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Buprenorphine versus butorphanol in cat spays

Clinical Scenario

Over pizza at a vet meeting in your practice you are talking about your peri-operative analgesia for cat spays. You currently use butorphanol with ACP as your pre-medication, followed by propofol and isoflurane. One of the team has just been to a course about pain in cats and it was suggested that buprenorphine may be superior at providing post-operative analgesia. You don’t seem to have had a problem with the cats undergoing surgery currently, but you wonder if buprenorphine would be a better choice.

3-Part Question (PICO)

In [female cats that are being neutered] does the use of [peri-operative buprenorphine compared to peri-operative butorphanol] provide [better post-operative analgesia]?

Search Strategy and Summary of Evidence

Search Strategy

MEDLINE(R) In-Process & Other Non-Indexed Citations and MEDLINE(R) 1946 to Present using the OVID interface

(cat.mp. OR cats.mp. OR feline.mp. OR felines.mp. OR felis.mp. OR exp Cats/)

AND

(neuter.mp. OR neutering.mp. OR sterilise.mp. OR sterilize.mp. OR sterilising.mp. OR sterilizing.mp. OR sterilisation.mp. OR sterilization.mp. OR sterilisations.mp. OR sterilizations.mp. OR spay.mp. OR spays.mp. OR spey.mp. OR speys.mp. OR desex.mp. OR desexed.mp. OR desexing.mp. OR de sex.mp. OR de sexed.mp. OR de sexing.mp. OR ovariectomy.mp. OR ovariectomies.mp. OR hysterectomy.mp. OR hysterectomies.mp. OR ovariohysterectomy.mp. OR ovariohysterectomies.mp. OR gonadectomy.mp. OR gonadectomise.mp. OR exp Sterilization, Reproductive/ OR exp Ovariectomy/ OR exp Hysterectomy/)

AND

(buprenorphine.mp. OR vetergesic.mp. OR temgesic.mp. OR exp Buprenorphine/ OR butorphanol.mp. OR torbugesic.mp. OR exp Butorphanol/ OR opiod.mp. OR opiods.mp.)

CAB Abstracts 1910 to Present using the OVID interface

(cat.mp. OR cats.mp. OR feline.mp. OR felines.mp. OR felis.mp. OR exp cats/)

AND

(neuter.mp. OR neutering.mp. OR sterilise.mp. OR sterilize.mp. OR sterilising.mp. OR sterilizing.mp. OR sterilisation.mp. OR sterilization.mp. OR sterilisations.mp. OR sterilizations.mp. OR spay.mp. OR spays.mp. OR spey.mp. OR speys.mp. OR desex.mp. OR desexed.mp. OR desexing.mp. OR de sex.mp. OR de sexed.mp. OR de sexing.mp. OR ovariectomy.mp. OR ovariectomies.mp. OR hysterectomy.mp. OR hysterectomies.mp. OR ovariohysterectomy.mp. OR ovariohysterectomies.mp. OR gonadectomy.mp. OR gonadectomise.mp. OR exp sterilization/ OR exp ovariectomy/ OR exp hysterectomy/ OR exp gonadectomy/)

AND

(buprenorphine.mp. OR vetergesic.mp. OR temgesic.mp. OR butorphanol.mp. OR torbugesic.mp. OR exp Butorphanol/ OR opiod.mp. OR opiods.mp.)

Search Outcome

MEDLINE

  • 33 papers found in MEDLINE search
  • 31 papers excluded as they don't meet the PICO question
  • 0 papers excluded as they are in a foreign language
  • 0 papers excluded as they are review articles/in vitro research/conference proceedings
  • 2 total relevant papers from MEDLINE

CAB Abstracts

  • 37 papers found in CAB search
  • 35 papers excluded as they don't meet the PICO question
  • 0 papers excluded as they are in a foreign language
  • 0 papers excluded as they are review articles/in vitro research/conference proceedings
  • 2 total relevant papers from CAB

Total relevant papers

2 relevant papers from both MEDLINE and CAB Abstracts

Summary of Evidence

Bortolami et al. (2013) UK

Title: Methadone in combination with acepromazine as premedication prior to neutering in the cat
Patient group: 45 cats visiting a single clinic for elective neutering (24 females)
Study Type: Randomised controlled trial
Outcomes:
  • Three groups compared (acepromazine + methadone/buprenorphine/butorphanol)
  • Level of sedation
  • Clinical parameters (temperature, pulse rate, respiratory rate)
  • Ease of restraint for intravenous (IV) catheter placement
  • Anaesthetic recovery
  • Degree of pain at surgical site using a visual analogue scale, mechanical nociceptive threshold and behavioural indicators
  • Any adverse events
Key Results:
  • A flank approach was used for all cats
  • No statistically significant differences between groups in relation to timing or recovery from anaesthesia, although cats in the butorphanol group had significantly shorter surgery durations than cats in the buprenorphine group
  • No significant differences between groups in relation to ease of restraint for IV catheter placement, clinical parameters (although blood pressure was not measured in all cats) or sedation scores 2-6 hours after premedication
  • No significant differences between groups in relation to degree of pain at surgical site using a visual analogue scale or mechanical nociceptive threshold
  • No adverse effects were seen
  • 6 cats required rescue analgesia (1 in buprenorphine group, 3 in butorphanol group - not significantly different)
Study Weaknesses:
  • Inclusion criteria state that only cats over 5 months were eligible to be included in the study; however, in the results the mean age was stated as 7 months +/- standard deviation of 4 months.  After contacting one of the authors for clarification, it appears that there may have been cats younger than 5 months in the final analysis
  • It is unknown whether the person who administered the intervention was blinded
  • The methods used to measure pain do not appear to have been previously published
  • Further analgesia was provided to all cats at 6 hrs (methadone) and 8 hrs (meloxicam) after premedication, respectively - this is likely to affect the interpretation of pain scores for the subsequent time points
  • Assessor was aware from the 7 hrs time point onwards that all cats had been given methadone at 6 hrs
  • It is unknown how many different surgeons were involved; in the discussion section it states that the surgeons were experienced but the average length of time for surgery seemed reasonably long (37 minutes +/- 13 minutes). However, it does not state how surgery length was determined, i.e. from induction to end of anaesthesia or induction to extubation etc.  One of the authors after being contacted confirmed that the surgeons were experienced
  • There were some missing values across the time points (see Table 2, Table 3 and text), although explanations were given for some of these by the authors
  • It was introduced in the discussion that the study was designed for regulatory purposes in order to obtain a marketing authorisation for use of methadone in cats; the study was funded by Eurovet Animal Health BV (subsequently acquired by Dechra) who manufacture methadone
Attachment:
No attachments.

