Introduction

To characterize solitary osseous plasmacytomas (SOP) in dogs, a rare disease, including diagnostics and treatment outcomes.

Methods

Retrospective review was conducted of records of dogs with SOP diagnosed and treated at the University of Missouri from 2004–2019. Data collected included demographics, presenting complaint, duration of clinical signs, treatment prior to referral, tumor location, pathology, diagnostics, treatment, response, date of progression, and death. Kaplan-Meier estimate was used to estimate median survival time (MST) and progression free interval (PFI).

Results

Thirteen dogs were included. Median age at presentation was 8 years (range 4–11). Vertebrae were affected in 8/13 (61.5%). Primary treatment was radiation therapy in 10/13 (76.9%), with all but one treated with a definitive, finely fractionated protocol. The median number of fractions was 20 and median total dose delivered to the planning target volume was 53Gy (range 48–54) (unavailable for 6 dogs). MST for those that completed radiation therapy was 1166 days. The MST and PFI for all dogs included in the study was 912 and 331 days, respectively. For dogs with vertebral SOPs, the MST was 42 days (range 5–1898). Two of these dogs were untreated. No dogs in this case-series developed multiple myeloma.

Conclusion

This is the first study to focus solely on this rare disease. Solitary osseous plasmacytomas in dogs can often be managed long-term with surgery or radiation therapy, similar to the human disease. SOP in dogs may progress to multiple myeloma less frequently than in humans.

Funding Information

No funding was utilized for this project.