Evaluating the Science Behind Dually® Headcollars: Methodology Matters
The Dually Interpreted: Not So Intelligent Science
by Dr Veronica Fowler
A STUDY CLAIMED THAT THE DUALLY® HEADCOLLAR COULD ‘NEGATIVELY IMPACT WELFARE’ – BUT IS THIS JUST BAD SCIENCE?’
Our expert, DR. VERONICA FOWLER (PhD, MSc, BSc Hons), has spent more than 17 years leading research projects in the field of animal health and welfare, and has published more than 25 scientific papers in peer review journals, including the only two which have scientifically evaluated Monty Roberts’ methods using Monty as the trainer. Veronica is extremely passionate about progressing understanding of animal welfare using high quality scientific research, but is very concerned that poor scientific studies are being published in increasing numbers, and are being further disseminated in the equine press as fact without critique. In her new column, Veronica will break down some of the most talked about equine science studies and give Intelligent Horsemanship members a unique insight into why sometimes conclusions are much less conclusive than we might think…
This issue’s example of bad science really breaks my heart, not because it’s close to home – after all, I am not an advocate of any particular method or apparatus – but because the fundamentals of scientific methodology have been broken. With the very best intentions, a group of English equine college staff and students recently published a study investigating the effects of the Dually® on compliance, discomfort, and stress in horses during handling.
The paper concluded that the Dually® increased discomfort but did not increase behavioural compliance above that of a non-pressure headcollar setting. Should we be quantifying the welfare effects of pressure headcollars, such as the Dually®? Absolutely yes, since data in this area is lacking. However, are the conclusions of this study supported by correct methodology? No, unfortunately not! In the words of Ben Goldacre, “pulling bad science apart is the best teaching gimmick for explaining how good science works,” so here we go…
Positive Aspects of the Study
Firstly, there are some good points about this paper:
- The authors recruited a statistically valid number of horses.
- All horses had no prior training in the use of the Dually® at the start of this study (nice blank canvases).
- Respectably challenging handling tests were used (crossing a tarpaulin and walking under frilly strands of plastic).
- Objective (yet non-conventional) welfare measures were implemented (facial pain expression and eye temperature).
- Finally, the principles of how to use the pressure and release of the Dually® were correctly described.
Major Mistakes in the Study
However, unfortunately, two rather big mistakes were made:
- Incorrectly fitting the Dually® too low.
- Not schooling the horses on the principles of pressure and release prior to undertaking the handling tests.
Importance of Proper Fitting
The Dually® halter should be fitted so that the upper non-pressure noseband sits just below the cheekbones. This is so that the lower pressure noseband sits up on the bridge of the nose and not on the softer cartilage. In this current study, the authors fitted the Dually® approximately 2 inches too low.
Importance of Schooling
Like any piece of training/riding kit, a horse must learn the principles of what it means. Placing a saddle on a horse’s back does not mean that horse knows how to be ridden. Simply fitting a Dually® and then expecting immediate and magic increased compliance is an unreasonable hypothesis. The Dually® works using the well-defined concept of negative reinforcement – you get it right and pressure is released. Horses need to demonstrate an understanding of the use of the Dually® in being led forwards, sideward, and backwards with minimum pressure applied to the rope.
Conclusion of the Study
Because of these fundamental flaws, it can only be concluded from this paper that if you fit the Dually® too low, you increase facial pain expression, and if you don’t school your horse in its use, you will not get increased compliance. Obvious, right?
Now ask yourself, are you sure you are correctly fitting your Dually®? I do think that this is an important point that can be taken from this study and one that we should make sure we follow. After all, when interviewed, the lead researcher said she had been using a Dually® for years, clearly not fitted correctly.
Final Thoughts
Now to end on a high, despite the problems highlighted above, the authors showed that horses being led from the pressure ring of a Dually® do not experience increased stress when compared to being led using the standard non-pressure ring. In fact, the authors acknowledge that stress was actually less in horses being led using the pressure ring of a Dually®. I find this remarkable given the horses had to navigate a scary object course whilst being led using a Dually® which undoubtedly exerted unfamiliar pressure at higher intensities than should be possible if fitted correctly.
Now, just imagine the results which could and should have been achieved if the Dually® had been fitted correctly, and the horses had been schooled in its use!
Reference
Ijichi C, Tunstall S, Putt E, Squibb K. (2018) Dually® Noted: The effects of a pressure headcollar on compliance, discomfort, and stress in horses during handling. Applied Animal Behaviour Science. 205; 68-73.
Consider This…
Pressure headcollars are often employed to help in situations where the handler feels that they need a little more control or the horse needs a little extra guidance. It would therefore perhaps be more fitting to compare the welfare effects of a Dually® with other traditional methods for getting a horse to complete such tasks – for example, leading in a bit, a chifney, a thin rope halter, a nose chain, or using a whip.
