MCP / MTP joint: flexural deformity in Horses (Equis) | Vetlexicon
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MCP / MTP joint: flexural deformity

ISSN 2398-2977


Introduction

  • Common condition of growing horses in which the joint is held in an abnormally flexed position Musculoskeletal: flexural deformity.
  • Called “contracted tendons” which implies a defect in the tendon itself but this is incorrect in light of the proposed pathogenesis – this term should consequently be avoided.
  • Affects soft tissue structures and occurs in the sagittal plane.
  • Cause: relative shortening of the musculotendinous unit.
  • Signs: flexural deformity Musculoskeletal: flexural deformity:
    • Congenital: present at birth.
    • Acquired: develops during the growing phase.
  • Metacarpophalangeal joint more commonly affected than metatarsophalangeal joint in the acquired form but vice versa in the congenital presentation.
  • Diagnosis: physical examination.
  • Treatment: farriery, analgesics, controlled exercise, external coaptations, IV oxytetracycline/tetracycline Therapeutics: tetracyclines. Surgery may be warranted in chronic or severe cases.
  • Prognosis: good to poor depending on the degree of deformity, presentation and response to treatment.

Print off the factsheet on Flexural limb deformities to give to your clients.

Presenting signs

  • Flexural deformity of the fetlock joint/s. Other deformities may be present elsewhere in the limb/s.

Acute presentation

  • Can present at birth as a congenital defect.

Age predisposition

  • Congenital: present at birth.
  • Acquired: during the first 18 months – period of rapid growth. Acquired fetlock deformities in foals between birth and weaning are less common than those noted post weaning, when substantial and rapid growth occurs between 4 and 18 months of age (varies between breeds and with different management and feeding regimens).

Breed/species predisposition

  • Possibly more common in rapidly growing breeds.

Cost considerations

  • Cost of treatment.
  • Loss of use of animal.

Pathogenesis

Etiology

Proposed etiopathogenesis

  • Congenital:
    • Uterine malpositioning.
    • Abnormal development of fetus in mare due to:
      • Exposure to teratogens.
      • Dominant gene mutation.
      • Disease state or malnutrition in mare such as an influenza outbreak Equine influenza.
      • Neuromuscular disorder.
      • Majority of causes unknown.
  • Acquired:
    • Multifactoral and complex but several theories have been proposed:
      • A mismatch in bone and tendon/ligament growth associated with periods of rapid and excess growth. Overnutrition, incorrect nutrition including trace element or mineral imbalances, and genetics may play a part.
      • Contraction of the musculotendinous unit in response to pain in the affected leg decreasing normal weightbearing over a prolonged period. Pain can be related to physitis or other developmental orthopedic diseases in the young growing foal or yearling.
      • In the older developing animal and adult, the flexural deformity may also occur secondary to long term injury and subsequent disuse/weightbearing of the affected limb.
  • Described in adult horses secondary to desmitis of the ALDDFT Accessory ligament DDFT: forelimb – desmitis.

Pathophysiology

  • Shortening of the musculotendinous unit:
    • Although traditionally associated with the superficial digital flexor tendon (SDFT), flexural deformity of the fetlock joint often involves a number of tendons and associated ligaments.
    • Congenital deformities of the fetlock have been noted alongside carpal, and more commonly, distal interphalangeal flexural deformities.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Caldwell F J (2017) Flexural deformity of the distal interphalangeal joint. Vet Clin North Am Equine Pract 33 (2), 315-330 PubMed.
  • Gaughan E M (2017) Flexural limb deformities of the carpus and fetlock in foals. Vet Clin North Am Equine Pract 33 (2), 331-342 PubMed.
  • O’Grady S E (2017) Routine trimming and therapeutic farriery in foals. Vet Clin North Am Equine Pract 33 (2), 267-288 PubMed.
  • Levine D G (2015) The normal and abnormal equine neonatal musculoskeletal system. Vet Clin North Am Equine Pract 31 (3), 601-613 PubMed.
  • Kidd J A & Barr A R S (2002) Flexural deformities in foals. Equine Vet Educ 14, 311-321 VetMedResource.
  • Kidd J A (2002) A new method of splinting a congenital metatarsophalangeal flexural deformity in a foal. Equine Vet Educ 14, 308-310 WileyOnline.
  • Adams S B et al (1999) Management of flexural limb deformities in young horses. Equine Pract 21 (2), 9-15 VetMedResource.
  • McDiarmid A (1999) Acquired flexural deformity of the metacarpophalangeal joint in five horses associated with tendonous damage in the palmar metacarpus. Vet Rec 144, 475-478 PubMed.
  • Lokai M D (1992) Case selection for medical management of congenital flexural deformities in foals. Equine Pract 14 (4), 23-25 VetMedResource.