnormal respiratory noise/ poor performance?
PHARYNX: DDSP, postural compression (nasopharyngeal collapse), pharyngeal cysts
LARYNX: RLN, AAE, arytenoid chondroitis
What causes an abnormal noise?
Turbulent flow (2 conditions for this - flow and decreased lumen size/obstruction)
Outline resistance in the airway
INSPIRATION: resistance is predominantly in the URT
EXPIRATION: resistance is predominantly in the lung
Poiseuille’s law: resistance is inversely proportional to teh 4th power of the radius of the airway
How can you refine the problem of URT obstruction causing abnormal noise? 3
- CONSTANCY - Fixed (mass lesions, chondritis, strictures), dynamic (RLN, DDSP, AEE)
- QUALITY - stridor (narrowed airway - RLN, chondritis, mass lesions, strictures), stertor (tissue vibration - DDSP, nostril problems)
- PHASE - inspiratory (RLN), expiratory (DDSP, AEE), both (mass lesions, chondritis)
What are the different sites of URT obstruction? 5
- NOSTRILS - alar fold collapse/flutter, incomplete dilation of the nares
- NASAL PASSAGES - septal disease, small nasal passages, eruption bumps (tubercula transitoria), mass lesions
- SINUSES (expansile lesions) - cysts, mass lesions
- PHARYNX - DDSP, postural compression, pharyngeal cysts
- LARYNX - RLN/ roaring, epiglottic entrapment, arytenoid chondritis
Describe the anatomic basis of DDSP
- normally the palate is buttoned onto the larynx forming an airtight seal. Free border of palate is under epiglottis –> obligate nasal breather
- In DDSP, the free border of the palate moves dorsal to the epiglottis during exercise –> functional obstruction (decreased CSA of nasopharynx and increased resistance to airflow).
CS - DDSP
‘choking down’ = expiratory noise (stertor),
- decreased athletic performance
- mouth breathing (pathognomic)
Dx - DDSP
- Gold standard = dynamic endoscopy*
- Difficult at rest
- Typical hx (normal at rest)
- Rule out other URT disorders
- Assess GPs (inflammation, exudation and retropharyngeal lymphadenopathy)
DDSP suspected if:
- horse readily displaces with nasal occlusion and doesn’t easily replace palate
- there is marked hypoplasia or deformity of the epiglottis
What are the 2 broad treatment options for DDSP?
Conservative and surgical
Outline conservative tx of DDSP
- Treat concurrent disorders (GP or LRT disease)
- Minimise poll flexion
- Keep mouth closed
- Tongue-tie
- The Cornell Collar (mimics function of TH mm)
Outline surgical treatment of DDSP
- Numerous procedures described (aetiology not well understood)
- Llewelyn procedure: sternothyrideus myectomy +/- staphylectomy (trim edge of palate)
- Thermal palatoplasty (thermal or cautery) - stiffen soft palate to prevent billowing, surgical tension palatoplasty with similar concept
- Laryngeal ‘tie-forward’ (Cornell) - placement of a prosthetic suture to mimic function of thyrohyoideus mm)
Name 3 different sites of pharyngeal cysts
- Subepiglottic (thyroglossal duct)
- Dorsal pharyngeal (craniopharyngeal duct)
- Palatine
CS - pharyngeal cysts?
Foals versus young adults
- FOALS - dysphagia, dyspnoea
- YOUNG ADULTS - poor performance, respiratory noise
Cause - Recurrent laryngeal neuropathy (RLN)
due to degenerative axonopathy of the recurrent laryngeal nerve. left side affected. most common in large stature horses. The result is the impaired function of the cricoarytenoideus dorsalis muscle (CAD mm), the primary abductor of the arytenoid cartilage.
RLN - CS
- asymptomatic (rest and low levels of exercise)
- inspiratory stridor (moderate to marked exercise)
- impaired athletic performance (high exercise)
Outline the grading system for RLN in resting, unsedated horses.
GRADES 1 - 4:
GRADE 1: synchronous full abduction of both arytenoid cartilages
GRADE 2: asynchronous movement of L arytenoid cartilage. Full abduction of the L arytenoid cartilage inducible by nasal occlusion
GRADE 3: asynchroous movement of L arytenoid cartilage, full abduction of L arytenoid cartilage CANNOT be induced and maintained by nasal occlusion.
GRADE 4: marked asymmetry at rest. No substantial movement of the L arytenoid cartilage.
Outline the grading system for RLN during exercise
GRADE A: full abduction
GRADE B: not fully abducted but not adducted from position
GRADE C: dynamic collapse
Outline tx of laryngeal dysfunction depending on resting and exercise grading
Grades 1 and 2: no tx, monitor grade 2 GRADE 2A: no tx GRADE 3B: ventriculocodectomy +/- laryngoplasty (laryngeal prostehsis/'tie back') depending on level GRADE 3C: treat same as grade 4 GRADE 4: depends on level of performance
Outline treatment of RLN grade 4
- HIGH PERFORMANCE HORSES: laryngoplasty (tie-back) +/- ventriculocordectomy
- LOW PERFORMANCE HORSES: ventriculocordectomy
- NEWER TX: CAD reinnervation by nerve anastomosis or nerve: muscle pedicle grafting.
