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Foot: keratoma

pequis

Introduction

  • Cause: abnormal keratinization of hoof wall Hoof: keratoma 01due to either hyperplasia or benign neoplasia.
  • Signs: lameness Musculoskeletal: gait evaluation due to pressure on sensitive laminae, distal phalanx and other deeper structures in the foot; irregularity of white line, misshapen hoof wall at toe, quarters or sole Foot / shoe: examination; may be fistulous tract(s) with secondary bacterial infection. Some cases show no external evidence (radiographic changes can be seen in the pedal bone).
  • Diagnosis: lameness examination, radiography Forelimb: radiography Distal phalanx: normal - DPrPaDiO radiograph- locally increased density of hoof wall, loss of density in third phalanx. Characteristic pressure atrophy of P3 adjacent to keratoma and also change in white line at that point. CT/MRI is useful to help achieve diagnosis and pre-surgical planning.
  • Treatment: surgery - to remove growth Hoof: keratoma 02 - pathology; protect hoof afterwards with bandaging and shoe (repair hoof wall defect with prosthetic material Hoof: repair 03 - filling defectHoof: repair 05 - defect filled).
  • Prognosis: guarded - may recur if incompletely excised.
Print off the Owner factsheets on Caring for your horse's feet and Keratoma - foot tumour to give to your clients.

Pathogenesis

Etiology

  • Aberrant keratin mass(es) that originate from the coronary band.
  • Caused by chronic irritation of laminae as a result of injury or infection, or a form of benign neoplasia.

Specific

  • Injury.
  • Infection.
  • Foreign body.

Pathophysiology

  • Some controversy exists in the literature regarding the precise etiology and pathophysiology of keratomas.
  • There is an abnormal proliferation or hyperplasia of keratinized tissue on the inner surface of the hoof wall (epidermal horn-producing cells) usually at the coronary band (stratum germinativum). Very occasionally they can originate further down the inner hoof wall or from the sole. The cause is not always clear but includes chronic irritation of laminae as a result of injury or infection, or benign neoplastic proliferation.
  • Commonly originates near coronary band and, as the abnormal horn tubules grow distally towards the toe, can extend to solar surface of foot at the white line.
  • Usually found at toe, or occasionally quarter, of foot from coronary band to sole or anywhere in between.
  • Lameness is due to enlarging keratoma in confined space between inner hoof wall and P3 exerting pressure on sensitive laminae and underlying P3; initially intermittent but progressively persistent and worsening.
  • Abnormal hoof growth → bulge in hoof wall, often starting at coronary band; focal thickening or inward deviation of white line of hoof.
  • Occasionally the core is necrotic or there is secondary bacterial infection allowed into the foot around the mass → purulent exudate at coronary band or sole - chronic or with intermittent flare-ups.
  • Chronic discharging tracts may form at the coronary band that can be confused with septic white line disease Foot: white line disease, subsolar abscesses Foot: subsolar abscess / infection or quittor Foot: lateral cartilage inflammation (quittor).

Timecourse

  • Often a prolonged history with intermittent flare-ups initially thought to be simple recurrent foot abscessation.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Gasiorowski J C et al (2011) Supracoronary approach for keratoma removal in horses: two cases. Equine Vet Educ 23, 489-493 VetMedResource.
  • Cullimore A & Booth T (2010) Clinical aspects of the equine foot. Part 5: Equine keratoma. UK Vet 15 (2), 11-15 VetMedResource.
  • Brounts S H, Adams S B, Vemireddi V & Holland C H (2008) A malignant glomus tumor in the foot of a horse. Equine Vet Educ 20 (1), 24-27 VetMedResource.
  • Back W, van Schie M J J & Bosch G (2007) Keratoma and its cutting edges. Equine Vet Educ 19 (6), 288-289 VetMedResource.
  • McDiarmid A (2007) Keratoma from the frog corium of a horse. Equine Vet Edu19 (6), 285-287 VetMedResource.
  • Boys Smith S J et al (2006) Complete and partial hoof wall resection for keratoma removal: post-operative complications and final outcome in 26 horses (1994-2004). Equine Vet J 38 (2), 127-133 PubMed.
  • O'Grady S E & Horne P A (2001) Lameness caused by solar keratoma: a challenging differential diagnosis. Equine Vet Educ 12, 286-291 VetMedResource.
  • Chan C C et al (1997) Treatment of keratoma in a Clydesdale horse. Vet Rec 140 (17), 453-456 PubMed.
  • Hamir A N et al (1992) Equine keratoma. J Vet Diagn Invest (1), 99-100 PubMed.
  • Seahorn T L et al (1992) Ultrasonographic imaging of a keratoma in a horse. JAVMA 200 (12), 1973-1974 PubMed.
  • Honnas C M (1991) Standing surgical procedures of the foot. Vet Clin North Am Equine Pract (3), 695-722 PubMed.
  • Berry C R et al (1991) Squamous cell carcinoma of the hoof wall in a stallion. JAVMA 199 (1), 90-92 PubMed.
  • Reeves M J et al (1989) Miscellaneous conditions of the equine foot. Vet Clin North Am Equine Pract (1), 221-242 PubMed.
  • Lloyd K C et al (1988) Keratomas in horses: 7 cases (1975-1986). JAVMA 193 (8), 967-970 PubMed.

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