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challenging technique in colic surgery

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          Proceedings of the 16th
Italian Association of Equine Veterinarians
                  Congress

                    Carrara, Italy
                 January 29-31, 2010




                        Next SIVE Meeting:


           Feb. 4-6, 2011 – Montesilvano, Pescara, Italy




      Reprinted in the IVIS website with the permission of the
        Italian Association of Equine Veterinarians – SIVE

                        http://www.ivis.org
Published in IVIS with the permission of SIVE                                    Close window to return to IVIS




 Challenging techniques in colic surgery

David Freeman
MVB, PhD, Dipl. ACVS, University of Florida, College of Veterinary Medicine,
Gainesville, FL 32610, USA



GASTROJEJUNOSTOMY                                          duodenal stricture beyond the hepaticopancre-
                                                           atic ampulla. A side-to-side jejunojeunostomy
Gastroduodenal ulcers are common in foals of               can be performed distal to the last two anasto-
all ages, and they can cause teeth grinding                moses to prevent intestinal contents from stag-
(odontoprisis), salivation, gastric reflux, fever,         nating in the blind loop between the obstruc-
diarrhea and signs of colic. Abdominal pain may            tion and the stoma, but this is optional. Ob-
be worse after nursing. Diagnostic signs on plain          struction of the common hepatic duct is a
radiographs include aspiration pneumonia, dilat-           complication of duodenal stenosis and causes
ed fluid-filled esophagus, and gastric distention.         cholangitis, cholagiohepatitis, and pancreati-
Air may be evident in the hepatic duct. En-                tis. Choledochojejunostomy is used to treat
doscopy is more sensitive and specific than ra-            this complication. Duodenal obstruction can
diography in diagnosing gastric and duodenal               cause reflux of duodenal contents into the bile
lesions, although ultrasonography could be                 and pancreatic ducts, inducing diffuse cholan-
useful to demonstrate any abnormalities in                 giolitis, perilobular hepatitis, pancreatitis,
peristalsis, wall thickness, and lumen size (see           with acute erosive and fibrinous inflammation
chapter on Ultrasonography in this issue). Ul-             of the large ducts. Contrast radiographs are
cers can be managed medically, although duo-               recommended 24 hours after surgery to con-
denal and gastric ulcers can perforate. The in-            firm successful bypass of the obstruction.
cidence of obstructive complications from ul-              Gastrojejunostomy is the most common pro-
cers appears to have diminished, possibly be-              cedure and can resolve most of these lesions,
cause of more aggressive early treatment with              and can perform well without a jejunojejunos-
ulcer medications.                                         tomy. A cranial midline incision is made and
Surgery is indicated if barium-contrast radi-              the stomach and jejunum are isolated. The
ographs suggest gastroduodenal obstruction,                proximal jejunum is traced from the left side
indicated by reflux of stomach fluid, enlarged             of the abdomen and directed from left to right,
gastric silhouette, and delayed gastric empty-             and a 10-cm segment is attached to the wall of
ing (failure of the stomach to empty in < 2                the stomach at a point where there are few if
hours). Foals under four months of age are at              any large surface vessels. A side-to-side anas-
greater risk of developing gastroduodenal ob-              tomosis is performed with staples or a hand-
struction secondary to ulcers at the cardia,               sewn technique (size 3-0 or 4-0 USP) to create
gastric antrum, pylorus and duodenum. The                  a stoma of 6 to 7 cm long. Two layers are used
procedures used depend upon the location of                for the handsewn anastomosis, an apposition-
the obstruction, and include esophagogastros-              al to appose the edges of the stomach and je-
tomy to bypass the obstruction at the cardiac              junum and a Cushing oversew. By placing the
sphincter, side-to-side gastroduodenostomy to              jejunum in the orientation described, so the
bypass pyloric stenosis, pyloromyotomy or                  proximal or oral segment is to the left and the
Heineke-Mikulicz pyloroplasty to correct a                 distal segment is to the right of the foal’s ab-
pyloric stenosis, and duodenojejunostomy or a              domen, the mesentery is not rotated as it
side-to-side gastrojejunostomy to bypass a                 would be with the opposite orientation.
