Ch 88 Salivary glands Flashcards
four major salivary glands
parotid, mandibular, sublingual, and zygomatic
Parotid Gland
- positioned superficial to the vertical ear canal, rostrally by the masseter muscle and TMJ, caudally by the sternomastoideus and cleidocervicalis muscles, ventrally by the mandibular salivary gland
- deeper surrounding structures, including, but not limited to, the facial nerve, maxillary and temporal arteries, internal maxillary vein
- duct: travels over the lateral aspect and ventral third of the masseter muscle and opens into the oral cavity at PM4
- arterial supply: parotid artery, a branch of the external carotid artery
Zygomatic Gland
- ventral and rostrolateral to the globe and medial to the zygomatic arch
- One major and up to four minor salivary ducts
- major duct opens at last upper molar
- supplied by a branch of the infraorbital artery
Mandibular and Sublingual Salivary Gland
- intimately associated and thus considered anatomically as a pair.
- two glands have a common capsule
- mandibular gland lies on medial aspect of the linguofacial and maxillary vein junction, mandibular lymph nodes ventral surface and the medial retropharyngeal lymph node and larynx on its medial surface
- duct: exits into the oral cavity at the sublingual caruncle
- major blood supply: branch of the facial artery
- sublingual salivary gland is composed of monostomatic and polystomatic portions.
- polystomatic salivary tissue consists of small clusters of glandular tissue rostral to the lingual nerve that typically empty directly into the oral cavity.
- duct courses alongside the mandibular duct and usually exits at the sublingual caruncle
- blood supply: glandular branch of the facial artery and sublingual branch of the lingual artery
Minor Salivary Glands
- buccal, labial, lingual, tonsillar, palatine, and molar
- molar gland is well developed in cats and is located just deep to the buccal mucosa at the angle of the mandible.
List the functions of saliva
Lubricate ingesta
Facilitates making a food bolus
THermoregulation
Cleansing
Buffering
Reduction of bacterial growth
Protection of oral surface epithelium
Describe the two phases of saliva production
Phase 1: Acinar cells absorb Na which draws water in, producing Na-rich saliva
Phase 2: Saliva enters the collecting ducts. Active reabsorption of Na with secretion of HCO and K. Occurs mainly in intralobular duct. Forms saliva rich in bicarb and K
WHat structures are closely associated with the parotid salivary gland?
Facial nerve
Maxillary and temporal arteries
Internal maxillary vein
Regions surround external acoustic meatus and stylomastoid formen
Where so the parotid and zygomatic salivary glands enter the oral cavity?
Parotid: Small papilla at the level of the upper 4th premolar
Zygomatic: Caudolateral aspect of last upper molar
What is the anatomical delineartion between the monostomatic and polystomatic portions of the sublingual salivary gland?
the lingual nerve
- Caudal is monostomatic
- Rostral is polystomatic
Secretions from what glands have a higher proportion of mucus?
Sublingual and zygomatic
What causes the stimulation of saliva production?
Autonomic nervous system
- Stimulation of parasympathetic nervous system stimulated the production of salvia by vasodilation of blood supply and by stimulation of cyclic guanosine monophosphate (cGMP) which directly upregulates the acinar cells
non surgical disease
What is sialadenosis?
Non-inflammatory, non-neoplastic bilateral swelling of the salivary glands. Most common mandibular glands
What is the treatment for sialadenosis?
Phenobarbital 1-2mg/kg PO BID.
Clinical signs should improve within 1-2 days. This response may support a diagnosis of limbic epilepsy (cause of sialadenosis is unknown)
List 2 proposed caused of noninfectious sialadenitis / necrotising sialometaplasia
Hyperstimulation of the vagus nerve, resulting in a neural reflex syndrome similar of hypertrophic osteopathy. Can have concurrent oesophageal or GI disease
Limbic epilepsy - response to phenobarbital reported
How can you differentiate sialadenitis from sialadenosis?
What breeds are predisposed to sialadenitis?
Sialadenitis will cause pain upon palpation of effected glands and vomiting
Terrier breeds are predisposed to sialadenitis
What breeds are predisposed to sialocoeles?
