Canine proliferative sparganosis: a case report and review of larval cestodiasis in dogs.

Larval cestodiasis is characterized by aberrant migration and proliferation of larval cestodes in body cavities or tissues and is a rarely reported entity in domestic dogs. Cestodes of the genera Mesocestoides and Spirometra are reported as causative agents, and can cause tetrathyridiosis and proliferative sparganosis, respectively. Reported herein is a case of abdominal larval cestodiasis in a companion dog from Florida, USA. During routine ovariohysterectomy, larval cestodes were noted throughout the peritoneum. Histologically, the larvae were characterized by asymmetric budding projections and contained tegument-lined cystic spaces. Polymerase chain reaction and Sanger sequencing of multiple gene targets, including NAD, COX-1 and mt12S, identified the cestodes as a Spirometra sp with 100 % sequence identity to reference sequences from multiple species, including Spirometra erinaceieuropaei, Spirometra ranarum and Spirometra mansoni. While human proliferative sparganosis cases are routinely attributed to Sparganum proliferum, this report supports previous findings that Spirometra spp can cause proliferative sparganosis in dogs. Spirometra spp should be considered as a differential aetiology of proliferative sparganosis in dogs, and additional attention needs to be given to morphological and genetic characterization of Spirometra cestodes to better understand the role of these parasites in cases of animal sparganosis.