Objective—To compare effects of electroacupuncture
and butorphanol on hemodynamic and respiratory
variables and rectal analgesia in mares after controlled
Animals—8 healthy mares.
Procedure—Each horse received saline (0.9% NaCl)
solution (0.01 mL/kg, IV; control treatment), butorphanol
tartrate (0.1 mg/kg, IV), or 2 hours of electroacupuncture
(EA) at acupoints Bladder 21, 25, and
27 on both sides of the vertebral column, Bai hui, and
Stomach 36 (right side only). Order of treatments in
each mare was randomized. At least 7 days elapsed
between treatments. A balloon was inserted in the
rectum of each mare, and controlled distention of the
balloon (pressures of ≤ 220 mm Hg) was used to measure
nociceptive rectal pain threshold. Rectal temperature
and cardiovascular and respiratory variables
were measured before (baseline) and 5, 15, 30, 60, 90,
and 120 minutes after onset of each treatment.
Results—Butorphanol produced greater increases in
rectal pain threshold, compared with EA (mean ± SD,
214 ± 24 vs 174 ± 35 mm Hg of balloon pressure).
Electroacupuncture produced minimal cardiovascular
and respiratory changes. Although clinically not important,
butorphanol produced moderate significant
increases in heart and respiratory rates, arterial blood
pressure, and rectal temperature and decreases in
arterial oxygen tension. Arterial pH, carbon dioxide
tension, bicarbonate concentrations, base excess,
Hct, and concentration of total solids were not significantly
different from baseline values after EA, butorphanol,
and control treatments.
Conclusions and Clinical Relevance—Electroacupuncture
and butorphanol (0.1 mg/kg, IV) may provide
useful rectal analgesia in horses. (Am J Vet Res 2003;64:137–144)
Objective—To determine the analgesic, hemodynamic,
and respiratory effects induced by caudal
epidural administration of meperidine hydrochloride in
Animals—7 healthy mares.
Procedure—Each mare received meperidine (5%;
0.8 mg/kg of body weight) or saline (0.9% NaCl) solution
via caudal epidural injection on 2 occasions. At
least 2 weeks elapsed between treatments. Degree
of analgesia in response to noxious electrical, thermal,
and skin and muscle prick stimuli was determined
before and for 5 hours after treatment. In addition,
cardiovascular and respiratory variables were
measured and degree of sedation (head position) and
ataxia (pelvic limb position) evaluated.
Results—Caudal epidural administration of meperidine
induced bilateral analgesia extending from the
coccygeal to S1 dermatomes in standing mares;
degree of sedation and ataxia was minimal. Mean (±
SD) onset of analgesia was 12 ± 4 minutes after
meperidine administration, and duration of analgesia
ranged from 240 minutes to the entire 300-minute
testing period. Heart and respiratory rates, rectal temperature,
arterial blood pressures, Hct, PaO2, PaCO2,
pHa, total solids and bicarbonate concentrations, and
base excess were not significantly different from
baseline values after caudal epidural administration of
either meperidine or saline solution.
Conclusions and Clinical Relevance—Caudal
epidural administration of meperidine induced prolonged
perineal analgesia in healthy mares. Degree of
sedation and ataxia was minimal, and adverse cardiorespiratory
effects were not detected. Meperidine
may be a useful agent for induction of caudal epidural
analgesia in mares undergoing prolonged diagnostic,
obstetric, or surgical procedures in the anal and
perineal regions. (Am J Vet Res 2001;62:1001–1007)
Objective—To determine cutaneous analgesia,
hemodynamic and respiratory effects, and β-endorphin
concentration in spinal fluid and plasma of horses
after acupuncture and electroacupuncture (EA).
Animals—8 healthy 10- to 20-year-old mares that
weighed between 470 and 600 kg.
Procedure—Each horse received 2 hours of acupuncture
and 2 hours of PAES at acupoints Bladder 18, 23,
25, and 28 on both sides of the vertebral column as
well as sham needle placement (control treatment).
Each treatment was administered in a random order.
At least 7 days elapsed between treatments.
Nociceptive cutaneous pain threshold was measured
by use of skin twitch reflex latency (STRL) and avoidance
to radiant heat (≤ 50°C) in the lumbar area. Skin
temperature, cardiovascular and respiratory variables,
and β-endorphin concentration in spinal fluid (CSF-EN)
and plasma (plasma-EN) were measured.
