Search Results

You are looking at 1 - 8 of 8 items for

  • Author or Editor: H. Richard Adams x
  • Refine by Access: All Content x
Clear All Modify Search
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association



To test the hypothesis that endothelium-derived nitric oxide modulates vasomotor reactivity in equine digital arteries.


Digital arteries were isolated from adult horses, and their vasodilator properties were examined in an in vitro controlled environment.


Five adult horses (1 gelding, 4 mares) without evidence of hoof or vascular disease were studied.


Arterial rings with or without endothelium were exposed to endothelium-dependent vasodilator drugs in the presence or absence of a pharmacologic inhibitor of the enzyme nitric oxide synthase.


Vasodilator effects of 3 endothelium-dependent vasorelaxant agents were significantly greater in endothelium-intact vessels than in endothelium-denuded vessels. Moreover, a nitric oxide synthase inhibitor reduced vasodilator responses to endothelium-dependent vasodilators in endothelium-intact arteries, but had no discernable effects in endothelium-denuded arteries.


These findings indicate the presence of endothelium-derived relaxing factor/nitric oxide in blood vessels of horses, and identify vascular endothelium as an endogenous modulator of vasomotor tone in the digital arteries of this species.

Free access
in American Journal of Veterinary Research


Butorphanol (0.025, 0.05, 0.1, 0.2, 0.4, and 0.8 mg/kg of body weight, and placebo) was given sc to 8 healthy unmedicated dogs to determine its efficacy for visceral analgesia, using a colonic balloon for minimal threshold nociceptor stimulation. Degree of sedation; systolic, diastolic, and mean arterial pressure; and pulse rate were recorded. The highest 3 dosages, 0.2, 0.4, and 0.8 mg/kg, were found to be most effective, with 0.8 mg/kg the only dosage that was significantly different from control responses at the 45-minute interval. Duration of analgesia ranged from 23 to 53 minutes for all 6 dosages and dosing durations were not significantly different from one another. Blood pressures did not change, but pulse rate was significantly decreased by 0.8 mg of butorphanol/kg. We concluded that butorphanol is an effective visceral analgesic of relatively short duration in the dog.

Free access
in American Journal of Veterinary Research


This study was designed to test analgesia, duration, and cardiovascular changes induced by meperidine (mep) and oxymorphone (oxy) following methoxyflurane (mof) and halothane (hal) anesthesia. Eight healthy dogs were given atropine and acepromazine, and anesthesia was induced with thiamylal and maintained with 1.5 minimal alveolar concentration of mof or hal for 1 hour during controlled ventilation. Eight treatments were given with each anesthetic: 3 with mep (0.5, 1.0, and 2.0 mg/kg, iv), 3 with oxymorphone (oxy; 0.05, 0.1, and 0.2 mg/kg, iv), and 2 placebos with sterile water. Test drugs were given at the end of anesthesia when early signs of recovery were evident. Minimal threshold stimulus/response nociception was assessed by use of an inflatable soft plastic colonic balloon. Blood pressures and pulse rate were measured with a noninvasive monitor. Meperidine and oxy were found to be effective analgesics and could be reversed with naloxone. Intravenous administration of 2.0 mg of mep/kg provided analgesia for 36 ± 6 minutes and 39 ± 15 minutes after mof and hal, respectively. In contrast, oxy was effective at all 3 doses with effects of iv administration of 0.2 mg of oxy/kg lasting 154 ± 13 minutes and 152 ± 12 minutes, after mof and hal, respectively. Analgesia could not be demonstrated after anesthesia for acepromazine, mof, or hal. Blood pressure was not changed by either anesthetic nor was it influenced by mep or oxy. Pulse rate was significantly depressed by the higher doses of oxy following hal, but was not changed by mep following either anesthetic. This study demonstrated the longer duration of analgesia of oxy. In addition, we could not find that analgesia was provided by either mof or hal following recovery from anesthesia.

Free access
in American Journal of Veterinary Research