Signalment:14-year-old male harbor seal
History:A 14-year-old male harbor seal presented with rotary nystagmus, involuntary head movement, and a mild right head tilt. The animal also developed mild intermittent facial swelling, specifically under/around the eyes. The animal was started on enrofloxacin and meloxicam for possible otitis interna or bacterial meningitis, ponazuril for possible Sarcocystis neurona or Toxoplasma gondii, and given a B complex injection with 100mg thiamine for possible thiamine deficiency. Two days later, the animal developed right-sided Horner’s syndrome, difficulty chewing on the right side of the mouth, a left-sided white aural discharge, and paresis of the right forelimb. The animal was sedated for blood collection (CBC/Chemistry panel unremarkable). Following sedation, the animal remained minimally responsive for a prolonged period of time and was found deceased the following morning.
Gross Lesions:Brain: A 10 x 15 x 6 mm, moderately well demarcated region of the right dorsal cerebellum was discolored grey to faintly yellow. Similar, smaller foci were observed within the ventral right cerebellum, midbrain, thalamus and pons. Respiratory system: The medial aspect of the right caudal lung lobe next to the right mainstem bronchus was effaced by a 5 x 5 x 6.5 cm, irregularly round, well demarcated, firm, beige mass. Lymph nodes: The lymph nodes were moderately to markedly enlarged (right axillary, tracheobronchial, bilateral inguinal). Ophthalmic system: There were bilateral mature cataracts. Auditory system: The ear canals were dark gray with a slight granular texture; the tympanic bullae were filled with tan/pink material.