522 PART TWO Soft Tissue Surgery
Sartorius muscle:
Cranial part
Caudal part
Descending Femoral
branch of the artery
lateral
circumflex
femoral artery
FIG. 19.8 Sartorius muscle flap in a cat. Transect the sartorius muscle distally at its insertion on
the medial aspect of the patella and elevate it to the level of the proximal vascular pedicle.
(Modified from Beittenmiller MR, Mann FA, Constantinescu GM, et al. Clinical anatomy and
surgical repair of prepubic hernia in dogs and cats. J Am Anim Hosp Assoc. 2009;45:
284–290.)
quiet, and the wound should be checked frequently for infection
or dehiscence. Vomiting, fever, and/or leukocytosis may indicate
peritonitis (see p. 527).
Inguinal
PROGNOSIS
The prognosis is generally good, and recurrence is uncommon.
When recurrence occurs, it is generally noted within a few days Femoral
of surgery. Most animals have excellent long-term results when
appropriate techniques are used.
INGUINAL, SCROTAL, AND FEMORAL HERNIAS
Scrotal
DEFINTIONS
Inguinal hernias are protrusions of organs or tissues through FIG. 19.9 Location of scrotal, inguinal, and femoral hernias.
the inguinal canal adjacent to the vaginal process. Scrotal hernias
occur when inguinal ring defects allow abdominal contents
to protrude into the vaginal process adjacent to the spermatic Causes of inguinal herniation in small animals are poorly
cord. Femoral hernias occur through a defect in the femoral understood. Both neutered and intact male and female dogs
canal. may develop nontraumatic inguinal hernias. They may be
unilateral or bilateral; unilateral inguinal hernias occur more
GENERAL CONSIDERATIONS AND CLINCIALLY commonly on the left side. Sex hormones have been incriminated
in the formation of inguinal hernias in mice, but their role in
RELEVANT PATHOPHYSIOLOGY dogs is unclear. Pregnancy and obesity may be associated with
Inguinal hernias may arise from a congenital abnormality of the the formation of an inguinal hernia. Traumatic inguinal hernias
inguinal ring or may be caused by trauma (Fig. 19.9). An inguinal may occur as a result of a congenital weakness of the musculature
ring defect allows abdominal contents (e.g., intestine, bladder, or abnormality of the inguinal ring.
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uterus) to enter subcutaneous spaces. Congenital hernias may Scrotal hernias are rare, indirect hernias (see Fig. 19.9). They
be associated with other abnormalities, such as umbilical hernias, are usually unilateral, and strangulation of abdominal contents
perineal hernias, and cryptorchidism. Whether inguinal hernias is common. Little is known about the cause and heritability. A
are heritable in most breeds is unknown; neutering is recom- congenital defect or trauma may predispose some dogs to hernia
mended in dogs with nontraumatic hernias until the genetics formation. An increased incidence of testicular tumors has been
of this condition become known. reported in conjunction with scrotal hernias.
CHAPTER 19 Surgery of the Abdominal Cavity 523
Femoral hernias are rare in dogs and cats. They occur when
abdominal contents or fat protrude through the femoral canal, Diagnostic Imaging
caudomedial to the femoral vessels (see Fig. 19.9). They may be Abdominal radiographs may help identify herniation of a gravid
mistaken for inguinal hernias. Femoral hernias may occur after uterus, intestine, or bladder in an inguinal hernia. Loss of the
trauma and avulsion of the cranial pubic ligament, or they may caudal abdominal stripe may be noted in affected animals.
result if the origin of the pectineus muscle is transected from Ultrasonography is useful with scrotal hernias to assess the
the pubis during subtotal pectineal myectomy. viability of testicular blood flow and to help determine if spermatic
cord torsion or a hydrocele is present.
DIAGNOSIS
Laboratory Findings
Clinical Presentation Laboratory abnormalities are uncommon unless intestinal
Signalment incarceration has occurred.
