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Large Animal Surgery > Equine Palate, Pharynx, & Larynx > Flashcards

Equine Palate, Pharynx, & Larynx Flashcards

1
Q

What is the normal anatomy of the larynx?

A
  • epiglottis sits on top of the soft palate
  • arytenoids able to be seen next to the aryepiglottic folds
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2
Q

What is dorsal displacement of the soft palate (DDSP)?

A

intermittent or persistent malpositioning of caudal edge of the soft palate dorsal to the epiglottis, allowing the horse to mouth breath (although they’re obligate nasal breathers)

  • soft palate should be ventral except when swallowing!
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3
Q

Normal soft palate position vs DDSP:

A

epiglottis not seen with DDSP!

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4
Q

What horses are most commonly affected by DDSP?

A

2-3 y/o Thoroughbreds —> racing horses, common to have high airway pressure

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5
Q

What clinical signs are indicative of DDSP?

A
  • horse chokes down (falters) towards the end of the race
  • EXPIRATORY (gurgling) noise caused by soft palate bellowing
  • bulging cheeks
  • coughing, salivation
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6
Q

What should be seen when a horse swallows on endoscopy? What are 3 ways a horse can be made to swallow?

A

soft palate should return to its normal position under the epiglottis

  1. hit dorsal pharyngeal wall with tip
  2. flush water through the scope
  3. press on the larynx
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7
Q

How can a horse be endoscopically made to dorsally displace their soft palate? How is DDSP diagnosed in this way?

A

hold nostrils shut and flex the neck

once displaced, pay attention to how quickly they replace the palate

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8
Q

What is an endoscopic finding of a chronic DDSP?

A

ulceration of the soft palate due to chronic turbulent airflow continually causing inflammation

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9
Q

What are 7 options for medically treating DDSP?

A
  1. treat underlying cause - antibiotics for URT infection
  2. anti-inflammatories - DMSO or steroid throat sprays
  3. increase fitness level
  4. noseband to keep mouth closed
  5. change bit to avoid having the horse playing with it
  6. tongue ties to keep the tongue retracted and pushed up on the palate
  7. Cornell collar - fitted to nose and mechanism to lift larynx dorsally
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10
Q

What are 2 surgical options for surgically treating DDSP?

A
  1. palatoplasty - create scar tissue to make the palate more stiff with lasers, irritants, or thermocautery
  2. staphlectomy - resect caudal margin of the palate (don’t take too much = aspiration!)
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11
Q

What is considered the best surgical treatment of DDSP? What is its goal? How is it performed?

A

tie forward = pull the larynx forward to allow the epiglottis to engage with the palate (80% success, best chance of returning to work)

suture passed from the thyroid cartilage to the basihyoid cartilage

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12
Q

How are strap muscle myectomies and Llewelyn procedures used to treat DDSP? What is their purpose?

A

transect muscle bellies of sternohyoideus and sternothyroideus

transect the tendons of the sternothyroideus at its insertion on the thyroid cartilage

reduces caudal retraction of the larynx, while still leaving other muscles available for swallowing

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13
Q

How does dynamic pharyngeal collapse affect the larynx? What are 3 possible etiologies?

A

rostral displacement of the palatopharyngeal arch

  1. guttural pouch distention causes disfunction of cranial nerves IX and X
  2. neuromuscular disease - EPM, HYPP, botulism
  3. nasal obstruction - increased negative pressure
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14
Q

What are the 2 most common clinical signs of dynamic pharyngeal collapse? How is it diagnosed?

A
  1. inspiratory noise
  2. exercise intolerance

endoscopy - dynamic preferred, can be performed at rest with nasal occlusion; check entire URT and guttural pouches!

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15
Q

How is dynamic pharyngeal collapse treated? What is prognosis like?

A

treat underlying disease + anti-inflammatories

guarded for high level of athletic function

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16
Q

What is the larynx? What cartilages are present?

A

conduit between the pharynx and trachea protected by the epiglottis

  • cricoid
  • thyroid
  • epiglottic
  • paired arytenoids
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17
Q

What muscle is responsible for abduction of the larynx?

A

(paired intrinsic) cricoarytenoideus dorsalis

18
Q

What are some acquired etiologies of laryngeal hemiplegia?

A
  • arytenoid condritis
  • damage to recurrent laryngeal nerve - perivascular injection, trauma, GP mycosis, strangles abscess
  • organophosphate toxicity
  • hepatic encephalopathy
  • lead toxicity
  • CNS disease
19
Q

What horses have higher incidences of left-sided laryngeal hemiplegia? What is the etiology?

A

larger horses —> draft breeds (35%), TB racehorses

recurrent laryngeal neuropathy —> idiopathic, genetic

20
Q

What are the 2 most common clinical signs of left laryngeal hemiplegia?

A
  1. inspiratory whistling (roaring) noise during expiration from turbulence caused by increased resistance
  2. decreased athletic performance or exercise intolerance
21
Q

What is the preferred diagnostic for left laryngeal hemiplegia? What else can be done?

