Page 63 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

38 CHAPTER 1

VetBooks.ir splint using either half-tubing PVC or, better still, 1.67
a bespoke splint. The latter system may be created
from fibreglass casting material (split a cast applied
to the limb into dorsal and palmar portions and use
the dorsal portion applied over a well-bandaged
limb). The cast should be taped to the limb in maxi-
mum extension incorporating wiring at the toe when
the DIP joint is involved. Alternatively, the distal
limb may be immobilised in a light fibreglass cast,
with the limb in extension. Both systems should be
re-applied every few days (3–5) to avoid pressure
sores. At each replacement the limb may be further
extended. In most cases the limb straightens within a
few days and normal limb conformation can usually
be expected.

CONGENITAL FLEXURAL DEFORMITY OF
THE DISTAL INTERPHALANGEAL JOINT

Congenital flexural deformity of the DIP joint
presents in newborn foals or within a few weeks of
birth as varying degrees of DIP joint flexion so that
the foal walks on its toe and the heel does not contact
the ground (‘ballerina foal’) (Fig. 1.67). Hoof shape
does not alter in the early stages, unlike in acquired
forms, although increased toe wear does occur. It is Fig. 1.67 Young Thoroughbred foal with a right
uncommon, can be uni- or bilateral, and be associated forelimb congenital flexural deformity of the distal
with other flexural deformities such as in the meta- interphalangeal joint. Note the typical ‘ballerina’ foal
carpophalangeal (MCP) joint. Increased tension in stance on the toe tip in the right fore.
the inferior check ligament and deep digital flexor
tendon (DDFT) may be present on palpation.
Treatment consists of a combination of regular gen- lengthening of the tendons and ligaments. Kidney
tle exercise, passive manipulation, analgesics (beware function should be checked prior to using this form
of gastroduodenal ulceration with the use of NSAID of treatment. Corrective foot trimming consists of
medication in foals), corrective foot trimming, splint- mild heel rasping. A short toe extension with a glue-
ing or casting. Encouraging the use of the affected on plastic shoe or placing a hoof composite over the
limb with gentle, regular exercise on hard, even sur- toe will prevent excessive toe wear and help to stretch
faces and specific exercises, such as walking up inclines, affected periarticular soft-tissue structures. Caution
are often beneficial. NSAIDs help reduce pain and in should be observed when using toe extensions that do
some foals this seems to be involved with the contrac- not support the solar surface of the foot as there is a
ture. Oxytetracycline may be useful (2–4 g in 500 ml significant risk of dorsal hoof wall fracture. Casts can
saline slowly i/v once or twice in the first 48 hours post be very useful in congenital DIP joint flexural defor-
partum or even, in some cases, later). The method of mities. Incorporation of the foot up to the carpus or
action is unclear but in-vitro research has indicated tarsus for 7–14 days leads to a relaxation of the mus-
that oxytetracycline inhibits tractional structuring cle–tendon unit. Care should be exercised with the use
of collagen fibrils by equine myofibroblasts through of casts in order to prevent the formation of pressure
an MMP-1 mediated mechanism leading to passive sores. In unresponsive cases, inferior check ligament