Poodles, GSD, Australian Silkies and Dachshunds
four main presentations are:
- exophthalmos (zygomatic sialocele)
- labored breathing (pharyngeal sialocele)
- dysphagia (sublingual sialocele or ranula)
- intermandibular or cranioventral cervical swelling (cervical sialocele)
diagnosis
- fluid-filled mass that contains a viscous, honey-colored, clear or blood-tinged fluid
- Cytological: moderate numbers of nondegenerate nucleated cells, homogenous pink- to violet-staining mucin, foamy Macrophages
Zygomatic Sialoceles
- exophthalmos, protrusion of the third eyelid, or a painless orbital swelling
- sialography, cross-sectional imaging
Tx: sialadenectomy or Use of a sclerosing agent
Pharyngeal Sialoceles
- caudal dorsal or lateral pharynx, just rostral to the level of the epiglottis
- Miniature Poodles and male overrepresented
- concurrent ipsilateral cervical sialoceles in 43% of affected dogs
- Pharyngeal sialoceles pose a risk for airway obstruction
tx: Immediate drainage or temporary tracheostomy if respiratory distress, marsupialisation and removal of mandibular and sublingual gland-duct complex
Sublingual Sialoceles
- Sublingual sialoceles, also called ranulas, likely result from leakage of the rostral sublingual salivary glands or duct
- esulting in difficulty with eating
- ranula should be drained and marsupialized into the oral cavity. Incomplete removal of the sublingual salivary chain can result in recurrence
Cervical Sialocele
- fluctuant in nature, nonpainful, and occasionally changes in size, Diagnosis is made primarily by aspirating
- mucin-specific stain, such as periodic acid–Schiff, help to confirm saliva
- radiographs, sialography, CT, MRI, ultrasonography, culture, and biopsy
- ddx branchial cleft cyst can be differentiated from a sialocele > demonstration of a true secretory lining on histo
- most cervical sialoceles originate from the sublingual gland-duct complex
- determining side: chronic, placed in dorsal recumbency > fluid accumulation usually displaces laterally to the affected side.
- may require sialography, CT, MRI, or an exploratory surgery
- If any question remains, bilateral sialadenectomy can be performed (dry mouth is not expected)
- Conservative treatment of sialoceles > high rate of recurrence
What is the reported rate of recurrence of sialocoele after surgical removal of the gland?
5%
complications: seroma, infection, recurrence, sublingual swell, bleeding
Where do sialoliths most commonly occur?
demonstrate a swelling on the lateral aspect of the face
Parotid duct
composition: calcium oxalate, phosphate, magnesium, or nonmineral
List the possible treatments of sialoliths
Surgical removal of effected duct-gland complex
Incision through oral mucosa directly over stone
Resection and anastomosis of duct
Marsupialisation of dilated duct
What glands are most commonly effects by neoplasia?
What are the most commonly reported neoplasms? (All are rare)
What is the reported rate of LN involvement?
Mandibular and parotid glands most commonly effected
Adenocarcinoma and acinic carcinoma most common
LN involvement in 17% dogs and 39% cats
salivary gland neoplasia
- staging recommended > prognosis is not correlated with histologic grade but is associated with stage of disease
- owner to understand whether the procedure is being performed for diagnosis, cytoreduction, palliation, curative intent, prevention, or metastasectomy
- Sentinel lymph node extirpation can be performed
- prognosis is largely unknown
Sublingual and Mandibular Sialadenectomy
- ventral approach permits removal of the entire sublingual gland-duct complex compared to lateral
Ventral Approach
- platysma muscle is incised to facilitate identification of the external jugular bifurcation; the mandibular gland sits at or just cranial to this bifurcation
- The capsule over both glands is incised and bluntly dissected, vessels on the medial side ligated
- The gland complex retracted caudally to allow blunt dissection of the sublingual gland under the digastricus muscle.
