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\begin{document}

\title{Strangulation of the small colon by ovarian pedicle in an adult
broodmare}



\author[1]{Kevin Claunch}%
\author[1]{Parker Wurst}%
\author[1]{Cari Chisholm}%
\affil[1]{Weems \& Stephens Equine Hospital}%


\vspace{-1em}



  
  \date{June 16, 2024}


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\selectlanguage{english}
\begin{abstract}
A 17-year-old Quarter Horse broodmare was taken to surgery for signs of
colic unresponsive to medical management. The small colon was
strangulated by a pendulous ovarian pedicle. The strangulation was
freed, and the affected ovary was removed. The mare developed signs of a
small colon obstruction 4 days after surgery. The mare was euthanized 6
days after surgery for signs of a GI rupture. A post-mortem examination
revealed necrosis of the affected portion of small colon.%
\end{abstract}%



\sloppy


Strangulation of the small colon by ovarian pedicle in an adult
broodmare

Kevin M. Claunch, DVM, DACVS-LA; Parker Wurst, DVM, Cari Chisholm, DVM

Weems \& Stephens Equine Hospital; 5960 Hospital Rd. Aubrey, TX, 76227
USA

Summary

A 17-year-old Quarter Horse broodmare was taken to surgery for signs of
colic unresponsive to medical management. The small colon was
strangulated by a pendulous ovarian pedicle. The strangulation was
freed, and the affected ovary was removed. The mare developed signs of a
small colon obstruction 4 days after surgery. The mare was euthanized 6
days after surgery for signs of a GI rupture. A post-mortem examination
revealed necrosis of the affected portion of small colon.

Keywords: Horse, Small colon strangulation, Ovarian strangulation, colic

Case History

A 17 year-old Quarter Horse broodmare presented to the hospital for
signs of abdominal pain of 7 hours duration. The mare was given flunixin
IV on the farm which did not reduce her abdominal pain. The mare
presented with marked abdominal distension and severe abdominal pain. At
admission the mare had a rectal temperature of 38.2C (100.8F), heart
rate of 80 beats/minute, and respiration rate of 36 breaths/minute.
Borborygmi was absent in all abdominal quadrants. The mare was sedated
with 3 mL of xylazine (Anased\textsuperscript{1} 0.55 mg/kg IV once) and
was administered 3 mL N-butylscopolammonium bromide
(Buscopan\textsuperscript{2} 0.11 mg/kg). Transrectal palpation of the
abdomen revealed severe GI distension that prevented full insertion of
an arm. Trans abdominal ultrasound did not reveal any excess peritoneal
fluid or small intestinal distension. The large colon was filled with
gas and was of normal wall thickness. Nasogastric intubation yielded 2
liters of net reflux. The mare had a PCV of 32\% and TP of 6.8 g/dL. An
intravenous catheter was placed in the left jugular vein. The mare was
taken to a stall and started on intravenous balanced electrolyte
solution (Plasma-Lyte\textsuperscript{3}) as a bolus. The mare was
extremely painful and difficult to keep standing. The mare was taken to
surgery due to unrelenting pain and concern for a large intestinal
obstruction.

