Proceedings,
Meeting of the American College of Veterinary Anesthesiologists
September 10, 2009
Chicago, Illinois
* Denotes presenter is in a training program
# Denotes presenter is in a training program (ACVA or
ECVAA resident) and eligible for the ACVA resident abstract award
Abstracts, Room 1
A COMPARISON OF
EPIDURAL BUPIVACAINE AND MORPHINE VERSUS EPIDURAL MORPHINE ON MOTOR AND
RESPIRATORY FUNCTION IN DOGS FOLLOWING SPLENECTOMY
Abelson AL1, Chan EA2,
Lindsey JC3, Wetmore LA1
1Cummings School of
Veterinary Medicine at Tufts University, Grafton, MA, USA; 2Royal
Veterinary College, London, UK; 3Harvard School of Public Health,
Boston, MA, USA.
Introduction: A comparison of epidural bupivacaine and morphine versus epidural
morphine on motor and respiratory function and pain scores in dogs following
splenectomy.
Methods: This was a prospective, randomized study using 16 client owned dogs
undergoing routine splenectomy. Epidural injections were administered after
splenectomy, immediately prior to anesthetic recovery, according to one of two
randomized drug combinations: morphine (0.1 mg/kg) (group MOR) or morphine (0.1
mg/kg) with a low concentration (0.167%) of bupivacaine (0.25 mg/kg) (group
MORB). Volumes were standardized to 0.15 ml/kg. Motor function and pain
assessments were performed at pre-determined times using a simple numerical
motor score and the University of Melbourne Pain Scale (UMPS) respectively.
Repeated measures ANOVA was used to test for treatment differences. An arterial
blood gas was performed 2 hours following epidural administration to check for
respiratory compromise. If patients scored > 7 on the UMPS or were deemed
painful by the observer, rescue analgesia (intravenous hydromorphone) was
administered. Dose and time of rescue analgesia was recorded and compared
between investigators using a Wilcoxon rank sum test.
Results: There were no statistically significant differences in motor scores,
pain scores, rescue analgesia or PaC02 between treatment groups. No dogs
demonstrated clinical motor dysfunction or respiratory depression at any time
point during the study. 9/16 (56%) of dogs required no rescue analgesia during
the first 18 hours following splenectomy.
Conclusions: The addition of low concentration bupivacaine (0.167%) to preservative-free
morphine (0.1mg/kg) administered epidurally appears not to compromise motor or
respiratory function.
GRAVITY HAS
LITTLE EFFECT ON EPIDURAL DISTRIBUTION OF CONTRAST MEDIUM AND METHYLENE-BLUE
DYE IN STERNALLY RECUMBENT ANESTHETIZED DOGS
Son W*1, Kim J1, Seo J1, Yoon J1,
Lee LY2, Lee I1
1College of Veterinary Medicine, Seoul National University, Seoul, Korea;
2College of Veterinary Medicine, Western University of Health
Sciences, Pomona, CA, USA.
Introduction: This study was performed to examine gravity effect on epidural
distribution of the solution in sternally recumbent anesthetized dogs.
Methods: Ten beagle dogs (7.5±1.3 kg, 4±0.9 years, 2F/8M) were anesthetized
with total intravenous propofol infusion. A volume of 0.2 ml/kg contrast medium
(CM; Iohexol®, 300 mg/ml) containing 1% methylene blue dye (MB) was
administered into the lumbosacral epidural space at a rate of 1 ml/min. A
horizontal LR lateral radiographic view in sternal recumbency was taken
immediately before, and at 0, 5, 10, 15, 20, 25, 30 and 45 minutes of CM
administration in order to determine time-related epidural distribution. The
perpendicular height (PH) between ventral surface of highest vertebra (T13) and
lumbosacral injection point was measured on radiographs. Dogs were euthanized
and a laminectomy was performed for visual evaluation of MB distribution. The
distributed distance of CM and MB as counted in number of vertebra was
compared, and each of these data sets were further compared to PH,
respectively, using a paired t test and linear regression analysi
Results: The mean PH was 4.2±0.9 cm. The most cranial distribution of CM was,
in 21.8±4.7 minutes, at 12.6 ±5.7 (range: T2-L1) vertebrae, and at 14.0±5.5
(T1-T12) vertebrae for MB staining. There was no significant correlation
between PH and distribution of CM (r=0.08) or MB (r=0.13), respectively, but
distribution of CM and MB was highly correlated (r=0.90).
Conclusions: We were not able to observe significant gravity effect on epidural
distribution of the solution. It is likely other factors play as greater
attributor on epidural distribution.
ELECTRICAL
NEUROSTIMULATION TO CONFIRM THE CORRECT PLACEMENT OF LUMBOSACRAL EPIDURAL
INJECTIONS IN DOGS
Garcia-Pereira FL1, Hauptman J1, Shih AC2,
Laird SE1, Pease A1
1College of Veterinary
Medicine, Michigan State University, East Lansing, MI, USA; 2College
of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
Introduction: Placement of a needle or catheter into the epidural space is
challenging. In veterinary medicine, correct needle placement is suggested by
the loss of resistance (LR) and hanging drop techniques. However, in clinical
patients, the proper placement of an epidural needle is never definitively
confirmed, unless additional techniques such as contrast medium injection and
subsequent radiography are used. In dogs, successful placement of an epidural
needle is reported to be variable and dependent on experience of operator.
Methods: In this prospective randomized blinded study, ninety-six dogs received
contrast medium in the lumbosacral space. Two groups either received medium in
(Gin) or out (Gout) of the epidural space. The objective of this study was to
find the minimal electrical threshold (MET) in and out of the lumbosacral
epidural space of dogs to cause muscle contraction of hind limb/tail using a
neurostimulator (NS) and then compare predictability using NS versus LR. The
correct placement of the needle was confirmed by epidurography. Data were
analyzed using two sample Student- t test (p=0.05).
Results: Using the NS test, MET was lower in Gin, 0.30 ± 0.07 mA, than in Gout,
1.2 ± 0.13 mA (µ ± SEM, p<0.000001). NS sensitivity and specificity were 74%
and 93%, respectively. The LR test sensitivity was 63% and specificity 90%. The
combination of both tests yielded a sensitivity of 89% and specificity of 83%.
Conclusions: NS is a useful tool to suggest correct lumbosacral epidural needle
placement in dogs.
ULTRASOUND-GUIDED
NERVE BLOCK OF THE PELVIC LIMB IN DOGS
Shilo Y#, Pascoe PJ, Cissel D, Johnson EG, Kass
PH, Wisner ER
School of Veterinary Medicine, University of California, Davis, CA, USA
Introduction: The objective was to evaluate the efficacy of ultrasound-guidance in
nerve blockade of the sciatic and saphenous nerves in dogs and to determine if
this technique allowed lower doses to be used with predictable onset and
duration of effect.
Methods: Six healthy adult dogs were studied in a randomized, blinded,
crossover design for dose and leg (right/left) with a 10 day washout period. An
ultrasound-guided, perineural injection was used with saline at 0.2mL/kg or
bupivacaine 0.5% at 0.05, 0.1, or 0.2mL/kg, divided 2/3 at the sciatic nerve
and 1/3 at the saphenous nerve. Blocks were performed using
dexmedetomidine/atipamezole with reversal immediately after completion of the
injection. Motor/proprioceptive and sensory functions were scored using 0-8 and
0-2 scales, respectively. Clinically relevant blocks were defined as a motor
score =2 and sensory score =1. A Friedman repeated measures ANOVA was used with
p<0.05 considered significant.
Results: No adverse effects were noted. There was a significant difference
between the treatments with bupivacaine and the saline control, but not between
the 3 bupivacaine treatments. Success rates of clinically relevant sciatic and
saphenous blocks were both 67% (CI 95% 0.22-0.96). The range of the onset and
duration of blocks was 20-160 and 20-540 minutes, respectively. The durations
of sciatic motor and sensory blocks were not statistically different.
Conclusions: None of the bupivacaine doses was superior and none of the blocks were
consistently successful at these doses. Either the technique or the doses used
need further modification before being useful in clinical practice.
EVALUATION OF A
PRE-INCISIONAL LOCAL ANESTHETIC BLOCK
McKune CM1, Pascoe PJ1, Lascelles BDX2,
Kass PH1
1School of Veterinary Medicine, University of California, Davis, CA, USA;
2College of Veterinary Medicine, North Carolina State University,
Raleigh, NC, USA.
Introduction: To test the effectiveness of a local anesthetic line block
administered before surgery in reducing postoperative pain scores in dogs
undergoing ovariohysterectomy.
