Page 185 - Canine Lameness

12.5 ­ onDcD oe ofs teaalres, ron os, rons Deriroce 157

condition from pathological conditions of the sesamoids. Local analgesic blocks may also be used
to evaluate whether sesamoid pathology contributes to a lameness. There is no consensus on treat-
ment; however, sesamoidectomy (removal of the affected sesamoid) is possible in cases that are
refractory to nonsurgical treatment (Mathews et al. 2001). DISTAL LIMB REGION

12.5 Conditions of Muscles, Tendon, and Ligaments

Numerous major muscles that insert in this region have their origins and muscle bellies well proxi-
mal on the limb. This allows for the muscle mass to be centralized towards the trunk rather than
add to the distal “pendulum” weight and inertia of the limb. This means that many of these mus-
cles cross multiple joints, which makes them more vulnerable to injury compared to those that
only cross a single joint. Any of these muscles may be injured and probably are. The manifestation
of these injuries might be obvious, for example an abnormally elevated digit (i.e. injury of the digi-
tal flexor muscles). Many, however, are insidious, as the impact of their injury may be muted by
muscles with similar function taking over their roles. These injuries may be detectable but require
familiarity with the regional anatomy upon a meticulous clinical examination. Treatment of these
conditions may involve surgical (such as apposition of the injured structures) and nonsurgical
(external coaptation, rest, and pain management) strategies.

12.5.1 Dorsal Digital Ligament Sprain
Dorsal digital ligament sprains occur when the distal phalanx is forcefully and excessively flexed
and has been described in active Greyhounds (Blythe et al. 2007). It may be associated with injury
of the adjacent digital extensor tendon. Animals might be slightly lame and on inspection of the
affected paw, the dorsal (cutaneous) concavity between the proximal interphalangeal joint and
claw is lost. This is caused by swelling of the area, which is accompanied by pain on palpation.
Radiographs to investigate any concurrent fractures, for example avulsion fractures, and ultrasono-
graphic examination are warranted to confirm the ligamentous injury.

12.5.2 Digital Flexor Muscle and Tendon Injuries

12.5.2.1 Superficial Digital Flexor Muscle
The superficial digital flexor muscle may be damaged through overexertion (causing overstretch-
ing or strain injury), or through external trauma, including contusion and laceration. The damage
may occur in both the muscle or in the long tendon and its synovial sheath. The entire paw may
be involved if the muscle is torn and elongates or if the main tendon or multiple branches are
ruptured, for example following a deep laceration to the palmar/plantar aspect of the paw (usu-
ally in the region of the metacarpal or metatarsal footpad). Animals may or may not be lame,
depending on the extent and chronicity of the condition. The clinical appearance is of one or
more digits that appear to lie parallel to the contact surface (Figure 12.8); the proximal inter-
phalangeal joint loses its normally flexed angle, referred to as “dropped toe” in dog racing circles.
If the deep digital flexor tendon is intact, the claw elevates and points forward (but is not cocked
dorsally, see Section 12.5.2.2).
Clinical diagnosis involves palpating for pain and swelling along the entire length of the
affected muscle, since the injury may not be located at the site of obvious abnormality (i.e. the
“dropped toe”). The affected digit(s) may be extended to a greater degree than their unaffected