Objective—To evaluate whether serial determinations of serum lactate dehydrogenase (LDH) activity in dogs with lymphoma could be used to predict outcome and assist in early recognition of disease progression. Design—Prospective cohort study. Animals—50 dogs with lymphoma. Procedures—LDH activity was determined in dogs with newly diagnosed lymphoma or that had not received treatment. The LDH activity was measured at time of initial diagnosis, at completion of chemotherapy, and at 1, 3, and 6 months after chemotherapy. Treatment response and recurrence were recorded. At the end of chemotherapy and at each time point thereafter, the proportion of dogs in complete remission with elevated LDH activity was compared between dogs that did or did not have recurrence within the successive 45 or 90 days. Use of the LDH activity at admission to predict disease-free and survival intervals was evaluated. Results—The proportion of dogs in complete remission with increased LDH activity at completion of chemotherapy and at 1 month after chemotherapy with recurrence during the successive 45 days was significantly higher (3/9 and 7/9 dogs, respectively) than the proportion of dogs without recurrence (0/32 and 1/26 dogs, respectively). At 3 or 6 months, only 1 dog without recurrence within 45 days had increased LDH activity. Increased LDH activity at time of diagnosis was not associated with disease-free and survival intervals. Conclusions and Clinical Relevance—Determination of LDH activity may help with identifying episodes of recurrence in dogs with lymphoma. Anticipation of recurrence is an appropriate reason to begin rescue treatment.
