stosis
situated on the mesial side of the distal end of the tibia. Cadiot and
Almy state that this condition (courbe) is of rare occurrence. Percivall
defines curb as "a prominence upon the back of the hind leg, a little
below the hock, of a curvilinear shape, running in a direct line
downwards and consisting of infusion into, or thickening of, the sheath
of the flexor tendons." Moeller's version of true curb is a thickening of
the plantar ligament (calcaneocuboid or calcaneometatarsal). Hughes and
Merillat consider curb as a synovitis having for its seat the synovial
bursa which is situated between the superficial flexor tendon
(perforatus) and the plantar ligament.

Occurrence.--Certain predisposing factors seem to favor the occurrence
of curb. A malformation of the inferior part of the tarsus so that its
antero-posterior diameter is considerably less than normal is a
contributing cause. Such hocks are known as "tied-in." Another fault in
conformation is the existence of a weak hock that is set low down on a
crooked leg, especially when such a member is heavily muscled at the
hip. Given such conformation in an excitable horse, and curb is usually
produced before the subject is old enough for service. It is certain
that in cases where conformation is bad, greater strain is put upon the
plantar ligament. This structure serves to bind the tibial tarsal
(calcis) bone to the metatarsus; traction exerted upon its summit by the
tendo Achillis is great when animals run, jump or rear and also at heavy
pulling. In animals having curby hocks, sprain is likely to result and
curb supervenes.

Symptomatology.--The characteristic swelling which marks curb may
develop quickly and lameness occur suddenly or the enlargement comes on
gradually and slowly, causing little lameness. Lameness is not
proportionate to the size of the swelling and in all cases whether
subacute or chronic, the condition improves with rest, but lameness is
again manifested upon exertion. A horse which "throws a curb" will go
lame until the acute inflammatory condition subsides and depending upon
treatment received and conformation of the hock, this requires from
three days to two or three weeks.

The character of the swelling varies; in some cases it is not large but
rather dense and lacking in evidence of heat and hyperesthesia; in other
cases there is considerable swelling, which is hot and doughy, somewhat
painful to the touch but not necessarily productiv