Effects of oxymorphone and hydromorphone on isoflurane minimum alveolar concentration in dogs

Comparison of plasma histamine levels after intravenous administration of hydromorphone and morphine in dogs

“…Dogs with intact endocrine and sympathetic functions may not develop hypotension despite the presence of high plasma histamine levels. In isoflurane-anesthetized dogs subjected to blood loss, however, significant fall in systemic blood pressure was documented following intravenous hydromorphone (Machado et al, 2006). It is plausible that the seemingly negligible systemic histamine release induced by hydromorphone in our study may produce clinically significant hemodynamic disturbances in dogs with impaired cardiovascular function.…”

“…Hydromorphone is a semisynthetic l-opioid receptor agonist derived from morphine that has been used as an analgesic in human medicine for over 80 years (Murray & Hagen, 2005). The use of hydromorphone in veterinary medicine is more recent, but it has been utilized in dogs for chemical restraint, sedation, analgesia, as part of induction of anesthesia and to decrease inhalant anesthetic requirement (Pettifer & Dyson, 2000;Smith et al, 2001;Campbell et al, 2003;Machado et al, 2005Machado et al, , 2006. The analgesic potency of hydromorphone is 5-10 times greater than that of morphine (Pettifer & Dyson, 2000;Golembiewski, 2003;Murray & Hagen, 2005).…”

“…Hypotension is the most common systemic anaphylactoid consequence related to histamine release (Owen et al, 1982;Moss & Rosow, 1983). While hydromorphoneinduced histamine release has not been fully examined, the cardiovascular effects have been investigated in more detail in one study (Machado et al, 2006). In experimental hypovolemic dogs, intravenous administration of hydromorphone caused minimal reduction in blood pressure beyond that caused by blood withdrawal in the conscious animals.…”

“…In experimental hypovolemic dogs, intravenous administration of hydromorphone caused minimal reduction in blood pressure beyond that caused by blood withdrawal in the conscious animals. Subsequent administration of isoflurane caused noteworthy reduction in blood pressure, presumably because of isoflurane-mediated sympathetic outflow inhibition (Machado et al, 2006). These results imply that dogs with limited cardiovascular performance and sympathetic function may be more prone to cardiovascular depression when given intravenous hydromorphone, an effect that may be related to histamine release (Pettifer & Dyson, 2000).…”

Effects of orally administered enalapril on blood pressure and hemodynamic response to vasopressors during isoflurane anesthesia in healthy dogs

“…The anesthetic dose (FE 0 Iso of 1.3%) at which BP parameters were evaluated may be greater than is necessary for clinical patients, depending on the surgical or medical procedure to be performed, and particularly following the injectable premedication protocol utilized. Both hydromorphone and diazepam have been shown to reduce the MAC of isoflurane in dogs (Hellyer et al 2001;Machado et al 2006). The depth of anesthesia achieved in this population was greater than necessary to maintain immobilization for the duration of the experiment, although no noxious stimulus was applied.…”