Parotid Duct Transposition
The information below was generously shared with us by Dr.Lindley,DVM,MS and Dr. Schmidt,DVM of Animal Eye Consultants.
Surgical Treatment - Surgical treatment should not be considered until medical treatment has been unsuccessful after at least 60 days.
1. Transposition of the parotid salivary duct. Lavingnette reported the successful treatment of a case of canine keratoconjunctivitis sicca with parotid duct transposition in 1966. Since then, others have modified this technique. The regional anatomy is illustrated below.
Cutaway drawing of the area where the parotid duct enters the mouth. Facial muscles have been omitted to illustrate the essential features. a. Entire face b. Close-up of area.
1. Dorsal buccal nerve
2. Anastomosis of dorsal buccal and ventral buccal nerves
3. Ventral buccal nerve
4. Parotid salivary gland
5. Parotid duct
6. Papilla of parotid duct
7. Facial vein
8. Upper carnassial tooth
2. The papilla of the parotid duct can be identified above the base of the upper carnassial tooth. Care should be taken to not confuse it with the papilla of the major duct of the zygomatic salivary gland which opens near the gingival border above the last molar. An 0 to 00 monofiliment nylon suture, that has had the tip flamed to glaze it, is passed through the parotid duct papilla. The suture can be seen moving beneath the skin as it passes down the parotid duct. When the suture cannot be passed any further. cut it so that it protrudes about 1 cm from the papilla. Place a pledget of cotton soaked with 1:50 Betadine solution over the papilla and return the lip to normal position.
Monofilament nylon suture in place in the parotid duct.
a. Suture in duct
b. A papilla of the zygomatic salivary duct seen near the last molar.
Surgical Technique:
Open technique. The nylon suture in the duct is palpable through the skin over the masseter muscle. Make an incision along the duct through the skin and panniculus muscle layer exposing the duct. Dissect the duct from the masseter muscle and pass a length of 1/8 inch umbilical tape beneath it. Use this to elevate the duct and avoid the possibility of damaging it with forceps. Dissect the duct free posteriorly to the angle of the mandible. Carefully start dissection forward, avoid the facial vein and the anastomotic branches between the buccal nerves. Continue dissection with small blunt scissors beneath the nerve and vein until the scissors tip can be seen in the connective tissue ahead of the vein. Force the tip out, making an opening that exposes the duct. Place another length of umbilical tape around the duct and continue dissection anteriorly to the point where the duct penetrates the orbicularis oris and the oral mucosa. Using a 6 mm biopsy punch or corneal trephine, remove a round plug of mucosa containing the papilla. Center the punch (trephine) over the papilla and cut the mucosa. Take care to avoid cutting the duct. Dissect the plug of mucosa free and pull it into the external facial wound. Suture the oral wound and set aside all instruments used in the mouth. Reglove. Continue dissection of the duct until it is free to the angle of the mandible. A canthotomy may be needed if the eyelid opening is small, but if the animal has a large eyelid opening the duct can be transplanted without canthotomy. Using small blunt scissors (curced corneal, strabismus, or tenotomy scissors), make a tunnel along the surface of the masseter muscle from the angle of the mandible to the lateral canthus. Apply pressure until the scissors tip appears subconjunctivally at the fornix of the lateral canthus. Force the scissors through the conjunctiva, grasp the point with a mosquito hemostatic forceps and then withdraw the scissors and forceps until the forceps appears in the facial wound. Grasp the edge of the mucosal plug (containing the papilla) with the forceps and draw the duct through the tunnel. Suture the mucosal plug to the conjunctiva with four simple interrupted sutures of 6-0 absorbable sutures. Reappose the panniculas muscle with the same suture, close the skin incision and canthotomy with nonabsorable suture. Remove the nylon suture from the parotid duct. Saliva will usually start flowing through the duct immediately.
Parotid duct transposition, open technique.
a. Umbical tape passed beneath the parotid duct so the duct can be manipulated without damaging it with forceps.
b. Dissection completed beneath the branches of the buccal nerves and facial vein.
c. Parotid duct dissected free to area where papilla opens into mouth.
d. Biopsy punch positioned to cut plug of mucosa papilla of parotid duct.
Parotid duct transposition, open technique.
e. Plug of mucosa containing parotid papilla and duct dissected from oral mucosa.
f. Mucosal plug with papilla pulled into wound.
g. Mucosal plug with papilla duct forced through tunnel beneath vein and nerve. Parotid duct and papilla are now dissected free to the angle of the mandible.
h. Tunneling along the fascia of the masseter muscles to the lateral fornix with blunt delicate scissors. The scissors tip penetrates the conjunctiva at the lateral fornix.
i. Scissors and forceps are rotated 90 degrees and pulled back through the tunnel made in h.
j. Oral mucous membrane plug with parotid papilla positioned for suturing to the conjunctiva.
k. Mucous membrane plug sutured to the conjunctiva with four simple interrupted absorbable sutures.
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