34 Diseases of the Equine Respiratory Tract 1

Congenital

Cleft palate is a/n *congenital or acquired* defect

Cleft palate

A foal has milk draining from its' nose after nursing and coughing from milk dribbling into the trachea. The mouth looks like this. Thoughts?

Dorsal displacement of the soft palate

This is intermittent or persistent malpositioning of the caudal edge of the soft palate dorsal to the epiglottis

Ventral to the epiglottis at rest (the only time this is different is when swallowing)

In health, where SHOULD the soft palate be?

Dorsal displacement of the soft palate

What is this?

A = normal

B = dorsal displacement of soft palate

Which of these images is normal? Which has an abnormality and what is it?

Dorsal displacement of soft palate

You watch a racehorse "choke down" or falter at the end of a race. His cheeks bulge and he is coughing. The owner is mad because the horse has *expiratory* noise and feels like this is limiting the horses performance. What is happening?

Inflammation (upper resp. tract infection) that affects the nerve for palate stability (pharyngeal branch of vagus nerve)

May also be due to hypoplastic epiglottis

What etiology commonly causes dorsal displacement of the soft palate?

Dynamic endoscopy

What is most likely the best way to diagnose dorsal displacement of the soft palate?

Make the horse swallow either by pushing on larynx or flushing water thru a scope

What "epiglottis trick" should get the horse's soft palate to move back to its' normal position under the epiglottis with dorsal displacement of the soft palate?

To see how long it takes them to replace the palate

You can manually dorsally displace the epiglottis in a horse with dorsal displacement of the soft palate by holding the nostrils shut and flexing their head. Why would you want to do this?

Ulceration of the soft palate (may cause chronic displacement)

What other endoscopic findings will be present with dorsal displacement of the soft palate?

Treat the underlying cause

Anti-inflammatory therapies like throat spray and steroids are often reached for to treat horses with dorsal displacement of the soft palate. What should you attempt to do BEFORE you reach for these?

Palatoplasty

This treatment of dorsal displacement of the soft palate involves creating scar tissue to make the palate more stiff, such as with a laser or thermocautery

Staphylectomy

This treatment of dorsal displacement of the soft palate involves resecting the caudal margin of the soft palate

TIE FORWARD

Which surgical treatment of dorsal displacement of the soft palate has the *BEST PROGNOSIS* in the literature, with 80% success?

Tie forward procedure

This treatment of dorsal displacement of the soft palate involves pulling the larynx forward to allow the epiglottis to engage with the palate by passing suture from the *thyroid cartilage to the basihyoid bone*

Strap muscle myectomy

This treatment of dorsal displacement of the soft palate involves cutting and removing the sternohyoideus muscle and sternothyroideus muscle to prevent the larynx from falling back

Llewelyn procedure

note: the idea is the same as the strap muscle myectomy, only the tendons are cut instead of a hunk of muscle

This treatment of dorsal displacement of the soft palate involves transecting the TENDON of the sternothyroideus tendon at the insertion on the thyroid cartilage

Reduce caudal retraction of the larynx

The goal of both strap muscle myectomy and Llewelyn procedure to fix dorsal displacement of the soft palate is what?

Post Myectomy to fix dorsal displacement of the soft palate

What post-op presentation is this? What did it fix?

Inspiratory noise

Where in the respiratory cycle will there be noise with dynamic pharyngeal collapse?

Dynamic pharyngeal collapse

What problem does rostral displacement of the palatopharyngeal arch cause in horses?

CN IX (glossopharyngeal) and X (vagus)

What nerves innervate the muscles of the pharynx?

Dynamic endoscopy

What is the best diagnostic test for dynamic pharyngeal collapse?

Conduit between the pharynx and trachea

Where is the larynx located?

Muscular process

What is A?

Thyroid cartilage

What is B?

Epiglottis cartilage

What is C?

Thyroarytenoideus muscle

What is D?

Arytenoideus transversus muscle

What is E?

