Hypothesis 3 - Bicipital Bursitis

Trauma, possibly caused by another horse kicking the foal, directly to the point of the 
shoulder could lead to inflammation of the bursa between the tendon of the biceps and 
the bicipital groove of the humerus.  Inflammation is caused when there are changes in 
the caliber of the blood vessels and the rate of blood flow through them.  This then leads 
to an increased capillary permeability, which allows for a leukocytic infiltration.  These 
leukocytes release inflammatory mediators, which lead to the sensation of pain.  There is 
also swelling due to the increased vascular permeability.  The pressure of the tendon of 
the biceps muscle on the inflamed bursa increases the pain.   When the leg is extended, 
the pressure of the tendon on the bursa is greater than when the leg is flexed.  The foal is 
then not going to move in a way to extend his leg, keeping it in a semiflexed position to 
reduce pressure on the bursa.  The foal will not want to have any movement of the tendon 
that will cause it to rub on the bursa, resulting in a decreased willingness to move the leg 
from the semiflexed position. The foal would have a shortened stride, and drag its toes in 
order to keep the leg in this position.
	Although inflammation of the bursa can occur, it is very rare.  More likely problems caused by trauma would be fractures, tendon and other soft tissue  damage, or nerve damage.