A

endoscopy - graded by abduction, at rest with NO SEDATION, dynamic most important for < grade 3

  • palpate larynx for CAD atrophy, which causes the muscular process of the arytenoid cartilage more prominent
  • slap test reflex - contralateral arytenoid SHOULD abduct in response to a slape on the withers
  • ultrasonography
22
Q

What are the 4 grades of left laryngeal hemiplegia?

A
  1. synchronous FULL abduction
  2. asynchronous FULL abduction
  3. asynchronous PARTIAL abduction
  4. NO appreciable abduction

progressive disease!

23
Q

Grade 1 and 2 LLH:

A

synchronous FULL abduction

asynchronous FULL abduction

24
Q

Grade 3 and 4 LLH:

A

asynchronous PARTIAL abduction

NO appreciable abduction

25
Q

How is a prosthetic laryngoplasty used for treating LLH? What 3 other procedures are commonly added? What is their purpose?

A

“tie back procedure” improves performance by placing suture material between the muscular process of the arytenoid cartilage and the cricoid cartilage to retract and anchor the paralyzed left side of the larynx

  1. ventriculectomy
  2. chordectomy
  3. ventriculocordectomy

noise reduction, nor effect on performance

26
Q

What is a more uncommon surgical treatment for LLH? What is its purpose? What horses are preferred?

A

pedicle nerve graft - reinnervation of CAD with the 1st cervical nerve

younger horses with grade 3 LLH —> required 6-12 months of recovery!

27
Q

What is considered a salvage procedure for treating LLH?

A

arytenoidectomy of affected cartilage

28
Q

What is the goal of performing a prosthetic laryngoscopy?

A

“tie back” —> enough abduction to allow for smooth airflow, but not too much that can cause aspiration pneumonia

29
Q

How are ventriculecomties and cordectomies performed?

A

through a laryngotomy - removal of the mucus membrane lining the laryngeal ventricle leading to adhesions between the arytenoid and thyroid cartilages and reduced filling of the ventricles

laser used via endoscopy biopsy channel —> need to know how much to take, while still allowing a seal to form while swallowing

30
Q

What are 5 possible complications associated with prosthetic laryngoplasty (tie back)?

A
  1. over-abduction - aspiration of feed
  2. implant failure - almost all relax
  3. infection
  4. coughing, dysphagia
  5. noise - NOT correlated with successful abduction
31
Q

What is the prognosis of prosthetic laryngoplasty and ventriculocordectomy alone to treat LLH?

A

70-80% will improve performance

80% noise reduction, no change in function of airway

32
Q

What is arytenoid chondritis? 2 etiologies? Clinical sign?

A

inflammation of infection of the arytenoid cartilage

  1. trauma
  2. young TB, thought to be secondary to URT infection

roaring —> can be severe enough to be at rest

33
Q

What are 4 signs of arytenoid chondritis on endoscopy?

A
  1. granulation tissue/tract of axial surface of arytenoid
  2. distorted corniculate process
  3. rostral displacement of the palatopharyngeal arch
  4. hemiplegia + restricted movement
34
Q

What conservative treatments are used for arytenoid chondritis? Surgical?

A
  • antibiotics
  • anti-inflammatories
  • rest

partial arytenoidectomy performed via laryngotomy

35
Q

What 5 complications are associated with partial arytenoidectomies for treating arytenoid chondritis? What is prognosis like?

A
  1. coughing
  2. dysphagia
  3. dyspnea
  4. webbing granulation tissue
  5. cartilage mineralization

62% in racing TB

36
Q

What is aryepiglottic fold entrapment? What are 3 etiologies?

A

epiglottis trapped by aryepiglottic fold

  1. hypoplastic epiglottis
  2. inflammation
  3. subepiglottic cysts, cleft palate, DDSP
37
Q

What are 3 clinical signs associated with aryepiglottic fold entrapment? What is seen with secondary DDSP?

A
  1. exercise intolerance
  2. inspiratory or expiratory noise during exercise
  3. coughing during eating

gurgling, expiratory noise

38
Q

When can incidental aryepiglottic entrapment be suspected?

A
  • no clinical signs
  • horse not used for athletic purposes
39
Q

What 3 things are seen on endoscopy with aryepiglottic fold entrapment?

A
  1. cannot see serrated border or vasculature of epiglottis
  2. ulceration at tip of epiglottis
  3. see back edge of the aryepiglottic fold
40
Q

What are 3 options for surgical treatment of aryepiglottic fold entrapement?

A
  1. resection via laryngotomy - requires GA, endoscopic guidance
  2. axial division per nasum - standing, endoscopic, hooked bistoury or laser
  3. axial division per os - same as per nasum, requires GA
41
Q

What complication is commonly seen with surgical treatment of aryepiglottic fold entrapment? What 3 other complications can be seen?

A

DDSP - especially with a hypoplastic epiglottis and excision of fold

  1. re-entrapment (10%)
  2. inadvertent laceration of soft palate or epiglottis
  3. deformity of epiglottis caused by chronic entrapment

Large Animal Surgery (32 decks)

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