636 
HEREDITARY DISEASES OF HORSES. 
description stand long, the circulation of the blood through 
the limbs is retarded ; for, as the contraction of the muscles 
which materially aid circulation are wanting, the blood in 
the veins rises with difficulty against its own gravity, while 
the soft and lax condition of the venous coats, and of the 
muscles in contact with them, permits the passage of the 
fluid parts of the blood, giving rise to a serous effusion which 
is soft and pits on pressure. This anasarcous condition, 
although troublesome and frequently recurring, is easily 
removed by friction, exercise, or a little physic, and does not 
unfit the animal for ordinary work. 
But the same conformation and constitution which induce 
simple swelled legs, also give rise to' the more serious affection 
known as weed , or a shot of grease. This consists in a 
disturbance of the balance which naturally subsists between 
the waste of the system and the supply of new material to 
repair that waste. Food is assimilated in larger quantity 
than the wants of the system require, the chyle so formed 
accumulates in the absorbent vessels and glands, which 
become in consequence irritated and inflamed. That part of 
the absorbent system situate in the hinder extremities is 
usually the principal seat of the disease. The animal sud- 
denly becomes lame, the inguinal and other glands in the 
groin become enlarged and very painful, and the swelling 
and pain gradually extend downwards along the course of 
the absorbents, whilst the limb becomes a great deal larger 
than its natural size. There is, at the same time, a good 
deal of constitutional fever, with a full and bounding pulse. 
The swelling of the leg is in the first instance inflammatory, 
being hot and tender, and the skin over the part affected, 
hard and tense. Such swellings may by judicious treatment 
be removed ; but, in cases of a chronic character, or where 
the same limb has been previously affected, lymph is effused, 
forming hard and nodulous and even diffuse swellings, 
which often cause lameness by interfering with the motions 
of the joints or tendons. These indurated swellings must be 
carefully distinguished from the serous effusions above 
noticed, which, although giving the animal an unsightly 
appearance, do not materially impair his usefulness. 
Grease consists in a morbid condition of the sebaceous 
glands of the horse’s heels and fetlocks. It occurs in 
various degrees of intensity ; sometimes as a mere scurfy 
itchiness of the skin about the fetlocks, more commonly of 
the hind extremities ; sometimes attended with much inflam- 
mation, causing great heat, pain, and swelling, and an icho- 
rous fetid discharge ; sometimes causing falling off of the 
