_The prognosis_ is always uncertain and should be guided somewhat by the
conformation of the limb, character of the work required of the animal,
position of the bony enlargement and the degree of lameness. The size of
the enlargement is changed very little by the treatment. Veterinarians
report recoveries in from fifty to sixty per cent of the cases treated.

_The object of the treatment_ is to destroy the inflammation and bring
about a union between the bones. The treatment recommended is
counterirritation and rest. The most satisfactory method of
counterirritation is firing followed by blistering. Following this
treatment, the horse should be placed in a stall and given no exercise for
a period of five or six weeks. It is sometimes advisable to repeat the
counterirritation if the results of the first firing are unsatisfactory.

BOG SPAVIN.--Bog spavin is an extensive distention of the capular ligament
of the hock-joint by synovia (Fig. 48). It is generally due to chronic
inflammation of the synovial membrane. This blemish or unsoundness is most
common in young horses. Thorough pin (Fig. 49) involves the sheath of the
large tendon only. (Compare Figs. 48 and 49.)

[Illustration: FIG. 49.--Thorough pin. Note the relation of the enlargement
to the tendon, and the freedom of the hocks from bog spavin.]

Certain conformations of the hock favor the development of bog spavin. This
is especially true of upright and "fleshy" hocks. Hard work may cause the
hocks to "fill" when followed by a brief period of rest. The common cause
is a sprain due to slipping and pulling heavy loads.

The _following symptoms_ may be noted: Lameness is not a common symptom of