Methods: An algometric pressure measuring device was used to determine
nocioceptive threshold, and compared to subjective pain scales. Group L/B
received a line block of lidocaine (4 mg kg-1) and bupivacaine (1 mg kg-1)
subcutaneously in the area of the incision site and saline subcutaneously as
premedication, group L/BM (positive control) received a similar block and
morphine (0.5 mg kg-1) subcutaneously for premedication, and group SS (negative
control) received a saline line block and premedication. Criteria for rescue
analgesia were defined before the study. All dogs were included in an initial
analysis. A secondary analysis was performed and included only dogs that
achieved a maximum algometer score (1000 g) at extubation in the L/B and L/BM
groups. The data were analyzed with a two-way ANOVA and chi square test of
homogeneity. P < 0.05 was considered statistically significant.
Results: Approximately 33% of dogs required rescue analgesia at some point
during the study, with no significant difference between groups. There was no
significant difference between treatment groups with any assessment method,
both in animals that did and did not receive rescue analgesia, in both the
initial and secondary analyses. Eighteen of 39 dogs were considered
successfully blocked, with no significant difference between L/B and L/BM.
Conclusions: As there were no statistically significant differences between
positive and negative controls, this technique was not proven to be
efficacious.
SEDATIVE AND
CARDIORESPIRATORY EFFECTS OF DEXMEDETOMIDINE AND BUPRENORPHINE ADMINISTERED TO
CATS VIA ORAL TRANS-MUCOSAL OR INTRAMUSCULAR ROUTES
Santos LCP#, Ludders JW,
Gleed RD, Erb HN, Basher KM, Kirch P
College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
Introduction: The objective was to evaluate whether the oral trans-mucosal (OTM)
route of administration produced similar sedation to the intramuscular (IM)
route for dexmedetomidine (20ug kg-1) plus buprenorphine (20ug kg-1) in cats
being catheterized by veterinary students.
Methods: Eighty-seven shelter-owned cats aged 5-48 months old, scheduled for
ovariohysterectomy were randomly assigned to one of the two treatments: OTM or
IM. Heart rate, respiratory rate, and systolic arterial pressure were recorded
before and 20 minutes after drug administration. At the time of catheter
placement, posture, response to clipper sound, response to clipping, and
response to restraint were scored by a blinded observer who also decided if
ketamine (5mg kg-1, IM) was needed for successful catheterization. The
significance of differences was measured within treatment groups using the
Wilcoxon signed-rank test and between treatment groups using the Wilcoxon
Rank-sum test. Significance was set at p<0.05.
Results: Cats in the IM group were more likely to maintain lateral recumbency,
to be amenable to restraint, and to be less responsive to clipper sound and
clipping. The need for rescue sedation did not differ between the two groups;
eighteen of eighty-seven cats required ketamine; seven (16%) in the IM group
and eleven (25%) in the OTM group. Heart and respiratory rates declined after
drug administration, at which time heart rate was lower in the IM group. No
differences in blood pressure were detected.
Conclusions: Although OTM provided significantly less sedation than IM, it provided
enough effect to allow an IV catheter to be placed in 75% of the cats.
SAFETY AND
EFFICACY OF CONCURRENT DEXMEDETOMIDINE AND CARPROFEN USE IN DOGS UNDERGOING
ELECTIVE SURGERIES
Ko JC1, Knesl O2 Martin D3,
Cosgrove S3
1Department of Veterinary Clinical Sciences, School of Veterinary
Medicine, Purdue University, West Lafayette, IN, USA; 2Pfizer Animal
Health, New York, NY, USA; 3Pfizer Animal Health, Veterinary
Medicine Research and Development, Kalamazoo, MI, USA
Introduction: Dexmedetomidine (Dex) and carprofen (Carp) that have been used
preemptively for perioperative pain management. The objectives of this
prospective study were to evaluate the safety and efficacy of Dex as a
preanesthetic and Carp as a perioperative analgesic in dogs.
Methods: Fifty healthy beagle dogs were randomly assigned to 5 treatment groups
with 5 males and 5 females per group in split-plot study: Dex 125 mcg/m2 IM
(LDex), Dex 375 mcg/m2 IM (HDex), Carp 4.4 mg/kg SC (Carp), Carp 4.4mg/kg SC
with LDex (Carp-LDex) and Carp with HDex (Carp-HDex). The dogs were
anesthetized with propofol-isoflurane 15 minutes post premedication and
castrated/spayed. Dose sparing on propofol-isoflurane were assessed. Vital
signs, sedation, and pain were assessed pre and 15 minutes post premedication
and at 30, 60, 90, 120 and 180 minutes postoperatively. Urine and blood
profiles were assessed pre- and 2 and 7 days post surgery. ANOVA (p < 0.05)
was performed.
Results: Significant propofol and isoflurane sparing effects were noted in all
of the dexmedetomidine treated groups. Adding carprofen did not further reduce
propofol or isoflurane requirements. Dexmedetomidine treated groups had lower
postoperative pain scores than those receiving carprofen alone. Wound healing
was normal in all dogs. Urine and blood profiles remained within normal limits
in all groups. Intraoperative mean blood pressures were significantly higher in
the HDex group compared to the Carp-only group. Heart rates were significantly
lower in the dexmedetomidine containing groups.
Conclusions: Dexmedetomidine and carprofen preoperatively, alone or in combination,
were safe and effective in dogs anesthetized with propofol-isoflurane for
routine spay/neuter.
Cardiovascular and Sedation Parameters During
Dexmedetomidine and Atropine Administration
Congdon J#, Marquez M,
Niyom S, Boscan P.
College of Veterinary Medicine and Biomedical Sciences,
Colorado State University, Fort Collins, CO, USA
Introduction: This study measured cardiovascular and sedation variables during intramuscular administration of dexmedetomidine or dexmedetomidine with atropine in dogs. Cardiac output during dexmedetomidine sedation with concurrent atropine use has not been previously reported.
Methods: Five adult Walker Hounds received a dorsal pedal artery and lateral saphenous intravenous catheters. All dogs received either dexmedetomidine 10 μg/kg IM (DM) +/- atropine 0.02mg/kg IM (DM-At). Cardiac output (CO), mean arterial blood pressure (MAP), heart rate (HR), respiratory rate (RR), temperature and sedation score (SS) were measured before drug administration (‘baseline’), 5, 15, 30 and 60 minutes later. Data were analyzed with a multivariable linear regression model for repeated measures.
Results: CO
decreased from baseline 5.07±1.0 to 2.1±0.9 L/min at 15 minutes, then plateaued
to 60 minutes. However, CO was not different between DM and DM-At groups
(p=0.29). MAP was higher in the DmAt
group over 60 minutes (p<0.0001); increasing from 102.8±17.1 to 179.8±48.7
mmHg in 30 minutes. MAP in the Dm group
did not change over time (p=0.39). HR
was higher in the DmAt group over 60 minutes (p<0.01). Mean HR in the DmAt group was 96.3 beats/min
(range: 69.6-122.4). HR in the DM group
decreased from 110±14.2 to 49.4±10.4 beats/min at 15 min, then plateaued to 60
minutes. Arrhythmias in the DmAt group
included AV block, VPCs and Bigeminy.
Conclusions: CO decreased after dexmedetomidine independently of atropine administration. Use of atropine with dexmedetomidine at 10 mcg/kg significantly increases arterial blood pressure and HR. Use of atropine with dexmedetomidine 10 μg/kg IM is not recommended.
Cardiovascular Parameters During
Dexmedtomidine Infusion UNDER PROPOFOL-Isoflurane Anesthesia in Dogs
Congdon J#, Marquez M, Niyom S, Boscan P
College of Veterinary Medicine and Biomedical Sciences, Colorado
State University, Fort Collins, CO, USA
Introduction: The
study evaluated the cardiovascular effects of a continuous infusion of
dexmedetomidine during anesthesia.
Methods: Five
adult Walker Hound dogs were sedated with dexmedetomidine 10 μg/kg IM an
average of 78 ±2.3 min before general anesthesia. Anesthesia was induced with propofol (2.49 ±
0.5 mg/kg) and maintained with isoflurane (1.5 %). Thirty minutes into
anesthesia dexmedetomidine 0.5 μg/kg IV was administered over 5 minutes
followed by a constant rate infusion of 0.5 μg/kg/h. Cardiac output, heart
rate, ECG rhythm, blood pressure and core temperature were measured before the
dexmedetomidine bolus and then 5, 30 and 60 minutes later. Data were analyzed via multiple linear
regression modeling of individual variables over time, compared to anesthetized
baseline reference. Results: Results show no statistical difference for any parameter
measured at any time. Mean baseline cardiac output was 3.11±0.9 L/min, then at
5, 30 and 60 minutes was 2.88, 3.08, 3.65 L/min, respectively. Mean baseline
heart rate was 78±18.4 beats/min then at 5, 30 and 60 minutes was 72.8, 79,
83.2 beats/min, respectively. No
arrhythmias were observed at any time. Mean baseline mean arterial blood
pressure was 95.9±10.0 mmHg, then at 5, 30 and 60 minutes was 97, 90.2, 80.2
mmHg, respectively.
