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Background: Peripheral nodal B-cell lymphomas (PNBCL) represent the most common presentation of lymphomas in dogs. Multiagent CHOP (C = cyclophosphamide, H = hydroxydaunorubicin [Doxorubicin], O = Oncovin, P = prednisolone)-based chemotherapy protocols have been widely accepted as gold standard 1st-line treatment. CHOP-25 and CHOP-19 are most commonly prescribed but have never been directly compared., Objectives: Our primary aim was to compare outcomes of dogs diagnosed with PNBCL, treated using a 1st-line CHOP-19 or CHOP-25 protocol. A secondary objective was to determine the impact of protocol-related variables on outcomes., Animals: Five hundred two dogs from 16 European oncology referral centers. One hundred fifty-five dogs were treated with CHOP-19 and 347 dogs with CHOP-25., Methods: Retrospective, multicentric cohort study of dogs diagnosed with PNBCL between 2014 and 2021., Results: The 6-month, 1-year, and median progression-free survival (PFS) were 56.5% (95% confidence interval [CI], 49.2-65.0), 14.1% (95% CI, 9.4-21.0), and 196 days (95% CI, 176-233) with CHOP-19; and 56.4% (95% CI, 51.4-61.9), 17% (95% CI, 13.4-21.6), and 209 days (95% CI, 187-224) with CHOP-25. The 1-year, 2-year and median overall survival (OS) were 36.9% (95% CI, 29.7-46.0), 13.5% (95% CI, 8.6-21.1), and 302 days (95% CI, 249-338) with CHOP-19; and 42.8% (95% CI, 37.7-48.7), 15.4% (95% CI, 11.7-20.4), and 321 days (95% CI, 293-357) with CHOP-25. No significant difference in PFS and OS was found between the 2 protocols., Conclusions and Clinical Importance: Our study confirmed similar outcomes for dogs with PNBCL treated with 1st-line CHOP-19 or CHOP-25. Both protocols therefore could be used as a standard of care in future trials., (© 2024 The Author(s). Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Myeloma-related disorders (MRDs) are rare and poorly documented neoplasms of cats., Hypothesis/objectives: To describe clinical, clinicopathologic, and imaging findings, response to treatment, and survival time and to identify factors associated with shorter outcomes in cats with MRD., Animals: Fifty cats with a diagnosis of MRD., Methods: Cats with paraproteinemia confirmed by serum protein electrophoresis (SPE) and either intramedullary plasmacytosis >10%, marked cytonuclear atypia with intramedullary plasmacytosis that ranged between 5% and 10%, or cytologically or histologically confirmed visceral infiltration were retrospectively included from several veterinary referral centers., Results: Bone marrow plasmacytosis and splenic or hepatic involvement were present in 17/27 cats (63%), 36/42 cats (86%), and 27/38 cats (71%), respectively. Anemia was reported in 33/49 cats (67%) and thrombocytopenia in 16/47 cats (34%). Some of the treatments that the cats received included melphalan and prednisolone (n = 19), cyclophosphamide and prednisolone (n = 10), chlorambucil and prednisolone (n = 4), prednisolone (n = 4), or other (n = 4). The overall response rates to melphalan, cyclophosphamide, and chlorambucil in combination with prednisolone were 87%, 90%, and 100%, respectively. Adverse events to melphalan or cyclophosphamide occurred in 65% and 23% of cats, respectively. Median survival time was 122 days (range, 0-1403) and was not significantly associated with chemotherapy protocol. Anemia (hazard ratio [HR], 3.1; 95% confidence interval [CI], 1.0-9.8) and thrombocytopenia (HR, 2.7; 95% CI, 1.2-6.0) were risk factors for shorter survival., Conclusions and Clinical Importance: Our study confirmed the guarded prognosis of MRD in cats and identified risk factors for shorter survival times., (© 2024 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)