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DOES KETAMINE PROVIDE ADEQUATE VISCERAL ANALGESIA WHEN USED ALONE OR IN COMBINATION WITH ACEPROMAZINE, DIAZEPAM, OR BUTORPHANOL IN CATS?
Proceedings of the 4th International Congress of Veterinary Anaesthesia
DOES KETAMINE PROVIDE ADEQUATE VISCERAL ANALGESIA WHEN USED ALONE OR IN COMBINATION WITH ACEPROMAZINE, DIAZEPAM, OR BUTORPHANOL IN CATS? D.C. Sawyer, R.H. Re&*, RA. Durham. Departments of Small Animal Clinical Sciences and Pharmacologyand Toxicology, *Departmentof Pharmacology and Toxicology, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan dose of ketamine (8 mg/kg IV),animals appeared to be anaesthetized but still responded to the colonic nociceptor stimulation. Certainly, the visceral analgesia provided by ketamine was not profound and as suggested by others, this drug may be more effective for surgery and post-operative analgesia involving the skeletal integumentary structures and extremities than for abdominal procedures in the cat. We do not recommend that ketamine be used for abdominal or thoracic procedures. The degree of sedation provided by KET alone, KET/ACE, or KET/BUT was not significantly different, one from the other. Nevertheless, the mean sedation score for KET/BUT tended to be slight to mild, whereas it was moderate to marked with ketamine alone. Cats were not significantly sedated by butorphanol alone. Pulse rate was increased by ketamine and in combination with butorphanol and diazepam suggesting that ketamine should not be used in cats in which profound tachycardia must be avoided. Respiratory rate was not affected. These studies demonstrated that ketamine is a weak visceral analgesic, that diazepam and acepromazine do not enhance this effect, and that 0.1 mg/kg butorphanol produces long lasting analgesia (348k11 min) alone and in combination with ketamine.
The analgesic effects of ketamine (KET), acepromazine (ACE), butorphanol (BUT), Ket/Ace, Ket/DiaZ, and Ket/But given IV were evaluated in neutered female cats. Analgesia (antinocicep tion) was measured by an increase in response to nociceptor stimulation induced by inflation of a balloon inserted into the colon per rectum. Ket/Ace provided analgesia at all three dose combinations (2.0/0.1, 4.0/0.1, 8.0/0.1) and was not different from ketamine alone. Responses to KET/DIAZ were not different from those of KET/ACE, although there was a trend toward a shorter duration of analgesia when diazepam was combined with ketamine. Butorphanol was most effective at 0.05 and 0.1 mg/kg compared to 0.025,O.q 0.4, and 0.8 mg/kg. KET/BUT was not different at all three doses (2.0/0.1, 4.0/0.1, and 8.0/0.1 mg/kg) but the combination provided significantly greater analgesia of longer duration than ketamine alone. It is interes&ing to speculate that this study supports the concept that ketamine acts, in part, at kappa opioid receptors. We did not test for antagonism of the effect of ketamine alone or KET/BUT with naloxone in the cat. Balloon volume did not increase when butorphano1 was combined with ketamine, suggesting that ketamine does not augment or interfere with the analgesic response to butorphanol. Ketamine increased the threshold response to nociceptor stimulation, thus providing visceral analgesia in the cat. The degree of analgesia was similar to that provided by butorphanol but there was no increase in the analgesic response with increasing doses of ketamine. Even at the highest 381
DOES KETAMINE PROVIDE ADEQUATE VISCERAL ANALGESIA WHEN USED ALONE OR IN COMBINATION WITH ACEPROMAZINE, DIAZEPAM, OR BUTORPHANOL IN CATS? D.C. Sawyer, R.H. Re&*, RA. Durham. Departments of Small Animal Clinical Sciences and Pharmacologyand Toxicology, *Departmentof Pharmacology and Toxicology, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan dose of ketamine (8 mg/kg IV),animals appeared to be anaesthetized but still responded to the colonic nociceptor stimulation. Certainly, the visceral analgesia provided by ketamine was not profound and as suggested by others, this drug may be more effective for surgery and post-operative analgesia involving the skeletal integumentary structures and extremities than for abdominal procedures in the cat. We do not recommend that ketamine be used for abdominal or thoracic procedures. The degree of sedation provided by KET alone, KET/ACE, or KET/BUT was not significantly different, one from the other. Nevertheless, the mean sedation score for KET/BUT tended to be slight to mild, whereas it was moderate to marked with ketamine alone. Cats were not significantly sedated by butorphanol alone. Pulse rate was increased by ketamine and in combination with butorphanol and diazepam suggesting that ketamine should not be used in cats in which profound tachycardia must be avoided. Respiratory rate was not affected. These studies demonstrated that ketamine is a weak visceral analgesic, that diazepam and acepromazine do not enhance this effect, and that 0.1 mg/kg butorphanol produces long lasting analgesia (348k11 min) alone and in combination with ketamine.
The analgesic effects of ketamine (KET), acepromazine (ACE), butorphanol (BUT), Ket/Ace, Ket/DiaZ, and Ket/But given IV were evaluated in neutered female cats. Analgesia (antinocicep tion) was measured by an increase in response to nociceptor stimulation induced by inflation of a balloon inserted into the colon per rectum. Ket/Ace provided analgesia at all three dose combinations (2.0/0.1, 4.0/0.1, 8.0/0.1) and was not different from ketamine alone. Responses to KET/DIAZ were not different from those of KET/ACE, although there was a trend toward a shorter duration of analgesia when diazepam was combined with ketamine. Butorphanol was most effective at 0.05 and 0.1 mg/kg compared to 0.025,O.q 0.4, and 0.8 mg/kg. KET/BUT was not different at all three doses (2.0/0.1, 4.0/0.1, and 8.0/0.1 mg/kg) but the combination provided significantly greater analgesia of longer duration than ketamine alone. It is interes&ing to speculate that this study supports the concept that ketamine acts, in part, at kappa opioid receptors. We did not test for antagonism of the effect of ketamine alone or KET/BUT with naloxone in the cat. Balloon volume did not increase when butorphano1 was combined with ketamine, suggesting that ketamine does not augment or interfere with the analgesic response to butorphanol. Ketamine increased the threshold response to nociceptor stimulation, thus providing visceral analgesia in the cat. The degree of analgesia was similar to that provided by butorphanol but there was no increase in the analgesic response with increasing doses of ketamine. Even at the highest 381