Retrospective analysis of 101 canine lymphoma cases diagnosed in surgical biopsies in Latvia (2011–2020)

Lymphoma is a malignant tumour commonly diagnosed in dogs representing 7-24% of all canine tumours. There have been no previous studies focused on characterization of canine lymphoma cases in Latvia. The goals of this retrospective study were to determine prevalence and characteristics of lymphoma cases among biopsy submissions to a private veterinary pathology service that receives approximately 80% of all biopsy submission in Latvia and to compare this data with published canine lymphoma reviews. Data were retrieved to select records from Latvian dogs diagnosed with lymphoma between 2011 and 2020, determining characteristics of dogs and types of lymphoma based on anatomic distribution and cellular morphology. In a ten-year study period, diagnosis of lymphoma constituted 1–4% of surgical biopsy submissions each year without upwards trend. Affected dogs were middle age (median 8 years; range 2–13), with a slight male predominance (58%). The majority of dogs (19%) were mixed breed. Top 3 affected dog breeds were Rottweiler, American Staffordshire terrier and French bulldog with 6–7 cases in each breed. Multicentric form of lymphoma predominated (55%) followed by alimentary and mucocutaneous lymphoma (21% and 14%, respectively). Within multicentric form of lymphoma two thirds were intermediate to large cell lymphomas. Included in this group would be diffuse large B cell lymphomas, the most common subtype of canine lymphomas; however, lack of immunohistochemical testing precluded complete lymphoma classification according to WHO guidelines. Results of this study correlate well with the previously published results and provide important information to Latvian small animal veterinarians and pathologists.