- hemostat placed from rostral to caudal under the digastricus muscle, the glands are excised
- remaining ducts and sublingual glands are pulled under the digastricus muscle, dissection are continued to the level of the lingual nerve (the mylohyoideus muscle is incised for best exposure)
- If a ranula is present, however, dissection should continue rostral to the lingual nerve under the mylohyoideus to the sublingual caruncle
- incisional drainage of the sialocoele with or without drain placement
Zygomatic Sialadenectomy
- aponeurosis of the masseter muscle is reflected off of the ventral aspect of the zygomatic arch, and the orbital fascia is reflected dorsally.
- portion of the arch is removed, as necessary, with a bone saw
- Orbital fat is dissected and retracted
- ## gland resides medial to the zygomatic arch and adjacent to the globe
Parotid Sialadenectomy
- facial nerve paresis or paralysis is a common complication.
- starting at a point below the external acoustic meatus and extending ventrally
- platysma and parotidoauricularis muscles are incised
- ## ligation and division of the caudal auricular vein, the parotid gland is bluntly dissected
conservative mgmt options
- Intralesional injections of sclerosing agents
(polidocanol) successfully used for orbital mucocele - radiation therapy
- N-acetylcysteine (gland preserving)
- medical antibiotics and nsaid
What additional step during parotid sialadenectomy should be performed if the patient presented with lateral cheek swelling?
Dissection and removal of accessory parotid gland just dorsal to the parotid duct
Outcomes and clinical features associated with surgically excised canine salivary gland carcinoma:
A multi-institutional, retrospective, Veterinary Society of
Surgical Oncology study
Bush 2023
Multi-institutional retrospective case series.
Animals: Seventy-two client-owned dogs
The overall median survival time (MST)
was 1886 days.
Local (42%) dogs with an overall (DFI) of 191 days.
Metastatic disease occurred in (31.9%) dogs
complications:
Nodal metastasis was a negative prognostic factor
Thirty-four dogs received adjuvant therapy following
surgery. Chemotherapy alone was administered to 8 dogs
(8/34, 23.5%), radiation therapy alone was administered
to 10 dogs (10/34, 29.4%), and nonsteroidal antiinflammatory
drug (NSAID) therapy alone was administered
to 4 dogs (4/34, 11.8
local recurrence rates are particularly high confirmed via cytology or histopathology in 18 dogs 26.1% (suspected in further 15%)
The perioperative complication rate was 23.6% (17/72).
The most common perioperative complications were
facial nerve injury resulting in paresis or paralysis (7/72,
9.7%) and swelling or seroma formatio
Intraoral approach for zygomatic sialoadenectomy in dogs: An anatomical study and three clinical cases
Viitanen 2023
compare this surgical approach to a modified lateral orbitotomy
approach (LOA).
Removal of the ZSG was complete in 8/10 and 10/10 dogs using the IOA and LOA, respectively
case series had no complications.
salivary gland papilla on a ridge of
mucosa at the level of the last maxillary molar tooth, catheterized using a 24-gage peripheral intravenous catheter and injected with
methylene blue.
IOA: reduced
surgical time compared to the modified LOA, no preoperative
clipping was necessary and less tissue dissection was
needed. IOA provided adequate exposure for ZSG while
minimizing invasiveness of the approach. Complete extirpation
of eight normal glands and near-complete removal
of the remaining two ZSGs in cadaveric dogs was
achieved.
Comparison between IOA and the ventral nonostectomy
approach described by Dörner and colleagues
would be interesting to further understand whether one is
better or if they can complement each other.
The overall sensitivity of CT
sialography to detect surgically confirmed diseased glands was 66.7% (95% confidence
interval: 48.8-80.8). In conclusion, these findings support the use of CT sialography as
an adjunct diagnostic test for treatment planning in dogs with sialoceles
duct catherised with contrast . leak via gland to sialoceole o confirm side.
The use of methylene blue to assist with parotid sialadenectomy in dogs
I. Gordo 2020
Methylene blue was either administered via cannulation of the parotid duct or directly injected into the abnormal gland.