Mean systolic and diastolic arterial pressure followed the same
trend as mean arterial pressure. Core
temperature was maintained between 37.2 and 38 ◦C.
Conclusions:
Dexmedetomidine infusion using a loading dose of 0.5 mg/kg IV, followed by a
constant rate infusion of 0.5 mg/kg/hr, does not cause any significant
cardiovascular changes during propofol-isoflurane anesthesia in dogs.
Effects of the non-steroidal anti-inflammatory
drug, tepoxalin and the alpha-2 adrenoceptor agonist medetomidine on
cardiovascular variables in dogs
Kushiro T#, Keegan RD, DeCourcey M, Grubb
TL, Greene SA
Department of Veterinary Clinical Sciences, College of
Veterinary Medicine, Washington State University, Pullman, WA, USA
Introduction:
Tepoxalin (TPX) is a non-steroidal anti-inflammatory drug (NSAID) that inhibits
both cyclooxygenase and lipoxygenase. NSAIDs have the potential to induce renal
injury particularly if concurrent renal compromise is present. TPX was not
associated with a decrease in renal function in dogs undergoing
propofol-isoflurane anesthesia. Medetomidine (MED) is a commonly used alpha-2
agonist that is associated with peripheral vasoconstriction, hypertension and
reduced renal blood flow.
The objective of this study was to evaluate the
cardiovascular effects of the combination of TPX and MED in dogs.
Methods: Six,
healthy dogs of either sex and weighing 14.7 ± 4.4 kg were studied. Feed but
not water was withheld for 12 hours prior to study. Each dog received four
randomized treatments with a minimum of 1 week intervals: saline control (C),
MED (750 µg/m2, IV), TPX (10 mg/kg PO for 3 days), and MT (TPX 10
mg/kg PO for 3 days plus MED 750 µg/m2, IV). Rectal temperature,
heart rate, respiratory rate, and direct arterial blood pressure (ABP) were
recorded at baseline and at 5, 10, 15, 20, 60, 120, 240, 360 minutes. Data were
analyzed using repeated-measures ANOVA and a Bonferoni post hoc test with
significance set at P<0.05.
Results: Heart
rate was significantly lower in the MED and MT groups than in C or TPX. Mean
ABP was significantly higher with MT compared to TPX.
Conclusions: We
conclude that MT increased ABP compared to TPX alone and that TPX was not
associated with any adverse effects at these doses in healthy dogs.
DURATION OF
RECOVERY FROM ANESTHESIA IS NOT DIFFERENT BETWEEN ISOFLURANE AND SEVOFLURANE
FOLLOWING PROLONGED CLINICAL ANESTHESIA IN DOGS
Guedes A, Land S, Lepiz M
College of
Veterinary Medicine & Biomedical Sciences, Texas A&M University,
College Station, TX, USA
Introduction: Experimental studies in dogs have shown faster anesthetic recoveries
after sevoflurane than isoflurane but clinical data is not readily available,
especially following prolonged anesthesia.
Methods: This retrospective clinical study compared the duration of recovery
from prolonged anesthesia in dogs undergoing tibial plateau leveling osteotomy.
Anesthetic records of 162 adult dogs anesthetized from September 2006 to April
2009 at the Veterinary Medical Center of Texas A&M University were
evaluated for duration of anesthesia, time from end of anesthesia to tracheal
extubation, body temperature at end of anesthesia and at tracheal extubation,
drugs used for premedication, induction of anesthesia and intra-operatively,
and subjective pain scores in the immediate recovery period. Data were analyzed
with t-tests or Chi-square with P<0.05 considered significant.
Results: One hundred dogs were anesthetized with isoflurane and 62 with
sevoflurane. Mean±SD duration of anesthesia (269±58 and 282±54 minutes), time
to tracheal extubation (24.7±22 and 20.2±20 minutes), body temperatures at end
of anesthesia (36.7±1°C and 36.8±1°C) and at tracheal extubation (36.8±1°C and
36.8±1°C) were similar between isoflurane and sevoflurane, respectively. Most
dogs anesthetized with isoflurane or sevoflurane, respectively, were
premedicated with glycopyrrolate and hydromorphone (56 and 53%) or
glycopyrrolate, hydromorphone and acepromazine (34 and 25%) subcutaneously,
induced with propofol (90 and 86%) intravenously and received morphine alone or
morphine with bupivacaine epidurally. No differences were detected for any of
these variables. Pain scores in the immediate recovery period were similar
between the two groups.
Conclusions: Duration of anesthetic recovery is not different between isoflurane
and sevoflurane following prolonged clinical anesthesia in dogs.
EFFECT OF
DURATION USING ISOFLURANE AND DESFLURANE ANESTHESIA ON TEAR PRODUCTION IN DOGS
Shepard MK, Accola
P, Lopez LA, Shaughnessy MR, Hofmeister EH
College of
Veterinary Medicine, University of Georgia, Athens, GA, USA
Introduction: General anesthesia has been implicated in decreased post-operative
tear production in dogs. A strong relationship between inhalant general
anesthetics and post-operative tear production has yet to be established in the
absence of injectable drugs. This randomized, blinded crossover study compared
the effect of inhalant anesthetic type and duration on perianesthetic aqueous
tear production in dogs.
Methods: Eight healthy beagle dogs were randomly placed in one of four groups
in a Latin square design: one hour isoflurane, one hour desflurane, four hour
isoflurane, and four hour desflurane. Each dog was anesthetized four times,
separated by one week, and tear production was measured by Schirmer tear test
at baseline (preanesthetic), at 10, 30, 60, 120, 180, and 240 minutes after
induction, immediately on recovery and at 2 hours, 10 hours and 22 hours after
anesthesia. A two-way repeated measures ANOVA was used to evaluate tear
production postoperatively.
Results: Aqueous tear production was significantly reduced in dogs during
anesthesia (p<0.0001), and tear production returned to baseline levels
immediately on recovery for all treatment groups. Additionally, tear production
remained normal in dogs through 10 hours post-anesthesia. No difference was
observed between different inhalant type (p=0.1457) or duration (p=0.5375)
groups. Neither lateral recumbency (left versus right) nor left versus right
eyes were significantly different (p=0.4063, p=0.7357, respectively).
Conclusions: This study suggests that inhalant anesthetics alone do not play a part
in reducing post-anesthetic tear production. Other agents, such as injectable
anesthetics and other perioperative drugs should be investigated as potential
causes of this perioperative complication.
THE EFFECTS OF
EXTUBATION WITH AN INFLATED VERSUS DEFLATED ENDOTRACHEAL TUBE CUFF ON
ENDOTRACHEAL FLUID VOLUME IN THE DOG
Farmer A, Hofmeister
EH, Laas C, Williams J
College of Veterinary Medicine, University of Georgia, Athens, GA, USA
Introduction: During extubation, the ETT cuff is routinely deflated before removal
in order to reduce trauma to the trachea and the larynx. If there is concern
about fluid remaining in the trachea, the ETT is sometimes removed with the
cuff partially inflated to remove excess fluid. The purpose of this study was
to investigate the effect of extubation with the ETT cuff inflated versus
deflated on endotracheal fluid volume in normal canine cadavers.
Methods: Sixteen cadavers were orotracheally intubated in lateral recumbency,
and the ETT cuffs were inflated before barium was introduced orad to the cuff.
The dogs were randomly assigned to an ETT cuff extubation condition of deflated
or inflated. After extubation, lateral thoracic radiographs were obtained and
scored by 3 independent blinded reviewers. Each reviewer ordered all 16 lateral
radiographs from most to least intratracheal contrast and estimated residual
intratracheal contrast volume. All cadavers were used once and the larynx was
not evaluated after extubation.
Results: Dogs extubated with a deflated ETT cuff had a median rank of 13 and
dogs extubated with an inflated ETT cuff had a median rank of 4.5
(P<0.0001). Dogs extubated with a deflated ETT cuff had a mean estimated
intratracheal volume of fluid of 1.8 mL and dogs extubated with an inflated ETT
cuff had a volume of 0.9 mL (P<0.0001). Fleiss Kappa for agreement among
evaluators was 0.875.
Conclusions: Extubation with the cuff inflated removed more liquid contents from
the trachea than extubation with the cuff deflated and may assist in the
prevention of pulmonary aspiration.
Maropitant, a NK-1 antagonist decreases the
sevoflurane MAC during visceral stimulation in dogs
Boscan P1, Monnet E1, Mama K1,
Twedt DC1, Congdon J1, Steffey EP2
1Department of Clinical Sciences, Veterinary
Teaching Hospital, Colorado State University, Fort Collins, CO, USA; 2School
of Veterinary Medicine, University of California, Davis, CA, USA
Introduction:
Maropitant is a neurokinin 1 receptor (NK-1) antagonist drug used for its
antiemetic properties in dogs. NK-1 receptors are the main target for substance
P (SP) neurotransmission and both are implicated in pain pathways. In the present study, we evaluated the
sevoflurane minimum alveolar concentration (MAC) requirements when maropitant
was administered as a continuous infusion.