                                                      82
   Proceedings of the Annual Meeting of the Italian Association of Equine Veterinarians, Carrara, Italy 2010
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ACQUIRED INGUINAL HERNIA                                   and abolish the risk of recurrence. In addition,
                                                           the involved testicle can become cystic or
In the early stages, a direct inguinal hernia in           nonfunctional in time, and postoperative
an adult horse can correct spontaneously after             swelling could induce degeneration of the oth-
the anesthetized horse is placed in dorsal re-             er testicle.
cumbency or can be corrected by applying                   When the vaginal tunic is closed, closure of
gentle traction to the bowel per rectum, with              the external inguinal ring is not essential and
or without external massage of the scrotum.                does not ensure against evisceration. Closure
External massage alone can also be effective               of the thick subcutaneous fascia and skin inci-
and can be guided by laparoscopy, which will               sion is accomplished in 2 layers and packing
also allow assessment of intestinal viability. In          is not used. The skin should be closed with ab-
such cases, laparoscopic inguinal herniorrha-              sorbable suture material. After surgery, the
phy may be performed 1 week later to prevent               scrotum on the castrated side usually con-
recurrence, using either a mesh onlay graft or             tracts, and swelling is minimal. Laparoscopic
a cylindrical mesh plug. Spontaneous reduc-                herniorrhaphy is an effective means of pre-
tion or reduction by traction does not rule out            venting recurrence if testis sparing is deemed
the possibility of complications from progres-             necessary.
sive intestinal necrosis.                                  Scrotal hernia with rupture of the vaginal tu-
A nonreducible inguinal hernia is corrected                nic can cause colic in neonates, and, unlike the
through an inguinal incision directly over                 more common indirect scrotal hernia in foals,
the external inguinal ring and along the sper-             is an emergency. These are treated as for
matic cord. The abdomen should be pre-                     adults, except that the bowel and testicle reach
pared for a ventral midline celiotomy, to al-              a subcutaneous location by passing through a
low intra-abdominal traction on the bowel if               rent in the tunic. The edges of the tear are
needed, to assess viability of the released bow-           identified after the tunic is dissected free, and
el, to decompress or examine proximal bowel,               these torn edges are grasped with hemostats or
or for a jejunocecal anastomosis. The tunic is             Allis tissue forceps. The herniated jejunum is
dissected from the surrounding tissues, with               usually healthy, although mild edema and
care taken to not damage the pudendal vein                 congestion are not uncommon. The simplest
and branches. A cranial incision is made in the            method of returning bowel to the abdomen is
vaginal tunic, and this needs to be extended far           to grasp a loop gently in the jaws of sponge or
enough distally to cut the constricting ring               ring forceps and to pass that loop down the
formed by the internal spermatic fascia and re-            vaginal tunic into the abdominal cavity. This
lease the strangulated intestine. The tunic edges          is repeated until all the small intestine is re-
should be grasped with hemostats to maintain               turned to the abdomen. The tunic, testicle, and
them within access for closure. Medial and cra-            instruments securing the torn tunic edges are
nial retraction on the edge of the internal abdom-         grasped and rotated to twist the tunic all the
inal oblique muscle with a Deaver retractor                way to the abdomen. An emasculator is then
will improve exposure to the tunic edges, and              applied to the tunic proximal to the tear and
a finger is used to direct bowel away from the             the tunic at this level is transected with the
suture line. The goal is to completely close the           emasculator and then closed with a transfixa-
vaginal tunic with heavy suture (size 1 metric             tion ligature.
or 4.0 metric) so that bowel cannot prolapse
through the incision in it.