R esults: In all cases, the gland stained dark blue within seconds without any evident leakage. Complete parotid gland resection and removal of the parotid duct was achieved successfully in all dogs
Subjectively, the staining was useful to identify innervation outside the coloured gland and facilitated dissection
Tumor size as a predictor of lymphatic invasion
in oral melanomas of dogs
Carrol 2020
kuntz
59 samples of oral melanomas
significant relationship was identified between the size of oral melanomas
and a single variable of histologic grade, lymphatic invasion,
lymphatic invasion
can confidently be ruled out for tumors < 0.65 cm in diameter (100%
sensitivity) and ruled in for tumors ≥ 2.45 cm in diameter (100% specificity).
Lymphatic invasion has been described as the
gold standard for identification of malignancy
invasion is negatively
associated with patient survival in dogs with
oral melanomas. Of the 52 melanomas investigated,
a significant (P = 0.014) difference was observed in
the MST of dogs with (7.3 months) and without (10.5
months) lymphatic invasion.
Nasopharyngeal sialoceles in 11 brachycephalic dogs
Davide De Lorenzi
2018
may cause obstruction of airway
Surgical deroofing of the sialoceles was performed under endoscopic guidance with biopsy forceps in 5 cases and by diode laser in 6 cases.
No recurrence was diagnosed
chronic nonphysiologic mechanical stress causing changes in minor nasopharyngeal
salivary glands. Direct visualization by nasopharyngoscopy is the best technique
for detection of NPS,
Comparison of three surgical approaches for zygomatic
sialoadenectomy in canine cadavers
Dörner 2021
2021
Study design: Cadaveric study.
Animals: Cadavers of mesocephalic dogs (n = 20).
lateral approach with zygomatic arch
ostectomy on the left (n = 20) and one approach without ostectomy on the
right, ventral (n = 10) or dorsal (n = 10) to the zygomatic arch.
ostectomy-based approach offered excellent surgical view and
good exposure of the zygomatic gland but caused more tissue trauma. The dorsal
nonostectomy approach did not allow complete zygomatic gland extraction
in nine of the 10 dogs, whereas the ventral nonostectomy approach enabled
complete extraction in all 10 dogs.
ventral approach
zygomatic gland could be seen, covered across its surface
by a branch of the deep facial vein.
dorsal
Dissection of the gland was
conducted relatively blindly
Intracanalicular injection of N-acetylcysteine
as adjunctive treatment for sialoceles in dogs:
25 cases (2000–2017)
Ortillé 2020
retrospective (no control group)
10% N-acetylcysteine
Boxers and mixed-breed dogs were most commonly represented
The zygomatic gland was mainly affected (23/25[92%] dogs)
condition was deemed idiopathic
in 22 (88%) dogs. Most IINACs were performed with local anesthesia
Other treatments included antimicrobials and anti-inflammatories.
Mean follow-up time was 18.8 months. All recurrences (5/23 [22%] dogs)
were controlled with medical management.
N-acetylcysteine, a cysteine prodrug and glutathione precursor, has been used mainly as a mucolytic and antioxidant agent.22 Thus, the expected effect when locally applied to a sialocele would be disruption of thick salivary secretions, generally by altering the degree of cross-linking > aim to preserve function of gland (vs surgical removal)
IINAC may be a useful adjunctive treatment for sialoceles that had not previously responded to orally administered medications.
could have a role as a first therapeutic approach to sialoceles in this species, potentially reducing the need for surgical intervention
sialadenectomy
remains as the gold standard for the treatment of
sialoceles in dogs, and medical therapy is mostly insufficient
to resolve the condition
External beam radiotherapy for the
treatment of feline salivary gland
carcinoma: six new cases and a
review of the literature
Blackwood 2019
Five were
treated after surgical excision of the primary tumour, but four had gross disease (primary or metastatic) at the time
of starting radiotherapy.
No cat died as a result of distant metastatic disease.
Survival time was known for three cats (55 days, 258 days and 570 days
5 cats also recieved chemo
RT side effects were very mild: all cats had VRTOG
grade 1 toxicity at the end of therapy
surgery and radiotherapy is superior to radiotherapy alone. However, the
benefits of postoperative radiotherapy compared with surgery alone are only clear in patients with high-risk tumours
(ie, those with large and invasive primary tumours, close or incomplete margins, high histopathological grade,
histological evidence of neural or vascular invasion, or positive lymph nodes). This
radiation therapy may help improve
locoregional control and survival in cats
Outcomes of surgically treated sialoceles in 21 cats:
A multi-institutional retrospective study (2010–2021)
Marti 2024
Study design: Multi-institutional retrospective cohort study.
