Nutritional support for critically ill dogs and cats is often delayed until diagnosis or appropriate medical/surgical intervention can occur.
Anorexia is a lack of food intake. Hyporexia is a reduction in food intake. Lack of food intake may not be recognized until cachexia or biochemical evidence of starvation occurs.
A 2001 survey found that, in hospitalized dogs, 73% of the days admitted were spent in negative energy balance. Reasons cited were poorly written orders (22%), orders to withhold food (34%), and the animal’s refusal to eat (44%).1
Animals in negative energy balance may be protein–calorie malnourished and have whole-body depletion of essential nutrients.
Animals undergoing simple starvation should be differentiated from those with medical conditions that result in physiologic stress or impaired hormone balance. Withholding energy and key nutrients from critically ill patients may cloud diagnosis, hinder response to treatment, and increase risk for sepsis.
Protein–calorie malnutrition results in decreased immune competence and catabolism of not only lean body mass, but organ and lymphatic tissues.
B vitamins are necessary for energy metabolism and adequate lymphocyte function.
Glutamine is important for normal enterocyte health; arginine and taurine are important for lymphocyte function.
Deficiencies in certain minerals, such as selenium, copper, zinc, and iron, increase rates of infection and decrease cell-mediated and humoral responses.
Deficiencies in vitamins A and E result in impaired lymphocyte function and delayed wound healing.
Causes & Risk Factors
Animals living in multianimal households or that have several caregivers may have prolonged hyporexia that goes unnoticed for days to weeks.
Overweight or obese animals may have significant muscle wasting that is overlooked due to degree of adiposity.
Animals on unconventional diets (eg, unbalanced home-prepared diets) may have whole-body depletion of essential nutrients that may impact immune function, wound healing, and response to medications.