Are Horses Stressed when Bitted for the First Time?

New research has found that introducing the bit to a young horse for the first time can be a stressful process for them. However, this stress could be difficult for most people to identify, as the horse may not show visible stress behaviours.

Introducing the bit is traditionally one of the most important training procedures in a young horse’s life. The majority of our performance horses are “bitted,” so this process forms a key part of the foundation training for many horses. Investigating procedures to optimise this introduction could lead to benefits in performance and, in some instances, improvements in welfare.

Many working horses exhibit expressions of mouth discomfort such as opening mouth, teeth grinding, or crossing the jaw when a bit is used and these behaviours could be indicative of pain or poor training. While there has been recent work investigating bit design for improved comfort in the horses’ mouth, there is little research surrounding the stress responses to the introduction of the bit for the first time.

A student dissertation project from Nicole Bradley at the Bishop Burton College in East Yorkshire, UK, led by Caroline Benoist, PhD, set out to assess the stress response of previously unbitted young horses to traditional bitting techniques.  Researcher Rebecca Brassington presented their findings at the 14th International Society of Equitation Science (ISES) conference in Rome in 2018.

Eleven horses – seven geldings and four mares – with an average age of 3.5, were introduced to the bit using a traditional method, over three consecutive days. The noseband and reins were removed from the bridles, leaving the bit attached to the head piece via the cheek pieces. The bits used were a mixture of single and double-jointed loose ring snaffles.

In all cases the handler stood facing forwards on the horses’ left side and presented the bit, then placed their thumb in the left corner of the horse’s mouth to cause the mouth to open so the bit could be introduced. All horses remained tied up using a headcollar and lead rope over the bridle for the first minute after bitting, they were then let loose in their stable for five minutes.

Several methods were used to assess each horse’s stress levels.

• Increases in eye temperature can indicate stress, so an infrared thermographic camera was used to measure the temperature of each horse’s left eye (ET).
• Thermographic images were taken immediately before bitting to establish the horse’s baseline, and then at zero, one, and five minutes post-bitting.