Objective—To determine whether intraluminal distention
and subsequent decompression of the equine
jejunum affects intestinal blood flow, hemodynamics,
and microvascular permeability.
Animals—5 healthy adult horses.
Procedure—Horses were anesthestized and underwent
exploratory laparotomy. Two jejunal segments
were identified as sham-operated or instrumented
segments. After baseline values were obtained, intraluminal
distention was created in the experimental
segment to induce an intraluminal pressure of 18 cm
H2O. After 120 minutes of distention, the intestine
was decompressed for 120 minutes. Mesenteric
blood flow, oxygen delivery, oxygen consumption,
microvascular permeability, wet weight-to-dry weight
ratio, neutrophil infiltration, and vascular resistance
were determined and comparisons made among control,
sham-operated, and experimental segments.
Results—Mean jejunal blood flow was 21.4 ml/min
per kg. There was a significant decrease in mesenteric
blood flow to the distended intestine (13.4
ml/min per kg). Blood flow increased significantly during
the decompression period (340% of baseline
blood flow). Intraluminal distention and subsequent
decompression resulted in a significant increase in
microvascular permeability, as determined by the
osmotic reflection coefficient. Oxygen delivery and
oxygen content decreased significantly during the distention
period and increased during decompression.
Morphologic evaluation revealed a significant
increase in edema and neutrophil infiltration after distention
and decompression, compared with results
for the sham-operated or control segments.
Conclusions and Clinical Relevance—Intraluminal
distention and decompression of the equine jejunum
results in low-flow ischemia and edema, which may
contribute to adhesions and ileus in the postoperative
period after surgery for obstructions of the small
intestines. (Am J Vet Res 2001;62:225–236)
Objective—To evaluate effects of Carolina rinse solution,
dimethyl sulfoxide (DMSO), and 21-aminosteroid,
U-74389G, on microvascular permeability and
morphology of the equine jejunum after low-flow
ischemia and reperfusion.
Animals—20 healthy adult horses.
Procedure—Under anesthesia, full-thickness biopsy
specimens of a distal portion of the jejunum were
obtained for baseline measurements. In addition to a
control segment, 2 jejunal segments were identified
as sham-operated or experimental segments.
Experimental segments underwent 60 minutes of
low-flow ischemia and 3.5 hours of reperfusion.
Treatments were as follows: U-74389G (3 mg/kg, IV; 6
horses), DMSO (20 mg/kg, IV; 6) diluted in 1 L of saline
(0.9% NaCl) solution, local perfusion (via jejunal artery)
of Carolina rinse solution (0.5 mL/kg; 4), and local perfusion
of lactated Ringer's solution (0.5 mL/kg; 4).
Results—Jejunal microvascular permeability was
significantly lower after treatment with Carolina rinse
solution or DMSO, compared with U-74389G or lactated
Ringer's solution treatments. After DMSO
treatment, serosal- and submucosal-layer edema
was significantly increased in experimental segments,
compared with control or sham-operated
segments; however, edema increases were significantly
less than for lactated Ringer's solution or
U-74389G treatments. Significant decreases in
intestinal wet weight-to-dry weight ratio were found
following Carolina rinse solution or DMSO treatments,
compared with lactated Ringer's solution or
U-74389G treatments. Edema formation and leukocyte
infiltration in jejunal segments of horses treated
with lactated Ringer's solution or U-74389G were
increased, compared with Carolina rinse solution or
Conclusions and Clinical Relevance—Carolina rinse
solution and DMSO may be protective against
ischemia-reperfusion injury in the equine jejunum.
(Am J Vet Res 2005;66:525–536)
Objective—To assess changes in systemic hydration,
concentrations of electrolytes in plasma, hydration of
colonic contents and feces, and gastrointestinal transit
in horses treated with IV fluid therapy or enteral
administration of magnesium sulfate (MgSO4), sodium
sulfate (NaSO4), water, or a balanced electrolyte
Animals—7 horses with fistulas in the right dorsal
Procedure—In a crossover design, horses alternately
received 1 of 6 treatments: no treatment (control); IV
fluid therapy with lactated Ringer's solution; or enteral
administration of MgSO4, Na2SO4, water, or a balanced
electrolyte solution via nasogastric intubation.
