Page 69 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

44 CHAPTER 1

VetBooks.ir of the disease. Surgical excision of an individual observed at the caudolateral aspect of the distal
Solitary osteochondromas have also been
exostosis may be indicated if it is shown to be caus-
radius, on the nasal bone, the lateral aspect of the
ing lameness.
proximal calcaneus (Fig. 1.76) and the ribs.
SOLITARY OSTEOCHONDROMA
UNILATERAL PHALANGEAL HYPOPLASIA
Solitary osteochondromas may be abortive expres-
sions of multiple exostosis, but unlike this condition Unilateral phalangeal hypoplasia is a rare condition
they do not appear to be inheritable. This benign where there are degrees of incomplete development
mass tends to be located at the caudomedial aspect and sometimes absence of the phalanges within an
of the radius and usually causes carpal sheath dis- otherwise normal foot (although the foot is often con-
tension and subsequent lameness. Radiography tracted) (Fig. 1.77). The condition occurs predomi-
and ultrasonography can confirm the extent of nantly in the hindlimbs. Affected foals are lame on
the lesion. Surgical excision is required and the the affected limb. Radiography can confirm the con-
prognosis for non-recurrence of the tumour and dition. The prognosis for a long-term athletic future
restoration of normal limb function appears to appears to be hopeless, although navicular agenesis was
be good. reported in a 2-year-old Thoroughbred in training.

1.76 1.77

Fig. 1.76 Lateral radiograph of the hock of a Fig. 1.77 Post-mortem specimens of sagittal sections
Clydesdale foal with a developing firm swelling of the feet of a foal that presented with unilateral
on the point of the hock. Note the mixed-pattern lameness and a very small digit. The upper limb is
osseous density mass present on the point of the affected by phalangeal hypoplasia, with a vestigial
calcaneus, adjacent to the physis, and due to a solitary third phalanx (red arrow) and navicular bone and an
osteochondroma (arrow). abnormal second phalanx (white arrow).