Because short segments of intestine are usual-             ENTRAPMENT IN THE EPIPLOIC
ly involved, resection is rarely needed if ap-             FORAMEN
pearance of the bowel improves markedly af-
ter the strangulation has been released. A uni-            The epiploic foramen, or foramen of Winslow,
lateral castration is recommended to allow                 is the 4-cm-wide entry into the vestibule of the
more complete closure of the vaginal tunic                 omental bursa from the peritoneal cavity. Its
                                                      83
   Proceedings of the Annual Meeting of the Italian Association of Equine Veterinarians, Carrara, Italy 2010
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dorsal and craniodorsal boundary is the vis-               ommended over stapling instruments because
ceral surface of the base of the caudate                   the ileal wall is so thick especially in chronic
process of the liver. The portal vein con-                 cases. There is no need to resect the involved
tributes to the cranioventral border, and the              ileum in chronic cases or the hypertrophied je-
gastropancreatic fold becomes evident as a                 junum proximal to it.
band where it forms the ventral border of the              In acute cases, the intussuscepted ileum and
foramen. Strangulation is typically in a left to           jejunum can be too edematous and hemor-
right direction. At surgery in most cases,                 rhagic to allow reduction. Removal of the in-
strangulation in the epiploic foramen can be               tussusceptum through a typhlotomy is recom-
corrected by careful traction combined with                mended in these cases, but can cause severe
pushing of the strangulated bowel in the same              contamination, although suturing an imper-
direction. Careful milking of fluid into the               meable plastic drape around the typhlotomy
empty and collapsed distal segment might be                can contain leakage. In a technique devised to
necessary to decompress the strangulated                   facilitate this surgery, the jejunum proximal to
bowel. If possible, nonstrangulated bowel can              the intussusception is transected with the GIA
be drawn into the foramen so distention of the             or ILA stapler as close to the ileocecal junc-
strangulated segment can be reduced by                     tion as possible. A 10-cm incision is made in
spreading its contents into the nonstrangulated            the cecum to allow the intussusception to be
bowel. This technique also replaces one thick-             exteriorized, and another incision is made
ened segment in the foramen with a thin-                   through the outer wall of the intussuscepted
walled normal segment, so that the total thick-            jejunum to expose the inner loop. This inner
ness of bowel is reduced at the point of en-               loop then is pulled through the incision in the
trapment. To avoid tearing the dorsal aspect of            outer layer until the closed transected end is
the portal vein and causing fatal hemorrhage               distal to the selected site for transection. If too
during traction, bowel should be drawn away                much bowel is drawn through this incision, or
from the foramen in a direction that keeps it              if the jejunal transection was made far from
level with the foramen, and not upward to the              the ileocecal junction, mesenteric vessels will
abdominal incision. When bowel cannot be                   tear and cause fatal hemorrhage. As much as
drawn back through the epiploic foramen by                 possible of the necrotic bowel is removed by
these methods, then jejunum approximately 1                incision along the edge of a TA90 applied
m proximal to the obstruction must be emp-                 across the inverted ileum within the cecum.
tied through an enterotomy or by transection.
The empty segment of jejunum then is drawn
through the foramen. After reduction, abnor-               JEJUNOCOLOSTOMY
mal bowel is resected to include the transec-              FOR CECAL IMPACTION
tion or the enterotomy sites.
                                                           Impaction is a common disease of the cecum
                                                           and can lead to cecal rupture. The cause is un-
ILEOCECAL INTUSSUSCEPTIONS                                 known, but most cases in the USA are in hos-
                                                           pitalized horses treated for an orthopedic dis-
In chronic intussusceptions of ileum, short                ease and that have received a nonsteroidal an-
segments (approximately 10 cm) are involved.               ti-inflammatory drug and general anesthesia.