Surgery details

The mare was administered potassium penicillin (22,000 units/kg IV) and
gentamicin (6.6 mg/kg IV). The mare was sedated with xylazine
(Anased\textsuperscript{1} 1 mg/kg) IV. She was then induced under
general anesthesia with ketamine (Ketaset\textsuperscript{4} 2.2 mg/kg
IV once) and midazolam (.03 mg/kg IV once). The mare was positioned in
dorsal recumbency and maintained on oxygen and isoflurane using
mechanical ventilation. The ventral abdomen was clipped. The clipped
area was aseptically prepped with chlorhexidine and alcohol and
routinely draped. A 30 cm ventral midline incision was made, and the
abdomen was entered. Exploration of the abdomen revealed a markedly gas
distended cecum and the large colon was markedly distended with gas and
ingesta. The small colon was firmly impacted with ingesta, and gas
distended at its oral aspect. An aboral segment of the small colon was
strangulated by the left ovary with an abnormally long mesovarium. The
strangulation was manually corrected. A controlled high enema was
performed to evacuate the small colon. The large colon was evacuated via
pelvic flexure enterotomy. The enterotomy was closed with 2-0
polyglactin 910 (vicryl\textsuperscript{5}) using a full thickness
simple continuous pattern oversewn with a Cushing pattern. The
strangulated portion of the small colon could not be exteriorized. When
looking into the abdomen with a headlight, a portion of the small colon
mesentery and serosal surface was light purple in color. The left ovary
was dark purple to black in color and was mildly enlarged. The left
ovary was considered non-viable. The left ovary was easily exteriorized
through the midline incision. The mesovarium was grasped with Carmalt
forceps and a vessel sealing device (Liga-sure\textsuperscript{6}) was
used to cauterize and transect the mesovarium. The ovary was sectioned,
placed in formalin, and submitted for histopathology. The linea alba was
closed with \#3 polyglycolic acid (PGA\textsuperscript{7}) using a
simple continuous pattern, the subcutaneous tissues were closed with 0
polyglactin 910 (vicryl\textsuperscript{5}) using a simple continuous
pattern, and the skin was closed with 2-0 poliglecaprone
(Monocryl\textsuperscript{5}) using a simple continuous pattern. The
incision was covered with a tightly rolled sterile Huck towel which was
sutured to the skin with 0 nylon using large cruciate sutures. The mare
recovered from anesthesia uneventfully with the aid of head and tail
ropes.

Post-operative care

Following surgery, the mare was maintained on 50mL/kg/day of balanced
electrolyte IV fluids (Plasma-Lyte\textsuperscript{3}) for 48 hours,
22,000 IU/kg potassium penicillin IV q6h, 6.6mg/kg gentamicin IV q24h,
and 1.1 mg/kg flunixin meglumine IV q12h. The mare immediately became
comfortable following surgery. She was started on a gradual refeeding
program beginning 48 hours after surgery. The mare had a good appetite
and had normal vital signs until 4 days after surgery when she developed
signs of abdominal discomfort, abdominal distension, and tachycardia
(64bpm). Transrectal palpation of the abdomen revealed firm ingesta
packed within the small colon consistent with a small colon impaction.
At this time there was concern that the mare could have delayed ischemic
damage of the small colon. Feed was removed, the mare was maintained on
IV fluids, and was administered laxatives via NG tube (alternating doses
of mineral oil, magnesium sulfate, and electrolyte water). Over the next
48 hours the mare remained mild to moderately uncomfortable and failed
to pass manure. Repeated rectal exams confirmed the small colon
obstruction was unchanged. The mare developed sudden profound
tachycardia, full body sweating, and purple mucous membranes 6 days
post-operatively. Transrectal palpation of the abdomen revealed free gas
in the abdomen. Transabdominal ultrasound revealed heterogenous free
abdominal fluid ventrally and free gas in the abdomen dorsally. An
abdominocentesis revealed dark green fluid and it was determined the
mare had suffered a rupture of the gastrointestinal tract. The mare was
humanely euthanized.

Post-mortem findings

A necropsy was performed which revealed ischemic damage of a 70 cm
section of small colon which corresponded to the site of the ovarian
strangulation. A full thickness rupture was present in the ischemic
section of the small colon.

Histopathology

Histopathology revealed extensive hemorrhage throughout the ovarian
stroma characterized by large pools of red blood cells as well as
congestion of blood vessels. The changes were compatible with acute
ovarian strangulation. No other abnormalities were observed.

