EOTRH – What Are We Looking for?

What is equine odontoclastic tooth resorption and hypercementosis (EOTRH)?

• This is a progressive and irreversible condition affecting the
• incisors and canines, and rarely the cheek teeth
• First recognised in 2004
• Presentation: swellings and/or draining tracts associated with
• the incisors
• Painful! Debilitating
• Most cases are seen in horses >14 years
• Similar clinical presentations described in cats (FORL) and
• humans (MIRR)
• It involves two processes:
  • Resorption of both tooth and bone: similar to cats/dogs/ humans
  • Hypercementosis: unique to equines, likely a reparative response

What causes EOTRH?

• Aetiology is unclear – likely multifactorial
• Hypotheses:
  • Immune-mediated syndrome
  • Mechanical stress on periodontal ligament increasing with age. Older teeth have proportionally less periodontal relative to occlusal surface (no occlusal forces on canines..?)
  • Treponema and Tanerella spp. – possible role o Dental tissue destruction
  • Cementum deposition (repair)
• Recently described condition of horses aged 14 and over which may present with swelling and/or draining tracts over multiple mandibular and maxillary incisors

Diagnosing EOTRH

Spectrum of clinical presentation:

• Clinical appearance and signs are highly variable. The condition is quite commonly identified incidentally
• Some of these horses are painful and have difficulty prehending food
  • ‘Carrot test’... variable reliability
  • Weight loss
  • Worse in grazing season/with haynets
  • Periodic inappetence
• Some are very painful on palpation, may have biting issues or signs of head-shaking
• Hypersalivation, halitosis
• BEWARE: some are very stoical... may be asymptomatic even with severe lesions
• Incisor/canine periodontal disease
  • Periodontitis/gingivitis
  • Gingival recession/hyperplasia
  • Calculus accumulation
• Gingival abscessation
  • ‘Gum boils’ (submucosal swellings)
  • Draining tracts
  • Probing may elicit teeth chattering/pain response
•  Firm submucosal bulbous enlargement of the roots
• Mobile/fractured/absent teeth
• Tends to begin at the corner incisors and progress mesially

Disease manifestations

• Predominantly tooth resorption, or
• Predominantly hypercementosis, or
• Combination of resorption and hypercementosis

Radiography

• Radiographically there is a huge spectrum of disease with some horses having mainly lytic changes whereas some have mainly hypercementosis
• When clinical signs are apparent, the radiographic changes will be advanced. Screening images will help to identify subclinical cases with clinically relevant disease
• Intraoral images:
  • Widening of the periodontal space
  • Intra-alveolar tooth resorption
  • Bulbous/blunted roots – cemental deposition o Pathological fracture

Resorption grading

The American College of Veterinary Dentistry classification of tooth resorption is a useful tool in planning treatment strategies and monitoring disease progression:

• Stage 1: Mild loss of hard dental tissue – cementum/ cementum + enamel
• Stage 2: Moderate loss of hard dental tissue – includes loss of dentine, pulp not involved
• Stage 3: Advanced loss of hard dental tissue – dentine loss extends to pulp. Tooth mostly intact
• Stage 4: Extensive loss of hard dental tissue – marked loss of tooth integrity
  • Stage 4A: crown + root equally affected
  • Stage 4B: crown more severely affected than root
  • Stage 4C: root more severely affected than crown
• Stage 5: only dental remnants remain, covered by gingiva. Rare in horses.

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