Nontraumatic inguinal hernias are most often reported in intact,
middle-aged female dogs or young male dogs (<2 years of DIFFERENTIAL DIAGNOSIS
age). Inguinal hernias presumably arise in young male dogs
because late testicular descent delays closure of the inguinal ring. Differentiation of mammary tumors, lipomas, lymphadenopathy,
Breeds that are predisposed to this condition include Pekingese, hematomas, abscesses, and/or mammary cysts from inguinal
Cairn terrier, basset hound, Basenji, and West Highland white hernias is facilitated by placing the animal on its back and
terrier. Older bitches may be predisposed to develop inguinal attempting to reduce the contents of the swelling. Incarceration
hernias because they have a relatively large-diameter ring with of intestine may prevent reduction and makes differentiation of
a short canal. Inguinal hernias are rare in cats. Scrotal hernias these abnormalities difficult. Differential diagnoses for scrotal
have been reported most commonly in chondrodystrophic dogs. hernias include trauma, testicular or scrotal neoplasia, orchitis,
No breed or sex predisposition has been reported for femoral and severe scrotal inflammation or swelling. Differential diagnoses
hernias. for femoral hernias include neoplasia, abscesses, and lymphade-
nopathy. Femoral and inguinal hernias may be difficult to dis-
History tinguish from each other before surgery.
Animals with inguinal hernias may be presented because of a
painless swelling in the inguinal region or for vomiting, lethargy,
pain, and/or depression if the hernial contents are incarcerated. NOTE Do not mistake the caudal abdominal fat pad in obese cats
for an inguinal hernia.
Small hernias often go unnoticed unless organ entrapment
or incarceration occurs. Omentum is the organ most commonly
present in canine inguinal hernias. The uterus is often in MEDICAL MANAGEMENT
hernias of affected intact females. These hernias are often chronic
and do not cause clinical signs until pregnancy or pyometra The animal’s condition should be stabilized before surgery.
develops.
Animals with scrotal and femoral hernias are usually presented SURGICAL TREATMENT
for evaluation of scrotal or medial thigh swelling, respectively,
or for vomiting and pain if intestinal incarceration occurs. Prompt surgical correction is recommended to prevent complica-
tions associated with intestinal strangulation or pregnancy.
Physical Examination Findings Undescended testicles should be removed during repair of an
Physical characteristics of the swelling vary according to hernial inguinal hernia. Necrosis of ipsilateral descended testicles may
contents and degree of associated vascular obstruction. Often a occur secondary to vascular obstruction and requires orchiectomy.
soft, painless, unilateral or bilateral swelling is noted in the If a gravid uterus is contained in the inguinal hernia, the animal
inguinal region. If intestinal strangulation has occurred or if a can be spayed, or if the fetus is viable and termination of the
gravid uterus or urinary bladder is in the hernia, the swelling pregnancy is not desired, an attempt can be made to reduce the
may be large, fluctuant, and painful. Finding nonviable small uterus and close the inguinal ring. However, parturition or uterine
intestine is more common in young male dogs (<2 years of age) enlargement may be associated with recurrence.
with nontraumatic hernias than in older animals. Associated
vascular or lymphatic obstruction (or both) may cause testicular NOTE Neuter animals with inguinal hernias. Warn owners of intact
and spermatic cord edema. Concurrent abnormalities may be female dogs that the hernia may recur if the dog is bred or develops
noted, such as perineal hernia or cryptorchidism. Unilateral pyometra.
inguinal hernias are more common than bilateral hernias. Bilateral
hernias occur more commonly in young dogs, and careful palpa-
tion of the contralateral inguinal region for occult hernias is Preoperative Management
recommended in all dogs. If intestinal incarceration or strangulation is suspected, antibiotics
A scrotal hernia usually appears as a firm, cordlike mass that should be given before surgery.