Reduction is difficult, even in the absence of             Treatment can be entirely medical with laxa-
adhesions, because of chronic folding of the               tives, or surgical with a typhlotomy at the
intestinal wall. Ileocecal and ileoileal intus-            apex of cecum to relieve the impaction. A je-
susceptions have been treated successfully by              junocolic anastomosis (jejunum to right ven-
reduction only. Incomplete bypass by ileoce-               tral colon) can be used to prevent recurrence
costomy is recommended if there are concerns               of cecal impaction, because some horses
about permanent ileal changes and the risk of              might be prone to repeated episodes, which
recurrence, and a handsewn technique is rec-               could end with cecal rupture. This anastomo-
                                                      84
   Proceedings of the Annual Meeting of the Italian Association of Equine Veterinarians, Carrara, Italy 2010
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sis can be a complete bypass (transection and              with a two-layer continuous inverting pattern
oversewing the jejunum) or an incomplete                   of 2-0 or 0 absorbable suture. Two layers of
bypass (no transection and the small intes-                continuous inverting sutures with 2-0 or 0
tine can empty through two routes). Tech-                  absorbable suture are placed in the cecum to
niques are similar to jejunocecostomy, but                 oversew the typhlectomy site. It might be
mesenteric closure must be complete. The                   necessary to resect an additional section of
jejunum should be orientated so that the dis-              necrotic cecum after reduction by this
tal or aboral end is directed towards the ce-              method. An ileocolostomy has been used to
cocolic junction.                                          bypass the intussusception, but is not recom-
                                                           mended and is less successful than the above
                                                           described method.
CECOCOLIC INTUSSUSCEPTION

Cecocolic intussusception is rare but can be a             COLOTOMY/LARGE INTESTINAL
surgical challenge. Surgical treatment is deter-           ENTEROTOMY
mined by the degree of difficulty involved in
correction and includes 1) reduction only,                 Colotomy is a dirty procedure that requires
with or without partial typhlectomy after re-              vigilance by all involved to prevent contami-
duction, 2) colotomy in the right ventral                  nation, and is more likely to lead to incisional
colon, with or without partial typhlectomy to              infection than to peritonitis. Methods to pre-
reduce the intussusception, and with or with-              vent adherence of intestinal contents to the
out partial typhlectomy after reduction. De-               serosa around the incision include almost con-
spite the difficulty of the procedure, the prog-           stant lavage of the bowel with warm saline or
nosis is very good for surgical treatment, if              precoating the proposed enterotomy site with
care is taken to minimize intraoperative con-              sodium carboxymethylcellulose. The entero-
tamination. This can be accomplished by su-                tomy is closed with a Lembert followed by a
turing a plastic or paper drape to the colon and           Cushing pattern, using 2-0 polydioxanone on
using saline-soaked lap sponges to completely              a taper needle. This method exposes less su-
isolate the proposed site for colotomy on the              ture material to the peritoneal cavity, and
right ventral colon from surrounding viscera.              could thereby reduce risk of adhesions to for-
An approximately 25-cm colotomy was made                   eign material; however, adhesions are very
in the right ventral colon between or along                rare in the large colon. Complications are very
teniae over the invaginated portion of the ce-             rare and the most common in the author’s ex-
cum, which is friable, hemorrhagic, and ede-               perience is hemorrhage from the colon inci-
matous. When manual reduction through a                    sion into the lumen, sometimes severe enough
colotomy is unsuccessful, a partial typhlecto-             to require blood transfusion or surgery to lig-
my is performed within the lumen of the right              ate the offending vessel.
ventral colon to allow reduction. For this pro-            An enterotomy might be required in the small
cedure, the medial and lateral cecal vessels are           colon to remove an impaction with food mate-
double ligated with transfixation sutures and              rial or enterolith. If the impaction is focal and
as much as possible of the affected apex and               composed of dehydrated colon contents, it can
body are removed. All the necrotic cecum                   be softened by injection of saline through an
does not have to be removed; simply enough                 18-gauge needle into the substance of the im-
to reduce the size of the strangulated segment             paction. If an enterotomy is used, an incision in
and reduce the intussusception. A simple con-              the antimesenteric taenia bleeds less than other
tinuous full thickness suture is used to appose            parts of the wall and is easier to close. The en-
the edges of the cecal stump by using large                terotomy is closed with a Lembert followed by
bites with size 2 absorbable suture material.              a Cushing pattern, taking care to cause minimal
The cecal stump is then everted through the                inversion and reduction of the lumen diameter.
