Cachexia (loss of lean body mass [LBM] in the face of chronic debilitating disease) and sarcopenia (loss of LBM in a normal aging patient without concurrent illness) are associated with high mortality and morbidity in humans, and veterinary studies are beginning to document similar trends. In certain disease states, alterations in various mediators (eg, insulin) decrease the body’s ability to make metabolic adaptations required to switch to fat utilization, causing muscle and LBM to be catabolized.
This retrospective study in dogs with chronic kidney disease showed that dogs classified as underweight had significantly shorter survival time as compared with both moderate and overweight dogs. This finding suggests that, as with humans, renal cachexia may affect survival time.
In humans, sarcopenia usually begins with muscle loss around the age of 30 and progresses throughout life. To date, sarcopenia has been documented in veterinary medicine but differences in pathophysiologic mechanisms have not been found between healthy young and healthy geriatric dogs. It is unclear how sarcopenia affects prognosis. As cachexia and sarcopenia are further studied, dietary and exercise recommendations may evolve to minimize the signs associated with them.
In humans, cachexia is associated with poor appetite, fatigue, muscle atrophy, and weakness. Veterinarians may be overlooking the importance of these signs in hospice or palliative care patients, and often such measures as formulating dietary plans to increase the patient’s metabolic rate and encouraging supplementation with essential fatty acids need to be addressed. Exercise also is important
in delaying the breakdown of muscle, although walking may be difficult for some of these patients. By understanding these conditions, however, practitioners can provide better care to affected patients. —Heather Troyer, DVM, DABVP, CVA