Hypothesis # 2

Fetlock joint capsule rupture.

Mare suspected of stepping on foal’s leg.


The negative hoof test result indicates that the lesion causing the lameness is 
noy located distal to the fetlock joint.  The slight elevation in temperature 
and respiratory rate may be contributable to an elevated epinephrine blood 
level, which may may intitiated by manipulation of the painful joint.  All other 
systems are normal, as wella s all other limbs, suggesting that this is a local 
problem.


Fibrous integrity of capsular tissue compromised by excessive shearing force.  
Capsular fluid is lost into surrounding tissues / structures, as the capsular 
space is now in communication with the extracapsular space.  Sensory nerves 
within the capsular tissue initiate pain response.  Disturbed blood vessels 
within capsular tissue initiates chemotactic response for neutrophils / 
basophils, as numerous inflammatory mediators are released and synthesized by 
endothelial cells and surrounding mast cells.  Increased pressure results from 
fluid extravasation, pain response to damaged capsular tissue, and inflammatory 
mediator release into circulation are all sequelae this insult.