ROUNDS IN VETERINARY DIAGNOSTIC IMAGING

Wednesday 3^rd June 2026

MARIANNA BIGGI

CASE 1�5 years old Polo Pony

• Right tarsus swelling – started 7 months ago after returning from the field
• Mild lameness 0.5/5
• Medication with triamcinolone improved the swelling.
• Swelling returned 1 month ago as well as 1/5 lameness; medication does not affect swelling this time.

CASE 3

T2*W GRE

T2*W GRE

T2W FSE

STIR

T2*W GRE

T2*W GRE

T2W FSE

T1W GRE

T2*W GRE

T2W FSE

T1W GRE

FINDINGS

• Tarsocrural joint effusion
• Round subchondral bone hyperintensity, distal lateral aspect of the talus (5x4mm in size); surrounded by reduce signal intensity in the trabecular bone.
• Axial hyperintensity within the suspensory ligament origin.

CONCLUSION

• Subchondral bone resorptive lesion in the talus involving the talocalcaneal joint
• Tarsocrural joint synovitis, possibly secondary to the talocalcaneal joint pathology
• Suspensory ligament hyperintensity, individual variation more likely than pathology

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• Selected horses that had tarsus CT performed (2010-2022)
• 108 horses/110 tarsal CT
• 8 lesion in the DDLC – all lesions in thoroughbred racehorses (20%)
• 2/4 horses had effusion of the tarsocrural joint
• 3/8 horses the lesion was considered the cause of lameness
• Likely or equivocal cause for lameness in all horses (3/8 slab fracture of the third tarsal bone)

Example 1

• 8 y old Percheron, RH tarsocrural joint effusion of 6 months duration, improved with medication but effusion reoccurred. Mild 1/5 lameness , positive to flexion and to intra-articular analgesia.

Example 2

• 12 y old SJ “off after jumps”, possibly unconfortable

CASE 2, 10 years old show jumping mare

• Acute onset of carpal swelling
• Moderate left forelimb lameness
• Presented 4 weeks after initial injury

T2*W GRE

T1W GRE

T2*W GRE

T1W GRE

STIR

T2W FSE

STIR

E = flexor carpi radialis muscle

• Severe desmopathy of the proximal medial aspect of the carpal retinaculum.
• Enthesopathy of the carpal retinaculum attachment on the radius.
• Complete tear in the carpal sheath with fluid visible between the carpal sheath and retinaculum.

• All horses injured the carpal retinaculum landing from a fence
• Fetlock and carpus hyperextend during landing with the leading leg receiving the majority of the breaking forces
• The main force is on the superficial digital flexor tendon; if this surpasses the flexor retinaculum capacity injury occur.

• Acute onset of lameness and swelling
• Lameness improves rapidly (carpal tunnel syndrome?)
• Swelling palmar medial just proximal to the accessory carpal bone

10 weeks follow up

Follow up

Original

Example 1

• 9 years old WBL high level show jumping
• Acute swelling but minimal lameness
• Avoid landing on the affected limb after a jump

10 weeks post injury

CASE 3, 5 years old Highland pony

• Slowly growing firm mass in the metacarpal region

T2*W GRE

T1W GRE

STIR

T1W GRE

T2*W GRE

T1W GRE

T2W FSE

STIR

• Heterogeneous mass, free fluid (T2Hyper/T1 Hypo); hemorrhagic material (T1/T2 iso)
• Thin capsule
• Deformation of the third metacarpal bone with no reaction

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CONCLUSION:

- Hematoma?

• Benign neoplasia?
• Congenital vascular malformation?

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CASE 4, 15 years old Warmblood mare

• Acute deterioration of the RF lameness, mild lameness at walk.
• Previous fetlock injection and management for synovitis

T2*W GRE

STIR

T1W GRE

STIR

T1W GRE

T2*W GRE

STIR

• Focal subchondral bone hyperintensity lateral proximal sesamoid bone
• Extensive bone oedema type lesion

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CONCLUSION:

- Subchondral bone resorption and secondary oedema lateral proximal sesamoid bone, traumatic or infectious in origin.

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• Lameness localized to the fetlock
• MRI diagnosis of osseous cyst-like lesion in the proximal sesamoid bone
• Axial border, subchondral bone, abaxial surface, base.
• Septic or aseptic nature

OCLLS with synovial lining – osteoarthritis?

Septic sesamoiditis

• Clinical deterioration – very uncomfortable
• Only minimal changes of the imaging appearance of the lesion

Why is the metacarpophalangeal joint not effused?

That’s all folks!