Bit-related lesions research page
Main research findings and media in english
- Bit-related lesions (bruises and wounds) were common after a race or competition despite only six trotters out of 261 showed external mouth bleeding.
- Trotters had more lesions and lesions of greater severity than event horses. Bruises and wounds were find in 84% of the trotters and 52% of the event horses after a competition. Of the trotters 20% and event horses 4% had severe wounds in the bit area.
- Of the trotters 10% had blood on the bit or inside the mouth. Only one event horse of 208 examined had blood inside the mouth.
- The most common lesion locations were: inner lip commissure, bars of the mandible, buccal area near 106 and 206 teeth, outer lip commissure.
- Oral examination and the lesion
scoring system for bit-related lesions were suitable for field conditions.
recordings from lesions were more suitable than photographs for documenting
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.
event horses, thin or thick bits, mare sex, and breed other than pony were risk
wearing unjointed bits were at higher risk of sustaining bar lesions than
horses wearing jointed bits.
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
- Results encourage adopting bit area
monitoring as a new routine by horse handlers and as a welfare measure by
competition organizers in
order to minimize pain and negative experiences by early diagnosis and
treatment of mouth lesions. (For example 5% of the competition horses examined after a competition).
- 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 for performing reliable bit area examination
Bit-related lesions (wounds and bruises) are inside the mouth and
- don't usually bleed outside. Therefore lesions can only be found by adequate oral examination.
- It is important to perform the examination with the headlamp and to carefully examine
- the contralateral (opposite side) inner lip commissures by holding the tongue, bars, outer lip commissures, and rostral buccal area.
- Removal of all head equipment before the examination in trotters is critical.
- In riding horses the examination is preferable done without bit and bridle, however it is possible to perform examination reliably in competitions by opening the noseband and curb chain and lifting the bit.
- 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 mucosal fold is pulled rostrally with the finger.
- 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.
- 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.
- 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 2017 (4 min)
Research in Media
04/10/2021 The Study Shows: A Painful Surprise Hides Inside Many Equine Mouths. The Chronicle of The Horse USA, Lieser Sara
06/04/2021 Research finds over half horses studied had mouth lesions after cross-country. Horse and Hound, Britannia, Radford Sarah
01/04/2021 Acute mouth lesions seen in more that half of Eventing horses after cross-country - study. Horsetalk, Uusi-Seelanti
31/03/2021 Study: Bit-Related Lesions Found in 52% of Eventing Horses. The Horse, USA, Lesté-Lasserre Christa.
02/03/2021 Certain bit styles linked to more mouth injuries in trotters. Horsetalk. Uusi-Seelanti
25/02/2021 Study Finds High Rate of Bit-Related Lesions in Trotting Horses. The Horse, USA, Lesté-Lasserre Christa
5/2/2021 Are bits a welfare issue. Videoblog, USA, Raleigh Lilith.
11/08/2019 Bit injuries prevalent among Finnish trotters, study finds. Horsetalk, Uusi-Seelanti
Research funding - grants
Finnish Trotting and Breeding Agency (Suomen Hippos Ry)
Finnish Foundation of Veterinary Research
Finnish Veterinary Foundation (Mercedes Zachariassen Foundation)
Finnish Cultural Foundation (Pirkanmaa regional fund)
Orion Research Foundation
Juliana von Wendt Foundation
Heli Castrén grant (SEY Animal Welfare Finland)
Erkki Rajakoski Foundation
Doctoral School in Health Sciences, University of Helsinki
Finnish Veterinary Assocation - Animal Welfare Award 2021
Poster award 2nd place. 2021
Media in svedish, på svenska
14/05/2021 Skador i munnen hos mer än varannan tävlingshäst. Hippson, Bref, Sara
06/04/2021 Vanligt med bettrelaterade skador på tävlingshästar. Ridsport, Högdahl Susanne
23/06/2020 Chockerande studie om mun skador. Travronden, Engelbo Dennis
28/02/2020 Så undersöker du hästens munhåla. Hippson, Anna Nordin
13/10/2019 Är gapandet okej? Ridsport, Cecilia Stenshamn
20/09/2019 Över 80 procent av hästarna i studie hade bettrelaterade skador i munnen. Hippson, Ida Röök