The Guttural Pouch

Question 1

The guttural pouch is present in what species?

Answer 1

Horses

Question 2

What is another name for the guttural pouch?

Answer 2

“Throat sac” or saccus qeroforus

Question 3

What is the guttural pouch?

Answer 3

A diverticulum of the Eustachian tube/auditory tube which connects the nasopharynx to the middle ear

Question 4

Where is the guttural pouch located?

Answer 4

Paired on either side of the horse’s face between the jaw and the ear

Question 5

What is the function of the guttural pouch?

Answer 5

• Located next to the internal carotid artery so that heat can be transferred from the artery to the guttural pouch
• Blood as it is will burn the brain if it is not cooled first, so the guttural pouch acts as a heat dissipation mechanism
• Reduces the temperature of the blood that goes to the brain

Question 6

What is the role of the stylohyoid bone in relation to the guttural pouch?

Answer 6

Demarcates the pouch into a medial compartment and lateral compartment

Question 7

What structures are found within the medial compartment of the guttural pouch?

Answer 7

• Internal carotid artery
• Cranial cervical ganglion
• CN 9, 10, 11, 12

Question 8

What structures are found within the lateral compartment of the guttural pouch?

Answer 8

• Maxillary vein
• External carotid artery
• Facial vein to a little extent

Question 9

What are the structures that are found in close proximity to the guttural pouch and why are they important?

Answer 9

• Cranial cervical ganglion just caudal to the pouch as well as retropharyngeal lymph node
• CN 9, 10, 11, and 12 just deep to the pouch
• We worry about these structures when we have any pathology that affects the guttural pouch

Question 10

What kind of infections are commonly seen in the guttural pouch and what are the characteristics of these infections?

Answer 10

Fungal infections:
- Usually only on one side
- No apparent predisposition
- Cause is unknown
- Usually has to do with Aspergillus spp.
- Can migrate into the nerves that are imprinted within the pouch and cause nerve paralysis

Question 11

What are the signs of a fungal infection of the guttural pouch?

Answer 11

• Cardiovascular problems due to the vagus nerve being affected
• Gastric or digestive issues due to vagus nerve
• Nose bleeding

Question 12

What are the treatment options for a fungal infection of the guttural pouch?

Answer 12

• Surgery
• Flush
• Antibiotics or antifungal agents

Question 13

Describe the air flow within the guttural pouch.

Answer 13

Air enters during swallowing via the plica salpingopharyngeus, which is a soft tissue structure that lies just beneath the nasopharyngeal opening of the guttural pouch; this flap opens and closes as air enters and exits

Question 14

What is guttural pouch tympany?

Answer 14

Issue in which air enters the guttural pouch but cannot exit and becomes trapped; associated with redundancy of plica salpingopharyngeus and can be either unilateral or bilateral

Question 15

Guttural pouch tympany is most commonly seen in what kind of horses?

Answer 15

Those up to 1 year old

Question 16

What are the causes of guttural pouch tympany?

Answer 16

Can be congenital or secondary to inflammation of the guttural pouch

Question 17

What are the signs of guttural pouch tympany?

Answer 17

• Swelling on one or both sides (usually 10-15 cm)
• Difficulty breathing
• Nasal discharge
• Nose bleeding
• Animal will want to keep the neck extended and won’t want to bring it back

Question 18

What are the signs of guttural pouch disease?

Answer 18

• Nasal discharge/bleeding due to compression and rupture of blood vessels
• Quidding: dropping of chewed food from the mouth
• Inflamed parotid gland
• Trigeminal-mediated head tilt/shaking

Question 19

What is Viborg’s triangle?

Answer 19

Safest surgical access point for the guttural pouch just caudal to the ventral region of the parotid gland

Question 20

What are the boundaries of Viborg’s triangle?

Answer 20

• Linguofacial vein
• Tendon of the sternocephalicus muscle (sternomandibularis in horses)
• Caudal edge of mandible

Question 21

How do you access the guttural pouch via Viborg’s triangle?

Answer 21

Palpate these 3 structures and penetrate the center of this region to confidently enter into the guttural pouch without fear of damage to other structures

Question 22

What are the various surgical approaches to the guttural pouch?

Answer 22

• Whitehouse approach
• Viborg’s triangle: most common
• Hyovertebrotomy

Question 23

What are the common procedures performed on the guttural pouch via Viborg’s triangle access?

Answer 23

• Lavage with sterile saline
• Tympany correction
• Access to the internal carotid artery via the guttural pouch

Question 24

What are the indications for guttural pouch surgery?

Answer 24

• Emphysema
• Empyema
• Food material within the pouch

Question 25

How is a guttural pouch lavage performed?

Answer 25

Scope inserted through the nasal cavity or Viborg's triangle and then the area is flushed with saline

Question 26

Inflammation of the guttural pouch affects what lymph nodes?

Answer 26

Retropharyngeal; when there is an infection of the guttural pouch these structures will swell as they are the LN's that drain it

Question 27

How can guttural pouch inflammation lead to roaring in horses?

Answer 27

Swelling of the retropharyngeal lymph nodes can put pressure on the recurrent laryngeal nerves causing laryngeal hemiplegia