Objective—To report the postoperative outcome in
horses undergoing jejunoileal anastomosis performed
with a 2-layer simple continuous technique.
Procedure—Information regarding signalment, clinical
signs, findings at surgery, and postoperative complications
was obtained from medical records of horses
that underwent exploratory ventral midline celiotomy,
small intestinal resection, and jejunoileal anastomosis
to correct various small intestinal strangulating
lesions. Follow-up information was obtained via telephone
conversations with owners or trainers.
Results—Six males and 1 female of various breeds
aged 10 months to 27 years and weighing 312 to 785 kg
(686.4 to 1,727 lb) were included. The most common
complications were mild to moderate tachycardia and
mild to moderate signs of abdominal pain. Two horses
developed incisional infections and soft, fluctuant
swelling at the incision site following resolution of the
infection. Follow-up time ranged from 7 to 17 months
after surgery. Owners reported no further colic episodes
and no diet change necessary following surgery. All
horses had returned to their intended level of use.
Conclusions and Clinical Relevance—Advantages to
the jejunoileal technique include maintaining the normal
ileocecal valve and a postoperative recovery period
similar to that described following other small
intestinal anastomoses. Jejunoileal anastomosis is a
viable alternative to ileal bypass. This technique
appears to result in a postoperative complication rate
similar to that reported following jejunojejunostomy
procedures. (J Am Vet Med Assoc 2002;221:541–545)
Objective—To determine messenger RNA expression
of cyclooxygenase (COX)-2, tumor necrosis factor
(TNF)-α, and interleukin- (IL)-1β from cultured
equine smooth muscle cells (SMC).
Sample Population—Segments of palmar digital
artery harvested from 6 clinically normal adult horses.
Procedure—Explants were collected from the tunica
media of arteries for primary culture of SMC. Equine
mononuclear cells were used as control cells.
Subcultured vascular SMC and control cells were
exposed to lipopolysaccharide (20 µg/ml and 100
ng/ml, respectively). Northern blot analysis with
equine-specific probes for COX-2, TNF-α, and IL-1β
was performed, using isolated total cellular RNA.
Results—Although no message was detected for IL-1β or TNF-α in control or endotoxin-exposed equine vascular SMC from all horses, COX-2 underwent a
distinct substantial up-regulation after endotoxin
exposure. Endotoxin-exposed equine mononuclear
cells had up-regulation of IL-1β and TNF-α mRNA.
Conclusions and Clinical Relevance—Increased
expression of COX-2 mRNA by equine vascular SMC
may be an important early pathophysiologic event in
the onset of endotoxemia in horses. Potentiated local
vascular production of various prostanoids after
increased expression of mRNA for COX-2 may result
in vasoactive events observed with laminitis. (Am J
Vet Res 2001;62:1957–1963)
Objective—To develop methods to isolate, culture,
and characterize smooth muscle cells (SMC) from
equine palmar digital arteries.
Sample Population—Segments of the medial or lateral
palmar digital arteries from the forelimbs of 6 horses.
Procedure—To obtain smooth muscle explants, arterial
segments were incised longitudinally. The tunica
intima was gently scraped from the underlying tunica
media, and explants were obtained from the tunica
media. Approximately 18 to 24 explants were
obtained from each palmar digital arterial segment. A
substrate-attached technique was used to initiate primary
culture of SMCCultured cells were identified as
SMC, using light microscopy, electron microscopy,
reverse transcriptase-polymerase chain reaction (RTPCR),
and northern blot analysis. The replication index
and serum dependence of equine SMC in culture was
characterized by use of bromodeoxyuridine.
Results—The SMC of equine palmar digital arteries
were successfully cultured, as confirmed by RT-PCR
and northern blot analysis techniques for smooth
muscle α-actin and detection of SMC-specific
organelles during electron microscopy. When characterized
by light and electron microscopy, SMC were
found to have undergone phenotypic modulation to a
more synthetic phenotype in culture while retaining
characteristics of SMC.
Conclusions and Clinical Relevance—Culture of
SMC from equine palmar digital arteries via an explant
protocol is a viable technique for studying vascular
biological mechanisms in horses. In vitro studies of
SMC may aid investigators in determining cellular
mechanisms involved in disease processes such as
laminitis. (Am J Vet Res 2000;61:1602–1608)