AZOTURIA. 
97 
sufficient supply of nutritive substance or to the accumulation 
of the products of decomposition, which produce a harmful 
action on the muscle fibres. When a muscle contracts its arte¬ 
rioles dilate, more blood passes through the muscle, and as a con¬ 
sequence the removal of the increased carbon dioxide formed is 
facilitated. For instance, when muscles are contracted those 
arising from one bone and inserted in another will in their con¬ 
traction either move both bones toward each other, or if one be 
fixed will approach the movable to the fixed bone. I think in 
these cases of azoturia the psoas muscles and abductors are as 
much in fault as the crural muscles, as they have their insertion 
almost perpendicular to the bones on which they act. As you 
know, in the posterior part of the horse four angles are met with 
—the hip joint, the patella, hock, and pastern joint. The pel¬ 
vis is very oblique relatively to the trunk in the horse, the femur 
is obliquely connected with the pelvis, downward motion of the 
pelvis, a backward motion of the femur from the body weight 
being prevented by the abdominal recti muscles, whose tendons, 
inserted in the pelvis, by their tension, tend to draw the hip 
joint anteriorly. The gluteal muscles arising from the ilium 
and passing over the hip joint to the femur, act in the same di¬ 
rection, not only preventing forcing backward of the hip joint, but 
in its contraction pressing the hip joint forward, so the leg is 
like the femur, flexed, its obliquity being limited by the tension 
of the tendons of the extensor muscles which pass over the an¬ 
terior surface of the limb. 
Often a rupture of fibres in the psoas muscles will prevent 
an animal from getting up on his feet, and frequently in this 
disease these muscle fibres are ruptured. 
Skin. —As to the skin and what assistance it gives in this 
disease in assisting nature to throw off the poisonous material. 
The skin may be regarded as an organ supplementary in its 
action to the lungs and kidneys, since the skin by its secretion is 
capable of removing a considerable quantity of water from the 
blood, small amounts of carbon dioxide, and small amounts of 
salts, and in certain instances, during suppression of renal secre- 
