The third phase consists in the development of more or less confluent vesicles, with exudation and discharge. The disease is not really visible externally until after the hair has become agglutinated by the discharge. This discharge is seldom as abundant as in eczema in the dog or horse. It is produced slowly and dries rapidly.
As the crusts fall, carrying with them a portion of the hair, the general symptoms disappear, but the sites of these vesicular patches now show cracks extending as deep as the dermis and often complicated by secondary infection involving suppuration, adenitis, abscess formation, or diffuse subcutaneous suppuration.
Acute eczema is generally confined to the limbs. It may develop fully in from twenty-four to forty-eight hours. The acute stage is attained in a few days, and the condition disappears in two to three weeks provided it does not assume the chronic form as the result of complications.
Diagnosis. The absence of parasites enables the condition to be distinguished from phthiriasis and acariasis, whilst the history prevents its being confounded with toxic eczema.
Prognosis. The condition is troublesome rather than grave. Suppuration is often persistent, and despite careful attention the discharge may only diminish slowly, while the disease is always liable to return.
The treatment is local and general. Local treatment consists in emollient and antiseptic washes and the application of drying powders. The former comprise glycerole of starch, bran water, boric ointments, camphorated vaseline, iodine and glycerine. At a later stage the skin can be washed with decoction of oak bark or a weak iodine solution, followed by the application of talc or starch powder. As far as possible this external treatment should be supplemented by the frequent use of mild purgatives and various diuretics, which seem to have a special action on the arthritic diathesis.
CHRONIC ECZEMA.
Comparatively few cases of chronic eczema have hitherto been described in oxen, and the details given are extremely meagre. Chronic eczema may assume that form from the first or may succeed acute eczema. The causes are probably the same in both conditions.
The symptoms appear to be those of the acute form, but are much less severe. They consist in papulation, a miliary vesicular eruption, pruritus, and the formation of crusts and epidermic scales.
In a case seen by Mégnin the crusts separated and fell away, leaving bare spots. The disease re-appeared for several years in succession. The spots finally remained bare, but showed no thickening of the skin and no microscopic changes.