Disease of the equine head and neck 2 Flashcards
What structures are separated by the soft palate?
Nasopharynx & Oropharynx
What makes the pharynx able to collapse during exercise?
Pharynx lacks rigid support by bone/cartilage
Describe the 2 functions of the pharynx
- Passage of air: Nasal cavity to larynx and lower airways
- Passage of ingesta: Oral cavity to oesophagus during swallowing
How do the structures of the pharynx protect the airway?
- Arytenoid closure
- Vocal cord closure
- Epiglottis retroversion
The pharynx is innervated by which 3 cranial nerves?
V - Trigeminal
X - Vagus
XI - Accessory
What are the 3 main functions of the larynx?
- Breathing
- Protect lower airway
- Vocalisation
Describe the structure of the larynx
Cartilage structure (in contrast to pharynx)
Name the cartilaginous structures that make up the larynx
- Cricoid cartilage
- Thyroid cartilage
- Epiglottis
- Paired arytenoid cartilages
Which muscle is involved in abduction of the glottis (opening)
Cricoarytenoideus dorsalis muscle
Which muscle is involved in adduction of the glottis (closure)
Cricoarytenoideus lateralis muscle
Which nerve innervates the Cricoarytenoideus muscles?
Recurrent laryngeal nerve
What are the 3 key presenting signs of larynx and pharynx disease?
- Respiratory noise
- Exercise intolerance
- Poor performance
How can these the larynx and pharynx be assessed in a clinical exam?
Palpation of the larynx: - Muscular process of arytenoid - Cricothyroid articulation Observation during exercise: - Listen! - Inspiratory / expiratory noise
During exercise a horses breathing is coupled with?
Their gait
What is the most important diagnostic tool for the pharynx and larynx?
Endoscopy
What are the clinical signs of pharynx abnormalities?
- Poor performance
- Respiratory noise: rest +/or Exercise
- Dysphagia
- Respiratory distress
- Nasal discharge
- Coughing
Name some of the key disorders of the pharynx
- Dorsal displacement of the soft palate (DDSP)
- Naso-pharyngeal collapse
- Pharyngeal lymphoid hyperplasia
- Cleft palate
- Foreign body
- Pharyngeal mass
What are the two types of Dorsal displacement of the soft palate (DDSP)?
Intermittent
Persistent
When does intermittent dorsal displacement of the soft palate occur?
During intense exercise only
How is intermittent dorsal displacement of the soft palate diagnosed?
Dynamic endoscopy
What are the 3 characteristics of soft palate displacement?
- Expiratory obstruction
- Gurgling noise
- Horse slows down / pulls up
If the soft palate has displaced, when does it return to normal?
On swallowing
What is the proposed pathogenesis of an intermittent dorsal displacement of the soft palate?
- Neuromuscular dysfunction
- Maybe caused by inflammation in guttural pouch or pharynx
- Lower airway disease
- Structural abnormalities
Describe a persistent dorsal displacement of the soft palate
- Soft palate permanently displaced
- Unable to replace on swallowing
- Often secondary to other disease
What signs from an animals history and clinical exam link to dorsal displacement of the soft palate?
- Exercise intolerance
- Gurgling / vibrating noise - Mostly expiratory
- Rider reports: choking down / up, swallowing its tongue
- Dysphagia: permanent DDSP only
How is persistent dorsal displacement of the soft palate diagnosed?
Resting endoscopy
How is intermittent dorsal displacement of the soft palate treated?
Conservative or surgical treatment
Describe the different conservative treatments for intermittent dorsal displacement of the soft palate
- Maturity: Common in youngsters
- Get horses fit: Train the respiratory muscles supporting pharynx
- Change tack: Keep mouth closed
- Tongue tie: Stop caudal movement of tongue
- Treat inflammatory conditions
Describe the different surgical treatments for intermittent dorsal displacement of the soft palate
• TIE FORWARD:
- Laryngeal advancement procedure
- Sutures placed between basihyoid bone & thyroid cartilage
- Positions the larynx more rostrally & dorsally
• Palatoplasty
• Staphylectomy: partial soft palate resection
What is pharyngeal lymphoid hyperplasia
Enlargement of lymphoid follicles on the walls & roof of nasopharnynx
When should pharyngeal lymphoid hyperplasia be treated?
If associated with iDDSP, treatment with anti-inflammatories
- if not its common in young horses and has little clinical significance
What are the main features of dynamic pharyngeal collapse?
