Bog Spavin

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Bog Spavin

Bog Spavin is a descriptive term for synovial effusion of the tarsocrural joint. The effusion is due to an acute or chronic low-grade synovitis which can come from any of several causes. Lameness is variable and depends upon the severity of the synovitis.

Bog Spavin is also known as Idiopathic Synovitis or Tarsocrural Effusion.

Tarsocrural joint effusion (bog spavin)- The arrows indicate significant effusion of the dorsomedial and plantarolateral joint pouches

Etiology

  1. Idiopathic
  2. Arthritis – chronic
  3. Conformational defect – too straight hock
  4. Injury to the hock joint as a result of quick stops, quick turns, or other trauma causes effusion due to injury of the joint capsule
  5. Deficiencies of calcium, phosphorus, vitamin A, or vitamin D, alone, or in any combination, apparently can produce bog spavin.
  6. Chronic zinc intoxication has also been implicated in TC effusion.

Clinical sign

  • TC effusion
  • There are 3 characteristic fluctuant swellings,
    • The largest of which is located at the dorsomedial aspect of the hock joint
    • Two smaller swellings occasionally occur on either side of the surface of the hock joint at the junction of the tibial tarsal and fibular tarsal bones.
  • Lameness, if present is due to synovitis

Diagnosis

  • Clinical signs
  • Ultrasound to evaluate synovial fluid
  • Radiography
  • CT
  • MRI

Treatment

  • Intra articular therapy – HA, steroids
  • Pressure bandage
  • Intra articular atropine
  • Treatment of bog spavin caused by nutritional deficiencies is usually of no avail unless proper corrections are made in the diet. If the deficient mineral(s) and/or vitamin(s) are added to the diet, the overall nutrition regulated, and the horse freed from internal parasites, bog spavins usually disappear in 4 to 6 weeks. Bog spavin resulting from nutritional causes is most common in horses 6 months to 2 years of age
  • Tarsocrural effusion due to chronic intoxication with zinc appears to respond to removal of the horse from the source of zinc and feeding a balanced ration supplemented with 60 grams of calcium carbonate/day.
  • Synovectomy may be useful when irreversible synovial membrane changes have occurred

Prognosis

  • Guarded if bog spavin due to trauma or nutritional deficiency
  • Unfavourable, in case conformatory defect
  • Good in majority of cases
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