Capped Hock.

Enlargements which occur upon the summit of the os calcis, whether
hypertrophy of the skin and subcuticular fascia, the result of injury or
repeated vesication, distension of the subcutaneous bursa or injury to
the superficial flexor tendon (perforatus) or its sheath, are generally
known as capped hock. However, the term should be restricted to use in
reference to distensions of synovial structures of that region.

Etiology and Occurrence.--Usually there occurs a hygromatous
involvement of the subcutaneous bursa due to contusion. As in bog
spavin, following certain infectious diseases (influenza, purpura
hemorrhagica, etc.) there remains a distended condition of the
subcutaneous bursa, after swelling of the member has subsided. In
feeding pens where numbers of young mules are kept in crowded quarters
many cases may be observed. In some instances where violent contusions
result from kicking cross-bars of wagon shafts (by nymphomaniacs or in
habitual kickers where there is opportunity for doing such injury) the
superficial flexor tendon and its synovial apparatus are injured and a
more serious condition may result.

Symptomatology.--In acute and extensive inflammation of the parts,
lameness is present, but in the average case no inconvenience to the
subject results. The prominent site of the affection is cause for an
unsightly blemish. This is undesirable, particularly in light-harness or
saddle horses. These affections are characterized by a fluctuating mass
which has a thin wall and in all cases of long standing the condition is
painless.

By careful palpation one may readily distinguish between a hygromatous
condition of the superficial bursa and involvement of the underlying
structures. Affection of the expanded portion of the flexor tendon and
contiguous structures makes for an organized mass of tissue which is
somewhat dense and in some instances painful to the subject when
manipulated. This is particularly noticeable in cases where the parts
are regularly and repeatedly injured as in habitual kickers.

[Illustration: Fig. 60--"Capped hock." Distension of the bursa over the
summit of the os calcis.]

Treatment.--In acute inflammation, antiphlogistic applications are
indicated and the subject must be kept quiet. The matter of bandaging
the hock is a difficult problem in some cases and needs be done with
care. As has been previously stated in this volume, the tarsus needs to
be well padded w