The authors respond: Thank you for your concern about the perioperative management of this cat. Pain management is of the utmost importance in
our patients, especially when they undergo surgical procedures. In this case, butorphanol was given 30 minutes before induction.
The total prep and surgery time lasted about 90 minutes, and the patient received another butorphanol dose about two hours
after the first one. The cat received intravenous fluids (26 ml/hr) throughout induction, surgery, and recovery. Also, patient
monitoring during anesthesia was routine and included pulse oximetry, ECG, capnography, blood pressure, and temperature. The
cat's temperature was controlled during prep, surgery, and recovery by using water-filled heating pads, warmed rice socks,
and intravenous fluid warmers.
As mentioned in the article, the patient was discharged to the referring veterinarian six hours after surgery. All additional
analgesic administration was given at the referring veterinarian's discretion. The referring veterinarian was also the cat's
owner. Therefore, the postoperative protocol in this case differed from that typically followed in our hospital. The referring
veterinarian reported that the cat was apparently comfortable while receiving butorphanol and returned to normal physiologic
activity within 24 hours.
Recent information suggests that the duration of analgesic action provided by any opioid, be it a full mu agonist, partial
mu agonist, or even an agonist-antagonist such as butorphanol, can be extremely variable depending on the dose, pain syndrome
treated, and patient's sex and species.1 The procedure we performed in this cat is considered to produce moderate pain; and as butorphanol is considered adequate
for mild to moderate visceral pain, it was deemed appropriate in this case.2
We use current anesthesia and analgesia protocols on a case-by-case basis with the welfare of the patient being of the highest
concern. We agree that a more potent and specific mu agonist could have been used, and in hindsight, perhaps, we should have
considered using an alternative medication. However, given our present knowledge concerning the tremendous variability in
individual pain tolerance and drug efficacy, the use of butorphanol would not necessarily be considered inappropriate as long
as it is coupled with aggressive pain assessment and patient monitoring.
1. Lascelles, B.D.; Robertson, S.A.: Antinociceptive effects of hydromorphone, butorphanol, or the combination in cats. J. Vet. Intern. Med. 18 (2):190-195; 2004.
2. Mathews, K.A.: Pain assessment and general approach to management. Vet. Clin. North Am. (Small Anim. Pract.) 30 (4):729-755; 2000.
Joshua F. Rexing, DVM
Veterinary Teaching Hospital
College of Veterinary Medicine
University of Illinois
1008 W. Hazelwood Drive
Urbana, IL 61802
Bradley R. Coolman, DVM, MS, DACVS
Veterinary Surgical Services
5818 Maplecrest Road
Fort Wayne, IN 46835