cecocolic junction and the colotomy closed                 A “high enema” can be used to relieve im-
                                                      85
   Proceedings of the Annual Meeting of the Italian Association of Equine Veterinarians, Carrara, Italy 2010
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paction of the small colon by passing a stomach            prolapse and herniation. Standing placement
tube through the anus and guiding it manually              is preferred, because in the anesthetized horse,
to the impaction to allow water infusion. This             incisional layers and landmarks shift when the
procedure can involve excessive colon handling             horse stands, and the stoma can be disrupted
in stubborn cases of long tubular impactions               during anesthetic recovery. The low flank in-
and this can lead to adhesions. Therefore, the             cision is made in line with the flank fold and
author prefers an enterotomy.                              midway between it and the costal arch and is
                                                           8 cm long. It is angled dorsally at its caudal
                                                           end by 20 to 30 degrees and small transverse
COLOPEXY                                                   incisions are made in muscles and fascia to
                                                           eliminate constricting bands around the colon.
Colopexy is also used to prevent recurrent                 The stoma should be large enough to reduce
large colon volvulus or displacement, but                  the risk of stomal obstruction but small
should only be performed on healthy colon,                 enough to prevent the more serious complica-
and is usually reserved for the first recurrence.          tions of prolapse and herniation.
There are concerns about the safety of this                The stoma is made in a segment of small
procedure, and recurrent displacement, colic,              colon at least 1 m from the rectum to allow
incisional sinuses, and colon rupture are rec-             easy access for colostomy reversal. The seg-
ognized complications. A laparoscopic tech-                ment of small colon is folded to form a loop,
nique has also been described. Selection of                and the two arms of the loop are sutured to-
colopexy over resection depends on surgeon’s               gether with an absorbable material in a con-
preference. I prefer resection because it is safe          tinuous Lembert pattern for 8 to 10 cm, mid-
and effective.                                             way between the mesenteric and antimesen-
                                                           teric teniae. This suture line creates a more
                                                           complete separation or septum between the
COLOSTOMY                                                  proximal and distal segments of small colon,
                                                           to obtain complete fecal diversion. It also sta-
Colostomy is indicated to bypass a rectal in-              bilizes the loop within the body wall, reducing
jury that needs absolute rest to repair. The               the risk of prolapse. The prepared loop of
loop-colostomy technique is preferred over                 small colon is subsequently inserted into the
the end-colostomy because it is easier and                 flank incision with the proximal loop proxi-
quicker to establish and to reverse later. Di-             mal and slightly ventral to the distal loop, and
version of feces is complete because gravity               the antimesenteric tenia about 3 cm beyond
and creation of a septum between the loops                 the skin. The seromuscular layer of the colon
will direct feces directly through the stoma.              is sutured to the abdominal muscles and fas-
Because fecal balls are eliminated individu-               cia using several interrupted sutures of 0 or 2-
ally through the stoma, the risk of obstruc-               0 absorbable material, taking care not to
tion is low.                                               puncture or occlude mesenteric vessels. An 8-
Sites for a loop colostomy are high left flank,            cm incision is made along the exposed an-
low left flank, or ventral midline. A single-in-           timesenteric tenia of the colon, and the cut
cision colostomy involves placing the stoma                edges are folded back and sutured to the skin
in the same incision as used to explore the ab-            with simple-interrupted sutures of 2-0 nylon
domen, as in a horse with colic. A double-in-              or polypropylene.
cision colostomy involves a separate incision              Antibiotics and laxatives (mineral oil, 2 to 4
for exploration of the abdomen or to locate                L/450 kg, and magnesium sulfate, 1 g/kg) are
and prepare the appropriate segment of small               continued for 3 to 5 days. Horses are held off
colon, and is recommended. The separate                    feed or fed grass, alfalfa hay, or complete pel-
flank incision can be made small enough to                 let feeds at half the usual amounts for the first
form a snug fit around the stoma, so the sur-              2 to 3 days after the colostomy is established,
rounding intact body wall reduces the risks of             and ointment is applied to the skin around the
                                                      86
   Proceedings of the Annual Meeting of the Italian Association of Equine Veterinarians, Carrara, Italy 2010
Published in IVIS with the permission of SIVE                                    Close window to return to IVIS

stoma to protect it from scalding. A cradle is             cussion of the thorax in some horses. Ultra-
applied because most horses have a tendency                sonography might be superior to radiography
to mutilate the colostomy. The mucosal pro-                in diagnosing a diaphragmatic hernia.
