tumors of
a splint or a jack; or it may be diffuse, as in severe fistulas of the
withers, in an extensive lung fever, in the legs in a case of grease, or
in the spavins which affect horses with poorly nourished bones. The
causes of inflammation are practically the same as those of congestion,
which is the initial step of all inflammation.

The temperament of a horse predisposes the animal to inflammation of
certain organs. A full-blooded animal, whose veins show on the surface
of the body, and which has a strong, bounding heart pumping large
quantities of blood into the vascular organs like the lungs, the
intestines, and the laminae of the feet, is more liable to have
pneumonia, congestive colics, and founder, than lymphatic, cold-blooded
animals which have pleurisies, inflammation of the bones, spavins,
ringbones, inflammation of the glands of the less vascular skin of the
extremities, greasy heels, thrush, etc.

[Illustration: PLATE I.

INFLAMMATION.

1--_Uninflamed wing of the bat._

2--_Inflamed wing of the bat._]

[Illustration: PLATE II.

INFLAMMATION.

1--_Non-inflamed mesentery of the frog, 400 diameters, reduced 1/2: a,
a, Venule with red and white corpuscles; b, b, Gelatinous nerve fibre;
c, Capillary; d, d, Dark-bordered nerve fibre; e, e, Connective tissue
with connective tissue corpuscles and leucocytes scattered sparsely
through it._

2--_Inflamed mesentery of the frog, 400 diameters, reduced 1/2: a, a,
Venule filled with red and white corpuscles, the red in the centre and
the white crowding along the walls; c, c, Capillary, distended with red
and white corpuscles, number of the white much decreased; d, d,
Connective tissue between venule and capillary filled with migrated
leucocytes; e, e, Connective tissue with less infiltration; f,
Dark-bordered nerve fibre; g, Number of nuclei, in sheaths increased._]

Young horses have inflammation of the membranes lining the air passages
and digestive tract, while older animals are more subject to troubles in
the closed serous sacs and in the bones.

The work to which a horse is put (saddle or harness, speed or draft)
will influence the predisposition of an animal to inflammatory diseases.
As in congestion, the functional activity of a part is an important
factor in localizing this form of disease. Given a group of horses
exposed to the same draft of cold air or other exciting cause of
inflammation, the one which has just been eating will be attacked w