Suspected fibrocartilaginous embolus in Asian small-clawed otter (Aonyx cinereus)

An 11-year-old neutered male Asian small-clawed otter fell down the stairs while sleeping, after which it developed left-sided paralysis. Initial treatment involved once daily administration of prednisolone at 0.5 mg/kg.

Despite slight clinical sign improvements by day 10, paralysis persisted. MRI (T2WI) identified a well-defined, hyper-intense lesion on the left side within the spinal cord at the C2-3 intervertebral level. Based on CT and MRI findings, fibrocartilaginous embolus (FCE) was suspected.

Prednisolone was then tapered and by day 23 of illness, the otter was able to walk normally, so prednisolone administration was discontinued. No neurological symptom recurrence was observed, and the course remained favorable.

One year later, a follow-up MRI revealed a diminished lesion compared to initial examination.

The results suggest that the possibility of a fibrocartilaginous embolus should be considered when an animal is experiencing acute paralysis with no worsening of symptoms.

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