Discussion

To the authors' knowledge this is the only report of ovarian
strangulation of the small colon in an adult mare. An almost identical
lesion has previously been reported (Pilatii 2013) as an acquired
condition in a seven-day old filly. Ovarian strangulation of the small
colon has also been reported in a newborn filly (Evard 1988). In
addition, primary ovarian torsion has been described in a neonatal foal
(Valk 1998). Disease of the small colon is only responsible for 2\%-18\%
of horses admitted for colic to referral centers (Prange 2019). More
typical diseases include small colon impaction, enteroliths/fecaliths,
strangulations from lipomas, volvulus, or neoplasia, and vascular
injuries including tearing of the mesocolon. Some form of large
intestinal obstruction was expected prior to exploratory celiotomy in
this mare. However, the highly unlikely nature of this type of
strangulation along with the location making visualization of the
strangulation impossible resulted in delayed recognition of the true
cause of the strangulation. In fact, it was originally thought that the
mare had a strangulating lipoma of her small colon after preliminary
exploration of the abdomen. This was due to a soft spherical structure
connected to a band being palpated tightly wrapped around the small
colon. It was not until after the strangulation was resolved and the
ovary was exteriorized did the true cause of strangulation become
apparent. Thankfully this strangulation was able to be resolved by
manual manipulation of the ovary around the mesovarium. If the ovary had
been blindly transected within the abdomen, severe hemorrhage could have
been encountered that would have been difficult to locate and control.
Although uncommon, ovarian strangulation should be considered as a
differential diagnosis when an intestinal strangulation is discovered
especially prior to blind transection of a strangulating band.

The cause of the pedunculated nature of this ovary was not readily
apparent. Presumably the mesovarium could be stretched by the weight of
the uterus associated with multiple pregnancies. However, the right
ovary/mesovarium was within normal limits. Ovarian strangulation being
reported in young foals may suggest that an elongated mesovarium could
be a congenital abnormality. Histopathology did not reveal any
predisposing causes for the elongated mesovarium.

Unfortunately, this mare was not able to survive due to ischemic damage
to the strangulated portion of the small colon. Conceivably a colostomy
could have been performed at the time of surgery as the location of the
strangulation made it difficult to be certain of viability, however this
was not a feasible option for this mare nor was a second abdominal
surgery. The initial rapid improvement in clinical signs made for a
hopeful initial prognosis. At the time that the mare developed
post-operative signs of small colon obstruction it was unknown if
obstruction was due to temporary dysfunction or delayed ischemic injury.
Supportive care was necessary until it became clear that the mare had a
hopeless prognosis. Similar to other strangulating lesions, the mare
likely would have had a better chance of successful outcome with earlier
surgical intervention. A definitive pre-operative diagnosis was not able
to be obtained and all signs associated with the initial colic
evaluation were commiserate with a large intestinal obstruction. The
amount of gas distension precluded palpation of the reproductive tract.
If the mare had presented early after the strangulation developed, prior
to the development of severe gas distension it is conceivable that the
ovarian strangulation may have been able to be palpated per rectum.

Conclusion

Ovarian strangulation has now been reported as a rare cause of small
colon strangulation as a congenital and acquired condition in foals and
in an adult broodmare. Ovarian strangulation should be considered in
cases of small colon strangulation especially in the caudal abdomen.

Author declaration of interests

The author has no conflicts of interest.

\textbf{Manufacturers' addresses}

\textsuperscript{\textbf{1}} Vet One, Boise, ID, USA

\textsuperscript{2}Boehringer Ingelheim, Duluth, GA, USA

\textsuperscript{3}Baxter, Deerfield, IL, USA

\textsuperscript{4}Zoetis, Parsipanny, NJ, USA

\textsuperscript{5}Ethicon, Johnson and Johnson, Somerville NJ, USA

\textsuperscript{6}Covidien, Dublin, Ireland

\textsuperscript{7}Covetrus, Portland,ME,USA

References

Evard et al. (1988) Ovarian strangulation as a cause of small colon
obstruction in a foal. Equine Vet J. \textbf{20} 217-218

Pilati et al. (2013) Small colon obstruction by an ovarian pedicle as an
acquired condition in a foal. Equine Vet. Educ. \textbf{25} 290-292

Prange et al. (2019) Transverse and Small Colon. In Equine Surgery
5\textsuperscript{th} edn., Ed: J Auer and J Stick, Elsevier, St.Louis.
pp621-631

Valk et al. (1998) Ovarian torsion as a cause of colic in a neonatal
foal. J. Am. Vet. Med. Ass. \textbf{213} 1454-1456

Figures\selectlanguage{english}
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\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

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Figure 1.

Figure1. Image of the left ovary after the strangulation was corrected,
exteriorized through the ventral midline incision.\selectlanguage{english}
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\includegraphics[width=0.70\columnwidth]{figures/IMG-8721/IMG-8721}

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