ALTERATIONS IN CARBOHYDRATE METABOLISM IN DOGS WITH NONHEMATOPOIETIC MALIGNANCIES

OBJECTIVE: To determine whether alterations in carbohydrate metabolism exist in dogs with nonhematopoietic malignancies but without evidence of weight loss or cachexia. ANIMALS: 90 dogs with nonhematopoietic malignancies and 18 control dogs. PROCEDURE: An intravenous glucose tolerance test was done in 90 dogs with previously untreated nonhematopoietic malignancies and in 18 clinically normal dogs. These dogs also had no evidence of unrelated diseases that would affect glucose metabolism. None of the dogs had evidence of cachexia. Samples were assayed for glucose, lactate, and insulin concentrations. This procedure was repeated for 45 of the tumor-bearing dogs from which all gross evidence of tumor was completely excised and evidence of diseases that would alter carbohydrate metabolism did not exist. RESULTS: The mean of all time points during the intravenous glucose tolerance test (ie, 0, 5, 15, 30, 45, and 60 minutes) for lactate (12.9 +/- 6.7 mg/dl) and insulin (69.1 +/- 44.9 microU/ml) concentrations in untreated dogs with nonhematopoietic malignancies were significantly higher than values for controls (lactate, 9.7 +/- 4.3 mg/dl; and insulin, 31.7 +/- 11.5 microU/ml). This increase in lactate and insulin values did not return to normal when the dogs were rendered free of all observable evidence of cancer after surgery. CONCLUSIONS: Carbohydrate metabolism is altered in dogs with a variety of nonhematopoietic malignancies and these abnormalities do not abate when dogs are rendered free of gross evidence of malignant disease after surgery. CLINICAL RELEVANCE: Alterations in carbohydrate metabolism may result in decreased quality of life and may be associated with the paraneoplastic syndrome, cancer cachexia.