OBJECTIVE To evaluate the effect of volume of IV regional limb perfusion (IVRLP) on amikacin concentrations in synovial and interstitial fluid of horses.
ANIMALS 8 healthy adult horses.
PROCEDURES Each forelimb was randomly assigned to receive IVRLP with 4 mL of amikacin sulfate solution (250 mg/mL) plus 56 mL (total volume, 60 mL) or 6 mL (total volume, 10 mL) of lactated Ringer solution. Horses were anesthetized, and baseline synovial and interstitial fluid samples were collected. A tourniquet was placed, and the assigned treatment was administered via the lateral palmar digital vein. Venous blood pressure in the distal portion of the limb was recorded. Additional synovial fluid samples were collected 30 minutes (just before tourniquet removal) and 24 hours after IVRLP began; additional interstitial fluid samples were collected 6 and 24 hours after IVRLP began.
RESULTS 30 minutes after IVRLP began, mean amikacin concentration in synovial fluid was significantly greater for the large-volume (459 μg/mL) versus small-volume (70 μg/mL) treatment. Six hours after IVRLP, mean concentration in interstitial fluid was greater for the large-volume (723 μg/mL) versus small-volume (21 μg/mL) treatment. Peak venous blood pressure after large-volume IVRLP was significantly higher than after small-volume IVRLP, with no difference between treatments in time required for pressure to return to baseline.
CONCLUSIONS AND CLINICAL RELEVANCE Study findings suggested that large-volume IVRLP would deliver more amikacin to metacarpophalangeal joints of horses than would small-volume IVRLP, without a clinically relevant effect on local venous blood pressure, potentially increasing treatment efficacy.
Objective—To evaluate the effects of anti-inflammatory
drugs on lipopolysaccharide (LPS)-challenged and
-unchallenged equine synovial membrane in terms of
production of prostaglandin E2 (PGE2) and hyaluronan,
viability, and histomorphologic characteristics.
Sample Population—Synovial membranes were collected
from the carpal, tarsocrural, and femoropatellar
joints of 6 adult horses.
Procedure—Synovial membranes from each horse
were minced and pooled and explants were treated
with one of the following: no drug (control), drug, LPS
alone, or LPS and drug. Treatment drugs were
phenylbutazone (PBZ), flunixin meglumine (FNX),
ketoprofen (KET), carprofen (CRP), meloxicam (MEL),
low-concentration methylprednisolone (METH), highconcentration
METH, dimethyl sulfoxide (DMSO), or
an experimental COX-2 inhibitor (dissolved in DMSO).
Following 48 hours of culture, medium was assayed
for PGE2 and hyaluronan concentration. Synovial
explants were assessed for viability and histomorphologic
Results—For the LPS-challenged explants, PBZ, FNX,
KTP, CRP, MEL, and low-concentration METH suppressed
PGE2 production, compared with LPS challenge
alone. Only MEL suppressed PGE2 production
from LPS-challenged explants, compared with unchallenged
explants. Synovial explants maintained > 90%
viability and there was no significant difference in viability
or hyaluronan production among explants.
Histomorphologic scores were significantly
decreased for explants treated with low-concentration
METH or DMSO.
Conclusions and Clinical Relevance—PBZ, FNX,
KTP, CRP, MEL, and low-concentration METH suppressed
PGE2 production in LPS-challenged explants.
Meloxicam appeared to have more selective suppression
of COX-2 activity. Histomorphologic scores suggest
detrimental effects of METH, DMSO, and the
experimental COX-2 inhibitor. Commonly used nonsteroidal
anti-inflammatory drugs suppress induced
synovial membrane PGE2 production without detrimental
effects on synovial membrane viability and
function. ( Am J Vet Res 2001;62:54–60)
Objective—To determine short- and long-term outcomes, including recurrence rates, for horses with cecal impaction treated medically or surgically.
Design—Retrospective case series.
Procedures—Medical records were reviewed for information on signalment, history, clinical findings, treatment (medical vs surgical), and short-term outcome. Information on longterm outcome was obtained through a mail survey and telephone interview with owners.
Results—54 horses were treated medically, 49 horses were treated surgically, and 11 horses were euthanized after initial examination without further treatment. Horses treated surgically were significantly more likely to have signs of moderate or severe pain than were horses treated medically. Forty-four of the 54 (81%) horses treated medically were discharged from the hospital. Twelve of the 49 horses treated surgically were euthanized at surgery because of cecal rupture. Thirty-five of the 37 (95%) horses that were allowed to recover from surgery were discharged from the hospital. In 34 horses treated surgically, typhlotomy without a bypass procedure was performed. Long-term (≥ 1 year) follow-up information was available for 19 horses treated medically and 28 horses treated surgically. Eighteen (95%) and 25 (89%) of the horses, respectively, were alive at least 1 year after treatment.
Conclusions and Clinical Relevance—Results suggested that medical and surgical treatment were both associated with favorable outcomes in horses with cecal impactions. In this population, typhlotomy alone without cecal bypass was associated with a low recurrence rate. The long-term prognosis for horses that were discharged from the hospital was good.
Objective—To evaluate the effect of a phospholipid
emulsion (PLE) on the initial response of horses to
administration of endotoxin.
Animals—12 healthy adult horses.
