Sx conditions of the equine larynx Flashcards
Describe 95% of laryngeal hemiplegia cases
Unilateral, left-sided, and idiopathic
What is left sided laryngeal hemiplegia?
Progressive neuropathy of the left recurrent laryngeal nerve
What innervates the majority of the laryngeal musculature?
The left recurrent laryngeal nerve
What is the main abductor muscle of the larynx in the horse?
The cricoarytenoideus dorsalis muscle
What breeds are predisposed to laryngeal hemiplegia?
TB, draughts, warmbloods
What are the most common causes of right laryngeal hemiplegia?
(1) 4-BAD
(2) Right arytenoid chondritis
What can cause laryngeal hemiplegia in horses?
(1) nerve damage
(2) organophosphate or lead toxicity
(3) CNS diseases/hepatic encephalopathy
What is the pathophysiology of laryngeal hemiplegia?
Unable to achieve max abduction -> reduced size of the rim glottides -> hypoxemia, hypercapnia, acidosis -> fatigue
You are called out to see a horse where the owner is complaining of exercise intolerance and poor performance. On exam, you hear “roaring,” which is abnormal inspiratory noise. What is your top differential?
laryngeal hemiplegia
How can you diagnose laryngeal hemiplegia?
Endoscopy, palpation and US
What is the gold standard of endoscopy and laryngeal hemiplegia?
Dynamic endoscopy, either overground or treadmill
What can you palpate on a horse with laryngeal hemiplegia?
Prominence of the muscular process of the arytenoid cartilage and the dorsal aspect of the cricoid cartilage
What is the name of the grading scale for standing endoscopy with laryngeal hemiplegia?
Havermeyer
Define a grade 1 havermeyer laryngeal hemiplegia
Movement of arytenoid cartilage is synchronous and symmetrical, full abduction is achieved
Define a grade 2 havermeyer laryngeal hemiplegia
Movement of arytenoid cartilage is asynchronous and/or larynx asymmetric at times but full abduction is achieved and maintained
Define a grade 3 havermeyer laryngeal hemiplegia
Movement of arytenoid cartilage is asynchronous and or asymmetric. Full abduction cannot be achieved and maintained
Define a grade 4 havermeyer laryngeal hemiplegia
Complete immobility of the arytenoid cartilage and vocal fold
When is sx indicated for laryngeal hemiplegia and why?
Only if it is necessary for the horse to perform because complications are frequent and often severe
What are the surgical options for laryngeal hemiplegia?
(1) prosthetic laryngoplasty
(2) Ventriculocordectomy
(3) Re-innervation of CAD muscle
(4) Re-innervation of CAD muscle + dynamic prosthetic laryngoplasty
Which surgical option for laryngeal hemiplegia results in a major improvement of airflow mechanics?
Prosthetic laryngoplasty
Which surgical option results in elimination/significant improvement of abnormal noise and some improvement of airflow dynamics?
Ventriculocordectomy
What is the most commonly performed surgical treatment for laryngeal hemiplegia in a horse and what procedure is it frequently combined with?
Prosthetic laryngoplasty + ventriculocordectomy
T/F The abnormal respiratory noise is removed with a prosthetic laryngoplasty
F: a ventriculocordectomy is the procedure that treats the abnormal noise
What type of horses are most commonly treated with a prosthetic laryngoplasty?
Horses performing at high speeds
What is the prosthesis made out of for a prosthetic laryngoplasty?
1-2 strands of non absorbable suture
Does a prosthetic laryngoplasty or a ventriculocordectomy cause more complications?
Prosthetic laryngoplasty
What are the complications that can be caused by a prosthetic laryngoplasty?
(1) Dysphagia (avoid over abduction)
(2) Chronic coughing
(3) Prosthesis failure
(4) Seroma
(5) Wound infection
(6) Arytenoid condritis
What is the scale used to measure post-op abduction after a prosthetic laryngoplasty?
Dixon
What is the most common indication for a ventriculocordectomy?
Sports horses where the primary complaint is noise and w/ minimal or no exercise intolerance
What are the sx techniques that can be used for a ventriculocordectomny and which is preferred?
(1) Via laryngotomy or (2) trans-endoscopically (preferred)
How is re-innervation of the CAD muscle done?
Branch of C1 is identified, isolated and fed through the CAD muscle
What does C1 innervate?
C1 innervates the accessory respiratory muscles
What is the time frame for re-innervation for the CAD muscle?
4-5 months at the earliest to 12 months
When can’t re-innveration of the CAD muscle be performed?
If the horse already underwent a laryngoplasty, there is fibrosis of the CAD muscle, or there is C1 disruption
What is the usual signalment for development of sub epiglottic cysts?
Young TB and SB, usually congenital
What are the CS of sub epiglottic cysts in foals and older horses?
Foals: dysphagia -> coughing and pneumonia
Older horses: dysphagia if large, resp noise
How do you diagnose a sub epiglottic cyst?
(1) endoscopy
2) oral endoscopy/palpation (speculum
Describe sub epiglottic cysts
- 1.5 - 5 cm, round, pink, mucosa-covered, smooth mass
- Asymmetric elevation of epiglottis
- +/- concurrent epiglottic entrapment
- Lift epiglottis as some cysts might slip under soft palate
What happens if you puncture and drain a sub epiglottic cysts?
It will refill rapidly
What is a two options for treatment for sub epiglottic cysts?
(1) Formalin injection
(2) Surgical excision
If you remove too much sub-epiglottic tissue when you excise a sub epiglottic cyst, what does that put the horse at risk for?
DDSP
With a surgical excision of a sub-epiglottic cyst, what do you administer post op?
IV dexamethasone, NSAIDs, and throat spray
What does 4-BAD stand for?
4th branchial arch defects
What are the 4 abnormalities that can exist in 4-BAD
(1) Lateral wings of the thyroid cartilage
(2) Crycoarytenoid articulation
(3) Crycothyroid
(4) Thyropharyngeus and cricopharynxgeus mm
CS of 4-BAD are rare but they include…..
(1) collapse of soft tissues or cartilage -> exercise induced respiratory noise. Normal CAD but ineffective due to abnormal joint
(2) dysphagia might be present
(3) Chronic colic due to dysfunction of cranial esophageal sphincter
How do you differentiate 4-BAD from LLH or chondrites?
4-BAD more commonly affects the right side while LLH or chondritis more commonly affects the left side
