There are wide possibilities in the treatment of canine lymphoma and the choice of the specific treatment in each case is dramatically important. Therefore, the therapy protocols should be adjusted to a prognostic index that allows an association between cases with similar risk factors.

To classify the prognosis as good or bad, there were selected six variables:

 Performance status: Stages 0-1, good prognosis; stages 2-3 bad prognosis.

 Clinical Stage: I-III, good prognosis; IV-V, bad prognosis.

 Clinical substage: A, good prognosis; B, bad prognosis.

 Amount of extranodal areas affected: 0-1 good prognosis; 2 or more, bad prognosis.

 Glucocorticoid pretreatment: without pretreatment or with less than 15 days of pretreatment, good prognosis; with more than 15 days of pretreatment, bad prognosis.

 Immunophenotype affected: B, good prognosis; T, bad prognosis.

On the basis of these variables there were made a classification in two mayor risk groups: low risk and high risk. There will be considered as "Low risk patient" those cases with a good prognosis in 0-2 variables excluding those under steroid pretreatment for more than 15 days and those with T immunophenotype because the inclusion in any of these groups determinates the inclusion of the patient into the high risk group.

Those patients with a bad prognosis qualification in 3-5 variables will be included in the high risk group.

58 canine patients with canine lymphoma were selected from the Teaching Hospital of the School of Veterinary Sciences of the UBA which were divided in groups and treated with different protocols. Some significant differences arose from the comparison between different protocols of therapy used and risk groups.

In the group treated with the COP (cyclophosphamide, vincristine, prednisone) protocol, the global survival time was significantly shorter in the high risk group than in the low risk group.

In the high risk group, those patients treated with the COP protocol had a significantly shorter global survival time than those treated with a more aggressive therapy. The association of COP protocol with L-Asparaginase or Doxorubicin, allowed to increase the global survival time in the high risk group patients, nearly to the global survival time present in the low risk group. The association of COP protocol with Bleomycin or Cytosine Arabinoside requires further clinical trials. The statistical method used was the Survival Analysis of Kaplan Meier (Survival curves). It was considered as significant, a p value equal or smaller than 0,05.