Body Condition Score and Prognosis in Dogs with Lymphosarcoma and Osteosarcoma

Dogs that were underweight at the time of lymphosarcoma diagnosis had shorter survival times than ideal-weight or overweight dogs, according to a report published in the Journal of Veterinary Internal Medicine. For dogs with osteosarcoma, body condition score was not associated with survival time.

In humans, obesity has been linked to an increased risk of death from cancer and an increased risk of cancer recurrence. However, being overweight at the time of cancer diagnosis has also been associated with longer survival times in people with B-cell lymphoma.

Researchers from the Cummings School of Veterinary Medicine at Tufts University investigated whether body condition score was associated with progression-free interval and survival time in dogs diagnosed with lymphosarcoma or osteosarcoma. The retrospective study included records of 270 dogs with lymphoma and 54 dogs with osteosarcoma seen at Tufts between January 2000 and December 2010.

Of the dogs with lymphoma, most were ideal weight (54.8%) or overweight (39.3%) at the time of diagnosis; 5.9% were underweight. All but two of the dogs received cancer treatment of some type. Most dogs experienced complete (61%) or partial (23.6%) remission. Survival time ranged from 7 to 2737 days. There was no relationship between body condition score at diagnosis and progression-free interval. On univariate analysis, median survival time was significantly shorter in dogs that were underweight at the time of diagnosis than in ideal-weight or overweight dogs. On multivariate analysis, body condition score was not associated with survival time.

Of the dogs with osteosarcoma, 50% were ideal weight, 46.3% were overweight, and 3.7% were underweight at the time of diagnosis. Survival time ranged from 20 to 1271 days. Body condition score at the time of diagnosis was not associated with either progression-free interval or survival time.

For both types of cancer, multivariate analysis showed that dogs that gained more than 10% body weight during treatment had a longer median survival time than dogs that lost weight, maintained weight, or gained a smaller amount of weight. (In dogs with osteosarcoma, body weights were adjusted to account for amputation.) The authors note that this could be a secondary effect; dogs that live longer have more time to gain weight. Shorter survival in underweight dogs could also be related to disease severity, loss of lean body mass, malnutrition, or earlier euthanasia.

In this study, being overweight or obese at the time of diagnosis did not shorten survival time or progression-free interval. The authors speculate that being overweight might have less effect than being obese (more dogs in the study were overweight than obese) and that obesity could affect different cancers in different ways.

Study limitations included the relatively small sample size, subjectivity of body condition scoring, variations in the timing of body condition assessments, and the inability to assess the contribution of muscle loss to body condition scores. The authors also point out that euthanasia, which was chosen for nearly all of the dogs, could affect survival time assessments.

Dr. Laurie Anne Walden received her doctorate in veterinary medicine from North Carolina State University. After an internship in small animal medicine and surgery at Auburn University, she returned to North Carolina, where she has been in small animal primary care practice for over 20 years. Dr. Walden is a board-certified editor in the life sciences and owner of Walden Medical Writing, LLC.