Page 549 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Distal Limb 515

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Figure 4.90. Lateral radiograph of the pastern demonstrating enthesophytes, subchondral lysis, and asymmetrical joint space
periosteal reaction and small osteophytes on the dorsal aspect of collapse indicative of severe OA within the joint. This horse would
the joint indicative of mild to moderate OA within the joint. not be expected to do well with medical therapy.
Dorsopalmar radiograph of the same pastern demonstrating

Periarticular new bone growth associated with lacera- abnormalities are usually not good candidates for non-
tions may be limited to the site of trauma unless the surgical treatments. It is important to note that the most
joint was invaded and/or infectious arthritis is present. important radiographic finding in grading the severity
Infectious arthritis of the PIP joint often causes severe of OA of the PIP joint is joint space narrowing, espe-
periosteal/periarticular bony proliferation, osteophyte cially when narrowing is asymmetrical (Figure 4.90).
formation, and subchondral lysis seen on radiographs. Horses with quite severe accumulation of periarticular
Older horses with trauma‐induced OA or young horses bone but normal joint space width would be more likely
with OC should have radiographs of the contralateral to respond to conservative therapy than horses with
PIP joint performed because these disease conditions joint space collapse, despite both groups having so‐
are often bilateral. called severe radiographic changes (Figure 4.91). Horses
In early acute cases, there may be minimal to no with mild to moderate radiographic abnormalities of
palpable changes of the pastern region, and even radio- the PIP joint may respond well to conservative treat-
graphic examination may not reveal abnormalities. In ment, depending on the horse’s intended use. Horses
these cases where pastern injury is still suspected, with a single traumatic injury to the pastern, such as
MRI 49,79 and/or ultrasound exam can be performed. those with an MRI diagnosis of a bone marrow lesion,
MRI findings in cases of OA of the PIP joint include the may respond well to rest with complete healing and no
same radiographic findings of osteophytes, joint space long‐term evidence of joint disease or OA (Figure 4.89),
narrowing, subchondral lysis, periosteal proliferation while others with bone marrow lesions may develop OA
with enhanced ability to detect subchondral bone in the following months (Figure 4.88). There are numer-
changes (lysis, sclerosis), bone marrow lesions, SCLs, articu- ous treatment options and the decision on how to treat
lar cartilage lesions, and joint effusion (Figure 4.87). horses with OA of the PIP joint is often made on a case‐
Alternatively, repeat radiographic examination can be by‐case basis.
performed in 1–2 months because evidence of periostitis Conservative management of PIP OA may involve
(periarticular new bone) and peripheral osteophyte forma- periods of rest, systemic and/or IA anti‐inflammatory
tion may be present at that time. therapy, trimming and shoeing, and a change in the
horse’s career. See Chapter 8 for more specific details on
Treatment these treatment modalities. In acute traumatic cases,
stall confinement and rest from exercise are important
Conservative Management
to prevent further trauma, reduce inflammation, and
The decision regarding treatment of horses with OA permit healing to occur. 16,68 Rest periods may extend
of the PIP joint depends on the severity of the disease, from weeks to months depending on the severity and
degree of lameness, age and intended use of the horse, type of the injury and the response to treatment.
and the owner’s expectations and financial constraints. Confinement and rest is rarely effective in horses with
Horses with severe lameness and advanced radiographic chronic OA of the PIP joint.