Methods: Eight,
one year of age, female, walker hound dogs were anesthetized with sevoflurane.
Following instrumentation and stabilization, the right ovarian ligament was
accessed using a laparoscopic approach to determine MAC when stimulating the
right ovarian ligament. The ovarian ligament was stimulated using 650-700 grams
of tension. MAC are depicted as mean ± SD, adjusted for calibration values and
to sea-level. Student’s t-test was used for comparison.
Results: The
control sevoflurane MAC for the visceral stimulus was 2.12 ± 0.4 %.
Administration of maropitant 1 mg/kg followed by 30 mg/kg/h IV decreased the
sevoflurane MAC to 1.61 ± 0.4 % (24 %, p<0.01). A higher maropitant dose of
5 mg/kg followed by 150 mg/kg/h IV decreased the MAC further to 1.48 ± 0.4 %
(30 %).
Conclusions: In
conclusion, maropitant decreases the anesthetic requirements during visceral
stimulation of the ovarian ligament in dogs. The results suggest for the first
time the use of a NK-1 receptor antagonist to manage visceral pain.
THE EFFECT OF
KETAMINE ON THE MACBAR OF SEVOFLURANE IN DOGS
Love LC#, Egger CM, Rohrbach BW, Cox SK, Hobbs M,
Doherty TJ
College of Veterinary Medicine, University of Tennessee, Knoxville, TN,
USA
Introduction: This study was designed to determine the effect of ketamine on
sevoflurane MACBAR.
Methods: In a crossover study, six dogs were anesthetized with sevoflurane on
two occasions, one week apart, and baseline MACBAR (B-MACBAR) was determined.
MACBAR was defined as the mean of the end-tidal sevoflurane concentrations
which prevented and allowed an increase (=15%) in HR or direct MAP in response
to a noxious stimulus (50V 50Hz 10msec). Dogs were then randomly given either a
low-dose (LDS) or high-dose series (HDS) of ketamine, and treatment MACBAR
(T-MACBAR) was determined during each dose in each series. The LDS consisted of
an initial loading dose (LD) of 0.5 mg/kg and CRI (6.25 µg/kg/min), followed,
after T-MACBAR determination, by a second LD (1 mg/kg) and CRI (12.5
µg/kg/min). The HDS had an initial LD (2 mg/kg) and CRI (25 µg/kg/min)
followed, after T-MACBAR determination, by a second LD (3 mg/kg) and CRI (50
µg/kg/min). Data were analyzed with a mixed-model ANOVA and are presented as
LSM ± SEM.
Results: The B-MACBAR (2.8 ± 0.22) did not differ between treatments (p=0.05).
No decrease (p=0.05) in B-MACBAR occurred with ketamine at 6.25 and 50 µg/kg/min;
however, the remaining treatments decreased (p=0.05) B-MACBAR, and the maximal
decrease (22%) was affected at 12.5µg/kg/min. The percentage MACBAR decrease
was not correlated (r=0.03, p=0.85) with the log plasma ketamine concentration.
Conclusions: Ketamine (12.5 and 25 µg/kg/min) decreased (p=0.05) sevoflurane
MACBAR, although the reduction was not dose-dependent, and was less than
expected considering the effect of ketamine on sevoflurane MAC.
ORAL
TRANSMUCOSAL BUPRENORPHINE PREMEDICATION IS EFFECTIVE FOR POSTOPERATIVE PAIN
MANAGEMENT IN DOGS UNDERGOING OVARIOHYSTERECTOMY
Ko JC1, Barletta M#1, Johnson BM1,
Freeman LJ1, Payton MA2, Weil AB1, Inoue T1
1Department of Veterinary Clinical Sciences, School of Veterinary
Medicine, Purdue University, West Lafayette, IN, USA; 2Department of
Statistics, Oklahoma State University, Stillwater, OK, USA
Introduction: High bioavailability (~47%) of 20 and 120 µg/kg oral transmucosal
(OTM) buprenorphine (Bup) in dogs has been previously demonstrated in our
laboratory. This prospective, randomized, blinded study was designed to compare
the efficacy of using two doses of OTM and a single IV dose of buprenorphine as
a sole agent for postoperative pain management in dogs undergoing routine
ovariohysterectomy (OHE).
Methods: Eighteen healthy mixed-breed dogs were randomly and equally assigned
to either 20µg/kg IV (IV20), 20µg/kg OTM (OTM20) or 120µg/kg OTM (OTM120)
buprenorphine administered immediately prior to propofol induction and followed
with isoflurane maintenance for OHE. Surgery was performed by a single surgeon
with total anesthesia duration approximate 50 minutes. Postoperative pain was
assessed using a dynamic interactive pain scale for 24 hours. The dog was
administered analgesics if the postoperative pain exceeded a predetermined
threshold. Data were analyzed using ANOVA with significance set at P< 0.05.
Results: There were no significant differences in body weights, anesthesia
duration, propofol dose, isoflurane maintenance concentrations and
cardiorespiratory parameters between treatment groups. There was a trend of
statistical significance in fewer dogs in the OTM 120 group (16%, 1/6) required
rescue, compared to the IV20 (50%, 3/6) and OTM20 (83%, 5/6) groups (p= 0.057).
The analgesic durations were 20.3 ± 3.7, 16.0 ± 3.8, and 7.3± 3.3 hours for
each treatment group (p= 0.066), respectively.
Conclusions: We concluded that buprenorphine 120 µg/kg OTM administered immediately
prior to induction was an acceptable option for postoperative pain management
following OHE in dogs.
DEVELOPMENT OF
SUSTAINED RELEASE BUPRENORPHINE FORMULATIONS FOR DOGS
Egger CM1, Qu W2, XU J2, Johnson
J2, Shukla A2
1Department of Small Animal Clinical Sciences, College of Veterinary
Medicine, University of Tennessee, Knoxville, TN, USA; 2College of
Pharmacy, University of Tennessee, Memphis, TN, USA
Introduction: The objective was to develop formulations of buprenorphine (BUP) that
maintain plasma concentrations > 1 ng/mL for 3-7 days following a
subcutaneous injection.
Methods: Seven mixed breed, male dogs (1-2 years old; 15-18 kg) were used. BUP
was injected IV (0.1 mg/kg) to determine the PK parameters for each dog.
Solutions of BUP prepared with triethyl citrate (TEC) (n=3), acetyltriethyl
citrate (ATEC) (n=2) or acetyltribuyl citrate (ATBC)(n=2) were administered SQ
at 1.5 mg/kg. Solutions prepared with tribuyl citrate (TBC) were administered
SQ at 0.35 mg/kg (n=3) or 0.7 mg/kg BUP (n=4). Plasma samples for BUP analysis
were collected at 0, 0.5, 1, 2, 4, 6, 8, and 12 hours, then every 12 hours
thereafter.
Results: With BUP solutions prepared with TEC, ATEC, or ATBC, plasma
concentrations were > 1 ng/mL for 5.5, 3, and 7 days, respectively.
Solutions containing TBC maintained plasma concentrations > 1 ng/mL for 4
(0.35 mg/kg) or 5 (0.7 mg/kg) days. Cmax was 21.9 ng/mL at 24 hours (TEC), 78.1
ng/mL at 6 hours (ATEC), and 20 ng/mL at 12 hours (ATBC). The Cmax was 4.93
ng/mL and 12.33 ng/mL at 24 hours for TBC at 0.35 and 0.7 mg/kg, respectively.
Dogs receiving BUP in TEC, ATBC and ATEC became hypoxemic and hypercarbic. All
dogs had a significant decrease in HR, RR, and MAP. Inappetance and mild
sedation were noted.
Conclusions: BUP base in TBC maintained plasma concentrations of buprenorphine >
1 ng/mL for at least 4 days after injection, without significant respiratory
depression.
EFFECT OF 6%
HETASTARCH OR LRS ON HEMOSTATIC VARIABLES IN DOGS UNDERGOING STIFLE ARTHROSCOPY
Chohan AS#, Greene SA, Grubb TL, Keegan RD, Wills TB,
Martinez SA
College of
Veterinary Medicine, Dept of Clinical Veterinary Sciences, Washington State
University, Pullman, WA, USA
Introduction: Hetastarch is used in small animals to provide rapid plasma volume
expansion and oncotic pressure support but may affect hemostasis. This
randomized, blinded, study compared hemostatic variables following
administration of 6% hetastarch (HET) or LRS in dogs undergoing stifle
arthroscopy.