List 4 complications of laryngoplasty (given airway is fixed open so can’t collapse during swallowing)
- lack of improvement (30-40%)
- cough after eating (10%)
- aspiration pneumonia (1%)
- suture sinus (1%)
Define AEE
AryEpiglottic Entrapment
What is AEE/ Aryepiglottic entrapment?
- Envelopment of the epiglottis by the subepiglottic mucosa and aryepiglottic folds.
CS - AEE - 4
- Most commonly horses with epiglottic hypoplasia or deformity
- may be intermittent
- typically causes expiratory stridor and decreased performance
- may be asymptomatic
Tx - AEE
MIDLINE DIVISION OF THE ENTRAPPING TISSUE: via laryngotomy, transendoscopic laser with bistoury hook
Complications of midline division of the entraping tisssue as a treatment modality for AEE
- re-entrapment (5-40%)
- can lacerate soft palate or epiglottis
- DDSP (10-15%)
Define arytenoid chondritis
= chronic infection of the body of the arytenoid cartilage resulting in thickening and intra-luminal granulations
Aetiology - arytenoid chondritis
UNKNOWN:
- may follow acute laryngitis
- experimentally reproduced by denuding of the arytenoid of mucosa.
CS - arytenoid chondritis - 3
- Mimic those of laryngeal hemiplegia (i.e. RLN)
- inspiratory stridor (intense work)
- asymptomatic (rest and low exercise)
Tx - arytenoid chondritis
- sharp or laser excision of intraluminal protuberances
- partial or complete removal of the affected arytenoid cartilage
List some examples of dynamic obstructions
- DDSP
- Nasopharyngeal collapse
- Epiglottic retroversion
- Axial deviation of the aryepiglottic folds (AEE)
- Intermittent epiglottic entrapment
How can dynamic obstructions be diagnosed?
only on dynamic endoscopy
How can the problem of epistaxis be defined/refined?
- LATERALITY: unilateral (nasal passages, sinuses, GP), bilateral (LRT)
- ASSOCIATION WITH WORK: exercise induced (EIPH), resting (GP mycosis, ethmoid haematoma, fungal sinusitis)
- QUANTITY - modest (EIPH, ethmoid haematoma, fungal sinusitis), profuse (GP mycosis)
List some examples of dynamic obstructions
- DDSP
- Nasopharyngeal collapse
- Epiglottic retroversion
- Axial deviation of the aryepiglottic folds (AEE)
- Intermittent epiglottic entrapment
How can dynamic obstructions be diagnosed?
only on dynamic endoscopy
How can the problem of epistaxis be defined/refined? 3
- LATERALITY: unilateral (nasal passages, sinuses, GP), bilateral (LRT)
- ASSOCIATION WITH WORK: exercise induced (EIPH), resting (GP mycosis, ethmoid haematoma, fungal sinusitis)
- QUANTITY - modest (EIPH, ethmoid haematoma, fungal sinusitis), profuse (GP mycosis)
How can you determine the source of blood in epistaxis?
- ENDOSCOPY - paranasal sinuses, GPs, LRT
- RADIOGRAPHY - sinuses, GPs
Define PEH
Progressive Ethmoidal Haematoma
Describe PEH
A progressively enlarging, non-neoplastic mass lesion originating in the ethmoid turbinate
Histology - PEH
- capsule of respiratory mucosa and fibrous tissue
- stroma of blood, fibrous tissue, macrophages, giant cells and haemosiderocytes
Describe the location of PEH
- appears to start in the sphenopalatine sinus near the ethmoid labyrinth
- may expand to occupy the nasal passages, maxillary/frontal sinuses or nasopharynx.
CS - PEH
- middle aged (6+ years) and older horses
- commonest complaint is spontaneous epistaxis
- haemorrhage usually slight in volume
- bilateral in 15-30% cases
Endoscopy - PEH
- smooth greenish-black to reddish-brown mass in the ethmoid region
- less commonly, endoscopy reveals no lesion or blood exiting the nasomaxillary opening
Radiography - PEH
- shows size and extent of haematoma
- smooth well-circumscribed mass rostral to the ethmoid labyrinth
- advanced = soft tissue density fully occupying the maxillary and frontal sinuses and/or nasal passages
- CT = better!
