Intrauterine Malpositioning

• If a foal grows too large for the mare's uterus, or is positioned awkwardly in the womb, it may develop contracted tendons.
  
  

Bony Malformations

• When a foal's skeletal system develops abnormally, the tendon and muscle structure may also grow incorrectly, resulting in contracted tendons.
  
  

Ingestion of Certain Plants During Pregnancy

• According to the University of Illinois report, there have been documented cases of contracted tendons in foals whose dams ingested either locoweed or hybrid Sudan grass during pregnancy.
  
  

Exposure to IIlness During Pregnancy

• According to Dr. Ted S. Stashak, DVM, author of "Horseowner's Guide to Lameness," there have been several cases of contracted tendons in foals whose dams were exposed to the influenza virus during pregnancy.
  
  

Gene Mutation

• Dominant gene mutation on the sire's side has been linked to contracted tendons in foals.
  
  

Equine Goiter

• Foals born with an enlarged thyroid, or goiter, are also apt to have contracted tendons.