Methods: Fourteen dogs were randomly assigned to receive either 10 mL kg-1
intravenous (IV) bolus of 6% HET or LRS followed by maintenance infusion of LRS
(10 mL kg-1hr-1) during anesthesia. Before (Baseline) and 1 and 24 hours after
fluid bolus administration, packed cell volume (PCV), total protein
concentration (TP), prothrombin time (PT), activated partial thromboplastin
time (APTT), platelet count, platelet aggregation, colloidal oncotic pressure
(COP) and buccal mucosal bleeding time (BMBT) were measured. A board certified
orthopedic surgeon blinded to treatments assessed bleeding. Comparisons were
made using T-tests with significance set at P < 0.05
Results: The BMBT increased while platelet count decreased significantly at
1-hour post-infusion in the HET group. PCV, TP, and COP decreased significantly
in both treatment groups 1-hour post infusion but COP was significantly higher
1-hour post-infusion in the HET group compared to the LRS group. PT was
significantly increased at 24-hours post-infusion in the HET group and at
1-hour post-infusion in the LRS group. No significant change in APTT or
platelet aggregation was observed in either of the groups. None of the dogs had
clinically significant bleeding.
Conclusions: Whilst both HET and LRS altered hemostatic variables in these dogs
undergoing arthroscopy the effect of HET was more profound. However, these
changes were not associated with increased clinical bleeding.
THE EFFECTS OF
ACEPROMAZINE UPON ADENOSINE DIPHOSPHATE- AND ARACHIDONIC ACID-MEDIATED PLATELET
ACTIVATION IN HEALTHY DOGS
Conner B*, Hanel R,
Swanson C
College of Veterinary Medicine, North Caroline State University, Raleigh,
NC, USA
Introduction: The purpose of the present study was to evaluate the effect of
intravenous acepromazine upon platelet function in healthy dogs using TEG®
Platelet MappingTM. Adenosine diphosphate (ADP) and arachidonic acid (AA) are
two known activators of platelets. Previous reports have suggested that
acepromazine may alter platelet function via inhibition of pathways involving
these mediators.
Methods: Six healthy mixed breed dogs received either 0.9% saline (1-2mL, IV)
or acepromazine (0.05mg/kg, IV and 0.1mg/kg, IV) in a randomized crossover
study. Blood samples were collected via jugular venipuncture from each dog at
time 0, 30min, and 240min. A platelet mapping assay, consisting of standard
thrombin-based thromboelastography (TEG), ADP-activated TEG, and AA-activated
TEG, was performed at each time point. A minimum 3-day washout period occurred
between treatment days. The role of platelet activation in clot formation was
evaluated using the MA of ADP- and AA-activated samples expressed as a percentage
of their paired, thrombin-activated TEG MA within each treatment group over
time. MA ratio data were analyzed using two-way repeated measures ANOVA with
significance accepted at p <0.05.
Results: There were no significant differences in thrombin-activated and ADP-
or AA-activated MA ratios between treatment groups.
Conclusions: Platelet activation as assessed using TEG® Platelet MappingTM was not
inhibited by acepromazine at test dosages.
Abstracts, Room 2
ANALGESIC ROLE
OF TRAMADOL AND KETAMINE IN HORSES WITH LAMINITIS-ASSOCIATED PAIN
Guedes A1, Matthews N1, Hood D2
1College of Veterinary Medicine & Biomedical Sciences, Texas A&M
University, College Station, TX, USA; 2Hoof Diagnostic and
Rehabilitation Clinic, Texas A&M University, College Station, TX, USA.
Introduction: Chronic laminitis-associated pain is common in horses and is often
poorly responsive to analgesics. This study investigated whether multimodal
therapy with tramadol and ketamine improve analgesia in horses with chronic
laminitis-associated pain.
Methods: Ten client-owned horses with naturally occurring chronic laminitis
were studied in a prospective, randomized, crossover design. Horses received
oral tramadol at 5 mg/kg twice a day for a period of 7 days or tramadol (as
above) plus intravenous ketamine during the first three days. Ketamine was
given at 0.6 mg/kg/h during six hours each day. Non-invasive mean arterial
blood pressure, heart and respiratory rates, intestinal sounds and forelimb
off-loading frequency (determined via force plate system) were assessed
immediately before drug administration, six hours after the start of drug
administration for the first three days, and every 24 hours thereafter. Data
were analyzed with repeated measures ANOVA, followed by Tukey-Kramer
multiple-comparison test with P<0.05 considered significant.
Results: After tramadol alone or with ketamine, respectively, forelimb
off-loading frequency decreased significantly from baseline (20.9±13.5 and
21.5±7.6) during therapy (14.1±2.2 and 15.4±1.5), and remained lower (13.8±0.6
and 15.3±0.7) during three days after discontinuation of therapy. Mean arterial
pressure also decreased significantly from baseline (98.3±26 and 90±18mmHg)
during therapy (84.6±4 and 83.8±2mmHg), and remained lower (78±2 and 83.6±3mmHg)
after therapy was discontinued. Heart rate decreased only when the horses
received ketamine, whereas respiratory rates and intestinal sounds did not
change.
Conclusions: In conclusion, enhanced pain relief in horses with naturally occurring
laminitis can be obtained through a multimodal analgesic approach using
ketamine and tramadol.
THE
PHARMACOKINETICS OF INTRAVENOUS AND SUBLINGUAL BUPRENORPHINE IN HORSES
Messenger KM#, Davis JL,
Barlow BM, LaFevers DH, Posner LP
College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
Introduction: There are limited analgesic options for the treatment of acute, severe
pain in horses. Buprenorphine is a potent, long-acting mu opioid agonist that
has been used to treat moderate to severe pain in several species. The purpose
of this study was to describe the pharmacokinetics and adverse effects of
intravenous (IV) and sublingual (SL) buprenorphine in horses.
Methods: Five healthy adult horses were administered a single intravenous or
sublingual dose of buprenorphine (0.006 mg/kg) in a randomized, crossover
experiment with at least a 1 week wash-out period between routes of
administration. Blood samples were collected immediately prior to drug
administration and at pre-determined intervals over a 24-hour period. At each
sampling period, horses were assessed for excitement and gastrointestinal
motility. Plasma buprenorphine concentrations were measured using ultra
performance liquid chromatography with mass spectrometry. Pharmacokinetic data
was analyzed using a noncompartmental model.
Results: After IV and SL administration mean +/- SD half- life was 6.05 +/-
1.46 and 3.88 +/- 2.34 h, respectively. Sublingual peak concentration (Cmax)
was 8.77 +/- 3.19 ng/mL and occurred in 0.72 +/- 0.30 h (Tmax). Systemic
clearance (Cl) following IV administration was 6.13 +/-0.86 mL/kg/min and
volume of distribution at steady-state was 3.16 +/- 0.65 L/kg. Mean +/- SD
bioavailability of sublingual buprenorphine was 138 +/- 72 %. Following IV
administration, horses showed signs of excitement. Gastrointestinal sounds were
decreased in both groups, however none of the horses exhibited signs of colic.
Conclusions: In horses buprenorphine has a long half-life and has complete
absorption via the sublingual route.
COMPARISON OF
CARDIOVASCULAR FUNCTION AND QUALITY OF RECOVERY IN ISOFLURANE-ANAESTHETIZED
HORSES ADMINISTERED A CONSTANT RATE INFUSION (CRI) OF LIDOCAINE OR LIDOCAINE
AND MEDETOMIDINE DURING ARTHROSCOPIC SURGERY
Valverde A, Sinclair
M, Rickey E, Rioja E, Hathaway A, Cruz A
Ontario Veterinary
College, University of Guelph, Guelph, ON, Canada.
Introduction: Lidocaine (L) and medetomidine (M) CRI are adjuncts to equine inhalant
anaesthesia. Our goals were to assess the effects of L alone or LM on cardiovascular
function and recovery.
Methods: Twelve horses (3-10 y.o.; 382-558 kg; 4 geldings, 8 females)
anesthetized with (IV) xylazine 1 mg.kg-1, diazepam 0.02 mg.kg-1, ketamine 2
mg.kg-1 and maintained on 1.1% ETIso and 35-45 mmHg ETCO2 with IPPV were randomly
allocated to: 1) L-group- 2 mg.kg-1 IV bolus and CRI of 50 µg.kg-1.min-1 IV, or
2) LM-group- same as L-group and M (5 µg.kg-1.h-1 IV). The CRI’s were started
30-min after induction. Lidocaine was interrupted 30-mins before the end of
surgery, whereas M, or a placebo CRI in the L-group was maintained until the
end. HR, MAP, CI, electrocardiogram, and blood gases were recorded at 29,60,90,
and 120 min post-induction by a blinded investigator that also assessed quality
of recovery using a numerical/descriptive score. A generalized mixed linear
model was used for cardiorespiratory data and a paired t-test for recovery
scores (P < 0.05).
