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Basics ⬇

Outline

BASICS

Definition!!navigator!!

PD is an equine oral disorder that compromises the structures supporting the teeth, namely the periodontal ligament, the gingiva, the alveolar bone, and the cementum.

Pathophysiology!!navigator!!

  • The predisposing feature of PD is food sequestrating in the interproximal space
  • Diastemata (valve/open) or abnormal gaps between cheek teeth (due to supernumerary, displaced, or rotated teeth) are commonly observed in conjunction with PD. Valve diastemata are more prevalent and are associated with more severe PD than open diastemata
  • Food material that becomes impacted incites focal gingivitis, leading to the development of a gingival sulcus. Impacted feed undergoes decay and bacterial fermentation (Prevotella spp. and Veillonella spp.), causing progressive destruction of the periodontal ligament and the alveolar bone, providing space for the impacted food to travel more deeply, advancing tooth destruction, and decreasing tooth support. Apical migration of the infection may result in periapical infection, abscess formation, and tooth root necrosis
  • Equine PD may be secondary to abnormalities in dental wear. These abnormalities include step, shear, or wave mouth; missing or unopposed teeth, and hooks and ramps, which generate unevenly distributed forces, resulting in separation of the normally tightly aligned adjacent teeth
  • Horses with mandibular or maxillary fractures can develop PD as a result of exposure of the periodontium to food material and as a result of alterations to normal mastication
  • Transient PD associated with emerging dentition may occur in the immature equine mouth if food gets trapped around improperly shed deciduous teeth. Gingivitis and periodontitis resolve when the permanent teeth come into wear

Systems Affected!!navigator!!

  • Gastrointestinal
  • Musculoskeletal
  • Respiratory (sinusitis)

Genetics!!navigator!!

N/A

Incidence/Prevalence!!navigator!!

The prevalence in the general equine population is reported to be 50%. In horses >15 years a prevalence of up to 60% has been described.

Signalment!!navigator!!

PD occurs more frequently in mature animals. Disease as a result of retained deciduous teeth usually occurs between 2.5 and 4 years of age.

Signs!!navigator!!

Oral pain including slow eating, dysmastication, oral dysphagia (quidding), hypersalivation, halitosis, anorexia, and weight loss. In the very early stages of disease no clinical signs may be present; however, changes will be observed during routine dental prophylaxis. If secondary maxillary sinusitis is present owing to oro-sinus fistulation purulent, malodorous nasal discharge, epiphora, and facial swelling may also be noted. Subtler clinical signs indicating oral pain may include head shyness, harness resentment, and resistance to the rider.

Risk Factors!!navigator!!

  • Domestic feeding practices and processed feeds often lead to abnormal mastication and decreased salivary fluid production, with resultant abnormality of wear and lowered local mechanical defense function, respectively
  • Various conformational abnormalities become more common in geriatric horses; in addition, as horses age, there is progressive exposure of the reserve crown and consequently a less secure apposition between adjacent teeth
  • Cushing syndrome and other systemic conditions that may alter immune function

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

Numerous pathologies of the oral cavity may lead to the clinical signs observed in conjunction with PD, highlighting the need for a very thorough oral examination.

CBC/Biochemistry/Urinalysis!!navigator!!

Nonspecific

Other Laboratory Tests!!navigator!!

N/A

Imaging!!navigator!!

Oral radiographs, especially open-mouthed oblique views of the teeth, may identify changes. Changes include destruction of the periodontal ligament as a loss of definition of the radiolucent ligament. Changes to the alveolus include bone lysis and sclerosis extending apically as far as the tooth roots as well as clubbing of tooth roots in more advanced cases. Other radiographic abnormalities include soft tissue densities and fluid lines in the sinuses. Many cases will require CT to identify the affected cheek teeth.

Other Diagnostic Procedures!!navigator!!

  • A general physical examination, a close examination of the head structures, and a thorough oral examination with the horse restrained in stocks well sedated using a full mouth speculum and a good light source is performed. Rinsing the oral cavity is recommended after initial examination with a gag in place; this will allow assessment of areas of impacted or pocketed feed prior to their displacement
  • Use of a dental mirror is inevitable for the evaluation of the buccal, lingual, and interproximal spaces of the cheek teeth. Oral endoscopy greatly enhances the assessment of the disorder and may also be helpful in measuring periodontal pocket depth
  • Palpation of the gingiva can identify areas of swelling, hyperemia, recession, and pain. A gingival probe may be used to measure the depth of the periodontal pocket and a dental pick to identify loose teeth

Pathologic Findings!!navigator!!

Histopathologically gingival erosion and ulceration, neutrophilic exudate, bacterial rods, cocci, and spirochetes were found. Interestingly changes of the periodontal ligament were only mild and not deemed irreversible, highlighting the potential of this ligament to recover from mild disease.

Treatment ⬆ ⬇

Outline

TREATMENT

Appropriate Health Care!!navigator!!