Outline intralesional formalin treatment of PEH
= transendoscopic injection of lesion with 4% formalin
- ADVANTAGES = standing procedure, low equipment cost
- DISADVANTAGE = need for repeated treatments
Conventional tx - PEH
- radical excision (via maxillary or frontonasal bone flap)
- profuse haemorrhage typical under GA therefore mostly standing sedation
Outline laser treatment of PEH
- used to thermally destroy the mass lesions, especially ethmoidal haematomata
- ADVANTAGES: standing procedures, avoids flap sinusotomy
- DISADVANTAGES: equipment cost, need multiple treatments (each laser treatment destroys the most superficial 5-10mm of the lesion)
Aetiology - GP mycosis
- Fungal infection (typically Aspergillus) involving the roof of the medial compartment near the articulation of the stylohyoid bone with the temporal bone.
- localised or spreads rostrally, laterally or axially into opposite pouch
CS - GP mycosis
= due to injury to pouch structures
Aetiology - GP mycosis
- Fungal infection (typically Aspergillus) involving the roof of the medial compartment near the articulation of the stylohyoid bone with the temporal bone.
- localised or spreads rostrally, laterally or axially into opposite pouch
What are CS due to in GP mycosis?
= due to injury to pouch structures
CS - GP mycosis - 4
- EPISTAXIS - injury to internal carotid artery and external maxillary artery
- DYSPHAGIA - injury to CN 9 and 10.
- NASAL DISCHARGE - injury to mucosa
- HORNER’S SYNDROME - sympathetic trunk
Where is the internal carotid artery?
runs medial to GP, towards the circle of willis. Thus, need to ligate this twice to prevent back bleeding.
Dx - GP mycosis - 2
- ENDOSCOPY - blood exiting pharyngeal opening of pouch, direct visualisation of mycotic lesion
- RADIOGRAPHY - fluid line in pouch, osteitis of stylohyoid bone
Tx - GP mycosis - 3
HINGES ON BLEEDING CONTROL:
- EPISTAXIS - ligation, balloon occlusion or coil occlusion of affected BVs
- MYCOTIC LESION - systemic antifungals, topical antifungals or antiseptics
- SUPPORTIVE CARE
How may fungal sinusitis present?
with nasal discharge or epistaxis
Define atheroma
a sebaceous cyst in the nasal diverticulum
Dx - fungal sinusitis
Sinoscopy (radiographs may only show a fluid line which is not diagnostic)
Tx - fungal sinusitis
- sinus lavage with DMSO or topical antifungals
Aetiology - sinus swelling
- sinus cysts
- neoplasia
- PEH
- obstruction of nasomaxillary orifice
- (dental disease is a common cause of sinusitis but a rare cause of sinus swelling)
Define atheroma
a sebaceuous cyst in the nasal diverticulum
CS - atheroma
- noticed shortly after birth and grow through first year or two
- unilateral or bilateral
- cosmetic not obstructive
Tx - atheroma
- Surgical excision en toto (via nostril or incision over atheroma)
- drainage and chemical ablation of the secretory lining
Aetiology - sinus swelling
- sinus cysts
- neoplasia
- PEH
- obstruction of nasomaxillary orifice
- (dental disease is a common cause of sinusitis but a rare cause of sinus swelling)
What are sinus cysts?
congenital cystic dysplasia of sinus mucosa
CS - sinus cysts
- usually presented at 1.5 years of age with facial swelling
- also mature horses but this isn’t clear whether it is a congenital problem or not
- concurrent signs may include decreased airflow of affected side, nasal discharge, epiphora
Tx - sinus cysts and prognosis
- breakdown of cyst walls via flap sinusotomy
- prognosis = guarded for work
What is the commonest sinus neoplasia
- SCC
- many varieties of sarcoma also reported
CS - sinus neoplasia
- older horses
- facial swelling
- decreased airflow on affected side
- nasal discharge
- epiphora
CS - GP tympany - 3
- tympanitis (drumlike) swelling in parotid region
- unilateral or bilateral
- severe = dysphagia, respiratory distress
Tx - GP tympany - 2
- UNILATERAL - fenestration of median septum of GP via Viborg’s triangle approach or transendoscopic laser or electroscalpel
- BILATERAL - fenestration of median septum coupled with resection of lateral lamina of auditory tube.
- CARE - many important structures in this region!
What is GP tympany?
excessive accumulation of air in the GPs
What are the 2 forms of GP tympany?
CONGENITAL - neonates, due to abnormal formation of pharyngeal opening of pouch because pressure can’t equalise
ACQUIRED - older foals, yearlings, due to swelling involving pharyngeal opening of pouch
CS - GP tympany
- tympanitis (drumlike) swelling in parotid region
- unilateral or bilateral
- severe = dysphagia, respiratory distress
Tx - GP tympany
UNILATERAL - fenestration of median septum of GP via Viborg’s triangle approach or transendoscopic laser or electroscalpel
BILATERAL - fenestration of median septum coupled with resection of lateral lamina of auditory tube.
