Issue 26   -  December 2016

Equine Ultrasound

Animal Imaging's clinical and portable ultrasound systems enable the practice's radiologists to visualize and diagnose pathologies affecting the equine. Ultrasound can be an extremely effective tool to evaluate joints, tendons and the axial and appendicular skeleton. This affordable and painless procedure is extremely safe in that it uses no ionizing radiation.

Magnetic Resonance Imaging of the Equine Fetlock
Patient History:
A 9-year-old Warmblood mare presented to Animal Imaging in March of 2014 for a left hind fetlock MRI. The mare is used as a jumper who became acutely lame 6 months prior to presentation. Radiographically there was evidence of moderate sesamoiditis as well as the presence of a proximal P1 bone cyst. An MRI was requested to fully understand the extend of the injury.
On examination at Animal Imaging in 2014 a slight left hind limb baseline lameness was noted, however lower limb flexion was markedly positive. Some pain was noted on palpation of the lateral suspensory branch, and a mild amount of fetlock effusion was appreciated.   

Original Study -2014- 
The mare was anesthetized and multiple MRI images were obtained. Significant bone edema was seen distal to the P1 cyst previously noted radiographically. There was a cartilage defect overlaying the cyst and cyst contents were bright on STIR sequences indicating likely articular communication. The fetlock joint was distended and proliferative. Proximal P1 appeared mildly sclerotic.
Sagittal Vibe Sequence- Cystic lesion -2014-
Recheck study- Sagittal Vibe sequence- progression of cystic lesion -2016-
Recheck Exam - 2016
This mare returned to Animal Imaging almost 30 months later for an MRI of the right front foot. A right forelimb lameness that was localized to the foot with a palmar digital nerve block has become increasing difficult to manage with intra-articular medication. The imaging request was to understand the extent of the refractory front limb lameness, however, this study afforded us an opportunity to reevaluate the left hind fetlock as well. The fetlock has been successfully managed with intra-articular regenerative therapy. No baseline lameness was noted, however the left hind fetlock was effusive and significantly painful on flexion. Some progression of the cyst was noted radiographically.
The mare was again anesthetized and multiple MRI images were obtained both front feet, as well the left hind fetlock.
Sag STIR - severe bone edema distal P1 cyst - 2014-

Sagittal STIR- persistent but decreased bone edema adjacent to cyst - 2016 -
The previously identified subchondral cyst is markedly enlarged measuring 1.8x1.2 cm. The cyst is STIR hyperintense and the surrounding bone has diffuse increased fluid signal. Evidence of articular damage is present. Progressive thickening of the joint capsule is present since the last study.

Impressions and Recommendations: 

1. The right front lameness was due to a chronic oblique fracture of an ossified lateral cartilage as well as marked P3 edema or a bone bruise.
2. Marked progressive subchondral cyst of the proximal phalanx with present, but decreased, surrounding bone edema-like signal
3. Mild progressive osteoarthritis and capsulitis of the fetlock
It is interesting to have the opportunity to chronicle this progression of the P1 cyst. The amount of compromised bone present may pose some risk to both horse and rider with a risk of pathologic failure. 

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