  • Debridement of food from the periodontal pockets is necessary so the gingival inflammation can regress and healing can commence. This may be done using high-pressure water and air, dental picks, and forceps (initially every 2 weeks and depending on the course of disease may be repeated every 2–3 months). Deposition of subgingival antibiotics or padding of the periodontal pocket with dental filling material, even though not evidence based, is performed by some clinicians. Widening (odontoplasty) of valve diastemata or areas of close interproximal contact is beneficial when feed material cannot be freed. Following odontoplasty feed material may be cleared from widened spaces during normal mastication
  • Abnormalities in dental wear are addressed by promoting normal masticatory activity. Appropriate crown reduction and thereby reduced occlusion of an affected tooth will reduce abnormal forces and diminish pain. In cases of severe PD a loose tooth may have to be extracted

Nursing Care!!navigator!!

N/A

Activity!!navigator!!

N/A

Diet!!navigator!!

Lateral excursion of the mandible, which is important for normal dental wear, is associated with fiber length. Adequate dietary roughage is therefore important for the prevention of PD.

Client Education!!navigator!!

PD is very common in older horses. Routine dental prophylaxis is the best method for preventing PD and should be performed annually or even biannually.

Surgical Considerations!!navigator!!

Standing tooth extraction is the method of choice. Alternative approaches in cases of fractured crowns include a minimally invasive buccotomy with screw extraction, intraoral tooth segmentation, or minimally invasive trephination and repulsion using Steinmann pins. Retrograde repulsion was traditionally widely practiced, but owing to the damage to the dental alveolus the above-mentioned minimally invasive techniques should be used. Postoperative radiography and/or oral endoscopy, confirming complete tooth removal, is recommended. Following tooth extraction, the resulting defect can be packed with swabs, dental wax, or similar to prevent feed impaction in the alveolus. In cases of secondary sinusitis following oro-sinus fistulation, the fistula should be debrided; local treatment is clinician dependent (honey, antiseptics, platelet-rich plasma), and sealing the alveolus from the oral cavity is a crucial step in the healing process. Sinus trephination and lavage should be performed and treatment with systemic antimicrobials may be necessary.

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Sedatives either per bolus injections or by constant rate infusion are required to complete a thorough and safe oral examination. α2-Agonists provide adequate sedation. Premedication with acepromazine and the addition of an opioid can increase the reliability of the sedation achieved
  • NSAIDs administered prior to extensive dental work helps to minimize discomfort both during and after dental treatment
  • Systemic antibiotics are unlikely to halt progression of PD without removal of the underlying cause. Some clinicians advocate the use of antimicrobials subgingivally in affected areas

Contraindications!!navigator!!

N/A

Precautions!!navigator!!

N/A

Possible Interactions!!navigator!!

N/A

Alternative Drugs!!navigator!!

N/A

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

Weight gain in horses with ill thrift should be monitored and is often impressive following successful treatment of PD. Mastication and feed intake should be monitored.

Prevention/Avoidance!!navigator!!

Regular dental prophylaxis can prevent the formation of dental conformational abnormalities as a result of abnormal wear. Feeding diets with adequate roughage may decrease abnormal dental wear.

Possible Complications!!navigator!!

Improper odontoplasty may lead to iatrogenic damage of pulp cavities. Following oral tooth extraction complications are few and may include sequestrum formation from a piece of alveolus, unextracted tooth fragments, or feed impaction in the vacated alveolus due to swab/dental wax dislodgment. There is mesial drift of the teeth distal to the vacated alveolus and supereruption of the opposing tooth demanding regular corrective dentistry (annually or biannually).

Expected Course and Prognosis!!navigator!!

Conservative treatment consisting of regular dental floating and a high-quality roughage diet may successfully manage PD. The condition is generally considered progressive. In 202 horses with associated severe PD odontoplasty led to permanent remission of clinical signs in 50%, temporary remission in 22% of the cases, and a partial response in 17% of the cases. Tooth extraction may be necessary in advanced cases (with loose teeth) to successfully resolve the disease. Often mild PD in younger horses, with malocclusion due to abnormalities of permanent tooth eruption or mild abnormalities of dental wear, is reversible following resolution of the underlying cause.

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

Ill thrift and weight loss are commonly associated with PD.

Age-Related Factors!!navigator!!

As horses age, the reserve crown is exposed and the gap between adjacent teeth increases. This increases the potential for feed to become impacted between adjacent teeth.

Synonyms!!navigator!!

  • Gingivitis
  • Periodontitis

Abbreviations!!navigator!!

  • CT = computed tomography
  • NSAID = nonsteroidal anti-inflammatory drug
  • PD = periodontal disease

Authors Andrea S. Bischofberger and Felix Theiss

Consulting Editors Henry Stämpfli and Olimpo Oliver-Espinosa

Acknowledgment The authors and editors acknowledge the prior contribution of Hugo Hilton.

Suggested Reading ⬆ ⬇

Dixon PM, Ceen S, Barnett T, et al. A long-term study on the clinical effects of mechanical widening of cheek teeth diastemata for treatment of periodontitis in 202 horses (2008-2011). Equine Vet J 2014;46(1):76–80.

Additional Further Reading ⬆

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