Animals: Twenty-one client-owned cats
dysphagia and ptyalism + rannula
Surgical treatment consisted of sialoadenectomy and/or marsupialization (4 cats).
Intraoperative complications 3 cats,
postoperative complications in 5 cats.
No recurrence > follow-up period (30–968 days).
sublingual and mandibular salivary glands were presumed to be the most commonly affected. Mandibular and sublingual sia
loadenectomy and/or marsupialization provided resolution of clinical signs to
the 21 cats that underwent these procedures.
post-op complications: 23.8% was slightly
higher than those reported in canine retrospective studies ( 15%). swelling
Surgery remains the treatment of choice for managing
sialoceles.3–5,10 Over half of the cats in the current study
had undergone previous drainage of the sialocele, which
recurred and prompted the need for surgery. Marsupialization
has previously been shown to be a less effective treatment
than sialoadenectomy in dogs, likely due to the propensity for the mucosa to heal and obstruct the site of
marsupialization.5
In one patient
the mandibular lymph node was inadvertently removed instead of the mandibular salivary glan
The aetiology of the sialocoele
was traumatic in two cases, neoplastic in one cat and unknown in most
With
the digastricus muscle limiting access through a lateral
approach, it is believed that the ventral approach may
yield better success at removing the sublingual salivary
gland tissue in dogs.3,17,18 The ventral approach has been
associated with a lower risk of recurrence but it has also
been associated with a higher risk of wound-related complications
in dogs.
Feline minor salivary gland
adenocarcinoma: retrospective
case series and literature review
Laureano 2023
caudal labial masses.
Curative
intent surgery was performed in three cats, whereas palliative surgery (debulking) owing to extensive soft tissue
invasion was performed in one cat. Survival times were in the range of 210–1730 (mean 787) days. All four cats
were euthanized owing to local recurrence and decreased quality of life, regardless of treatment modality.
propose that early aggressive surgical treatment with wide surgical margins should be performed for cats with
salivary gland adenocarcinoma of minor salivary gland origin. Surgery increased the quality and duration of life
Clinical findings, surgical treatment and outcome in dogs with parotid duct ectasia: 14 cases (2010-2023)
Martinez 2024
Salivary duct ectasia, defined as dilation of the salivary duct, has been rarely reported in veterinary literature
Fourteen dogs were included. Lateral facial swelling was the most common clinical presentation. CT revealed a tortuous cavitary tubular fluid-filled structure consistent
Surgical treatment included marsupialisation of the parotid duct papilla, surgical exploration of the duct alone, parotid duct marsupialisation with surgical exploration of the duct, parotidectomy or en-bloc parotid duct resection
No recurrence of clinical signs was noted during the follow-up period (range 21 to 2900 days
The treatment method should be selected based on the location
of the stricture and the extent of the ductal dilation. If the
stricture is present near the parotid duct orifice or in the parotid
duct near the oral cavity, reimplantation or marsupialisation represent
two valid options (Baurmash, 2007; Han et al., 2020; Yoon
et al., 2009). Whereas if the obstruction is near the parotid gland,
parotidectomy or duct ligation are preferable
In the authors’ opinion, parotidectomy should be reserved
for animals where the aetiology or diagnostic imaging findings
indicate that main lesion is in, or close to, the parotid gland, as
it carries a high risk of facial or trigeminal nerve injury
Complications between ventral and lateral approach for mandibular and sublingual sialoadenectomy in dogs with sialocele
Cinti 2021
- ventral and lateral approaches for mandibular/sublingual sialoadenectomy, n=140
complications: lateral 20%, ventral 31% - no difference in incidence; overall 24%
- recurrence more likely after lateral approach and with prolonged sx
- wound-related complications more likely after ventral approach
