<i>Taenia crassiceps</i> associated with neural cysticercosis in a domestic dog in the United States

A 2-y-old spayed female mixed-breed dog was presented with a 3-mo history of seizures. Coalescing intra-axial complex cystic lesions in the right cerebral hemisphere identified on MRI were suggestive of hydatid cysts; however, PCR testing of a fecal sample for <i>Echinococcus</i> spp. was negative. The dog was euthanized after 3 mo of treatment due to worsening signs and was submitted for postmortem examination. Coalescing 0.5-3-cm cavitations effaced ~20% of the left and 40% of the right cerebral hemispheres, and contained numerous 3-5-mm long ovoid-to-elongate, soft, white-to-clear metacestodes. Similar structures extended into the subarachnoid space. Histology revealed multiple larval cestodes consistent with invaginated cysticerci present in bladder compartments. Cysticerci each had a scolex, convoluted invaginated spiral canal, and spinous tegument with numerous calcareous corpuscles. Within many of the cysticerci, visible armed rostella had refractile hooklets and muscular suckers. Light microscopic evaluation of whole cysticerci preserved in ethanol revealed rostellar hooks with blade-to-guard length and handle-to-guard length that were within RIs for <i>Taenia crassiceps</i>. Sequencing of DNA amplicons obtained via PCR confirmed 100% sequence identity to <i>T. crassiceps</i>. To our knowledge, canine neural cysticercosis attributed to <i>T. crassiceps</i> has not been reported previously. Our case highlights the successful integration of multiple diagnostic modalities in a case of canine neural cysticercosis.