Results: Anesthesia time was similar: LM-171±29 min and L-190±49 min. The
LM-group had better quality of recovery although recoveries were longer
(54±10.9 min versus 22±3.9 min). HR, CI and blood gases were similar between
the two groups (mean values; HR [beats.min-1], L: 28-32; LM: 31-33; CI
[mL.kg-1.min-1], L: 53-56, LM: 53-56). Blood pressure was significantly higher
in the LM-group (MAP [mmHg], L: 77-95, LM: 96-101).
Conclusions: Stable cardiovascular function was present with both; however LM
improved the quality of recovery compared to L.
DANTROLENE
SODIUM PREVENTS MYOPATHY IN HORSES UNDERGOING HYPOTENSIVE ANESTHESIA
McKenzie EC, Mosley CA
College of Veterinary Medicine, Oregon State University, Corvallis, OR,
USA
Introduction: It was hypothesized that dantrolene would prevent muscle damage in
healthy horses undergoing hypotensive anesthesia.
Methods: Seven horses were anesthetized twice, 60 minutes after receiving
dantrolene (6 mg/kg in 2L of water) via nasogastric tube and after receiving
water alone. Isoflurane anesthesia was maintained for ~90 minutes on an
unpadded recovery room floor. The
vaporizer setting was adjusted to maintain hypotension (50-55 mmHg). Blood pressure was recorded every 5 minutes
and plasma [dantrolene] was measured by HPLC every 10 minutes from 40 to 160
minutes after administration. Serum CK was measured before and 4, 8, 12 and 24h
after anesthesia. Data were analyzed via repeated measures ANOVA.
Results: Serum CK activity was significantly higher and above reference range
when horses received the placebo versus dantrolene at 4h (1666 ± 619 vs. 456 ±
78 U/L; p=0.005), 8h (1601 ± 545 vs. 422 ± 44, p=0.0076) and 12h (1393 ± 451
vs. 443 ± 49, p=0.0227) after anesthesia. Total recumbency time did not differ
between placebo and dantrolene treatments (136 ± 11.6 and 138 ± 15.9 minutes,
respectively, p=0.69) nor did recovery duration (42 ± 4 vs. 47 ± 7 minutes,
respectively, p=0.12). Mean arterial pressure ranged from 51 ± 2.2 to 63.3 ±
3.8 mmHg during anesthesia with the placebo, and from 49 ± 3.0 to 60.5 ± 4.3
mmHg with dantrolene and was not different between the treatments at any time
point. Blood [dantrolene] peaked at ~330 ng/ml at 100 minutes after
administration.
Conclusions: Dantrolene sodium (6 mg/kg enterally) 60 minutes prior to hypotensive
general anesthesia appeared to prevent muscle damage in horses without
prolonging recovery time.
COMPARISON
OF THE EFFECTS OF ALPHA-2-AGONISTS ROMIFIDINE AND XYLAZINE ON QUALITY OF
RECOVERY FROM GENERAL ANESTHESIA IN HORSES
Robinson
KJ#1, Brosnan RJ2, Nguyen K3, Galuppo L2,
Moniz G1,Willits N4
1Veterinary
Medical Teaching Hospital, University of California; 2Department of
Surgical and Radiological Sciences, University of California; 3Department
of Clinical Pharmacy, University of California San Francisco, CA, USA; 4Department
of Statistics, University of California, Davis, CA, USA.
Introduction:
During recovery horses can experience excitement and uncoordinated attempts
to stand that can lead to injury. Romifidine is approximately ten times more
potent than xylazine, has a longer duration of action and reportedly produces
less ataxia. We hypothesized that sedation with romifidine will produce better
recoveries than sedation with xylazine and there will be a dose effect on
recovery quality.
Methods: One hundred and one horses
presenting to the University of California Davis VMTH were enrolled. Patients
were American Society of Anesthesiologists physical status I or II, 2 years or
older and 350-700kg. The anesthetic protocol and monitoring were
standardized. Excluded procedures
involved surgery of the head or eye, myelography, midline-laparotomy, or long
bone fractures. Horses receiving any intraoperative opiates or ketamine within
the last 30 minutes of anesthesia were excluded. For recovery, horses were
randomly allocated to receive xylazine 0.1mg/kg IV (25), xylazine 0.2mg/kg IV
(25), romifidine 0.01mg/kg IV (26) or romifidine 0.02mg/kg IV (25). Treatment
was administered at the time of first spontaneous breath. Time to first
movement, head lift, sternal recumbency, standing and extubation were recorded.
The number of attempts to sternal and stand, and the degree of ataxia and
injury after standing were assessed. Recoveries were videotaped and assessed
independently by one blinded scorer using a visual analogue score (VAS).
Results: Preliminary statistical
analysis by linear regression suggests high dose romifidine is a positive
predictor for VAS. Long anesthetic time, surgery and certain breeds are
negative predictors of recovery quality.
Conclusions: Higher dose romifidine
improves recovery quality in horses.
ELECTROLYTE
ABNORMALITIES IN MARES PRESENTING FOR DYSTOCIA BIRTH
Bidwell LA, Bone NL, Steele RD
Rood and Riddle
Equine Hospital, Lexington, KY, USA.
Introduction: Understanding the electrolyte status of mares presenting for dystocia birth can give the anesthetist insight when selecting protocols. The purpose of this study was to evaluate the levels of ionized calcium, magnesium and potassium in mares that presented for dystocia birth at a private referral practice in Lexington, Kentucky during a single breeding season.
Methods: Pre-anesthetic venous blood and intra-operative arterial samples were drawn from 28 Thoroughbred mares presenting for dystocia birth. Venous blood was evaluated for magnesium levels. An arterial blood sample was used to determine ionized calcium and potassium levels with a laboratory reference range of calcium at 1.4-1.74 mmol/L, potassium at 3.4-5.2 mmol/L and magnesium at 1.8-2.3 mEq/L.
Results: Of the 28 mares, 22 of the foals were delivered by controlled vaginal delivery and 6 by cesarean section. Statistical analysis was done using one sample t-test with a sensitivity of P<0.05. In mares that underwent controlled vaginal delivery, the average ionized calcium level was 1.26 mmol/L, the average potassium level was 3.63 mmol/L and magnesium was 1.97 mEq/L. Results from mares that underwent cesarean section delivery resulted in an average ionized calcium level of 1.205 mmol/L, potassium of 3.448 mmol/L and magnesium of 2.09 mEq/L.
Conclusion: Potassium levels and magnesium levels were
within normal limits for mares undergoing controlled vaginal delivery or
cesarean section, calcium levels were significantly lower than the median
laboratory reference range in both situations.
Therefore, the inclusion of calcium in the anesthetic protocol is
recommended
A dog model to study MAC during visceral
stimulation of the ovarian ligament
Boscan P1, Monnet E1, Mama K1,
Twedt DC1, Congdon J1, Steffey EP2
1College of Veterinary Medicine and Biomedical
Sciences, Colorado State University, Fort Collins, CO, USA; 2School
of Veterinary Medicine, University of California, Davis, CA, USA
Introduction: A
canine model was developed to evaluate the anesthetic minimum alveolar
concentration (MAC) during visceral stimulation. The stimulus consisted of
ovarian ligament traction to imitate spay surgeries.
Methods: Twelve,
one year old, female walker hounds were anesthetized with sevoflurane.
Following stabilization, the right ovarian ligament was accessed using a
laparoscopic approach with three 5 mm cannulas. A 2-0 suture was placed around
the ovarian ligament and exteriorized through the abdominal wall. The abdomen
was deflated for the study. A stimulus–response curve was created for the
visceral stimulus in 3 dogs with 200, 400, 800, 1200 and 1600 grams. The
ovarian ligament MAC using a force transducer (600-750 grams) was compared to
the tail clamp technique using carmalt forceps before and after laparoscopy in
9 dogs. MAC is depicted as mean ± SD, adjusted for calibration values and to
sea-level. Student’s t-test was used for comparison.
Results: The
stimulus-response curve MAC ranged between 1.59-3.11% with a hyperbolic
presentation. The tail clamp MAC before laparoscopy was 1.86 ± 0.28 %. The
visceral stimulus MAC was 2.16 ± 0.46 %, which was no different to the tail
clamp MAC (p>0.05). At the end of the study, the tail clamp MAC was 1.77 ±
0.38 %, which was no different to initial tail clamp or ovarian stimulation MAC
(p>0.05). Dogs recovered from anesthesia without complications.
Conclusions: The
ovarian ligament stimulation model appears to be an adequate and repeatable
means of producing visceral stimulation to determine MAC in dogs.