Procedures—Horses were assigned to 2 treatment
groups (6 horses/group). The control group was
administered 1 L of saline (0.9% NaCl) solution, and
the treated group was administered PLE (200 mg/kg,
IV); treatments were administered during a period of
120 minutes. An infusion of endotoxin was initiated in
both groups starting 1 hour after initiation of the
saline or PLE solutions. Physical examination and
hemodynamic variables were recorded, and blood
samples were analyzed for concentrations of tumor
necrosis factor (TNF)-α, interleukin-6, thromboxane B2
(TxB2), 6 keto-prostaglandin F (PGF)1α, total leukocyte
count, and PLE concentrations. An ANOVA was used
to detect significant differences.
Results—Administration of PLE resulted in significantly
lower rectal temperature, heart rate, cardiac
output, right atrial pressure, and pulmonary artery
pressure and higher total leukocyte counts in treated
horses, compared with values for control horses. The
TNF-α concentration was significantly less in treated
horses than in control horses. The TxB2 and 6 keto-
PGF1α concentrations were significantly different
between treated and control horses at 30 minutes
(TxB2) and at 30 and 60 minutes (6 keto-PGF1α).
Conclusions and Clinical Relevance—Prior infusion
of PLE in horses administered a low dose of endotoxin
decreased rectal temperature, heart rate, pulmonary
artery pressure, and TNF-α concentrations.
Results of this study support further evaluation of PLE
for use in the treatment of horses with endotoxemia.
(Am J Vet Res 2002;63:1370–1378)
Objective—To evaluate the diagnostic value of serum
concentrations of total magnesium (tMg) and ionized
magnesium (iMg), concentrations of magnesium
(Mg) in muscle, intracellular Mg (icMg) concentrations,
urinary Mg excretion (EMg), Mg clearance (CMg),
and fractional clearance of Mg (FCMg) in horses fed
diets with Mg content above and below National
Research Council recommendations.
Animals—9 young female horses.
Procedures—6 horses were fed a reduced-Mg diet
for 29 days followed by an Mg-supplemented diet for
24 days. Control horses (n = 3) were fed grass hay
exclusively. Blood, urine, and tissue samples were
collected, and an Mg retention test was performed
before and after restriction and supplementation of
Mg intake. Serum tMg, serum iMg, muscle Mg,
icMg, and urine Mg concentrations were measured,
and 24-hour EMg, CMg, and FCMg were calculated.
Results—Reductions in urinary 24-hour EMg, CMg, and
FCMg were evident after 13 days of feeding a reduced-Mg diet. Serum tMg and iMg concentrations, muscle
Mg content, and results of the Mg retention test
were not affected by feeding the Mg-deficient diet.
Spot urine sample FCMg accurately reflected FCMg calculated
from 6- and 24-hour pooled urine samples.
Mean ± SD FCtMg of horses eating grass hay was 29
± 8%, whereas mean FCtMg for horses fed a reduced-Mg diet for 29 days was 6 ± 3%.
Conclusions and Clinical Relevance—The 24-hour
EMg was the most sensitive indicator of reduced Mg
intake in horses. Spot sample FCMg can be conveniently
used to identify horses consuming a diet deficient
in Mg. (Am J Vet Res 2004;65:422–430)
To determine the effectiveness of a digital interactive multimedia tutorial (DIMT) for preparing veterinary students to perform ultrasonography in horses.
42 third-year veterinary students.
Students were randomly assigned to 3 instructional methods: independent study (ie, 45 minutes to read a highlighted textbook chapter), lecture (ie, 45-minute lecture by a faculty member), or digital interactive multimedia tutorial (DIMT; ie, 45-minute narrated, interactive module). Written and practical tests were administered after each instruction session. For the practical test, each student was required to obtain a series of ultrasound images of a live horse, and images were later scored for quality by an individual unaware of the instructional method used.
Higher-quality ultrasound images were obtained by veterinary students who had reviewed the DIMT rather than the analogous information in textbook chapters. No difference in scores was identified between students in the lecture group and those in the DIMT group. Students’ perceptions suggested that practical instruction facilitated by clinicians was a key component of learning how to perform ultrasonography in horses.
CONCLUSIONS AND CLINICAL RELEVANCE
Results supported the use of DIMTs in preparing veterinary students to perform ultrasonography in horses.
Case Description—6 horses were determined to have torsion of a liver lobe at 4 referral institutions over a 21-year period.
Clinical Findings—Clinical findings were nonspecific but often included signs of marked inflammation. Two of the 6 horses were examined because of colic, and 2 were assessed because of peritonitis that failed to respond to treatment; the remaining 2 horses were examined because of nonspecific clinical signs that included inappetence, lethargy, and weight loss. The results of laboratory tests were widely variable, and values for liver enzyme activities were typically within reference limits or only mildly increased. Most affected horses had markedly increased peritoneal nucleated cell counts.
Treatment and Outcome—Exploratory laparotomy and resection of the affected liver lobe was performed in 5 horses. Three of those patients survived to discharge.
Clinical Relevance—Results suggested that diagnosis of liver lobe torsion in horses may be difficult because clinical signs and results of laboratory testing are nonspecific and variable. Most affected horses had markedly abnormal peritoneal fluid. The prognosis for hepatic lobe torsion can be good, and early surgical correction is expected to improve outcome.