Limb position, not exercise or sedation, affects power Doppler neovascularization detection in equine superficial digital flexor tendon core lesions

Objective: To determine the effect of limb position, exercise, and sedation on neovascularization detectability with the use of power Doppler ultrasonography (PDU) in superficial digital flexor tendon core lesions of the equine forelimb. Methods: 9 Thoroughbred horses with superficial digital flexor tendon core tendinopathies were assessed with PDU before lesion induction (week 0) and 12 weeks after lesion induction, with 5 horses in the study period ranging from January to April 2024 and 4 horses from January to April 2025. During weeks 0 and 12, ultrasound examinations were performed 24 hours apart, with the limb weight-bearing and non-weight-bearing, before and after light exercise, and before and after IV detomidine sedation. The opposite forelimb served as a control. Results: Limb position was the only variable with statistical significance. No blood flow was visualized in the prelesion surgical or control limb under all conditions. After lesion induction, neovascularization was significantly increased under all conditions when the limb was imaged during non-weight-bearing. Conclusions: Practitioners may utilize the information from this study to acknowledge the importance of non-weight-bearing limb position for neovascularization detection with PDU and may continue the standard exercise performed during a lameness examination and detomidine sedation administration to facilitate a complete diagnostic evaluation. Clinical Relevance: Light exercise, such as a typical lameness examination, and the administration of IV detomidine sedation to facilitate an ultrasound evaluation will not impact the detectability or degree of neovascularization with the use of PDU. Imaging the limb during non-weight-bearing will significantly increase the detectability and is a critical component of a complete evaluation.