ANALGESIC
EFFECT OF BUPIVACAINE ELUTING PORCINE SMALL INTESTINAL SUBMUCOSA (SIS) IN A
FERRET ACUTE ABDOMINAL HERNIA DEFECT MODEL
Johnson BM*1, Ko JC1, Lantz GC1, Hall P2,
Saunders S2, Weil AB1, Inoue T1
1Department of Veterinary Clinical Sciences, School of Veterinary
Medicine, Purdue University, West Lafayette, IN, USA 2Cook Biotech
Introduction: Porcine small intestinal submucosa (SIS) is used as a biological graft
for abdominal wall hernia repair to facilitate wound healing and increase local
tissue strength. This prospective, randomized, double blinded study evaluated
efficacy and duration of analgesia using bupivacaine adsorbed to SIS for repair
of acutely created abdominal wall full thickness muscle/fascial defects in
ferrets.
Methods: Eighteen one year old, healthy male ferrets were assigned to three
groups: 1) SIS with bupivacaine subjected to surgery, 2) SIS with no
bupivacaine subjected to surgery, and 3) anesthesia only control group. Ferrets
in groups 1 and 2 were anesthetized with butorphanol and sevoflurane for
creation and repair of the abdominal body wall defect with SIS. Control ferrets
were anesthetized in the same fashion without surgery. Behavior and pain were
evaluated using a visual analogue scale, heart and respiratory rates, algometer
and palpometer measurements at various hour intervals for 96 hours after
surgery. When pain reached a predetermined threshold, buprenorphine was used as
a rescue analgesic. Plasma concentration of bupivacaine was analyzed using
LC-MS/MS. Data was analyzed using Repeated Measures ANOVA and Kaplan-Meier
Survival Analysis with p<0.05.
Results: While there was no statistical significance between groups with HR,
RR, algometer and palpometer values, there was a clinical physiologic
difference in these values. All ferrets in SIS alone group were rescued while
33% of the SIS-bupivacaine group were rescued (p<0.01). Peak plasma
bupivacaine concentrations was 1.2 µg/mL.
Conclusions: Bupivacaine adsorbed to SIS provided pain relief with no side effects
observed in this ferret abdominal wall defect model.
Correlation between invasive and non-invasive arterial
blood pressure in chickens (Gallus gallus) under normotension, hypotension and hypertension
Costa A,
Moraes AN, Beier SL, Rosa AC, Oleskovicz N
School
of Veterinary Medicine, Santa Catarina State University – UDESC, Lages, Brazil.
Introduction: Blood pressure measurement has been increasingly
used in avian medicine, being the non-invasive method the most frequently used.
The goal of this study was to evaluate the reliability of the doppler in
normotensive, hypotensive and hypertensive chickens.
Methods:
Fourteen adult domestic fowls weighing 1,557±443 grams. The doppler was placed
on the cranial tibial artery for non-invasive arterial pressure (NIP). For
invasive pressure (IP), the ulnar artery with a 24G catheter was used. Normotension was evaluated first, followed by
hypotension, which was induced with increasing expired
concentration of isoflurane, followed by
hypertension obtained with use of intravenous epinephrine 0,1mg/kg in the ulnar
vein. The means of NIP were compared to IP using t-test
(α=95%).
Results: The values for systolic (SAP), mean (MAP) and
diastolic arterial pressures (DAP) using the invasive method were: 101±6; 90±5;
80±9 mmHg in the normotension; 60±4; 48±6; 40±8 mmHg in the hypotension, and
138±21; 126±18; 121±14 mmHg in the hypertension. During normotension the NIP
was 91±9, being lower than of SAP (p= 0.002), and
equal to MAP (p=
0.891). During hypotension the NIP was 57 ±19, equal to SAP
(p=0.521), and different to MAP (p=0.023). Only one fowl showed an audible flow on the doppler
when during severe hypertension, and NIP was different to SAP and MAP in mild
hypertension.
Conclusion: During normotension the NIP has been associated with
MAP, and during hypotension with SAP. Severe hypertension rarely produced
audible sound. In mild hypertension had no correlation with SAP or MAP when
NIP.
Toe pinch and electrical stimulation in determining the minimum
anesthetic concentration (MAC) of isoflurane in chickens (Gallus gallus)
Costa A,
Moraes AN, Beier SL, Rosa AC, Oleskovicz N
School
of Veterinary Medicine, Santa Catarina State University – UDESC, Lages, Brazil
Introduction: Toe pinch has been the nociceptive stimulus to determine the minimum
anesthetic concentration (MAC) in birds, different from work in mammals, which
has been using the electrical stimulation, obtaining a better accuracy and
repeatability. Evaluated if the digital clamping meets the premise to be
supramaximal stimulus in determining the MAC, and the viability of electric
stimulation in the determination of MAC.
Methods: 15 adults chickens were used (Gallus
gallus). The birds were subjected to each of the
three groups at intervals of 10 days. All birds were equilibrated for 15
minutes at a fixed concentration of anesthetic before stimulation. Toe pinch
was hemostatic forceps in the distal part of the second phalanx of digit III
(P), maintained for 1 minute or positive response. Electrical stimuli were 50mA
and 50Hz, 3 simple and two continuous stimuli. The first (E1) with two aluminum
rings, one in the digit III, one in tarsometatarso. The second (E2) way was with
two hypodermic needles at 5 cm distance, transfixing the skin at the
tibiotarso. The determination of the MAC was the up-and-down method.
Significance was set at p<0.05.
Results: The MAC of isoflurane in P was 1.12 ± 0.07%, in the E1 was 0.92 ±
0.20%, and in the E2 was 1.47 ± 0,09%.
Conclusions: This study demonstrates the feasibility of using electrical stimulation
to determine the MAC in chickens. Not supramaximal, the clamping can be done at
higher intensity, leading to higher values of MAC. By providing a higher value
of CAM, the E2 is supramaximal nociceptive stimulus.
MELOXICAM
REDUCED THE MINIMUM ANESTHETIC CONCENTRATION (MAC) OF ISOFLURANE IN CHICKENS
(GALLUS GALLUS DOMESTICUS)
Costa A,
Moraes AN, Beier SL, Rosa AC, Oleskovicz N
School
of Veterinary Medicine, Santa Catarina State University – UDESC, Lages, Brazil.
Introduction: The nonsteroidal anti-inflammatory meloxicam has been safely used in
avian medicine, however its efficacy and safety during inhalation anesthesia is
still unknown. The objective of this study was to evaluate whether meloxicam
reduces the minimum alveolar concentration (MAC) of isoflurane in adult
chickens.
Methods: Thirty adult chickens (Gallus gallus) were allocated into two groups:
control group (CG/n=15) and meloxicam group (MG/n=15). Meloxicam 0.5 mg/kg was
administered intramuscularly in MG 15 minutes before induction of anesthesia,
and 55 to 65 minutes before clamping. After fifteen minutes equilibration
period, the cardiopulmonary and blood gas were measured before and after the
nociceptive stimulus. The toe pinch was used as a nociceptive stimulus and
maintained for 1 minute or until a positive response. Determination of
isoflurane MAC was the up-and-down method. Each animal is stimulated once in a
given expired concentration isoflurane (EtISO). If there is a positive
response, the next animal EtISO is increased by 10%, and if there is a negative
response, reduced by 10%. For comparison between groups, T-test was used (mean
± SD). Significance was set at p<0.05.
Results: The MAC of isoflurane in the control group was 1.12 ± 0.07% whereas in
the meloxicam group was 0.72 ± 0.07% (p <0001).
Conclusions: The treatment with meloxicam in chickens reduced the MAC of isoflurane
by 66.28%. Meloxicam apparently is not involved with hypnotic effects. It is
possible that the reduction in MAC seen is due to its analgesic properties. The
safety of meloxicam associated with inhalation anesthesia must be further
investigated in birds.
EFFECT OF
ELECTROACUPUNCTURE ON TUMOR-INDUCED NOCICEPTION AND TUMOR GROWTH IN A MOUSE
MODEL OF EXPERIMENTALLY-INDUCED OSTEOSARCOMA
Al-Gizawiy MM, Beitz AJ
College of
Veterinary Medicine, Department of Veterinary & Biomedical Sciences,
University of Minnesota, St Paul, MN, USA
Introduction: The use of electroacupuncture (EA) to study and potentially treat
osteosarcoma (OSA) is a novel concept.
Methods: 260 young adult male and female Balb-c mice received EA (4 Hz) at the
ST-36 acupoint. EA+1: once, 24 hours after tumor implantation. EA+: once weekly
for 3 weeks. EA++: twice weekly for 3 weeks, starting on day 3
post-implantation. EA+5: twice weekly for 3 weeks, starting on day 5
post-implantation. EA+7: twice weekly, starting on day 7 post-implantation.