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extends into the caudal aspect of the scrotum. Pain and bluish-
black tissue discoloration may be noted if intestinal strangulation Anesthesia
has occurred. Femoral hernias cause swelling on the medial aspect If the animal is healthy, a variety of anesthetic protocols can be
of the thigh that may extend into the inguinal region. The swelling used safely (see Table 19.1). For patients in which nonviable
is located caudal to the inguinal ligament and ventrolateral to intestine is present, see Table 19.2. See p. 513 for additional
the pelvic brim. anesthetic recommendations for animals undergoing intestinal
524 PART TWO Soft Tissue Surgery
Female Male
Caudal
superficial External Internal
epigastric abdominal abdominal
artery and vein oblique muscle oblique muscle
External
inguinal
ring
Pectineus muscle
External Genitofemoral nerve Spermatic
pudendal cord
artery and vein
FIG. 19.10 Components of the inguinal canal.
surgery. Anesthetic protocols for pregnant animals can be found
on p. 725.
Surgical Anatomy
The inguinal canal is a sagittal slit in the caudoventral abdominal
wall through which pass the genital branch of the genitofemoral
nerve, artery, and vein, the external pudendal vessel, and the
spermatic cord (males) or round ligament (females) (Fig. 19.10).
The vascular structures are located in the caudomedial aspect
of the canal. The inguinal canal is bounded by the internal and
external inguinal rings. The internal inguinal ring is formed by
the caudal edge of the internal abdominal oblique muscle
(cranial), the rectus abdominis muscle (medial), and the inguinal
ligament (lateral and caudal); the external inguinal ring is a
longitudinal slit in the aponeurosis of the external abdominal
oblique muscle. Direct hernias occur when peritoneal evagination
occurs as a separate, distinct outpocketing from the vaginal FIG. 19.11 Incision for repair of an inguinal hernia.
process; indirect hernias are protrusions through the normal
evagination of the vaginal process.
Positioning of recurrent or large traumatic defects requires placement of
The animal is positioned in dorsal recumbency, and the caudal synthetic mesh (see p. 521) or a cranial sartorius muscle flap
abdominal and inguinal areas are prepared for aseptic surgery. (see p. 229). Bilateral orchiectomy is recommended with scrotal
hernias to lessen recurrence.
Surgical Techniques
The goal of surgery is to reduce the abdominal contents and Inguinal Hernias
close the external inguinal ring so that herniation of abdominal Make a caudal abdominal midline skin incision in female dogs
contents cannot recur. The approach for inguinal hernias depends cranially from the brim of the pelvis (Fig. 19.11). Deepen the incision
on whether the hernia is unilateral or bilateral; if the contents through subcutaneous tissues to the ventral rectus sheath. Expose
can be reduced; and if intestinal strangulation or concurrent the hernial sac by bluntly dissecting beneath mammary tissue and
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abdominal trauma is a factor. Although an incision can be made identify the hernial sac and ring (Fig. 19.12A). Reduce the abdominal
parallel to the flank fold directly over the lateral aspect of the contents by twisting the sac and milking the contents through the
swelling, a midline incision is usually preferred in female dogs ring; or, if necessary, incise the hernial sac and make an incision
because it allows palpation and closure of both inguinal rings in the craniomedial aspect of the ring to enlarge it (see Fig. 19.12B).
through a single skin incision. Inguinal hernias can usually be After reducing the abdominal contents, amputate the base of the
closed without using prosthetic materials. Occasionally repair hernial sac and close it with horizontal mattress sutures in a simple
CHAPTER 19 Surgery of the Abdominal Cavity 525
Hernial
External abdominal External
sac
oblique muscle inguinal (contents
ring reduced)
A B C
Genitofemoral
nerve, external
pudendal
artery and vein
D E
FIG. 19.12 Inguinal hernia repair. (A) Bluntly dissect beneath mammary tissue and identify the
hernial sac and ring. (B) If necessary, incise the hernial sac. (C) Reduce the hernial contents and
amputate the base of the sac. Close (D) the sac and (E) the inguinal ring.
