Section II
Etiopathogenesis of Cruciate
Ligament Rupture
Introduction
Historically, cruciate ligament rupture (CR) in
the dog has been considered a consequence
of accidental injury, with subsequent develop-
ment of stifle arthritis. However, particularly
since the late 1980s, this paradigm has been
challenged. Second cruciate ruptures were
found to be common in affected dogs, with
many dogs initially presenting with bilateral
CR. More recent work has shown that stifle
arthritis is present during the early phase of
the disease as cruciate ligament fiber rupture
develops in the stable stifle. Disease progres-
sion then leads to the development of complete
CR and associated stifle instability in most
affected dogs. Recent publications have shown
that stifle synovitis is a significant factor in
progression of the disease over time. Although,
a substantial genetic contribution to risk of CR
exists, the specific events that initiate the dis-
ease remain poorly understood. Recent genetic
research has highlighted the polygenic nature
of the trait and confirmed moderate heritability.
Future research should be focused on advanc-
ing understanding of the factors that lead to
disease initiation, particularly causal genetic
variants.45