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Bit-related lesions research page 

Research findings and media in english

Main research findings 2017-2022

  1. Bit-related lesions were common after a race or competition despite only six trotters showed external mouth bleeding.
  2. The most common lesion locations were: inner lip commissure, bars of the mandible, buccal area near 106 and 206 teeth, outer lip commissure.
  3. Trotters had more lesions and lesions of greater severity than event horses.
  4. Oral examination and the lesion scoring system for bit-related lesions were suitable for field conditions.
  5. Video recordings from lesions were more suitable than photographs for documenting oral lesions.
  6. Crescendo bit, unjointed mullen mouth regulator bit, and straight plastic bit (model Happy Mouth) and female sex (mare) were recognized as risk factors for moderate or severe oral lesions in trotters.
  7. In event horses, thin or thick bits, mare sex, and breed other than pony were risk factors.
  8. Horses wearing unjointed bits were at higher risk of sustaining bar lesions than horses wearing jointed bits.
  9. Results may at least partly reflect driveability or rideability issues, and thus, rein tension differences because drivers or riders may change to distinctive bit designs if they have difficulty eliciting an appropriate response with rein cues.
  10. Results encourage adopting bit area monitoring as a new routine by horse handlers and as a welfare measure by competition organizers.
  11. The pilot questionnaire study on "Horse industry stakeholders' attitudes towards bit-related lesions in harness racing horses"" indicated differences in attitudes towards bit-related lesions between stakeholder groups but also within a group. This might reflect differences in conflicts of interests, moral values, empathy, or over-exposure to oral lesions. Not removing horses with severe oral lesions from the race may compromise horse welfare and undermine trust in the surveillance system.

Critical points when examining horses mouth to find possible bit-related lesions

Bit-related lesions (wounds and bruises) are inside the mouth and (1) don't usually bleed outside. It is important to perform the examination (2) with the headlamp and to carefully examine the (3) contralateral  (opposite side) inner lip commissures by holding the tongue, bars, outer lip commissures, and rostral buccal area. (4) Removal of all head equipment before the examination in trotters and (5) opening the noseband and curb chain in riding horses  is critical for a reliable visual inspection. (6) Careful palpation and visual assessment of the bars and the area in front of the lower cheek teeth is necessary since some of the bar lesions are hidden behind swollen mucosal folds and thick mucus. In some cases, bar lesions may become visible only after the (7) mucosal fold is pulled rostrally with the finger. 

Bit-related lesions and risk factors in competing trotters and event horses - thesis


Peer-reviewed publications

  1. Tuomola, K., Mäki-Kihniä, N., Kujala-Wirth, M., Mykkänen, A., and Valros, A. (2019) Oral Lesions in the Bit Area in Finnish Trotters After a Race: Lesion Evaluation, Scoring and Occurrence. Front. Vet. Sci. 6:206. doi: 10.3389/fvets.2019.00206.
  2. Tuomola, K., Mäki-Kihniä, N., Valros, A., Mykkänen, A., and Kujala-Wirth, M. (2021) Risk factors for bit-related lesions in Finnish trotting horses. Equine Vet J. 53: 1132- 1140. doi: 10.1111/evj.13401.
  3. Tuomola, K., Mäki-Kihniä, N., Valros, A., Mykkänen, A., and Kujala-Wirth, M. (2021) Bit-related lesions in event horses after a cross-country test Front. Vet. Sci. 8:651160. doi: 10.3389/fvets.2021.651160.

Mouth examination video 4 min 2017

Research in Media

Mouth examination instructions in pdf

EVJ Infographics

ISES congress 2022 Poster, Hartpury UK

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