HYGROMA OF THE KNEE IN CATTLE. 811 



Causes. The chief causes are injuries sustained in lying down 

 and rising in badly-paved stalls and on insufficient bedding. The 

 repeated bruising may cause extravasation of blood under the skin, 

 or into the sheaths of the tendons, and proliferation of connective 

 tissue. That bleeding often occurs is shown both by the presence 

 of clots in the serous fluid, and by the pigmented condition of the 

 newly-formed connective tissue. A single severe bruise from falling 

 on uneven, hard ground, as occurs in working-oxen, may produce 

 the disease. Chronic processes, like tuberculosis, invading the 

 carpal joint, may also induce such swellings, but the nature of the 

 cases hitherto reported is seldom fully explained. 



Symptoms and course. The chief symptom consists of swelling 

 of the front of the knee, which sometimes increases rapidly, some- 

 times slowly, but is continued. The growth may become immense 

 (as much as a yard in circumference), and even reach to the ground. 

 The degree of pain varies, sometimes being considerable, but chiefly 

 depending on the mode of origin of the disease. When caused by 

 a single violent bruise it is generally painful ; but the slower the 

 development the less the pain. The swelling, though at first soft 

 and fluctuating, at a later stage becomes firm, and is often covered 

 with thick masses of horn. In cutaneous " capped knee " the tumour 

 remains movable on the subjacent tissues for a long time ; in the 

 synovial form it takes an elongated shape corresponding to the 

 direction of the sheaths of the tendons, and extends over the meta- 

 carpus from the region of the extensor pedis tendon. The articular 

 form is more diffuse ; it often covers the sides of the knee, and is 

 firmly attached to the underlying parts. Induration or ossification 

 is denoted by unusual hardness, and by greater difficulty in moving 

 the joint than in the two other forms. Lameness, except in the 

 articular form, is usually slight ; only when the disease is acute and 

 causes great pain, or when the swelling becomes excessive, is move- 

 ment much interfered with. 



The treatment of " capped knee " is as varied as its causes, and 

 must depend on the nature of the injury and the anatomical changes. 

 Fresh bruises and acute inflammation, accompanied by great pain, 

 are best combated by cold applications, followed later by warmth 

 and moisture. In skin injuries search must' be made for foreign 

 bodies like splinters of glass, fragments of gravel, &c, and the 

 dressings should be saturated with disinfecting fluid ; in any case 

 plenty of clean straw must be provided, and it is well to cover the 

 floor of the stall with sawdust or chalk. 



Where superficial fluctuation can be detected, cavities should be 



