Rein Forces In Double Bridles Versus Snaffle Bridles

There has been a huge amount of speculation concerning double bridles recently, with many suggesting that snaffles are “kinder” or “more gentle”. Last year, a large group of researchers, including myself, undertook a study to measure rein tensions and under-bridle pressures in 13 high-level dressage horses being ridden in both a double-bridle (DB) and a snaffle (SB). We presented the results for the first time at the British Equine Veterinary Association 2024 conference in Liverpool last weekend. 

Is there a difference in mean rein-forces for high-level dressage horses when ridden in a double bridle compared to a snaffle bridle? (2024)

D.J. Marlin, R. Murray, M. Fisher, D. Fisher, V. Walker, J. Williams, H. Clayton and R. MacKechnie-Guire. Equine Veterinary Journal, Volume 56, Issue S59, Supplement: Clinical Research Abstracts of the British Equine Veterinary Association Congress 2024, Pages 32-33.

Is there a difference in mean rein forces for high‐level dressage horses when ridden in a double bridle compared to a snaffle bridle? – 2024 – Equine Veterinary Journal – Wiley Online Library

The main findings were that:

• No difference between Double Brides (DB) and Snaffle Bridles (SB) in collected walk
• DB force was less than SB in sitting trot (see figure below)
• No difference between DB and SB in sitting canter
• Total force was lower for the curb bit than the bridoon bit in collected walk, sitting trot and sitting canter
• In all gaits, total force for the bridoon was lower than the snaffle bit

For under-bridle pressures, we found that: 

• There was no difference in mandibular pressures or horse movement symmetry in sitting trot
• The DB had lower mean and maximal dorsal nasal pressure values than the SB in sitting trot

In high-level dressage horses, does bridle type influence noseband pressures and movement symmetry parameters when ridden in a sitting trot? (2024)

R. MacKechnie-Guire, R. Murray, M. Fisher, D. Fisher, V. Walker, J. Williams, D.J. Marlin and H. Clayton. Equine Veterinary Journal, Volume 56, Issue S59, Supplement: Clinical Research Abstracts of the British Equine Veterinary Association Congress 2024, Pages 32-32.

In high‐level dressage horses, does bridle type influence noseband pressures and movement symmetry parameters when ridden in a sitting trot? – 2024 – Equine Veterinary Journal – Wiley Online Library

These studies are important as they illustrate why we should conduct research to provide evidence to understand the implications of decisions to support horse welfare. From this we cannot conclude that snaffle bridles are less severe than double bridles, at least in the hands of high-level riders on high-level dressage horses. 

Furthermore, rein-force is only part of the picture. Force divided by contact area equals pressure and this is what the horse experiences. The greater the contact area, the lower the pressure, provided the contact within the mouth is even (which we do not know if it is). Potentially, the double bridle, with greater contact area within the mouth could result in lower pressures on the tongue and bars. This is the focus of ongoing research.