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.

The aim of this prospective clinical trial was to investigate the efficacy and toxicity of a short-term, maintenance-free chemotherapy protocol in feline lymphoma. Twenty-six cats with confirmed diagnosis of high-/intermediate-grade lymphoma were treated with a 12-week protocol consisting of cyclic administration of L-asparaginase, vincristine, cyclophosphamide, doxorubicin and prednisolone. Complete (CR) and partial remission (PR) rates were 46 and 27%, respectively. Median duration of first CR was 394 days compared with a median PR duration of 41 days. No factor was identified to significantly influence the likelihood to reach CR. Overall survival amounted to 78 days (range: 9-2230 days). Median survival in CR cats was 454 days and in PR cats was 82 days. Toxicosis was mainly low grade with anorexia seen most frequently. In cats achieving CR, maintenance-free chemotherapy may be sufficient to attain long-term remission and survival. Factors aiding in prognosticating the likelihood for CR, strategies enhancing response and targeting chemotherapy-induced anorexia need to be identified in future.

Stage migration is described in humans and dogs as a sequel of using more sensitive diagnostic methods. One hundred eighty-six dogs with multicentric lymphoma were enrolled with results of conventional staging as well as ultrasonographic and cytological examination of liver and spleen being available. The addition of splenic respective hepatic ultrasound and cytology findings resulted in slightly lower number of dogs classified as having liver and spleen involvement. In dogs with multicentric lymphoma, addition of cytology led to a significant shift of individuals from stage IV to stage III. Findings of hepatic and splenic ultrasound and cytology exerted no significant influence on complete remission and survival durations in dogs with combination chemotherapy. Staging methodology in canine lymphoma should be redefined, considering that the prognostic significance of splenic and hepatic ultrasound and cytology warrants further investigation.

Ocular manifestations of lymphoma are described in humans and dogs but rarely in cats. In this prospective study, cats with newly diagnosed and treatment-naïve lymphoma were evaluated concerning clinical stage and ophthalmologic findings. Twenty-six cats were included. In 12 cats (48%), ocular changes were documented. Uveitis anterior and posterior were predominant findings, being present in 58% of affected individuals. Other findings included exophthalmos, corneal surface lesions and chemosis. Eight cats received chemotherapy, two of which had ocular involvement. In these two cats, a complete remission of an anterior and a partial remission of a posterior uveitis were documented. Due to the detection of ocular involvement, a stage migration from stage IV to V occurred in four patients. In the light of these findings, an opthalmological examination may be considered as an important part of staging in feline lymphoma as well as of follow-up examination in affected cats.

Background High-grade lymphoma in dogs is a chemotherapy-responsive neoplasia with remission rates exceeding 80% under combination chemotherapy protocols. Usually these protocols are intensive and 24 + weeks. The objective of the present study was to investigate if a shorter protocol combined with an oral lomustine maintenance treatment (3 × in 8 weeks) would present an acceptable result, both for B- and T-cell lymphomas, and for the different types of lymphomas normally encountered in private veterinary practice. Results 144 dogs entered the study. Lymphoma types included multicentric (n = 123), alimentary (n = 13), miscellaneous (n = 7), and mediastinal lymphoma (n = 1). Overall response rate was 83.3% (B-cell: 86.6%, T-cell: 79.4%). Complete remission (CR) was achieved in 72.2% (B-cell: 77.3%, T-cell: 67.6%) and partial remission (PR) in 11.1% (B-cell: 9.3%, T-cell: 11.8%) of the dogs. Median duration of first CR amounted to 242 days (B-cell: 263 d, T-cell: 161 d). Median survival in dogs with CR was 374 days (B-cell: 436 d, T-cell: 252 d), and median overall survival time was 291 days (B-cell: 357d, T-cell: 210d). Immunophenotype demonstrated an independent significant influence on duration of remission and survival in the whole group. Findings of splenic and hepatic cytology were not significant associated with patient outcome. Treatment was well tolerated; the majority of adverse events were classified as grade 1 or 2. Conclusions Short-term chemotherapy followed by lomustine consolidation leads to compara-ble remission and survival times compared to conventional protocols with cyclophosphamide, doxorubicin, vincristine and prednisolone with acceptable toxicosis in dogs with both B-cell and T-cell lymphoma.