Page 192 - Canine Lameness

164 12 Distal Limb Region

stifles). Excessively long nails may be due to reduced wear, for example after injury to the digital
DISTAL LIMB REGION 12.8.1 Trauma
flexor tendons resulting in diminished downward rotation of the digit.

Trauma (such as traumatic split, cracked, bruised, and avulsed claws) is a frequent cause of claw
injury and associated lameness. It usually affects a single, or only a small number of claws. To
establish a diagnosis, the claw should be carefully observed for integrity and color abnormalities,
palpated for pain, and pulled away from the nail bed to determine the firmness of its attachment.

12.8.2 Paronychia
Paronychia describes a nonspecific inflammation of the claw fold (Mueller 1999) whereby the nail
bed becomes swollen, red, and painful, with possible purulent discharge (Figure 12.10d). The area
is usually very sensitive to palpation. There are numerous causes for this condition; trauma is con-
sidered the most common primary cause, while bacterial infections are usually secondary. An
allergic or immune-mediated cause is also common. In addition to the examination, skin scrapings
for Demodex, exudate cytology, bacterial and fungal culture, and fine-needle aspirates (FNAs) may
be indicated. Radiographs of the affected digit are useful to identify any underlying bone involve-
ment. Paronychia may lead to deformity and accelerated growth of the claw.

12.8.3 Deformed Claws
Deformed claws usually indicate previous, unappreciated physical injury to, infection, or immune
insult of the nail bed. They may also cause lameness via various mechanisms. For example,
although claws may not be painful themselves, they may impinge on adjacent skin causing abra-
sion and pain. Accelerated growth of the claw may lead to ingrown claws, where the apex curves
back and impinges on the adjacent digital footpad or skin.

12.8.4 Symmetrical Lupoid Onychodystrophy
Symmetrical lupoid onychodystrophy/onychitis, also called symmetrical onychomadesis (Ziener
and Nødtvedt 2014), is a claw-specific disease of mainly young to middle-aged dogs. Gordon Setters
and German Shepherd Dogs appear to be predisposed. The usual presentation is licking of the
paws, lameness, and sloughing of the affected claw(s). Inspection of the claw reveals paronychia
and separation or sloughing of the claw. Claws may be dry, roughened, short, and misshapen as
they regrow (Figure 12.10E). The condition usually progresses until all claws are affected. A puru-
lent discharge may be present due to secondary bacterial infection. Diagnosis is based on signal-
ment, clinical appearance, and the absence of clinical manifestation elsewhere. Diagnosis can be
confirmed histopathologically. Treatment is difficult but involves removal of damaged claw plates,
treatment of secondary infections, as well as pharmacologic therapy to allow for regrowth of nor-
mal claws (Ziener and Nødtvedt 2014).

12.9 Other Conditions Affecting the Distal Limb Region

12.9.1 Neurological Conditions
Neurological conditions causing lameness and proprioceptive deficits (Chapters 16 and 21) may
cause abnormal claw (Figure 4.4) and footpad wear or result in abrasive damage to the dorsal
aspect of the digital skin. Neurological conditions may also manifest in hyper- or paresthesia, with