Page 181 - Canine Lameness

12.3 Arthritis 153

involved. The condition may be secondary to trauma or associated with strain injuries of the collat-
eral ligaments and is sometimes seen with flexor tendon injuries or, as observed by the author, in dogs
with excessively long nails and apparent rotary angulation of the digits and their joints. Clinical signs
may be absent or mild. However, dogs with visible swelling are more likely to have clinical lameness
(Franklin et al. 2009) and affected joints may be painful during the early stages of the disease. In DISTAL LIMB REGION
chronic cases, there is thickening of the joint and loss of range of motion. Severe joint thickening may
cause cutaneous impingement of the adjacent digit(s), with ensuing abrasion and pain. Radiographic
imaging may reveal soft tissue proliferation, osteophytosis and enthesopathy, as well as extensive
periosteal reaction, which may give the appearance of a neoplastic process (Franklin 2009). In the
author’s experience, the condition may also be accompanied (and potentially related) to the clinical
syndrome of the hyperextension of multiple digits frequently seen in geriatric dogs (Figure 12.5).
Infective and immune-mediated arthritis are uncommon conditions for this region. The former
may occur from bacterial introduction through local wounding or from adjacent infected tissues,
or spontaneously through hematogenous bacterial extension (see Section 14.12). Typical signs
include acute onset lameness with a warm, swollen, and painful joint (usually single). Immune-
mediated arthritis usually involves multiple joints and may be erosive or nonerosive (Chapter 13).
Erosive forms show bone erosions, subluxation, or luxation of the joints with periarticular bone
proliferation and mineralization of the periarticular soft tissue possible. Joint fluid analysis and
culture is required for diagnosis of both conditions.

(A)

(B) (C) (D)

Figure 12.5 Metacarpophalangeal osteoarthritis: (A, B) this dog presented with hyperextension of all
digits; (C, D) note the severe degenerative changes of the metacarpophalangeal joints of the second and
fourth digits with soft tissue proliferation, osteophytosis, and enthesopathy, as well a periosteal reaction.