A Collection of Veterinary Nutrition Studies
I spent last week in Seattle, WA at the 2013 American College of Veterinary Internal Medicine Forum. My professional organization, the American Academy of Veterinary Nutrition, held its 13th Clinical Nutrition and Research Symposium in conjunction with the forum. The symposium features oral and poster abstract presentations of recent or soon to be published studies. I would like to spend the next three blogs filling you in on some of the interesting research findings featured at that symposium.
Glycemic Index and Diabetic Dogs
As many of you know, the Glycemic Index (GI) of carbohydrates is a ranking system for sugar containing foods based on the speed and quantity that glucose is absorbed from the gut and the intensity of the insulin response to the elevated glucose. Foods with a low glycemic index number (Glycemic Index Chart) elevate blood sugar and insulin levels more slowly. Low glycemic index foods are helpful in regulating insulin requirements for human diabetics. These foods also reduce abdominal fat without total body fat loss and reduce the risk of cardiac complications for human diabetics.
A new study in dogs evaluated the effects of a diet with a high glycemic carbohydrate, white rice (GI=70), and a diet with a low glycemic carbohydrate, peas (GI=40). The absolute calorie counts, protein, fat and carbohydrate amounts were identical. The dogs were fed to maintain their present obese weight. The researchers found that dogs fed the pea diet had a reduced insulin response and reduced abdominal fat despite maintaining overall body fat. These dogs also showed smaller increases in the heart wall thickness ratio than the rice fed dogs.
Increased heart wall ratios correlate with heart disease risk and are part of “the metabolic syndrome” associated with abdominal fat in humans. More studies to confirm these findings may spark more interest in the Glycemic Index of pet food.
Dog Milk Replacers
This was a particularly disturbing presentation. Researchers evaluated 15 milk replacers, many well-known, compared to collected bitches’ milk. The dietary requirements of the bitches were controlled so that contents of the milk were not influenced by diet and supplementation. None of the milk replacers were a nutritional match for “mom’s milk.”
Calorie counts varied despite identical feeding instructions and some contained levels of lactose that would cause diarrhea in newborns; 14 of the 15 had DHA levels below that of bitch milk.
Over half of the products had a key amino acid, arginine deficiency, and 1/3 had a calcium-phosphorus ratio well below bitch milk and below accepted nutritional standards.
The study did not identify specific brands and problems so I cannot make any recommendations. Suffice it to say, orphaned dogs on milk replacers will be behind the nutritional eight ball and will need to be weaned to a liquefied or blenderized balanced puppy formula as quickly as possible.
Taurine Deficiency Cardiomyopathy in a Dog
Cat owners are well aware of the cardiac consequences of taurine deficiency in cats. Because the taurine requirement is lower in dogs, they typically can easily meet this requirement with the meat protein in dog food and seldom develop this condition as a result of diet.
This was a case study poster presentation about an English Bulldog that presented to the Ohio State Veterinary School teaching hospital in heart failure. The dog was diagnosed with the same dilated cardiomyopathy found in taurine deficient cats.
As it turns out, this dog had severe allergies and the owners were feeding a diet exclusively composed of lentils, brown rice, and potatoes using an online recipe to control the dog’s skin problem. The owners supplemented with a daily multi-vitamin/multi-mineral capsule and calcium citrate tablet, so they felt that the diet was nutritionally adequate. Non-animal sources of protein are extremely deficient in taurine and this dog’s blood taurine level was 2nmol/ml versus a normal of 60-120nmol/ml (don’t worry about the meaning of the units).
Happily, the dog was put on a taurine supplement and a complete hypoallergenic, limited ingredient dog food that controlled his allergies. On the balanced diet and supplements, the heart changes reversed and the dog was tapered off taurine supplementation.
My now stale but important message: Always get professional assistance and/or proof of nutritional content (all 42-44 essentials) when feeding your pets homemade diets.
Dr. Ken Tudor