Refeeding syndrome in dogs & cats | VETgirl Veterinary Continuing Education Videos
In today’s VETgirl online veterinary CE video, we discuss refeeding syndrome, which is a condition that can occur after chronic malnourishment. This was first described during WWII and has since been well documented in human medicine. Chronic malnourishment can occur with severe parasitism, malabsorptive or maldigestive disorders, neglect, animal abuse, starvation, etc.
This middle-aged, male intact Pit Bull mix was rescued from an abuse situation and presented laying on a sled on frozen urine-soaked cardboard boxes. He was hypoglycemic, hypothermic, hypotensive, and minimally responsive. He responded well to initial stabilization and within 12 hours, was stable, ambulatory, and eating well.
This dog’s body reserves were completely depleted and he was at clear risk for developing refeeding syndrome. Other veterinary patients at risk would be those with severe malabsorptive intestinal diseases, obese animals with extreme and rapid weight loss, or prolonged anorexia or starvation. NOTE: this condition is different than hepatic lipidosis seen in anorexic obese cats; that said, a similar slow feeding protocol should be used to implement nutritional support in these patients too!
Total body reserves of sodium, potassium, phosphorous, and magnesium are depleted in these states, while serum levels are maintained. Natiuresis during anorexia can lead to volume depletion. Typically, the body uses protein and fat for energy during starvation; during re-feeding, the body isn’t equipped for the carbohydrates that are present in the diet, tube feeding mixture, or parenteral nutrition that we commonly use. This is more marked in ill patients versus simple starvation.
When malnutrition is reversed, there is a significant shift back to the use of carbohydrates, rather than fat reserves, resulting in a significant insulin release. Insulin will increase the update of glucose, potassium, phosphorous and magnesium. Naturiesis stops and edema can develop. Increases in HR, BP and cardiac output can lead to volume overload and pulmonary edema, even in dogs with no previous history of heart disease.
Just like when you give insulin to a diabetic ketoacidotic patient, the endogenous release of insulin with refeeding syndrome can result in both potassium and phosphorous shifting from the extracellular to intracellular compartments, resulting in severe hypokalemia and hypophosphatemia within the first few days. If severe enough, muscle weakness, respiratory depression, and intravascular hemolysis can occur.
So how do you prevent refeeding syndrome? Calculate the resting energy requirements (and give the exponential RER formula), then feed 25% of RER the first day, increase to 50% on the 3rd day, 75% on the 5th day, and 100% on the 7th day. while closely monitoring the blood glucose, potassium, phosphorous and magnesium levels. If abnormalities develop, consider reducing the amount that you are feeding by 50% to avoid dropping the glucose intake too rapidly. Also, make sure to supplement the electrolytes as needed in IV fluid therapy.
When refeeding, feed a recovery/critical care diet, ideally, unless the patient has underlying conditions that warrant limitations in fat or protein (e.g., like pancreatitis and renal disease). When in doubt, check with a veterinary nutritionalist for treatment and management, if available.
During re-feeding, make sure to monitor body weight closely and supplement with Vitamin B complex. The majority of weight gain in the first week should be fluid weight, not body mass. After the first week, re-calculate energy requirements based on ideal body weight and slowly increase from there. Although it is tempting to feed these patients as much as they want to eat, refeeding syndrome is a life threatening condition that must be avoided for the patient’s survival.