Cricoarytenoideus dorsalis muscle

What is F?

Cricoarytenoideus lateralis muscle

What is G?

Cricothyroideus muscle

What is H?

Cricoarytenoideus dorsalis muscle

What is the only muscle of the larynx that abducts?

The arrow is pointing to the NORMAL side. This is unilateral laryngeal hemiplegia

Is this normal or abnormal? What is happening?

ABNORMAL = bilateral laryngeal hemiplegia

Is this normal or abnormal? What is happening?

Left (esp. problems with left recurrent laryngeal nerve)

Is it more common to have *right or left* laryngeal hemiplegia?

This shows cutting of the aryepiglottic fold with a guarded hook for aryepiglottic fold entrapment

What is this treatment for?

Draft breeds

Left sided laryngeal hemiplegia (although the more common side overall), typically affects what breed of horse?

Left laryngeal hemiplegia

A draft horse presents with inspiratory whistling and *roaring* during exertion. This horse has exercise intolerance and decreased athletic performance. On endoscopy you see this. Thoughts?

Inspiratory whistle and ROARING on exertion

Increased resistance causes turbulence to make what sounds in horses with left laryngeal hemiplegia?

Atrophy of cricoarytenoideus dorsalis muscle

What muscle can you feel that might be atrophied with left laryngeal hemiplegia in horses, allowing you to palpate the muscular process of the arytenoid cartilage?

FALSE = DO NOT USE SEDATION

TRUE OR FALSE: If you do endoscopy in a horse to see left laryngeal hemiplegia at rest, you should use sedation to prevent them biting off your endoscope.

Progressive

Left laryngeal hemiplegia is a *progressive or static* disease

Grade 1 - Grade 4

1. synchronous full abduction

2. asynchronous full abduction

3. asynchronous partial abduction

4. no abduction

What are the grades of left laryngeal hemiplegia?

A. vocal cords

B. saccule/ventricule

What are these?

Prosthetic laryngoplasty (aka tie back)

What is the TREATMENT OF CHOICE for left laryngeal hemiplegia?

Ventriculectomy, chordectomy (vocal cords), ventriculocordectomy (combo of the previous two)

Prosthetic laryngoplasty is the treatment of choice for left laryngeal hemiplegia, the only one that actually improves performance. However, what other procedures should you do that are STRICTLY FOR NOISE REDUCTION, but should be done to make the owner happy?

DONT OPEN TOO MUCH = aspiration

What do you need to be careful of when performing a prosthetic laryngoplasty on a horse?

Cordectomy (for noise reduction ONLY)

What is this procedure for laryngeal hemiplegia?

Arytenoid chondritis

What is this?

Arytenoid chondritis

This is inflammation of the arytenoid cartilage that causes roaring in horses

Granulation tissue

What is this, causing arytenoid chondritis?

Distorted corniculate process

What is this, causing arytenoid chondritis?

Rostral displacement of the palatopharyngeal arch

What is this, causing arytenoid chondritis?

Coughing, dysphagia, dyspnea, webbing granulation tissue, cartilage mineralization

What are the COMMON COMPLICATIONS of a partial arytenoidectomy for arytenoid chondritis treatment?

Aryepiglottic fold entrapment

What is this?

Aryepiglottic fold entrapment

This occurs when the epiglottis is entrapped by the aryepiglottic fold, where clinical signs are often secondary to dorsal displacement of the soft palate (gurgling, expiratory noise)

Dorsal displacement of the soft palate, especially if the animal has hypoplastic epiglottis

What other abnormality is aryepiglottic fold entrapment associated with?

Ulceration at the tip of the epiglottis from aryepiglottic fold entrapment

What is this?

1. BEST: dorsal displacement of the soft palate

2. left laryngeal hemiplegia

3. WORST: arytenoid chondritis

Order these from best to worst prognosis with each gold standard treatment:

1. arytenoid chondritis

2. dorsal displacement of the soft palate

3. left laryngeal hemiplegia