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Flunixin for pain relief in surgical calf castration

Clinical Scenario

You are sitting in the pub talking to your colleagues about pain relief in calves after a CPD meeting by a drugs company that markets one of the NSAIDs currently licensed for cattle. It seems everyone does something different and you are the only one in the practice who uses flunixin, which you do because that is what your first practice always did. You wonder what the evidence base is for the efficacy of this drug for pain relief in calves post castration........

3-Part Question (PICO)

In [calves undergoing surgical castration] does [flunixin plus local anaesthetic compared to local anaesthetic alone] [reduce clinical signs of pain after the procedure]?

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

(calf.mp. OR calves.mp. OR bovine.mp. OR bovines.mp. OR young stock.mp. OR youngstock.mp. OR cattle.mp. OR exp Cattle/)

AND

(castrat$.mp. OR sterilis$.mp. OR steriliz$.mp. OR neuter$.mp. OR desex$.mp. OR de sex$.mp. OR orchiect$.mp. OR orchidect$.mp. OR gonadect$.mp. OR exp Castration/ OR exp Orchiectomy/)

AND

(NSAID.mp. OR NSAIDs.mp. OR nonsteroidal.mp. OR non steroidal.mp. OR exp Anti-Inflammatory Agents, Non-Steroidal/ OR flunixin.mp. OR finadyne.mp.)

AND

(local anaesthe$.mp. OR local anesthe$.mp. OR regional anaesthe$.mp. OR regional anesthe$.mp. OR nerve block.mp. OR exp Anesthetics, local/ OR exp Anesthesia, local/ OR exp Nerve block/)

CAB Abstracts 1910 to Present using the OVID interface

(calf.mp. OR calves.mp. OR bovine.mp. OR bovines.mp. OR young stock.mp. OR youngstock.mp. OR cattle.mp. OR exp calves/ OR exp cattle/)

AND

(castrat$.mp. OR sterilis$.mp. OR steriliz$.mp. OR neuter$.mp. OR desex$.mp. OR de sex$.mp. OR orchiect$.mp. OR orchidect$.mp. OR gonadect$.mp. OR exp gonadectomy/ OR exp castration/)

AND

(NSAID.mp. OR NSAIDS.mp. OR nonsteroidal.mp. OR non steroidal.mp. OR exp non-steroidal antiinflammatory agents/ OR finadyne.mp. OR flunixin.mp. OR exp flunixin/)

AND

(local anaesthe$.mp. OR local anesthe$.mp. OR regional anaesthe$.mp. OR regional anesthes$.mp. OR nerve block.mp. OR exp local anaesthetics/ OR exp local anaesthesia/

Search Outcome

MEDLINE

  • 14 papers found in MEDLINE search
  • 9 papers excluded as they don't meet the PICO question
  • 3 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

  • 23 papers found in CAB search
  • 13 papers excluded as they don't meet the PICO question
  • 7 papers excluded as they are in a foreign language
  • 1 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

Webster et al, 2013, America

Title:

Effects of local anaesthesia and flunixin meglumine on the acute cortisol response, behavior, and performance of young dairy calves undergoing surgical castration.

Patient group:

30 weaned, 2-3 month old Holstein Friesian bull calves.

The calves were split into 5 groups: 1) castration only, 2) local anaesthetic (neck of scrotum and into testes) only, 3) flunixin only, 4) local anaesthetic and flunixin, 5) sham castration.

Study Type:

Randomised controlled trial

Outcomes:
  • Feed intake
  • Body weight gain
  • Plasma cortisol concentration
  • Behaviour for 8 hours post castration
Key Results:
  • Feed intake and body weight gain did not significantly differ between groups (p = 0.98 and p = 0.66 respectively).
  • Calves given local anaesthetic and flunixin and the sham castrated calves had significantly lower mean cortisol than the calves castrated without any drugs at 3 hours (p < or = 0.004) and 8 hours (p < or = 0.002) post castration. There were no significant differences in mean cortisol between other treatment groups.
  • Plasma cortisol did not significantly increase above baseline in the sham castration or the local anaesthetic and flunixin group (p > or = 0.18), but did in the other groups (p < 0.0033).
  • At 30, 45 and 60 minutes post castration plasma cortisol levels were significantly higher in the local anaesthetic group than in calves given local anaesthetic and flunixin (p < or = 0.004).
  • Plasma cortisol levels at 120 minutes were significantly higher in the local anaesthetic only group compared to calves receiving flunixin alone (p = 0.008) and flunixin in combination with local anaesthetic (p = 0.007).
  • The local anaesthetic only group demonstrated significantly more statue standing and head turning in the 3 hours post castration compared with the local anaesthetic and flunixin group (p = 0.002).
Study Weaknesses:
  • No sample size calculation was performed, we do not know if the study was adequately powered to detect differences between the treatment groups (n = 6 calves per group)
  • Unclear if administration of treatments was blinded
  • The behavioural outcome measures are subjective
  • For outcomes that were measured at multiple time points, the timepoint of most interest was not identified in the methods
  • Inadequate comparison of the groups at baseline
Attachment:
Evidence appraisalEvidence appraisal