Results—Acupuncture and EA significantly increased
STRL and skin temperature. The CSF-EN was significantly
increased from baseline values 30 to 120 minutes
after onset of EA, but it did not change after
acupuncture and control treatments. Heart and respiratory
rates, rectal temperature, arterial blood pressure,
Hct, total solids and bicarbonate concentrations,
base excess, plasma-EN, and results of blood gas
analyses were not significantly different from baseline
values after acupuncture, EA, and control treatments.
Conclusion and Clinical Relevance—Administration
of EA was more effective than acupuncture
for activating the spinal cord to release β-endorphins
into the CSF of horses. Acupuncture and PAES provided
cutaneous analgesia in horses without adverse
cardiovascular and respiratory effects.
(Am J Vet Res 2002;63:1435–1442)
Objective—To compare the effects of acupuncture
(AP), electroacupuncture (EA), and transcutaneous
cranial electrical stimulation (TCES) with high-frequency
intermittent currents on the minimum alveolar
concentration (MAC) of isoflurane and associated cardiovascular
variables in dogs.
Animals—8 healthy adult female Beagles.
Procedure—Each dog was anesthetized with isoflurane
on 4 occasions, allowing a minimum of 10 days
between experiments. Isoflurane MAC values were
determined for each dog without treatment (controls)
and after treatment with AP and EA (AP points included
the Large Intestine 4, Lung 7, Governing Vessel 20,
Governing Vessel 14, San Tai, and Baihui) and TCES.
Isoflurane MAC values were determined by use of
noxious electrical buccal stimulation. Heart rate,
mean arterial blood pressure (MAP), arterial blood
oxygen saturation (SpO2) measured by use of pulse
oximetry, esophageal body temperature, inspired and
expired end-tidal isoflurane concentrations, end-tidal
carbon dioxide concentration, and bispectral index
(BIS) were monitored. Blood samples were collected
for determination of plasma cortisol concentration.
Results—Mean ± SD baseline MAC of isoflurane was
1.19 ± 0.1%. Acupuncture did not significantly change
MAC of isoflurane. Treatments with EA and TCES significantly
lowered the MAC of isoflurane by 10.1%
and 13.4%, respectively. The SpO2, heart rate, MAP,
BIS, esophageal body temperature, and plasma cortisol
concentration were not significantly different after
AP, EA, TCES, and control treatments at any time
Conclusions and Clinical Relevance—Use of EA
and TCES decreased MAC of isoflurane in dogs without
inducing adverse hemodynamic effects. However,
the reduction in isoflurane MAC by EA and TCES treatments
was not considered clinically relevant. (Am J Vet Res 2005;66:1364–1370)
Objective—To compare the analgesic and cardiopulmonary
effects of medetomidine and xylazine when
used for premedication of horses undergoing general
Design—Randomized clinical trial.
Procedure—Twenty horses were premedicated with
medetomidine (10 µg/kg [4.5 µg/lb], IM) and the other
20 were premedicated with xylazine (2 mg/kg [0.9
mg/kg], IM). Horses were then anesthetized with a
combination of guaifenesin and ketamine; anesthesia
was maintained with halothane. Additional doses of
medetomidine or xylazine were given if horses were
not sufficiently sedated at the time of anesthetic
induction. After induction of anesthesia, sodium pentothal
was administered as necessary to prevent limb
movements. Hypotension was treated with dobutamine;
hypoventilation and hypoxemia were treated
with intermittent positive-pressure ventilation. The
quality of anesthetic induction, maintenance, and
recovery and the quality of the transition to inhalation
anesthesia were scored.
Results—Scores for the quality of the transition to
inhalation anesthesia were significantly higher for
horses premedicated with medetomidine than for
horses premedicated with xylazine. However, other
scores, recovery times, and numbers of attempts
needed to achieve sternal recumbency and to stand
were not significantly different between groups.
Conclusions and Clinical Relevance—Results suggest
that medetomidine is suitable for premedication
of horses undergoing general anesthesia. Analgesic
and cardiopulmonary effects of medetomidine were
similar to those of xylazine, except that the transition
to inhalation anesthesia was smoother when horses
were premedicated with medetomidine, rather than
xylazine. (J Am Vet Med Assoc 2002;221:1144–1149)