continuous suture pattern or an inverting suture pattern (i.e., Scrotal Hernias
Cushing plus Lembert) (see Fig. 19.12C and D). Close the inguinal Incise the skin over or lateral to the inguinal ring and parallel to
ring with simple interrupted sutures of absorbable or nonabsorbable the flank fold (Fig. 19.13). Expose the hernial sac and reduce the
synthetic suture material (see Fig. 19.12E). Avoid compromising abdominal contents (incise the hernial sac if necessary). If hernial
the external pudendal vessels and genitofemoral nerve, which exit repair is performed in conjunction with orchiectomy (preferred),
from the caudomedial aspect of the ring (or the spermatic cord in open the hernial sac and ligate the contents of the spermatic cord
intact male dogs). Palpate the contralateral ring and close it if (Fig. 19.14A). Remove the testicle after disrupting the ligament of
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necessary before skin closure. the tail of the epididymis and ligate the hernial sac at the level of
If the hernial contents cannot be reduced, perform a celiotomy the internal inguinal ring (see Fig. 19.14B). If castration is not
and explore the abdominal contents. Expose the inguinal ring as performed, make an incision into the hernial sac (parietal vaginal
described earlier and reduce the hernial contents (enlarge the tunic) and evaluate the hernial contents (see Fig. 19.14C). Reduce
inguinal ring if necessary). Resect nonviable intestine or perform the herniated contents and place a transfixing ligature or several
an ovariohysterectomy and close the inguinal ring (or rings). horizontal mattress sutures in the hernial sac to reduce the size of
526 PART TWO Soft Tissue Surgery
the vaginal orifice (see Fig. 19.14D). Partly close the external inguinal
ring with interrupted sutures (see Fig. 19.14E). Do not compromise
the spermatic cord or vascular structures at the caudomedial aspect
of the ring.
If the hernial contents cannot be reduced or if viscera are
strangulated and necrotic, perform a midline celiotomy as described
previously. After resecting the intestine, expose the inguinal ring
and repair the hernia. Perform a scrotal ablation if the vaginal
process and scrotum have been severely contaminated.
Femoral Hernias
Incise the skin parallel to the inguinal ligament and expose the
hernial sac. Reduce the contents and ligate the hernial sac as high
in the femoral canal as possible. If the inguinal ligament is intact,
close the femoral canal by placing sutures between the inguinal
FIG. 19.13 Incision for Scrotal hernia repair. ligament and the pectineal fascia. Do not damage or compromise
External
inguinal
ring
Spermatic
cord
A
B
Hernial
sac
(parietal
vaginal
tunic)
Abdominal
contents
C D
E
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FIG. 19.14 Scrotal hernia repair in conjunction with orchiectomy. (A) Open the hernial sac and
ligate the contents of the spermatic cord. (B) Remove the testicle and ligate the hernial sac at
the level of the internal inguinal ring. If castration is not performed, (C) make an incision into the
hernial sac, reduce the contents, and (D) reduce the size of the vaginal orifice. (E) Partly close
the external inguinal ring.
CHAPTER 19 Surgery of the Abdominal Cavity 527
External and Iliopsoas muscle may indicate compromise of the femoral nerve during the repair;
internal reoperation is warranted in such cases.
abdominal Inguinal
oblique muscle ligament
PROGNOSIS
Sartorius The prognosis is excellent unless intestinal leakage and perforation
muscle occur. The overall complication rate with inguinal hernias is
External generally very low with little or no associated mortality.
iliac artery
PERITONITIS
DEFINITIONS
Deep Primary generalized peritonitis refers to spontaneous inflam-
femoral mation of the peritoneum without any obvious intraabdominal
artery and reason for leakage of bacteria. Secondary generalized peritonitis
vein
Femoral occurs in conjunction with an intraabdominal reason for the
artery and inflammation/infection and may be further classified as infectious
vein or noninfectious.