Polson et al. (2012) UK

Title: Analgesia after feline ovariohysterectomy under midazolam-medetomidine-ketamine anaesthesia with buprenophine or butorphanol, and carprofen or meloxicam: a prospective, randomised clinical trial
Patient group: 100 female cats at two RSPCA hospitals
Study Type: Randomised controlled trial (Factorial design - comparison of two different NSAIDs and two different opioids)
Outcomes:
  • Four groups compared (Ketamine, midazolam and medetomine + carprofen/buprenorphine or meloxicam/buprenorphine or carprofen/butorphanol or meloxicam/butorphanol)
  • Duration of surgery and recovery
  • Surgical condition as judged by the surgeon
  • Any abnormalities (e.g. pregnancy) noted
  • Clinical parameters (heart and respiratory rate)
  • Level of sedation
  • Pain using a descriptive scale based on the cats appearance, a visual scale and mechanical nociceptive threshold
Key Results:
  • A midline approach was used for all cats
  • There were no significant differences between groups in relation to duration of surgery or recovery, or surgical condition as judged by the surgeon
  • There were no significant differences between groups in relation to abnormalities noted or clinical parameters
  • The level of sedation, or pain using any of the 4 methods, were not significantly lower or higher on comparison between groups
Study Weaknesses:
  • It is unknown whether the person who administered the interventions was blinded
  • Mostly aggregated data were given so it is difficult to determine absolute numbers and whether all cats were assessed at all time points
  • The standard deviation in Table 2 suggests an age less than zero is possible. The authors were contacted and stated that a median and interquartile range should have been used; most cats in the study were young with a few older cats
  • The lack of difference between the groups in relation to the level of pain could be due to the drugs used in the anaesthetic protocol having analgesic properties (medetomidine, ketamine) and the use of a multimodal regime (NSAID and opiod peri-operatively); the authors also conclude this
  • Some conflict of interest is declared (one of the authors works for the company that produces the nociceptive threshold measuring device)
Attachment:
No attachments.

Comments

The quality of design of both of these studies as assessed by our methods is reasonably high in comparison with the other literature assessed previously by the authors for BestBETs for Vets.  It is difficult, however, to separate the effects of the anaesthetic drugs and the analgesics, particularly in the immediate post-operative period.  Neither of the studies had the comparison between butorphanol and buprenorphine as their main aim, which could have an effect on study results.  Additionally, there is a lack of published studies which have validated the pain assessment methods, adding to the difficulty in the interpretation of these studies.

Although the findings of both studies were broadly similar, there are some significant points which limit the extent to which comparisons may be made between them. For example, the two studies used different surgical approaches (midline in Polson study, flank in Bortolami study).  Additionally, whilst opioids and NSAIDs were both administered peri-operatively in the Polson study, NSAIDs were given 8 hours after opioid administration in the Bortolami study. The use of NSAIDs in addition to opioids for post-surgical analgesia is common in clinical practice, but makes the singling out of the analgesic contribution of each opioid more difficult.  The dosage of the different opioids used does differ to some extent between the two studies with a higher dose of butorphanol used in the Bortalami study compared with the Polson study.  Both used low doses of buprenorphine.

Other factors such as cost are also important to consider when selecting analgesics.

Bottom line

Based on the available pain assessment methods, the use of peri-operative buprenorphine or butorphanol appears to result in equivalent post-operative analgesic effects.  WIthout additional evidence therefore, either are suitable to use.

Disclaimer

The BETs on this website are a summary of the evidence found on a topic and are not clinical guidelines. It is the responsibility of the individual veterinary surgeon to ensure appropriate decisions are made based on the specific circumstances of patients under their care, taking into account other factors such as local licensing regulations. Read small print

References

Bortolami E, Murrell JC, Slingsby LS (2013) Methadone in combination with acepromazine as premedication prior to neutering in the cat.  Veterinary Anaesthesia & Analgesia 40: 181-93.

Polson S, Taylor PM, Yates D (2012) Analgesia after feline ovariohysterectomy under midazolam-medetomidine-ketamine anaesthesia with buprenophine or butorphanol, and carprofen or meloxicam: a prospective, randomised clinical trial.  Journal of Feline Medicine and Surgery 14: 553-9.

About this BET

First author:
Marnie Brennan
Second author:
Jenny Stavisky
Institution:
University of Nottingham
Search last performed:
2014-07-16 16:18:26
Original publication date:
2014-09-05 16:18:26
Last updated:
2014-09-05 16:18:26
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