A 6 yr old Standard poodle was presented with a right hindlimb (8/10) lameness of 3 weeks duration. Patellar reflex was reduced while the remaining segmental spinal reflexes were intact on that limb. A similar episode occurred 4 months earlier and resolved with conservative management.

MRI showed an ill-defined area of T2W and STIR hyperintensity within the belly of the right iliopsoas muscle at L6 and L7 associated with contrast uptake. The muscle at that level shows a mildly increased volume. The MR images shown on the right are, clockwise starting from left dorsal image: dorsal STIR, Transverse T2W, Transverse T1W post-contrast and Transverse T1W pre-contrast. The right femoral nerve is visible within the belly of the affected iliopsoas muscle and appears mildly enlarged (orange arrow). These findings were suggestive of right iliopsoas muscle injury (most likely strain and partial rupture).

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The iliopsoas muscle is a sublumbar muscle formed by the fusion of the major psoas and iliac muscles, originating from the ventrolateral aspect of the lumbar vertebrae and inserting onto the lesser trochanter of the femur. Iliopsoas strain (tear) results from excessive stretching of this muscle during strenuous activities or slipping into a splay-legged position. This type of traumatic myopathy is commonly associated with lameness, pain on extension or internal rotation of the ipsilateral hip joint and femoral neuropathy (explaining the abnormal patellar reflex and reduced extensor tone of the stifle) due to the close anatomic relationship between the femoral nerve and the iliopoas muscle. Management of this condition is essentially conservative approach (rehabilitation therapy, muscle relaxant and NSAIDs).

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Courtesy Dr. Alison Kennair. Moorview Referrals Hospital UK

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