Objective—To compare induction with hydromorphone
and diazepam (HydroD) or oxymorphone and
diazepam (OxyD) followed by maintenance with
isoflurane in dogs with induced hypovolemia.
Animals—6 healthy mixed-breed dogs.
Procedure—The study used a crossover design.
Measurements were obtained in normovolemic dogs
during isoflurane. Hypovolemia was induced (blood
loss of 30 mL/kg) and measurements repeated following
recovery from anesthesia, after HydroD
(hydromorphone, 0.1 mg/kg; diazepam, 0.2 mg/kg; IV)
or OxyD (oxymorphone, 0.05 mg/kg; diazepam,
0.2 mg/kg; IV), after another dose of the same opioid,
during administration of isoflurane (end-tidal concentration,
0.9%), and after glycopyrrolate (0.01 mg/kg,
IV). Significant changes were identified.
Results—Induction effect was evident within 1 minute.
All dogs were intubated after the second dose of opioid.
No significant differences were found between inductions.
The HydroD decreased heart rate (mean ± SEM,
–41 ± 9.8 beats/min), whereas both inductions
increased stroke index (0.4 ± 0.09 mL/kg/beat) and
caused moderate respiratory depression. Cardiac index
was decreased (±30.2 ± 6.04 mL/kg/min) and there was
minor metabolic acidosis during isoflurane following
HydroD, compared with values for anesthetized normovolemic
dogs. Glycopyrrolate increased heart rate (50 ±
8.6 beats/min) and decreased systolic blood pressure
(–23.2 ± 4.87 mm Hg) in dogs induced with HydroD and
decreased stroke index (–0.3 ± 0.08 mL/kg/beat) for both
Conclusions and Clinical Relevance—Similar effects
were detected after administration of HydroD or OxyD
in hypovolemic dogs. Either combination should be
safe for use in hypovolemic dogs. Administration of
glycopyrrolate was not beneficial. (Am J Vet Res