Clinical presentation, treatment and outcome in 31 dogs with presumed primary colorectal lymphoma (2001-2013)

The objective of this multicentre retrospective study was to describe clinical presentation, treatment and outcome and to determine prognostic factors for dogs with presumed primary colorectal lymphoma (PCRL). A total of 31 dogs were included. The predominant features of PCRL were high grade (n = 18) and immunophenotype B (n = 24). Most dogs were substage b (n = 25) with higher prevalence of haematochezia (n = 20). One dog had surgery only. Thirty dogs received chemotherapy; amongst them 13 had surgery or radiotherapy. Progression free survival (PFS) was 1318 days and disease-related median survival time (MST) was 1845 days. Fourteen dogs were alive at the end of the study with a median follow-up time of 684 days (3-4678 days). Younger dogs had longer PFS (P = 0.031) and disease-related MST (P = 0.01). Presence of haematochezia corresponded with longer PFS (P = 0.02). Addition of local treatment to chemotherapy did not significantly improve the outcome (P = 0.584). Canine PCRL has considerably longer PFS and MST than other forms of non-Hodgkin's lymphoma.