This disease for which a variety of names is given, among them honeycomb ringworm, is characterized by the formation of sulphur-yellow crusts. These are generally rounded and present a peculiar appearance; in their earlier stages they resemble much the eruption in ringworm, namely: thin, roundish scales pierced by a hair. These scales then form in their centre a yellow prominence which rapidly increases in size and at their bases the surface is slightly hollow; thus nearly all present an outer concave and an inner convex surface, what is called a crab's eye appearance.

The crusts throw off a peculiar musty odor, and when removed a cuplike depression is found in the skin, which may be ulcerated or have but a thin scarf-skin covering it.

In some instances the disease appears as minute vesicles, formed in circles, which dry to yellow crusts (scutula).

Favus is a disease rarely seen in the dog; it is the result of a parasite which penetrates deeply; the hairs then becoming brittle, lose their lustre and finally fall out. Itching is not a symptom, the eruption being attended with pain. Damp kennels and general neglect favor this affection as they do other parasitic diseases of a similar nature.

Treatment

The crusts should first be soaked with oil or lard, then removed, and the hair shaved. Many local remedies have been advised; among them the oleate of copper promises especially well. The sulphuret of potassium is an agent of great value in parasitic diseases, and if the eruption is not extensive may be applied in the following compound. -

℞ Potassii Sulphureti ℥ i Sapo. Viridis ℥ss.

Adepis ℥ iss.

Ft. Ungt. Sig. Apply three times daily.

Where the disease is extensive, the quantity of potassium should be lessened one half or one fourth as it appears judicious.

The solution of carbolic acid and Canada balsam advised in follicular mange, will prove as destructive in favus as in that disease, and if used, the same caution is to be observed. The hair will be renewed excepting where the crusts have persisted too long, and by pressure on the skin induced ulceration, which in healing has left a scar.