Studies were initiated to determine if animals with cancer have altered energy expenditure and to determine if elimination of cancer with chemotherapy or surgery alters energy expenditure.80,81 In the first study80, indirect calorimetry was performed on dogs with lymphoma that were randomized into a blind study and fed isocaloric amounts of either a high fat diet, or a high carbohydrate diet before and after chemotherapy.89 Surprisingly, during the initial evaluation period, resting energy expenditure was significantly lower than tumor-free controls. Six weeks after the start of the study, EE was significantly lower in both groups of dogs with lymphoma when compared to the controls and the pretreatment values from the dogs with lymphoma. Dogs fed the diet that is relatively high in fat maintained a more normal energy expenditure than dogs fed a diet relatively high in carbohydrates.
Another study was undertaken to determine energy expenditure of client-owned dogs with nonhematopoietic malignancies in an apparently resting state before and after each tumor was surgically excised.81 Surgical removal of the tumor did not significantly alter any parameter when all dogs were assessed as a single group, or when these animals were subdivided into the following groups: carcinomas and sarcomas, osteosarcomas and mammary. The values obtained prior to any treatment from the dogs in any group were not significantly different from controls. These data suggest that energy expenditure, and presumably caloric requirements of dogs with non-hematopoietic malignancies, are not different from those obtained from healthy client-owned dogs. Furthermore, these parameters do not change significantly when the tumor is removed surgically and the patient is re-assessed after 4-6 weeks.