Physical examinations were performed and samples
of blood, RDC contents, and feces were collected
every 6 hours during the 48 hour-observation period.
Horses were muzzled for the initial 24 hours but had
access to water ad libitum. Horses had access to hay,
salt, and water ad libitum for the last 24 hours.
Results—Enteral administration of a balanced electrolyte
solution and Na2SO4 were the best treatments
for promoting hydration of RDC contents, followed by
water. Sodium sulfate was the best treatment for promoting
fecal hydration, followed by MgSO4 and the
balanced electrolyte solution. Sodium sulfate caused
hypocalcemia and hypernatremia, and water caused
Conclusions and Clinical Relevance—Enteral
administration of a balanced electrolyte solution promoted
hydration of RDC contents and may be useful
in horses with large colon impactions. Enteral administration
of either Na2SO4 or water may promote
hydration of RDC contents but can cause severe electrolyte
imbalances. (Am J Vet Res 2004;65:695–704)
Objective—To determine effects on anal pressure of
horses after local injection of the external anal sphincter
with Clostridium botulinum toxin type B.
Animals—11 healthy adult horses.
Procedure—Peak and resting anal sphincter pressures
were measured with a custom-made rectal
probe that was connected to a pressure transducer.
Pressures were measured before treatment and after
injection with botulinum toxin type B (BTB) or saline
(0.9% NaCl) solution. Dose titration with 500, 1,000,
1,500, and 2,500 U of BTB was completed. Physical
changes, behavior, and anal pressure were recorded
for each horse.
Results—Injection of 1,000 U of BTB caused a significant
reduction in peak anal pressure from days 2 to
84, compared with pressure in control horses.
Maximal effect of the toxin was observed within the
first 15 days after injection, followed by a slow return
to baseline during the 168-day period. Injection of
2,500 U of BTB in the anal sphincter in 1 horse resulted
in lethargy, generalized weakness, and dysphagia
for 14 days. Adverse clinical effects were not
observed in horses after injections with 500, 1,000, or
1,500 U of BTB.
Conclusions and Clinical Relevance—The effect of
focal intramuscular injection of BTB in horses is similar
to that reported for other species. However, horses
appear to be more sensitive to BTB, compared
with other species, and clinical signs of botulism may
develop at doses exceeding 1,500 U. Injections of
BTB in the external anal sphincter of mares may be
useful to reduce incisional dehiscence after repair of
perineal lacerations. ( Am J Vet Res 2004;65:26–30)
OBJECTIVE To evaluate agreement among diplomates of the American College of Veterinary Anesthesia and Analgesia for scores determined by use of a simple descriptive scale (SDS) or a composite grading scale (CGS) for quality of recovery of horses from anesthesia and to investigate use of 3-axis accelerometry (3AA) for objective evaluation of recovery.
ANIMALS 12 healthy adult horses.
PROCEDURES Horses were fitted with a 3AA device and then were anesthetized. Eight diplomates evaluated recovery by use of an SDS, and 7 other diplomates evaluated recovery by use of a CGS. Agreement was tested with κ and AC1 statistics for the SDS and an ANOVA for the CGS. A library of mathematical models was used to map 3AA data against CGS scores.
RESULTS Agreement among diplomates using the SDS was slight (κ = 0.19; AC1 = 0.22). The CGS scores differed significantly among diplomates. Best fit of 3AA data against CGS scores yielded the following equation: RS = 9.998 × SG0.633 × ∑UG0.174, where RS is a horse's recovery score determined with 3AA, SG is acceleration of the successful attempt to stand, and ∑UG is the sum of accelerations of unsuccessful attempts to stand.
CONCLUSIONS AND CLINICAL RELEVANCE Subjective scoring of recovery of horses from anesthesia resulted in poor agreement among diplomates. Subjective scoring may lead to differences in conclusions about recovery quality; thus, there is a need for an objective scoring method. The 3AA system removed subjective bias in evaluations of recovery of horses and warrants further study.