Pectineus
muscle
GENERAL CONSIDERATIONS AND CLINCIALLY
RELEVANT PATHOPHYSIOLOGY
Secondary generalized peritonitis is the predominant form of
peritonitis in dogs and is usually caused by bacteria. Most cases
arise through contamination from the GI tract, often secondary
to surgical wound dehiscence or GI neoplasia. Other important
FIG. 19.15 Neurovascular structures of the femoral canal.
causes include gallbladder perforation, rupture, or necrosis;
perforation due to gastric or intestinal foreign bodies; intus-
susception; mesenteric avulsion; gastric dilatation-volvulus;
the neurovascular structures of the femoral canal (Fig. 19.15). Close necrotizing cholecystitis; prostatic abscesses; iatrogenic GI rupture
the subcutaneous tissues and skin. If abdominal organs have due to gastroscopy, or foreign body penetration of the body wall.
strangulated, perform a midline celiotomy. Reduce the abdominal In a 2014 study, GI perforation was found to have occurred in
contents, then invert and ligate the sac. Dissect laterally from the 1.6% of cats and 0.1% of dogs that underwent endoscopy during
skin incision to the femoral canal and close the femoral canal defect a 17-year study period (1993–2010).1 Risk factors for perforation
as described earlier. were suggested to be small intestinal infiltrative disease in cats
and preexisting GI ulceration in both cats and dogs. Candida
peritonitis has been reported in dogs associated with duodenal
SUTURE MATERIALS AND SPECIAL INSTRUMENTS perforation due to nonsteroidal antiinflammatory drug therapy;
Monofilament absorbable (e.g., polydioxanone [PDS], polygly- leakage after intestinal resection and anastomosis or intestinal
conate [Maxon], poliglecaprone 25 [Monocryl], or glycomer foreign body removal; and after cholecystectomy due to gallblad-
631 [Biosyn]) or nonabsorbable (e.g., polybutester [Novafil], der rupture and dehiscence of intestinal biopsy sites.2
polypropylene [Prolene], or nylon) suture material should be Primary peritonitis is defined as an infection of the peritoneal
used to close the hernial ring. Multifilament nonabsorbable suture cavity with no identifiable intraperitoneal source of infection or
may be associated with a higher incidence of wound infection. history of a peritoneal penetrating injury. Primary, septic peritonitis
Mesh can be used as an overlay to reinforce the primary hernia of unknown origin (despite exploratory surgery) is occasionally
repair (see p. 521). seen in cats and dogs. Gram-negative organisms are most commonly
cultured from septic abdomens in dogs and cats with secondary
peritonitis and reflects the high incidence of GI rupture in these
POSTOPERATIVE CARE AND ASSESSMENT animals. Gram-positive organisms are more commonly cultured
Routine use of drains is not recommended; however, hernial from the abdomens of dogs and cats with primary peritonitis.
sites should be assessed postoperatively for evidence of infection Whereas infections associated with secondary peritonitis are often
or the formation of a hematoma or seroma. If abscessation occurs, polybacterial, infections associated with primary peritonitis are
prompt removal of skin sutures, drainage, and topical therapy more likely to be monobacterial. Differentiating primary and
are indicated to prevent dehiscence of the hernia repair. Exercise secondary peritonitis is important because surgery is not routinely
should be restricted to leash walks for several weeks. An Eliza- indicated in the former but is requisite in the latter; however, it
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bethan collar may be necessary to prevent the animal from licking is often very difficult to make this distinction without surgery.
at the surgical site. Postoperative testicular swelling may indicate Sclerosing encapsulating peritonitis (SEP) is a clinical syndrome
compromise of testicular lymphatic or vascular drainage (or associated with an irreversible sclerosis of the peritoneal membrane.
both). With femoral hernias, hobbles may be necessary during In people it may occur secondary to ambulatory peritoneal dialysis,
healing to prevent limb abduction, and femoral nerve function severe acute bacterial or fungal peritonitis, chronic infections, blunt
should be assessed postoperatively. Nerve deficits or severe pain abdominal trauma, and intraperitoneal administration of drugs