Currah et al, 2009, Canada

Title:

The behavioural assessment and alleviation of pain associated with castration in beef calves treated with flunixin meglumine and caudal lidocaine epidural anaesthesia with epinephrine.

Patient group:

One hundred and one bull calves across 2 locations:

Location 1: 30 3 month old Angus-cross bull calves

Location 2: 71 Hereford cross bull calves (median age 95 days, 94 days and 67 days in each treatment group)

The calves were split into 3 intervention groups: 1) surgical castration, 2) surgical castration following lidocaine/epinephrine epidural, and 3) surgical castration following flunixin meglumine (IV) and lidocaine/epinephrine epidural.

Study Type:

Randomised controlled trial

Outcomes:
  • Stride length
  • Number of steps taken
  • Visual assessment of pain as they left the chute - 'in pain' or 'not in pain' based on posture and willingness to move
  • Vocalisation during castration
  • Force exerted by calf on table
  • Behaviour activity: lying down, standing or nursing in 12 hours post castration
Key Results:

For the 30 calves at location 1:

  • Significant decrease in the number of steps after castration compared to before (p < 0.05) in group one (no local anaesthesia or flunixin).
  • No significant decrease in number of steps before and after castration in groups 2 (local anaesthesia only) and 3 (local anaesthesia and flunixin).

For the 71 calves at location 2:

  • Calves in group 3 (local anaesthesia and flunixin) had significantly longer stride lengths than calves in groups 1 (no local anaesthesia or flunixin) and 2 (local anaesthesia only) at 4 and 8 hours post castration, but significantly shorter stride lengths at 24 hours post castration (p < 0.05).
  • Calves in group 1 (no local anaesthesia or flunixin) were significantly more likely to be classified as ‘in pain’ at 4 and 8 hours post castration compared with group 3 (local anaesthesia and flunixin).
  • Age and weight of the calves was also significantly associated with being classed as ‘in pain’. For every day a calf was older it was 3.7 times more likely to be ‘in pain’.
  • No significant differences in vocalisation, movement during castration, and post castration behaviours were found between groups.
Study Weaknesses:
  • No description of how randomisation was performed
  • Full background data not given for all calves
  • Unclear whether treatment administration was blinded and no indication that outcome assessment was blinded other than one specific measurement (in pain/not in pain)
  • Unvalidated outcome measurements were used
  • Some of the outcome measurements were subjective and how behaviour was assessed was not adequately described
  • No sample size calculation was performed, we do not know if the study was adequately powered to detect differences between the treatment groups
  • Inadequate description of all of the basic data e.g. no results described or shown for post castration behaviours
Attachment:
Evidence appraisalEvidence appraisal

Comments

The two included studies use different methods of local anaesthesia (the Currah paper uses an epidural) which may affect the relevance to current clinical practice.

Both the included studies have some involvement (authorship/funding) from pharmaceutical companies.

Neither study had reported a sample size calculation so it is unclear if there was sufficient power to have confidence in the significant finding.

Bottom line

Flunixin in combination with local anaesthetic reduces the signs of pain in calves following surgical castration compared to local anaesthetic alone.

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

Webster HB, Morin D, Jarrell V, Shipley C, Brown L, Green A, Wallace R, Constable PD (2013) Effects of local anesthesia and flunixin meglumine on the acute cortisol response, behavior, and performance of young dairy calves undergoing surgical castration. Journal of Dairy Science 96:6285-6300.

 

Currah JM, Hendrick SH, Stookey JM (2009) The behavioral assessment and alleviation of pain associated with castration in beef calves treated with flunixin meglumine and caudal lidocaine epiduralanesthesia with epinephrine. Canadian Veterinary Journal 50:375-382.

About this BET

First author:
Rachel Dean
Second author:
Kathryn Wareham
Institution:

Centre for Evidence-based Veterinary Medicine, University of Nottingham

Search last performed:
2016-01-29 17:33:19
Original publication date:
2016-01-29 17:33:19
Last updated:
2016-01-29 17:33:19
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