Page 40 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 3 · Surgery of the oral cavity and oropharynx

Necrosis in mastication. Vestibuloplasty is designed to increase the
depth of the vestibule, allowing the lower lip to swing free
Extensive lacerations, avulsions, bite wounds, insect stings
VetBooks.ir and thermal injuries can cause necrosis of lip and cheek caudal to the labial frenulum. A deep frenotomy is
of the incisor teeth.
The incision is begun in the mucogingival junction
tissue. If insufficient rostral skin is available to cover bare
sites, advancement, rotation or transposition flaps can be
harvested from the intermandibular or neck areas. performed, avoiding the neurovascular structures that exit
from the middle mental foramen. The incision is continued
It may be necessary to incise the lip commissures to in the mucogingival junction around the mandibular
mobilize sufficiently large flaps. The donor area can be
incisors to the opposing labial frenulum, where the same
repaired easily by using the loose skin of the neck. If injury procedure is performed. Once the lip has been fully
to the rostral upper lip has caused loss of one nostril, dissected from the bone with a periosteal elevator, the
patency of both nasal passages can be achieved by creat-
periosteum is incised at the ventral border of the flap with
ing a window into the rostral portion of the nasal septum. a scalpel blade. The lip flap is sutured down and back on
Alternatively, if sufficient tissue is present, a modified nasal
itself to the underlying tissues at several sites. The frenu-
rotation flap with incorporation of dorsal nasal planum lum incisions are sutured in a similar manner. On comple-
tissue can be used for reconstruction of the nares (ter Haar
tion, the lip will appear to dip ventrally at a steep angle,
et al., 2013). which is the desired result. A mucosal graft can be placed
Lip and cheek necrosis can result in stricture of the between the cut edges to prevent their healing together.
commissure and inability to open the mouth. This is Another option is to cut a piece of Penrose drain length-
corrected by incising the scar at the commissure, and wise to open it up, and then customize its shape to
closing the mucosa and skin in two layers to lengthen the the defect created. The Penrose template is sutured to the
commissure. Z-plasty techniques (Fowler, 1999) can also edges of the defect circumferentially, and sutures are
be attempted to resolve strictures due to excessive scar used at the depth of the defect to tack down the material
formation in the cheek tissue. to the underlying tissue. After the incised edges of
the defect have sufficiently epithelialized, the Penrose
Cheilitis and dermatitis template is removed.
An abnormal congenital lip-fold conformation is com- Harelip
monly seen in spaniels and setters and occasionally in
other dog breeds. The indentation of the tissues laterally See Palate, below.
causes saliva and debris to collect on the skin of the lip.
The result is a foul-smelling, chronic moist cheilitis and
dermatitis. Conservative treatment (clipping the hair, Tongue
frequently washing the lip-fold area with chlorhexidine
solution or benzoyl peroxide shampoo, followed by appli- Lacerations and avulsions
cation of a benzoyl peroxide gel, corticosteroid ointment
Injury to the tongue can be secondary to burns, external
or topical antibiotic) may be helpful. Severe cases are
treated by resection of the folds. trauma, self-trauma during recovery from anaesthesia or
seizures, foreign bodies, strangulation from elastic mater-
Infection of the lip skin may also occur following partial
or total mandibulectomy, as a result of constant lateral ials and frenulum laceration by ‘string’ foreign bodies.
Clean lacerations are sutured with absorbable material.
extrusion of the tongue. This can be corrected by rostral
advancement of the lip commissure on the involved side Jagged lacerations require careful conservative debride-
(commissuroplasty). The mucocutaneous junction tissue of ment before suturing. Treatment of irregular lacerations or
avulsions includes irrigation of the affected areas with
the upper and lower lips is resected to the level of the max-
illary second premolars. The incised edges are sutured dilute chlorhexidine and nursing care to assist with feeding
until the injured areas heal.
with separate layers for apposition of the mucosa and skin.
A loose tape or fabric muzzle may be kept in place during Trauma to salivary gland ducts in the sublingual tissues
has been proposed as a cause of sublingual sialocele
the healing period to prevent dehiscence when the dog
opens its mouth fully. (ranula). If ducts are injured by acute trauma, ligation of
transected ducts will result in transient glandular swelling,
followed by atrophy.
Inappropriate drooling
Heavy pendulous lower lips in large and giant-breed dogs Electric cord injury and other burns
may form a channel through which saliva flows directly on This occurs most often in young animals. Neurogenic pul-
to the skin or hangs in ropes down to the floor. This can be monary oedema is an immediate life-threatening concern.
treated by bilateral mandibulosublingual salivary duct liga- It may take several days before the extent of local injury is
tion through a small incision in the sublingual mucosa, clearly defined. Necrosis of the lips, cheeks, tongue and
combined with resection of excessive lip tissue by making hard palate is common. More extensive burns cause
a V-shaped incision through the skin and mucosa. The two necrosis of dental pulp tissue and incisive bones, maxillae,
layers (mucosa and skin) are sutured separately. palatine bones or mandibles.
Initially, the patient is managed conservatively; injured
Tight lip tissues are left to necrose so that all the viable tissue is
retained. Once the necrotic tissue is evident, surgical inter-
Shar-Peis often have very tight lower lips due to insuffi- vention may be initiated. If the injury resulted in osteo-
cient depth to the lower rostral vestibule. This causes the necrosis or oronasal fistula, further surgery is required.
lower lip to extend over the incisal edge of the incisor When electric cord injuries include the tongue, tube
teeth, which can restrict the complete growth potential of feeding may be necessary for several days. Once the
the lower jaw and may result in malocclusion and difficulty necrotic portion of the tongue has sloughed, the remaining

31

Ch03 HNT.indd 31 31/08/2018 10:39