Dose and Duration of Upfront Steroid Administration Have no Prognostic Impact in Dogs With Multicentric Diffuse Large B-Cell Lymphoma.

Steroids provide rapid clinical improvement in dogs with multicentric diffuse large B-cell lymphoma (DLBCL). However, their use before chemotherapy can induce chemoresistance and compromise diagnostic yield due to increased apoptotic cells. This retrospective study assessed the impact of steroid dose and duration on flow cytometry (FC) diagnostic yield and clinical outcomes in dogs with DLBCL subsequently treated with chemotherapy. Of 273 dogs diagnosed with DLBCL between January 2014 and March 2024, 67 (24.5%) received steroids before treatment (median dose: 1 mg/kg, range: 0.5-3 mg/kg; median duration 8 days, range: 1-1080 days). In 94.0% of cases, steroids were administered for lymphoma management. All dogs received CHOP-based chemotherapy, and 38 (56.7%) also received immunotherapy. Median time to progression (TTP) and lymphoma-specific survival (LSS) were 143 days (95% CI: 111-175) and 196 days (95% CI: 152-240), respectively. Steroid dose, duration, and cumulative dose had no significant impact on TTP or LSS. However, the addition of immunotherapy was associated with longer LSS (p = 0.023). FC diagnostic yield was lower in steroid-treated dogs compared to 67 non-pre-treated dogs (p = 0.042). However, within the pre-treated group, neither dose nor duration impacted diagnostic yield (p > 0.05). In addition, TTP (p = 0.003) and LSS (p < 0.001) were significantly longer in non-pre-treated dogs compared to steroid-treated dogs. These findings suggest that the detrimental effects of upfront steroids are independent of dose or duration. Given their potential to compromise diagnosis and treatment outcomes, corticosteroids should be used with caution and reserved for cases where clinical benefits clearly outweigh the risks.