Objective—To describe the ultrasonographic and
quantitative histologic effect of injecting 2% iodine in
almond oil (IAO) and ethanolamine oleate (EO) in the
medial and middle patellar ligaments of horses and to
determine whether a difference in response exists
between IAO and EO treatment.
Animals—10 healthy horses.
Procedure—In 5 horses, the medial and middle patellar
ligaments of 1 limb were injected with EO, whereas
IAO was injected in the medial and middle patellar
ligaments of another 5 horses. Ultrasonographic evaluation
was performed on the experimental and control
limb before injection of IAO and EO and prior to
euthanasia to determine cross-sectional area and
evaluate fiber pattern. The patellar ligaments were
harvested 2 weeks after injection and examined histologically
to evaluate the inflammatory response,
fibroplasia, and chondroid metaplasia.
Results—Injection of the patellar ligaments with IAO
resulted in a greater increase in cross-sectional area
on ultrasonography than EO. Both agents caused a
decrease in echogenicity of the ligament.
Histologically, significantly greater infiltration of
inflammatory cells and fibroplasia developed after
injection with IAO, compared with EO. Both agents
resulted in significantly greater fibroplasia relative to
Conclusions and Clinical Relevance—Injection of
the medial and middle patellar ligaments with IAO
induces more severe inflammation and fibroplasia
than EO. Maturation of the inflammatory and fibrous
response may contribute to resolution or attenuation
of upward fixation of the patella by subsequent stiffening
of the ligaments. (Am J Vet Res