Pathophysiology

The beneficial effects derived from the nutritional support of diseased human patients and experimental animal models include enhanced immune function, wound repair, response to therapy, recovery time, and survival. Despite these benefits, the nutritional needs of hospitalized patients are often ignored due to the intense focus on life-threatening medical and surgical problems. The goal of nutritional support is to provide energy and nutrients in proportions that can be utilized by the patient with maximal efficiency.

Sean J. DELANEY
BS, MS, DVM, Dipl ACVN

Dr. Delaney holds a Bachelor's degree in Zoology from the University of California, Santa Barbara, a Master's degree in Nutrition and a Doctorate degree in Veterinary Medicine from the University of California, Davis. He attained Diplomate status with the American College of Veterinary Nutrition following completion of a clinical nutrition residency at UC Davis. He is currently an Assistant Clinical Professor at the Veterinary Medical Teaching Hospital at UC Davis. He is also the founder of Davis Veterinary Medical Consulting, Prof. Corp., which specializes in nutritional consulting for the pet food industry.

Andrea J. FASCETTI
DVM, PhD, Dipl ACVIM, Dipl ACVN

Andrea Fascetti graduated from the University of Pennsylvania School of Veterinary Medicine. Following graduation she completed an internship and medicine residency at The Animal Medical Center in New York City. She holds a doctoral degree in nutrition from the University of California, Davis. She is a Diplomate of the American College of Veterinary Internal Medicine and the American College of Veterinary Nutrition. Andrea is currently an Associate Professor of Nutrition at the University of California, Davis. She is also the service chief for the Nutrition Support Service in the Veterinary Medical Teaching Hospital of the University of California, Davis. Her current research interests are trace mineral metabolism in dogs and cats, improvement of pet foods and taurine bioavailability and metabolism in the dog.

Denise A. ELLIOTT
BVSc (Hons) PhD Dipl ACVIM, Dipl ACVN

Denise Elliott graduated from the University of Melbourne with a Bachelor in Veterinary Science with Honors in 1991. After completing an internship in Small Animal Medicine and Surgery at the University of Pennsylvania, Denise moved to the University of California-Davis where she completed a residency in Small Animal Medicine, a fellowship in Renal Medicine and Hemodialysis, and a residency in Small Animal Clinical Nutrition. Denise received board certification with the American College of Veterinary Internal Medicine in 1996 and with the American College of Veterinary Nutrition in 2001. The University of California-Davis awarded a PhD in Nutrition in 2001 for her work on Multifrequency Bioelectrical Impedance Analysis in Healthy Cats and Dogs. Denise is currently the Director of Scientific Communications for Royal Canin USA.

Malnutrition is probably more common in veterinary patients than is recognized. Malnutrition is an unbalanced intake of protein and/or calories to support tissue metabolism and has the potential to undermine proper medical or surgical therapeutic management of a hospital case (Remillard et al., 2001). Some dogs are likely to be deficient in either protein and/or calories due to a reduction in food intake.

A recent publication estimated the proportion of hospitalized canine patients in a negative energy balance (Remillard et al., 2001). The study was conducted at four veterinary referral hospitals across the USA. Overall, daily feeding data and outcomes for 276 dogs over 821 days in the hospital were evaluated. In 73% of those days a negative energy balance was obtained (< 95% RER [resting energy requirement]).

This was attributed to three main factors:

- 22% due to poorly written orders

- 34% due to orders to withhold food

- 44% of the dogs refused to eat.

Overall, the study found that caloric intake had a significant, positive effect on patient outcome.

1. Pathophysiology

Simple starvation implies that the patient is healthy, but is somehow deprived of food, while complicated starvation is reserved for patients where disease has induced a state of anorexia. The ability of the body to respond to starvation is often altered in disease. Therefore, the healthy dog's ability to cope with starvation should not be relied upon exclusively as a model for the sick and anorexic patient. Many disease states may result in an increased need for both energy and additional nutrients beyond what is required during simple starvation (Table 1).

There are marked elevations in catecholamines, glucocorticoids and glucagon in patients that are physiologically stressed. Although the exact increase in nutrient requirements in differing states of complicated starvation is not known, it is significant justification for nutritional support.

No evidence suggests that there are specific and consistent risk factors for needing nutritional support. Disease severity has been the only common factor among patients in need of nutritional support.

Independent of breed predisposition for diseases that require nutritional support for patient management, no breed is more likely to need nutritional support than another.