Soft tissues of the oral cavity

Question 1

According to Jones 2020 in Vet Surg, how did the volume of brachycephalic tongues compare to those of mesaticephalic patients?

Answer 1

Volume of the tongue greater relative to body weight and skull length (relative macroglossia).

Also 10 times denser. Proportion of air/soft tissue in the oropharynx and nasopharynx reduced by 60%.

Question 2

In a study by Goldschmidt 2023 in JAVMA, what percentage of dogs with oral cancer had a major incidental finding on skull and neck CT scan? When head CT, lymph node CT, thoracic screening, and AUS were performed what was the chance of a major finding in at least 1 test? What patients had the highest prevalence of metastatic disease at the time of staging?

Answer 2

5% of dogs had major incidental findings on skull and neck CT scan (predominantly secondary extraoral tumours). Risk of major incidental findings was increased with age.

28% (or 1/4) patients had a major finding on either head CT, lymph node cytology, thoracic screening, and AUS. Major incidental findings were most commonly identified with AUS in 1 of 12 patients (although metastatic disease most commonly identified on thoracic imaging).

Oral malignant melanoma, oral SCC, and T3 tumours had the greatest prevalence of metastatic disease.

Question 3

In a study by Treggiari 2023 in JVIM, what was the MST for dogs with tonsillar carcinoma? What were 4 factors associated with improved survival?

Answer 3

MST 126 days.

Surgery (MST 196 days), chemotherapy, use of NSAIDs, and absence of clinical signs were associated with improved survival.

Distant metastasis occurred in 15% of patients, majority pulmonary. Of the 76% of dogs that had regional LNs sampled, 80% had regional metastasis.

Question 4

What nerve supplies motor innervation to the lips and cheek?

Answer 4

Facial nerve

Question 5

What nerve supplies sensory innervation to the lips and cheek?

Answer 5

Trigeminal nerve

Question 6

What vessels supply the lips and cheeks?

Answer 6

Branches of the facial supply the lower lips, branches of the infraorbital the upper.

Question 7

What nerve innervates the extrinsic muscles of the tongue? What are the three main extrinsic muscles of the tongue?

Answer 7

Hypoglossus nerve.

The three main muscles are the genioglossus, styloglossus, and hyoglossus.

Question 8

What is the name of the mucosal fold that runs longitudinally adjacent to the frenulum of the tongue and ends at the sublingual caruncle?

Answer 8

Sublingual fold

Question 9

What nerve controls the actions of the intrinsic muscles of the tongue?

Answer 9

Hypoglossal nerve

Question 10

Label the following diagram.

Answer 10

Question 11

What are the gustatory and nongustatory papillae of the tongue?

Answer 11

Gustatory: fungiform, vallate, foliate.
Nongustatory: filiform, conical.

Question 12

What artery is the lingual artery a branch of? Where does the lingual vein empty?

Answer 12

The external carotid. The lingual vein empties into the facial vein.

Question 13

Which muscles make up the soft palate?

Answer 13

Tensor and levator veli palatini, palatine, palatopharyngeal, pterygopharyngeal.

Question 14

What nerves control the muscles of the soft palate?

Answer 14

The vagus and glossopharyngeal nerves.

Question 15

What vessel supplies the soft palate?

Answer 15

Minor palatine artery (a branch of the maxillary artery).

Question 16

What is the main arterial supply of the palatine tonsil?

Answer 16

The tonsilar artery (a branch of the lingual artery)

Question 17

Where do the efferent lymphatics of the tonsils drain?

Answer 17

The mandibular and retropharyngeal lymph nodes

Question 18

What is the name of the additional tonsils seen in cats?

Answer 18

The paraepiglottic tonsils (craniodorsal to the base of the epiglottis).

Question 19

What are the phases of deglutition?

Answer 19

1. Oropharyngeal
   a. Oral: formation of a food bolus. Sensory and motor innervation supplied by the facial, trigeminal, and hypoglossal.
   b. Pharyngeal: tongue and pharyngeal constrictor muscles transport the food bolus to the pharynx. The epiglottis covers the larynx and the palate the nasopharynx. Under the control of the vagus and glossopharyngeal nerves.
   c. Pharyngoesophageal: passage of food through the cricopharyngeal sphincter. Terminates with closure of the sphincter, also under the control of the vagus and glossopharyngeal nerves.
2. Esophageal
3. Gastroesophageal

Question 20

Which lymph nodes receive afferent lymphatic drainage from the oral cavity?

Answer 20

The parotid, mandibular and medial retropharyngeal. The superficial cervical lymph nodes should also be sampled as they receive afferent lymphatics from the aforementioned nodes.

Nodes on both sides should be sampled as lymph vessels can cross midline.

Question 21

Why should spring loaded mouth gags be avoided in cats?

Answer 21

Can cause compression of the maxillary arteries and neurologic deficits, including blindness.

Question 22

What is the most common congenital disorder affecting the lips in dogs?

Answer 22

Primary cleft palate

Question 23

What are surgical treatment options for tight lip syndrome (only described in Shar-Peis)?

Answer 23

Incision of the lip mucosa at the gingival margin to allow the lip to retract, excising a segment of skin on the chin to pull the lip margin ventrally, deepening of the rostral and lateral vestibule.

Question 24

What surgery is described for treatment of lower lip redundancy and eversion?

