Surveys and Population Studies
Radiological prevalence of equine odontoclastic tooth resorption
* , W. SCHR
, C. STASZYK
and C. LISCHER
Equine Clinic: Surgery and Radiology, Department of Veterinary Medicine, Freie Universit
at Berlin, Berlin, Germany
arztliche Klinik f
ur Pferde und Kleintiere Isernhagen, Isernhagen, Germany
Institute of Veterinary Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, Justus-Liebig-University Giessen, Giessen, Germany.
*Correspondence email: firstname.lastname@example.org; Received: 29.06.17; Accepted: 11.10.17
Background: Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a painful and progressive dental disease that mainly affects the
incisors and canine teeth of aged horses. Diagnosis is based on radiographs to detect early stages of the disease. EOTRH is probably underdiagnosed
and its prevalence in Germany unknown.
Objective: This study was performed to determine the radiological prevalence of EOTRH in a large horse population in Berlin-Brandenburg, Germany.
Study design: Prevalence study.
Methods: The study population (142 horses) consisted of all horses 10 years and older that were presented at the Equine Hospital for a routine dental
examination. The horses were either presented as clinical cases (CC population) or belonged to a riding school (RS population). Digital radiographs of
the incisor dentition were taken and evaluated for changes related to EOTRH, leading to an overall classiﬁcation for each horse.
Results: The mean age of the study population was 21 years and ranged from 10 to 37 years. Overall, 94% of all horses had at least minor and 62% had
moderate to severe radiological changes of the incisor teeth associated to EOTRH. No horse older than 14 years was without radiological signs of
EOTRH and all horses over 28 years of age had at least moderate radiological changes of the incisor teeth.
Main limitations: The clinical cases group might have a bias towards horses with existing dental problems such as EOTRH, because they were
presented explicitly for dental care to a clinic.
Conclusion: Focusing on radiological changes, this study shows that EOTRH is a common condition of horses in Berlin-Brandenburg. With older age,
disease is more frequent and radiological changes become more severe. Since no horse older than 14 years was without radiological ﬁndings, it is likely
that mild changes may be associated with the normal tooth ageing process.
Keywords: horse; dentistry; incisors; teeth; EOTRH; prevalence
Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a
painful disease primarily affecting equine incisor and canine teeth. The
condition is histopathologically characterised by concomitant occurrence
of resorption lesions and massive deposition of reparative cementum
(hypercementosis) at the reserve crown. The surrounding periodontal
tissues, periodontal ligament and alveolar bone show typical signs of
inﬂammation [1–8]. Horses presenting with EOTRH may clinically show
varying degrees of oral pain, periodontitis, gingivitis, gingival hyperplasia or
recession, ﬁstulas often in combination with a focal subepithelial swelling
(referred to as parulis or gum boils), bulbous enlargement of dental
structures, tooth mobility, tooth fractures and missing teeth [8,9].
Radiographic ﬁndings typically include different levels of dental resorption
and hypercementosis, loss of periodontal ligament space, alveolar bone
loss, osteomyelitis and tooth fractures [8,9].
Concurrent appearance of resorptive lesions and hypercementosis is the
common ﬁnding in EOTRH, as well as in the human disease MIRR (multiple
idiopathic root resorption ), and the feline syndrome FORL (feline
odontoclastic resorptive lesions [11–13]). However, in equine teeth,
hypercementosis proportionally exceeds that found in human and feline
teeth. While the prevalence of the resorptive lesions is assessed to be very
low in humans , epidemiological studies have shown that up to 75% of
cats are affected [11,15].
The aetiology of EOTRH remains unclear. However, it seems to have a
correlation with the tooth age and is considered to be multifactorial
[6,16,17]. Staszyk et al.  proposed mechanical stress of the periodontal
ligaments in older horses with shorter reserve crowns as an initiation
factor, which was recently conﬁrmed more detailed by Schrock et al.
The interest of veterinarians and dental practitioners towards this
progressive dental condition is increasing as it reduces the quality of life of
the affected horses. So far, the focus of most research projects lays on the
clinical and radiographic presentation of clinically diseased horses, or on
elucidating aetiological approaches. However, since cases are usually
presented with obvious clinical ﬁndings, when radiological changes are
already advanced, the disease seems to be underdiagnosed. Recently,
Henry et al.  have determined the radiological prevalences of tooth
resorption and hypercementosis in a North American horse population.
However, the prevalence of EOTRH in Germany is unknown. Therefore, the
present study includes not only clinical cases, but also a riding school
It has already been shown that full-mouth radiography is the best way to
detect early stages of FORL in cats and MIRR in human patients [14,19], as
well as tooth resorption in dogs . Hence, we designed this study with
focus on radiological changes to determine the radiological prevalence of
EOTRH in a large horse population in Berlin-Brandenburg.
Materials and methods
All horses which were presented for routine dental care at the Equine
Hospital of the Freie Universit
at Berlin (FU Berlin) from March 2011 to
December 2014 were included in the study if they were at least 10 years
old and the owner gave written consent to the participation in our study,
including the taking of x-ray images of their horses’ incisor teeth. A total of
142 horses met those criteria and could be included in the study. The
study population consisted of two subpopulations. Horses were either
routine clinical cases (CC population) being brought to our clinic and
presented to a dental veterinarian by their owner or they belonged to a
riding school (RS population). Since the horses of the riding school were all
in need of routine dental care, all horses being at least 10 years old could
be included. In addition to the distinction by population or sex, the horses
were divided by age into two groups (age group 1: 10–20 years; age
Equine Veterinary Journal 50 (2018) 481–487 © 2017 EVJ Ltd
Equine Veterinary Journal ISSN 0425-1644