trusion of the stoma becomes markedly con-                 All attempts should be made to repair the defect
gested in the first week after surgery and slow-           because recurrence of intestinal incarceration is
ly sloughs, to be replaced with healthy mu-                highly likely if a horse recovers from anesthesia
cosa. Ventral edema in the ventral body wall               with an unrepaired defect. At surgery, a respira-
resolves with time. When the tear has started              tor should be used to provide controlled positive
to granulate (5 to 7 days), the terminal small             pressure ventilation and correct the diminished
colon and rectum are flushed through the                   pulmonary function. An advantage of preopera-
stoma with approximately 20 L of warm wa-                  tive diagnosis is that the abdominal incision can
ter to exercise these segments and prevent the             be placed further cranially than the standard ap-
atrophy that can complicate reversal. The                  proach. Access to ventral defects is not difficult,
colostomy can be reversed after the tear has               but access to more dorsal defects can be im-
healed, at approximately 6 weeks. The horse                proved by extending the cranial end of the inci-
is anesthetized in right lateral recumbency, the           sion laterally for approximately 12 to 15 cm at
stoma is resected en bloc, and a colonic anas-             an angle of 60 to 90 degrees in a paracostal fash-
tomosis is performed through the resulting                 ion. The table can be tilted to raise horse’s head
flank incision. The postoperative feeding, an-             so abdominal contents can fall away from the
tibiotic, and laxative regimens are similar to             diaphragm.
those used after the colostomy was made.                   A small defect might have to be enlarged with
Complications of colostomy are dehiscence,                 scissors or curved fetotome to release the
abscessation, peristomal herniation, prolapse,             bowel. Most defects can be closed with a
prolapse with rupture of mesenteric vessels,               continuous pattern using heavy absorbable
infarction, rupture of the colostomy, sponta-              or nonabsorbable material, and the suture
neous closure, and stomal obstruction. Com-                line should be completed at full inspiration to
plications of reversal are incisional infection            reduce pneumothorax. Mesh coverage will be
and anastomotic impaction and dehiscence.                  required for defects that cannot be sutured be-
                                                           cause of their large size or because the edges
                                                           are too firm to allow apposition. Laparoscop-
DIAPHRAGMATIC HERNIA REPAIR                                ic techniques alone or combined with thoraco-
                                                           scopic techniques can be used for dorsal tears.
A diaphragmatic defect can be congenital or                Successful repairs of diaphragmatic hernias
acquired, although the distinction is difficult.           have been reported in adult horses and foals,
A congenital diaphragmatic defect or a di-                 participate successfully in various forms of
aphragmatic tear inflicted by a rib fracture,              competition, and deliver foals after repair.
usually at or close to the costochondral junc-
tion of ribs 3 to 8, are likely causes of di-
aphragmatic hernia in foals. The most com-                 INCISIONAL HERNIA REPAIR
mon causes in adult horses are trauma, partu-
rition, particularly dystocias, and recent stren-          Hernias of ventral midline incisions may ap-
uous activity. Large defects are more likely to            pear weeks to months after the initial surgery.