Answer 24

Anti-drool chelioplasty, alternatively the redundant fold of tissue can be resected with a full-thickness wedge resection.

Question 25

How is traumatic lip avulsion surgically corrected?

Answer 25

Small lesions can be left to heal by second intention. Large avulsions often occur at the gingival margin which has poor holding power, may require placement of suture subgingivally around incisor teeth or the use of bone tunnels.

Question 26

What are the most common tumour types of the canine and feline lip?

Answer 26

Canine: melanoma, SCC Feline: SCC, mast cell tumours, fibrosarcomas.

Question 27

What is the MST for dogs with lip melanoma?

Answer 27

34 months with excision of well-differentiated tumours. May be less for poorly differentiated disease.

Question 28

What is the metastatic rate for oral nontonsillar SCC?

Answer 28

0-38%

Question 29

When might buttons be useful in closure of the lip?

Answer 29

In resections of the commissure, to prevent unzipping of the incision.

Question 30

What reconstructive technique of the lip is depicted?

Answer 30

Question 31

What is the most common site of penetrating oral injury?

Answer 31

Directly underneath the tongue

Question 32

Why is the tongue a rare site for infection?

Answer 32

Rich blood supply, ability to avoid penetrating injury, tough dorsal surface, continual contact with saliva.

Question 33

What are the three types of calcinosis circumscripta? Is the tongue a common site?

Answer 33

Dystrophic: secondary to trauma. Metastatic: due to abnormal calcium balance. Idiopathic: unknown cause. The tongue is the second most common location. Treatment is not usually required unless dysphagia is present.

Question 34

What are the most common malignant oral tumours in dogs? What is the most common site for oral tumours in dogs?

Answer 34

Melanoma, SCC, fibrosarcoma Gingiva, followed by tonsils and lips.

Question 35

What are the most common malignant oral tumours in cats? What is the most common site for oral tumours in cats?

Answer 35

SCC (70-80%), fibrosarcoma. Gingiva and tongue.

Question 36

What breeds of dog are at increased risk of lingual melanoma and SCC?

Answer 36

Melanoma: Shar Pei, Chow Chows SCC: Poodles, labradors, Samoyeds. Female dogs predisposed

Question 37

Which part of the tongue is most commonly affected in cats with lingual SCC?

Answer 37

Ventral portion near the frenulum.

Question 38

What are 4 risk factors in cats for developing squamous cell carcinoma?

Answer 38

Canned food diets, canned tuna fish, flea collars (5 x incidence), environment with a smoker. Compare to study by Zaccone in JVIM that found the following risk factors: rural environment, outdoor access, environmental tobacco smoke, and petfood containing chemical additives.

Question 39

What percentage of malignant melanoma of the mouth are amelanotic?

Answer 39

33%

Question 40

Which lymph nodes should be sampled when staging oral melanoma?

Answer 40

Ideally mandibular, retropharyngeal and parotid. Only 54% of dogs with regional lymph node metastasis have mandibular lymph node involvement.

Question 41

What is the MST for lingual melanoma and SCC in dogs?

Answer 41

Melanoma: 216 days SCC: 241 days Survival much longer for both tumours when lesions <2cm (818 days). Local recurrence reported in 28% of dogs following glossectomy.

Question 42

What surgical margin is recommended for tumours of the tongue?

Answer 42

2cm. Less than 1cm margins associated with an increased risk of recurrence.

Question 43

How can large wedge excisions of the tongue be closed?

Answer 43

The rostral portion of the tongue can be rotated up to 90 degrees.

Question 44

What are the different types of glossectomy?

Answer 44

Partial: amputation of the free portion of the tongue rostral to the frenulum. Subtotal: removal of the entire free tongue and a portion of the genioglossus and geniohyoid muscles caudal to the frenulum. Near total: >75% of the entire tongue. Amputation: total glossectomy.

Question 45

What percentage resection of the tongue is well tolerated in dogs and cats?

Answer 45

50% in the dog. Glossectomy less well tolerated in cats.

Question 46

What is the MST for SCC of the oral cavity in cats?

Answer 46

44 - 203 days.

Question 47

What are the most common causes of dysphagia?

Answer 47

Space occupying mass, congenital abnormalities, functional abnormalities.

Question 48

What are the most common pharyngoesophageal dysphagias?

Answer 48

Cricopharyngeal asynchrony and cricopharyngeal achalasia.

Question 49

What are common sites of penetrating injury to the pharynx?

Answer 49

Esophagus, lateral and dorsal pharyngeal walls, sublingual region.

Question 50

What structure needs to be carefully preserved when performing a ventral midline exploration for penetrating pharyngeal foreign body?

Answer 50

The recurrent laryngeal nerves

Question 51

What is the most common tonsillar neoplasia in dogs and cats?

Answer 51

SCC

Question 52

What is the regional and distant metastatic rate for canine tonsillar SCC?

Answer 52

73% regional, 42% distant. 70% of dogs had normal sized lymph nodes on palpation in one study despite 45% of these having metastatic disease.

Question 53

What is the MST for dogs with tonsillar SCC?

Answer 53

2 months. In a more recent study the combination of tonsillectomy +/- chemo +/- radiation resulted in prolonged survival (212 days). Presence of metastatic disease does not seem to affect survival, most likely due to difficulty in controlling the primary tumour.

Question 54

What is the MST for cats with tonsillar SCC?

Answer 54

2-14 weeks.