PxEA+: 3 treatments prior to implantation. Each group was accompanied by a sham
treatment group (no current). Primary hyperalgesia was evaluated using von Frey
filaments. Spinal samples underwent avitin-biotin/DAB immunohistochemistry to
quantify c-fos expression using light microscopy. Tumor size was measured using
calipers. Tumor tissue innervation and vascularization were also analyzed using
confocal microscopy. Statistical comparisons between groups were carried out
using a Repeated Measures ANOVA (p = 0.05). Single time-point comparisons
between groups or within a group utilized a Paired Student-t test.
Results: Hyperalgesia consistently increased with tumor growth, although less
so in EA+1, EA+, EA++, EA+5 mice. Tumors in control animals showed a 49.54%
growth increase from baseline, while in mice receiving late and infrequent EA
treatments it was more than 100%. Significantly smaller tumors were noted in
mice undergoing early and frequent treatments (10.79% growth increase). With
few exceptions, there were no significant gender differences in tumor growth or
von Frey scores.
Conclusions: We conclude that the early and frequent use of EA (4Hz) at ST-36 has
inhibitory effects on nociception and tumor growth.
INFLUENCE OF
SALINE, ACEPROMAZINE OR MIDAZOLAM AS PREMEDICATION ON THE QUALITY OF INDUCTION,
RECOVERY AND OVERALL ANESTHESIA IN NEW ZEALAND WHITE RABBITS
Cremer J#, Alworth L, Harvey SB, Hofmeister E
College of
Veterinary Medicine, University of Georgia, Athens, GA, USA.
Introduction: Certain procedures in laboratory animals (i.e. blood sampling), require
short term anesthesia or sedation. Acepromazine and midazolam are commonly used
sedatives in small animals, however, their sedative effects have not been
evaluated in rabbits. The purpose of this study was to investigate the effects
of premedication with acepromazine, midazolam, or saline on sedation,
induction, and recovery in normal New Zealand White (NZW) rabbits.
Methods: Twelve adult female NZW rabbits were randomly assigned to one of three
groups in a crossover design: sterile saline 0.2ml/kg, acepromazine 1mg/kg, and
midazolam 0.5mg/kg, all given IM. Thirty minutes after premedication the
rabbits were anesthetized by mask with 5% isoflurane in 2L/min oxygen.
Induction was considered completed when the animal could be placed in lateral
recumbency. Quality of sedation, induction, recovery, and anesthesia were
evaluated using a VAS, and data were analyzed with a one-way ANOVA.
Results: No significant difference was seen in quality of sedation (mean VAS
scores: saline: 2.7+/-3.0, midazolam: 3.1+/-3.8, acepromazine: 5.8+/-3.0) and
quality of induction (saline: 4.6+/-3.9, midazolam: 5.2+/-3.0, acepromazine:
4.2+/-2.4). Induction time was similar for all three treatments (saline:
280s+/-98, midazolam: 230s+/-232, acepromazine: 264s+/-215). No difference was
seen in quality of recovery (saline: 8.0+/-1.7, midazolam: 7.0+/-2.7,
acepromazine: 8.1+/-1.2) or overall quality of anesthesia (saline: 6.8+/-2.5,
midazolam: 7.4+/-2.5, acepromazine: 7.5+/-1.1).
Conclusions: There was no effect of premedication with acepromazine or midazolam on
sedation, induction time or quality, or recovery time or quality in
laboratory-used NZW rabbits.
tHE sparing effect of ketamine ON ISOFLURANE
Minimum alveolar concentration (MAC) determination IS NOT AFFECTED BY PRIOR MAC
DETERMINATION OF ISOFLURANE ALONE in rabbits
Gianotti G#, Valverde A
Department of Clinical
Studies, Ontario Veterinary College, University of Guelph, Ontario, Canada
Introduction: Noxious stimuli can 1)
induce a hyperalgesic state making MAC determinations less accurate,
2) activate nociceptive pathways facilitating the MAC sparing effect of
analgesics.
Methods: Eight female New Zealand
rabbits randomly received two treatments (T), 5 days apart in a crossover
design. Rabbits were induced using
isoflurane in oxygen via mask. T1 consisted of a bolus and constant rate
infusion (CRI) of saline and MAC determination for isoflurane after
equilibration (1-MI) followed by a bolus (1.0 mg kg-1) and CRI of
ketamine (40 mcg kg-1 min-1) and second MAC determination
(1-MIK), followed by a third MAC determination after discontinuing the CRI for
30 min (1-MI-after). T2 consisted of the
same previous doses of ketamine for MAC determination (2-MIK) followed by a
bolus and CRI of saline and second MAC determination (2-MI-after). The noxious stimulus (50 V at 50 cycles sec-1
for 10 msec) was applied after 15 min of equilibrium using the bracket
technique. Paired t-tests were used to compare 1-MIK and
2-MIK and 1-MI-after and 2-M1-after.
Results: The 1-MI was 2.15 ± 0.09%.
Ketamine induced a significant reduction in 1-MI. There was no significant difference between
1-MIK (1.63 ± 0.07%) and 2-MIK (1.53 ± 0.22%) or between 1-MI-after (2.04 ±
0.11%) and 2-MI-after (1.94 ± 0.25%).
There were significant differences between isoflurane values after
discontinuing the ketamine CRI and 1-MI.
Conclusions: Prior MAC determination of
isoflurane alone did not affect the MAC obtained on the same or separate days
after ketamine. Both methodologies are
valid for research studies.
THERMAL THRESHOLD
TESTING FOR EVALUATION OF ANALGESICS IN RABBITS
Barter LS, Kwiatkowski AE
School of Veterinary Medicine, University of California, Davis, CA, USA
Introduction: Rabbits are common household pets and widely used in biomedical
research. Investigation into the pharmacology of analgesics is needed in this
species. For that purpose, a thermal analgesiometric device was evaluated for
use in unrestrained rabbits.
Methods: Nine adult female New Zealand white rabbits, 3.68 ± 0.10 kg, were
acclimatized to wearing the thermal threshold device in a laboratory
environment. Each rabbit received intramuscular morphine sulfate at a dose of 3
mg/kg and an equivalent volume of saline at least 7 days apart with the order
of treatment randomized. A blinded observer assessed thermal thresholds prior
to, and at 30, 60, 90, 120, 180, 240 and 300 minutes after treatment. Data were
analyzed by repeated measures ANOVA followed, where appropriate, by paired
t-tests with correction for multiple comparisons. An alpha level of 0.05 was
selected
Results: There was no significant effect of saline on thermal threshold or
temperature rise (threshold minus skin temperature) over time. Temperature rise
was significantly greater than baseline from 30 to 240 minutes after
administration of morphine. Subjectively, thermal threshold devices were well
tolerated by rabbits. Rabbits were noticeably sedated after receiving morphine
treatment.
Conclusions: Morphine at 3 mg/kg provided antinociception for approximately 3 hours
in this group of rabbits. Thermal threshold testing may be useful for
evaluation of analgesic pharmacology in rabbits.
USE OF A
MINIMUM ANESTHETIC CONCENTRATION (MAC) DEPRESSION MODEL TO STUDY THE EFFECTS OF
VARIOUS ANALGESICS IN GOLDFISH (CARASSIUS AURATUS)
Ward JL, McCartney SP, Chinnadurai SK, Posner LP
College of Veterinary Medicine, North Carolina State University, Raleigh,
NC, USA
Introduction: The objective was to assess the feasibility of a MAC depression model
to evaluate the analgesic effects of morphine, butorphanol, medetomidine, and
ketoprofen in goldfish. A prospective randomized crossover study was designed
using 44 sarasa comet goldfish.
Methods: MAC was determined by an up-down method of sequential population
sampling. Fish were anesthetized for 4 minutes with tricaine methanesulfonate
(MS-222) in concentration increments of 10 parts per million (ppm). Needle
insertion into the cervical epaxial muscles was used as a supramaximal noxious
stimulus. MAC was determined in triplicate at the beginning (MACi) and conclusion
(MACf) of the experiment (~ 60 days). For drug trials, MAC was redetermined 1
hour after administration of morphine (10, 20, 40 mg/kg IM), butorphanol (0.1,
0.2, 0.4 mg/kg IM), medetomidine (0.01, 0.015, 0.025 mg/kg IM), ketoprofen
(0.5, 1.0, 2.0 mg/kg IM), or saline control. Each drug/dose was tested in
random order with > 6 day washout period. Differences between groups were
tested with 2 tailed t-test.
Results: MACi and MACf differed at 163 (+/-7.5) and 183 (+/- 7.5) ppm,
respectively (p=0.02). All doses of morphine and ketoprofen decreased MAC below
MACi. The highest dose of medetomidine decreased MAC below MACi. The lowest
dose of butorphanol decreased MAC to below MACi, but higher doses increased MAC
above MACf.
Conclusions: MAC determination in fish using MS-222 was feasible and reproducible
in the short term. Increased MAC over time and/or exposure may limit the
usefulness of MS-222 in MAC depression studies. Morphine and ketoprofen likely
provide analgesia in goldfish.