Lecture 37: Diseases and Disorders of the Equine Guttural Pouch and Trachea

guttural pouch anatomy

• air filled diverticulum of the auditory canal

• extend from the roof of the pharynx to the base of the skull and from the atlanto-occipital joint to the pharyngeal recess

• pouches communicate with the nasopharynx and open routinely during swallowing

what are the arrows showing?

openings into the guttural pouch (pharyngeal orifice)

the medial compartment of the guttural pouch contains

• internal carotid artery

• cranial cervical ganglion

• cervical sympathetic trunk

• vagus nerve

• glossopharyngeal nerve

• hypoglossal nerve

• spinal accessory nerve

• cranial laryngeal nerve

the lateral compartment of the guttural pouch contains

• external carotid artery

• facial nerve

what is 1?

internal carotid artery

what is 2?

ventral straight mm

what is 3?

cranial nerves

what is 4?

stylohyoid bone

what is 5?

external carotid artery

guttural pouch tympany is

air distension in the guttural pouch

etiology of guttural pouch tympany

• congenital → mucosal flap acts as one-way valve to trap air

• idiopathic → no gross abnormality

occurrence of guttural pouch tympany

• seen shortly after birth to 1yr

• typically unilateral, may be bilateral

• arabian and paint foals over-represented

• fillies > colts

clinical signs of guttural pouch tympany

• air distended GP → swelling in parotid

• possible → respiratory distress, interference with deglutition

treatment of guttural pouch tympany

• needle decompression → short term

• make a permanent hole to deflate → median septum, salpingopharyngeal fistula

what is this showing?

salpingopharyngeal fistula (guttural pouch tympany)

guttural pouch tympany prognosis

good with surgery

guttural pouch empyema is

pus in the guttural pouch

guttural pouch empyema etiology

• sequel to URT infection

• commonly strep equi (strangles) → horse becomes an S. equi carrier

• can occur secondary to rupture of a retropharyngeal LN abscess into the GP

clinical signs of guttural pouch empyema

• chronic mucopurulent nasal discharge → no odor, seen when head is lowered

• swelling adjacent of LNs

• extended head carriage

• excessive respiratory noise

• difficulty swallowing/breathing

• typically NO external swelling of the GP

• usually unilateral, may be bilateral

chondroids =

inspissated pus

what is this?

guttural pouch empyema

diagnosis of guttural pouch empyema

• clinical signs

• not clearing a strep equi infection

• endoscopy

• culture and sensitivity

• ± radiographs

what is this radiograph showing?

guttural pouch empyema

treatment for guttural pouch empyema

• can be a challenge

• flush GP

• systemic antibiotics

• remove chondroids and pus

• prognosis is good once resolved

what is included in Viborg’s triangle?

• tendon of the sternocephalicus

• linguofacial vein

• vertical ramus of the mandible

what is A?

hyovertebrotomy

what is B?

Viborg’s triangle

what is C?

modified whitehouse

what is D?

whitehouse

guttural pouch mycosis is

fungal infection of the guttural pouch

etiology of guttural pouch mycosis

• most common fungus = aspergillus fumigatus

• diphtheric membrane

• necrosis of underlying structures → carotid arteries

clinical signs of guttural pouch mycosis

• epistaxis → may be mild and intermittent initially; may have several nosebleeds before fatal hemorrhage

• dysphagia

• respiratory noise

• horner’s syndrome

what are these showing?

guttural pouch mycosis

treatment for guttural pouch mycosis

• medical → topical antifungals

• surgical → semi-emergency if blood vessels involved

• prognosis → 50% of horses with hemorrhage bleed to death; neurologic deficits may not resolve or take months to recover

surgical treatment of guttural pouch mycosis

• occlude affected artery

• retrograde flow → occlude both sides of lesion

• fluoroscopic guidance

medical treatment for guttural pouch mycosis (if no artery involvement)

• topical antifungal via indwelling catheter → enilconazole, fluconazole

• systemic antifungal → itraconazole

• remove diphtheric membrane endoscopically

temporohyoid osteoarthropathy (THO)

• progressive disease of the middle ear

• affects the temporohyoid joint → includes stylohyoid, tympanohyoid cartilage, squamous part of temporal bone

THO etiology

• inner or middle ear infection

• spreads to temporohyoid structures → joint fuses with possible fracture of petrous part of temporal bone

• CN 7 and 8 damage

• degenerative process

clinical signs of THO

• variable → depends on structures affected

• early → behavioral issues like head tossing/shaking, ear rubbing, resistance under saddle

• TH joint fuses → movement of the tongue and larynx → fracture of the petrous temporal bone → acute neurologic deficits

• can occur with oral exams and teeth floating

advanced neurological signs of THO

• vestibulocochlear nerve damage → asymmetric ataxia, head tilt with poll toward affected side, spontaneous nystagmus

• facial nerve damage → facial paralysis, decreased tear production, inability to close eye

• glossopharyngeal and vagus nerve damage

treatment of THO

• medical for mild cases → systemic antibiotics, NSAIDs

• surgical for advanced cases

• prognosis is fair

surgical treatment for THO

• goal is to relieve pressure on temporal bone

• partial stylohyoidectomy → bone tends to regrow

• ceratohyoidectomy

tracheotomy

emergency procedure if there is a complete airway obstruction

tracheotomy procedure

• junction of cranial and middle third of neck

• rough prep

• local anesthetic

• final prep

• 10 cm vertical incision through skin (midline)

• blunt dissection between bellies of sternothyrohyoideus

• incise horizontal through annular ligament between rings

• 1/3 to ½ circumference only

clinical signs that a horse needs immediate tracheotomy

• cyanotic mucous membranes

• weakness

• labored breathing

• reduced airflow at both nostrils

tracheotomy cut

½ circumference, horizontal between tracheal rings!

tracheotomy healing

• clean twice daily

• heal by second intention when no longer needed → close pretty quickly, small scar, pretty cosmetic