The Science - ClipFitter

Quantitative assessment of pain associated behaviours of male lambs

“Overall, the data are supportive of ClipFitter as an alternative method of castration and tail docking that induces a lower pain response to use of rubber ring alone and equivalent to the use of pharmaceutical pain relief. Tissues were shed more quickly than with rubber rings, and the lesions EVID4 Evidence Project Final Report (Rev. 06/11) Page 3 of 23 and responses to palpation were equivalent or better than seen by other methods as applied in this study”

UK DEFRA Official Trial of ClipFitter 2022

Prof Cathy Dwyer explains the SRUC scientific trial results for ClipFitter & Numnuts

This Podcast session looks at pre-lambing decisions and features an insight from Dr Cathy Dwyer (SRUC Research), Fiona Crowden (SRUC Vets) and Lorna Shaw (SAC Consulting), as they share information, advice and latest thinking on lamb castration, lambing without antibiotics and pre-lambing nutrition.

Please Note ClipFitter was known as ClampEasy in trials work (CE)

Charted data summarises results and helps clarify

Listen to the relevant part of the Podcast

There had to be a more humane alternative to rubber rings – Evidence submitted to AWC 2022

More than 20 years ago we showed that lambs of all ages suffered severe pain for up to 2 hours after castration with tight rubber rings.

We also showed that this (acute) early pain could be followed by chronic inflammation and evidence of pain for up to 6 weeks as the scrotum and its contents became necrotic and fell off.

We went on to show that the early pain could be greatly reduced by injection of local anaesthetic at the time of castration and that sheep farmers could obtain similar reductions in pain, at least in ‘lowland’ lambs of < 1 week.

An alternative is required, one which sheep farmers will prefer to rubber rings and will enthusiastically adopt. This is a very ambitious target, because rubber rings are so cheap, quick/easy to apply and are reliably effective.

We tried (2012) to improve rubber rings so that they would produce rapid anaesthesia, as can be achieved with a Burdizzo clamp. We did not succeed and concluded that rubber castration rings could not be made to achieve the necessary crushing pressure.

However, we thought that the necessary crushing pressure might be achieved with a disposable castration clamp and this has evolved into the practical and potentially commercially viable solution called CLAMPEASY (ClipFitter).

Evidence submitted to AWC

Opinion on the Implications of Castration and Tail Docking for the Welfare of Lambs

The late Peter Jinman chaired the Animal Welfare Committee when they examined all the evidence they could uncover on the topic of Castration and Tail Docking of Lambs, in 2022. Their role was to advise UK Gov, DEFRA, on the future of a long (60 years) debated animal welfare topic.

AWC Report on the future of Castration & Tail Docking of Lambs

Trials on Calf Castration with ClipFitter – Kansas State University

Prof Bortoluzzi reported in March 2025

“We are currently in the process of putting together a presentation from the trial we used the ClipFitter last year to present internally on our Phi Zeta Research Day at K-State. Unfortunately, due to funding restrictions we were only able to follow them for 7 days and I would like to follow them for longer until the scrotum sloughs off. What we noticed on our longer trials is that with banding the blood flow restrictions in the first week causes discomfort but latter when the band cut through the tissues, we continue to see discomfort behaviors.

With the ClipFitter we were able to find that temperature of scrotum decreases significantly by 168 hours post castration compared to calves that where not castrated.

I will continue to update you as we move forward with presentations and possible publication. Regarding new trials, I am still looking for available funding to support future studies. Right now, US grant funding is paused due to changes in the government. So, we are uncertain of when this will be made available again.”

Calf Castration at Kansas State University

Our Own Summary of the Science and our Project prospects

This confidential research submission outlines the development and trials of a novel clamp system designed as a practical, more humane alternative to rubber rings for lamb castration. The study, led by Professor V. Molony of the University of Edinburgh with Brian Eadie and Brian Falconer, compared the new clamp to conventional methods.

Results showed the novel clamp caused dramatically less pain than rubber ring castration — reducing average pain behaviour scores from 239.5 (rubber ring) to just 18.8. Healing was clean, recovery was rapid, and performance was unaffected.

Developed in Scotland, the project focused on creating a lightweight, biodegradable, quick-loading clamp and an applicator suitable for farm use. The research concluded that, if refined for practical on-farm handling, this method could allow farmers to castrate lambs humanely and efficiently, without the severe pain associated with rubber rings.