Page 787 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Proximal Limb 753

appearance. Pain is often elicited with deep palpation
over the greater trochanter and hip region. It can often
VetBooks.ir and therefore the lameness is often progressive, whereas
be confused with trauma to the limb but the infection
a traumatic injury often improves with time. Any young
foal with severe hindlimb lameness but no definable
lesions in the lower limb should be suspected of having
infection of the hip joint. In addition, infections of the
capital physis can spread to the hip musculature, and the
foal may present with an abscess in the gluteal region.

Diagnosis
A complete blood count is often very helpful to help
differentiate trauma from a potential hip infection. High
white blood cell counts and fibrinogen concentrations
help confirm the presence of an infection. However, a
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definitive diagnosis of infectious arthritis is made by
analyzing the synovial fluid of the hip joint following
A arthrocentesis, with or without adjunctive IS anesthe-
sia. Synovial white blood cell counts of 30,000 cells/μL
4
or more and total protein concentrations of 4.0 g/dL or
more are consistent with infection. Physeal infections
can be documented with radiographs of the hip region,
where lysis around the capital physis, epiphysis, and
occasionally the acetabulum is seen (Figure 5.159B).

Treatment
Treatment is similar as for any other joint/physis with
a hematogenous infection. Broad‐spectrum systemic
antimicrobials, IA antimicrobials, and joint lavage/
drainage are all important. Arthroscopy can be per-
formed in small horses and foals to help lavage and
debride these lesions, but cannula lavage alone can be
very helpful. 4,39,62–64 Unfortunately, many of these infec-
tions are not diagnosed in the early stages, and sig-
B nificant osteomyelitis is often present, worsening the
prognosis (Figure 5.159B).
Figure 5.159. Ventrodorsal radiographs of the pelvis of two
3‐month‐old fillies with a history of increasing lameness. (A)
Remodeling of the femoral head and acetabulum (arrows) consist- Prognosis
ent with a developmental abnormality. (B) Lysis of the left acetabu- The prognosis is usually poor because the diagnosis is
lum (arrows) consistent with infectious arthritis and osteomyelitis.
seldom made before significant joint abnormalities and
osteomyelitis have occurred. However, foals with
respiratory tract. 54,68,84 Affected foals usually have a history coxofemoral infectious arthritis without radiographic
of failure of passive transfer. Bacteria localize in and abnormalities should respond well to aggressive treat-
around the physes and joints because of the specific low‐ ment, and their prognosis for athletic use is similar to
flow circulation that is present in these areas. The syn- that of foals with joint ill at other locations. 4
drome may be classified according to the location of the
lesion: S‐type involves the synovium/joint, E‐type involves
the epiphysis, and P‐type involves the physis. Most PARTIAL TEAR/RUPTURE OF THE LIGAMENT
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infections are from Gram‐negative bacteria. Infection OF THE HEAD OF THE FEMUR (ROUND
of the proximal femoral physis may spread to the cox- LIGAMENT)
ofemoral joint and surrounding tissues of the hip region.
A partial tear or rupture of the ligament of the head
Clinical Signs of the femur (round ligament) of the coxofemoral joint
is a relatively rare condition that can affect any age or
Infection of the coxofemoral joint can be a diagnostic breed of horse. Nevertheless, it appears to be more com-
challenge because joint effusion, heat, and pain are often mon in small‐breed horses (miniatures and ponies) and
not found on physical examination. Typically, these young horses. The hip joint is usually very stable, but
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foals are less than 4 months of age and often present occasionally a partial tear or complete rupture of
with a unilateral hindlimb lameness of unknown cause. ligament of the head of the femur can occur without a
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They may have a characteristic toe‐out, stifle‐out, hock‐in complete joint luxation. In these cases, the head of the