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Mammals (other)
Bilaterally symmetrical lesions of the caudate nucleus in a northern fur seal pup (Callorhinus ursinus)
  1. Vanessa Fravel1,
  2. William Van Bonn2,
  3. Sophie Dennison3 and
  4. Terry Spraker4
  1. 1Vet Clinic, Six Flags Discovery Kingdom, Vallejo, CA, USA
  2. 2Vet Clinic, Shedd Aquarium, Chicago, IL, USA
  3. 3Vet Clinic, Animal Scan, Redwood City, CA, USA
  4. 4Department of Pathology, The Colorado State University College of Veterinary Medicine, Fort Collins, CO, USA
  1. Correspondence to Dr Vanessa Fravel, vfravel{at}


A northern fur seal (Callorhinus ursinus) pup was stranded and brought to The Marine Mammal Center (TMMC) in Sausalito, California, USA, for rehabilitation. Upon admission, the animal was lethargic, underweight and ataxic. Clinical diagnostics, including complete blood cell count (CBC), serum chemistry, protozoal antibody titres, radiographs and cisterna magna ultrasonography, were completed and considered within normal limits. MRI of the brain revealed bilaterally symmetrical focal lesions of the rostrolateral caudate nucleus. Treatment for thiamine deficiency and immune-mediated disease was initiated, but the pup did not improve. The pup was euthanased and postmortem examination revealed no gross lesions. Histopathology revealed bilateral regions of oedema, and areas of early malacia, within the caudate nucleus. Although the aetiology is not identified, the distribution of the lesions suggests a toxic insult or could be related to a developmental neurodegenerative disease. This case also gives an insight into the potential role of the caudate nucleus in fur seals.

  • Marine mammals
  • Diagnostic imaging
  • Brain diseases
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