- Lateral or dorsal walls
- Yearlings/2yo
- May resolve if mild
What are the features of a cleft palate?
Congenital defect diagnosed as foals
See milk coming from the nostrils
How is a cleft palate diagnosed?
- Oral examination / endoscopy
- May affect soft / hard palate, variable size and shape
Why is surgical repair of a cleft palate often not attempted?
- Direct access difficult via mouth / nasal passages
- Split mandible at symphysis
- Difficult, Expensive & dehiscence of repair may occur
What are the key clinical signs of laryngeal disorders?
- Respiratory noise
- Poor performance
- Dysphagia
- Coughing
- Respiratory distress
What is the cause of LEFT unilateral paresis / paralysis of the arytenoid cartilage
Recurrent laryngeal neuropathy
Describe the pathophysiology of recurrent laryngeal neuropathy
- Progressive loss of large myelinated nerve fibres of recurrent laryngeal nerve
- Neurogenic atrophy of intrinsic laryngeal muscles
- Loss of abductor and adductor function (cricoarytenoid muscles)
How can the history and clinical exam of an animal help diagnose recurrent laryngeal neuropathy?
- Most commonly large breeds
- Abnormal noise at exercise (‘roaring’) inspiratory
- Poor performance
Describe how endoscopy is used to diagnose recurrent laryngeal neuropathy
Assessment of artenoid cartilages for:
- Symmetry
- Synchrony
- Maintenance of abduction
- Remember it is the left side that will be abnormal
Which grading system is used to assess dynamic laryngeal function, describe it?
- Havermeyer system I = normal II = can fully abduct III = can't fully abduct IV = paralysis
Which factors will influence the management of a horse with recurrent laryngeal neuropathy?
- Clinical findings
- Use of horse
- Age / concurrent problems
- Degree of arytenoid collapse at exercise
- Owner expectations
- Economics
Name some of the surgical treatments used for recurrent laryngeal neuropathy
- Prosthetic laryngoplasty
- Ventriculo-cordectomy
- Laryngeal re-innervation (Nerve graft)
- Arytenoidectomy
Prosthetic laryngoplasty is also known as?
‘Tie back’
Describe how a Prosthetic laryngoplasty is performed
- Standing / under GA
- Suture placed: cricoid cartilage and muscular process of left arytenoid cartilage
- Mimics the action of CAD
- Permanent abduction of left arytenoid
Which potential complications can occur following a Prosthetic laryngoplasty procedure?
Coughing Seroma formation Infection of the implant Dysphagia Prothesis failure Chondritis
Describe the features of a vocalcordectomy procedure
• Removal of left +/- right vocal cord
- Reduce noise
- Remove tissue collapsing into airway
• Standing sedation – laser removal
Describe the features of a Ventriculo-cordectomy procedure
- Laryngeal ventricles (saccules) removed - Reduce vibration and noise
- Laryngotomy (GA or Standing)
- Or Laser (standing)
Describe a laryngeal re-innervation procedure
- Nerve graft
- Neuromuscular pedicle graft
- Re-innervation of the CAD
Congenital laryngeal dysplasia most commonly occurs on which side?
Abnormal development of laryngeal cartilages
- most commonly RHS
What is the main sign of vocal cord collapse?
Produces a lot of noise!
INSPIRATORY: WHISTLE
What are the main features and signs of axial deviation of the aryepiglottic folds?
- Collapse of the ary-epiglottic folds
- INSPIRATORY
- THICK NOISE
- Treatment: Laser resection of the aryepiglottic folds
What is arytenoid chondritis?
Infection/inflammation of arytenoid cartilage
- Mucosal ulceration
- Progressive & painful
What are the clinical signs of arytenoid chondritis and how is it diagnosed?
Clinical Signs: respiratory noise / obstruction +/- respiratory distress
Diagnosis: Endoscopy
How is arytenoid chondritis treated?
- Antibiotics: topical + systemic
- Partial arytenoid resection
- Arytenoidectomy (Salvage procedure)
- Permanent tracheostomy
How does epiglottic entrapment occur?
Loose subepiglottic tissue wraps over and entraps the epiglottic cartilage
What are the clinical signs of epiglottic entrapment
- Respiratory noise
- Coughing during eating
- +/- poor performance
What are the clinical signs of a sub-epiglottic cyst?
- Respiratory noise
- Dysphagia (milk / feed)
- Exercise intolerance
