BackgroundMolecular techniques that detect canine lymphoma cells by their clonal antigen receptor gene rearrangement play an increasing role for diagnosis as well as for monitoring minimal residual disease during and after cytostatic therapy. However, the methods currently available are time-consuming and/or cost-intensive thus impeding the use in clinical routine. The aim of the present study was to develop and evaluate a real-time polymerase chain reaction (PCR) with subsequent melting curve analysis (MCA) for the detection of clonally rearranged antigen receptor genes in dogs with B and T cell lymphoma on non formalin-fixed and paraffin-embedded lymph node samples.ResultsIn lymph node aspirates from 30 dogs with multicentric B cell lymphoma, real-time PCR with MCA detected clonal rearrangement in 100% and conventional PCR with polyacrylamide gel electrophoresis (PAGE) in 93% of samples. Both methods correctly identified clonality in 80% of lymph node aspirates of 10 dogs with T cell lymphoma. None of the two PCR systems detected clonal rearrangement in samples from 9 dogs with lymph node hyperplasia. Using a dilutional series with regular lymphoid desoxyribonucleic acid (DNA), detection limits of lymphoma DNA were as low as 0.8% and 6.25% for B and T cell clonal rearrangement with real-time PCR and MCA and at 3.13% and 12.5% with the conventional system. Median absolute detection limits of lymphoma DNA were shown to be at 0.1 ng and 1 ng for the B and T cell immunophenotype with the real-time PCR system and at 10 ng each with conventional PCR and PAGE.ConclusionsReal-time PCR with MCA is a convenient and reliable method with a good analytical sensitivity. Thus, the method may assist the detection of clonal antigen receptor gene rearrangement in canine lymphoma patients in a clinical setting also in the presence of small amounts of neoplastic cells.

Background: Different chemotherapy regimes have been described for feline lymphoma with varying outcomes. Hypothesis: In cats with lymphoma, a long-term, multiagent chemotherapy protocol will be effective and carry acceptable toxicity.Animals: Twenty-three cats with histologically or cytologically confirmed diagnosis of lymphoma. Methods: Prospective, single-arm clinical trial in which cats were treated with a chemotherapy protocol consisting of a cyclic combination of L-asparaginase, vincristine, cyclophosphamide, doxorubicin, methotrexate, and prednisolone with a planned total treatment time of 122 weeks.Results: Complete remission (CR) rate was 74% (n 5 17). Fourteen percent of cats attained partial remission (PR). Median duration of first CR was 264 days (range, 45-2,485 days). Six-month, 1-, and 2-5-year remission rates were 75, 50, and 34%, respectively. Duration of PR ranged between 23 and 63 days. Median survival in cats with CR was 296 days (range, 50-2,520 days). Six-month, 1-, 2-, and 3-5-year survival rates in cats with CR were 82, 47, 34, and 27%, respectively. Survival of cats achieving PR ranged between 38 and 120 days. Of the analyzed variables, only anatomical location had a significant influence on remission duration (P5.022). Actual median treatment time in cats with CR was 128 days (18 weeks). Hematologic and gastrointestinal toxicosis was infrequent and mostly low grade.Conclusions and Clinical Importance: In this population of cats with lymphoma, chemotherapy was effective. With infrequent and mostly low-grade toxicosis, tolerability of the protocol may be considered good.

In this group of dogs the 12-week maintenance-free chemotherapy protocol was well tolerated and had satisfactory results.

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