Objective—To determine whether free radicals are
produced in ischemic and reperfused canine skeletal
muscle, whether free radicals can be detected from
effluent blood by use of spin-trapping electron paramagnetic
resonance (EPR) spectroscopy, and
whether free radical-induced skeletal muscle damage
is detectable by use of light microscopy.
Animals—6 healthy mixed-breed dogs.
Procedures—Dogs were anesthetized and both gracilis
muscles were isolated, leaving only the major
vascular pedicle intact. Ischemia was induced in 1
flap for 4 hours; the contralateral flap served as the
control. Ischemic flaps were then reperfused for 15
minutes. α-Phenyl-N-tert-butylnitrone, a spin-trapping
agent, was administered intravenously to each dog 1
hour prior to reperfusion. Following reperfusion, effluent
blood samples from muscle flaps were obtained
and processed for EPR spectroscopy. Muscle biopsy
specimens were obtained for histologic evaluation,
and dogs were euthanatized.
Results—Spin adducts were not detected in blood
from control flaps. However, spin adducts were
detected in all ischemic-reperfused muscle flaps.
Principal signals identified were characteristic of oxygen-
and carbon-centered radicals. Significantly more
muscle damage was detected in ischemic-reperfused
flaps, compared with control flaps.
Conclusions and Clinical Relevance—Free radicals
may be an important component of injury
induced by ischemia and reperfusion of canine
skeletal muscle. Spin-trap adducts of free radicals
can be detected in effluent blood of canine muscle
flaps by use of spin-trapping EPR spectroscopy.
Spin-trapping EPR spectroscopy may be useful for
the study of antioxidants and free radical scavengers
in attenuating ischemia and reperfusionmediated
skeletal muscle damage. (Am J Vet Res
Objective—To determine whether adenosine pretreatment
attenuates free radical production and muscle
damage in ischemic and reperfused canine skeletal
Animals—9 healthy mixed-breed dogs.
Procedure—Dogs were anesthetized, and both gracilis
muscles were isolated, leaving only the major
vascular pedicle intact. Saline (0.9% NaCl) solution
was injected into the artery supplying the control flap,
whereas adenosine (10 mg) was injected into the contralateral
artery. Ischemia was induced in both flaps
for 4 hours. α-Phenyl-N-tert-butylnitrone was administered
IV to each dog 1 hour prior to reperfusion.
Following 15 minutes of reperfusion, effluent blood
samples from each muscle flap were obtained and
processed for spin-trapping electron paramagnetic
resonance (EPR) spectroscopy. Muscle biopsy specimens
were obtained for histologic evaluation, and
dogs were euthanatized.
Results—EPR spectra of strong intensity were
obtained from analysis of 5 of 9 paired samples.
Signals identified were characteristic of oxygen- and
carbon-centered free radical adducts. Signal intensity
of spectra from adenosine-treated flaps was significantly
less than that of control flaps; mean signal
attenuation was 36% in the adenosine-treated group.
Histologic evaluation of muscle flaps did not reveal
significant differences between groups.
Conclusions and Clinical Relevance—Treatment of
canine muscle flaps with adenosine prior to a period
of ischemia reduced but did not completely attenuate
free radical production after reperfusion. However,
adenosine pretreatment did not affect histologic
abnormalities. (Am J Vet Res 2002;63:175–180)
Objective—To determine the level of clinical agreement
between 2 methods for the measurement of
resting energy expenditure (REE).
Design—Prospective case series.
Procedure—Oxygen consumption (O2) and CO2 production
(CO2) were measured with an open-flow indirect
calorimeter in healthy (n = 10) and ill (67) dogs.
Measurements were collected at 3 time periods on 2
days. The O2 and the CO2 measurements were then
used to calculate the REE values.
Results—Mean values of measured (MREE) and
predicted (PREE) REEs in healthy dogs and a dog
with medical illnesses or trauma were not significantly
different. There was a significant difference
on day 2 between the MREE and PREE in the group
of dogs recovering from major surgery. More importantly,
there was significant variation between the
PREE and MREE on an individual-dog basis. The
PREE only agreed to within ± 20% of the MREE in
51% to 57% of the dogs.
Conclusions and Clinical Relevance—The level of
agreement between these two methods for determining
the 24-hour REE was poor in individual dogs.
The level of disagreement between the 2 methods
indicates that these methods may not be used interchangeably
in a clinical setting. Measurement of REE
by use of indirect calorimetry may be the only reliable
method of determining REE in an individual ill or
healthy dog. (J Am Vet Med Assoc 2004;225:58–64)
Objective—To assess accuracy and reliability of
open-flow indirect calorimetry in dogs.
Animals—13 clinically normal dogs.
Procedure—In phase 1, oxygen consumption per
kilogram of body weight (VO2kg) was determined in 6
anesthetized dogs by use of open-flow indirect
calorimetry before and after determination of VO2/kg
by use of closed-circuit spirometry. In phase 2, four
serial measurements of VO2 and carbon dioxide production
(VCO2) were obtained in 7 awake dogs by use
of indirect calorimetry on 2 consecutive days. Resting
energy expenditure (REE) was calculated.
Results—Level of clinical agreement was acceptable
between results of indirect calorimetry and spirometry.
Mean VO2/kg determined by use of calorimetry
before spirometry was significantly greater than that
obtained after spirometry. In phase 2, intraclass correlation
coefficients (ICC) for REE and VO2 were 0.779
and 0.786, respectively, when data from all 4 series
were combined. When the first series was discounted,
ICC increased to 0.904 and 0.894 for REE and VO2,
respectively. The most reliable and least variable measures
of REE and VO2 were obtained when the first 2
series were discounted.
Conclusions and Clinical Relevance—Open-flow
indirect calorimetry may be used clinically to obtain a
measure of VO2 and an estimate of REE in dogs. Serial
measurements of REE and VO2 in clinically normal
dogs are reliable, but a 10-minute adaption period
should be allowed, the first series of observations
should be discounted, multiple serial measurements
should be obtained, and REE. (Am J Vet Res