cause dyspnea from pulmonary compression                   Although an incision can heal with scattered
by intrathoracic displacement of the colon but             areas of attenuation in the body wall, these are
do not incarcerate bowel and cause colic.                  not true hernias and can withstand full athlet-
Small defects are more likely to strangulate               ic activity and foaling. Hernias develop be-
small intestine and manifest as acute and se-              cause the linea alba does not heal and the su-
vere colic, clinically indistinguishable from              tures may have cut through one side or both
strangulation by any other cause. Abnormali-               sides of the linea alba. Horses with incisional
ties can be detected on auscultation and per-              complications have an increased risk of devel-
                                                      87
   Proceedings of the Annual Meeting of the Italian Association of Equine Veterinarians, Carrara, Italy 2010
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oping hernias, especially those incisions that             of the ring, which can be irregular and attenu-
become infected, have incisional drainage, or              ated in areas where sutures tore through, and
had a repeat celiotomy through a recent inci-              separate it from the underlying retroperitoneal
sion. Horses larger than 300 kg have a greater             fat and peritoneum. The latter step can be ac-
risk for the development of a hernia than do               complished with blunt dissection to create a 3
smaller patients. Odds of incisional hernia are            to 4 cm deep shelf for the mesh, and inadver-
62.5 times greater for horses that had inci-               tent penetration of the peritoneum is likely
sional drainage, and incisional drainage and               during this step because it is usually so close
herniation can have a negative association                 to the fascial layer of the sac. Peritoneal punc-
with survival.                                             ture is usually of no consequence, adhesions
Hernia repair should be postponed for approx-              to underlying viscera are rare, and peritoneal
imately 3 to 4 months after the first surgery to           closure is rarely necessary.
allow inflammation and infection to fully re-              Mesh is usually placed between the internal
solve and for the hernial ring to become firm              sheath of the rectus muscle and the peritoneum
and well organized. Timing of hernia forma-                as a single sheet, although a doubled application
tion in a broodmare might not allow for repair             has been described. Mesh placement between
before foaling, but mares can foal uneventful-             skin and body wall has the disadvantage of al-
ly with very large hernias. However, the con-              lowing little soft tissue protection of the mesh in
cern exists for conversion of this sized hernia            such a superficial location, but very favorable
to a more complete rupture of the abdominal                results can be attained. Mesh edges are folded
wall, and assisted foaling is encouraged to re-            on themselves for 3 to 4 cm to reinforce the
duce this risk.                                            point of suture purchase, and the edges of the
Large hernias can be repaired by suture clo-               mesh are placed towards the fascia. Sutures can
sure or by mesh. Mesh should never be placed               be preplaced in horizontal mattress fashion with
in an infected area or even in skin with a raw             bites of 2 to 2.5 cm wide on one side of the
defect or suspect integrity, because bacteria              mesh to facilitate placement along one side of
will become established within the interstices             the ring. The mesh should overlap the ring so
of the mesh, and the mesh will be rejected.                that sutures are approximately 2 cm lateral to
This will delay final resolution considerably,             the edge, and the mesh should be placed under
because mesh removal will have to be fol-                  even tension to reduce the size of the defect and
lowed by sufficient time to allow the infection            to prevent subsequent sagging. The size of the
to resolve before final repair. One means of               ring can be reduced by tension on the mesh to
solving this problem is to remove the mesh                 the point that suture apposition of the commis-
and repair the wound by secondary closure.                 sures is possible. Some sutures can be preplaced
Closure without mesh is preferable when                    to facilitate inclusion of the mesh in the last few
possible, although mesh herniorrhaphy can                  sutures. Care must be taken not to tear the mesh,
be very effective. Also, some hernias can get              because small intestine can become strangulat-
smaller over time to reach a tolerable size that           ed in such tears, and all fibrous layers that can
does not limit performance, and defects that               be identified superficial to the mesh should be
do not alter the ventral abdominal contour                 closed. If possible, a flap of hernial sac fascia
usually do not need to be repaired.                        should be laid over the mesh to protect it,
With any method of repair for a ventral medi-              strengthen the repair, and reduce swelling. An
al incisional hernia, the skin and subcutis can            abdominal bandage should be applied to reduce
be incised in a semicircle around one edge of              postoperative swelling.
