Radiographic Evaluation of Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH) in Horses Living Under Natural Conditions in Iceland.

Overview

• This study investigated the presence and severity of Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH) in older Icelandic horses living in natural conditions in Iceland, using radiographic and clinical examinations.
• The findings suggest that while age-related dental changes occur, the prevalence and severity of EOTRH are low in Icelandic horses grazing mostly on natural pasture, especially when compared to populations living in Germany.

Background and Objectives

• EOTRH is a dental disease affecting horses, characterized by tooth root resorption and excessive cementum deposition.
• The Icelandic horse breed, outside Iceland, is known to be prone to developing EOTRH, often with significant clinical signs.
• This study aimed to determine:
• The prevalence of radiographic signs consistent with EOTRH in elderly Icelandic horses (aged 15-30) living in Iceland.
• The clinical signs associated with the disease in this population.
• Any relevant husbandry, nutritional, or environmental factors possibly impacting disease prevalence.

Methods

• Participants: 170 elderly Icelandic horses (ages 15 to 30 years) living under natural grazing conditions in Iceland.
• Clinical Examination: The rostral (front) oral cavity of each horse was visually and physically inspected for clinical signs related to EOTRH such as fistulae, root enlargement, or tooth mobility.
• Radiographic Evaluation: Radiographs of 188 horses were taken from 2 to 4 different views to identify early or advanced stages of EOTRH.
• Data Collection: Information about management practices, including grazing duration and nutrition, was collected through questionnaires completed by horse owners or handlers.
• Data Analysis: Radiographic images were classified according to a numerical staging system for EOTRH severity. These stages were then correlated with clinical examinations and management data.
• Comparative Analysis: The results were compared to a similar population of Icelandic horses living in Germany to assess differences in disease prevalence.

Results

• Prevalence of Radiographic Changes:
  • 45.7% of horses had no radiographic changes indicating EOTRH.
  • 26.6% were suspicious for early EOTRH changes.
  • Another 26.6% showed mild radiographic stages of EOTRH.
  • Only 1.1% showed moderate radiographic signs.
  • No horses exhibited severe stage radiographic changes.
• Clinical Signs:
  • No horses showed clinical signs commonly associated with EOTRH, such as fistula formation, bulbous root enlargement, or tooth mobility.
• Age Association:
  • Radiographic signs increased with age, indicating changes were likely part of normal aging rather than pathological EOTRH.
• Environmental and Management Factors:
  • 82.4% of Icelandic horses spent most (9-12 months) of the year grazing on natural pasture.
• Comparison to Germany:
  • The risk of developing EOTRH was 7.8 times lower for horses living in Iceland compared to those living in Germany.
  • These findings suggest that the natural environment and lifestyle in Iceland may protect against EOTRH development.

Conclusions and Implications

• While mild age-related radiographic changes to the teeth were observed, true clinical EOTRH was rare or absent in Icelandic horses living in natural grazing conditions in Iceland.
• The significantly lower prevalence compared to the same breed in Germany suggests environmental factors such as natural grazing and husbandry methods play an important role in disease development.
• This study highlights the importance of considering lifestyle and environment when evaluating dental health and disease risk in horses.
• Further studies could explore specific environmental or dietary factors in Iceland contributing to protection from EOTRH.
• Veterinarians managing Icelandic horses abroad might consider these findings when diagnosing and treating dental diseases.