the ring to create a flap that can be trimmed of           Materials used for mesh herniorrhaphy in
redundant skin later. This flap can be drawn               horses are polypropylene (Prolene®, Ethicon,
over the final body wall repair to protect it              Somerville, NJ; and Marlex®, C R Bard, Inc,
with an intact tissue layer. Hemostasis should             Murray Hill, NJ) and the less available woven
be established by cautery during dissection.               plastic (Proxplast®, Goshen Laboratories,
The goal of dissection is to expose the edges              Goshen, NY). Compared with polypropylene,
                                                      88
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the plastic mesh is less expensive and less                SECONDARY CLOSURE
elastic, a property that reduces abdominal wall
sagging. However, its edges tend to unravel.               Secondary closure of an equine linea alba
Complications of mesh herniorrhaphy are                    can be used to repair wounds with infection,
drainage/infection and, rarely, peritoneal ad-             wound dehiscence, and necrosis, or to cor-
hesions and bowel abrasion. Absorbable mesh                rect infected hernias. All existing suture is
materials (Vicryl woven or knitted mesh,                   removed and the tissue edges debrided by
Ethicon, Somerville, NJ) and porcine small-                sharp dissection and abrasion with a saline-
intestinal submucosa (Surgisis®, Cook Surgi-               soaked sponge.
cal, Bloomington, IN) could find applications              Retention sutures of 18 gauge stainless steel
as temporary scaffolds in equine herniorrha-               wire are preplaced in vertical mattress fash-
phy. Most large-size non-absorbable suture                 ion with a large cutting needle so that each
materials are suitable for mesh attachment.                suture spans a bite 4 to 5 cm from the skin
Large incisional hernias can be closed by di-              edge through the full thickness of the body
rect suture repair without mesh, depending on              wall (excluding retroperitoneal fat) and then
surgeon preference, thickness of the hernial               is passed through skin and subcutis at 2 to
ring, and chances of apposition with accept-               2.5 cm from the skin edge. To protect the
able tension. Techniques used for this purpose             skin, the wire is passed through hard and
are interrupted mattress, NFFN, and simple                 thick plastic or rubber tubing (stomach tube
interrupted patterns, as well as secondary clo-            or thick suction tube) cut to a length of 2.5
sure techniques. Another technique is to ap-               cm, and the suture knot is placed at the end
pose the ring edges by 2 surgeons working si-              of the tubing furthest from the incision,
multaneously from opposite sides of the                    where it can be subsequently located for re-
horse, each alternating bites to form a contin-            moval. Silicone rubber or fine plastic tubing
uous crossing pattern.                                     should not be used, because these will allow
If the hernia has developed an indurated sac,              premature recession of the wire into the skin
a crescent-shaped flap of this subcutaneous                and rapid loss of tension. The retention su-
tissue can be preserved as an onlay graft to               tures are spaced 2.5 cm apart and then the
cover the repair. All these direct hernial re-             ends are twisted down securely to produce
pairs can be performed with an absorbable                  eversion of skin and subcutis for ventral
material, either size 2 or 3, and some attempts            drainage. It is essential that, as the wires are
should be made to freshen the ring edges be-               tightened, all the slack is taken out of the
fore apposition. Dissection and preparation of             deep component so it cannot form a loop to
the hernial ring is the same as described for              ensnare small intestine. Once the twist is se-
mesh herniorrhaphy.                                        cure, the wire is cut to leave 1 to 1.5 cm of
The success of any technique for repair of a               the twist, which is then coiled so the sharp
large hernia can be influenced by preopera-                ends turn into the tubing.
tive diet, such as 7 to 14 days on an all pel-             The sutures and bolsters should be removed in
let, low bulk diet, to reduce intestinal fill.             approximately 3 to 5 weeks, by which time
The horse can be starved for 12 to 24 hours                most sutures are loose and no longer effective.
before surgery and slowly reintroduced to                  Removal can be staged so that some sutures
the same diet over 7 days after surgery, to be             that appear functional are left in place as long
continued for another 14 days.                             as possible. Ultrasound can aid in the location
Many horses have low grade abdominal pain                  of bolsters since some can become embedded
for 24 hours after herniorrhaphy, and require              in granulation tissue and are not visible. The
analgesics.                                                tissue reaction around the tubing usually re-
Management also includes perioperative an-                 solves after removal and following local
tibiotics and stall confinement for at least 6             wound care. Although this procedure exposes
to 8 weeks after surgery before turnout in a               infected tissue to the abdominal cavity, peri-
small paddock for the same period.                         tonitis does not ensue.
                                                      89
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