Limited Ingredient Diet
A limited ingredient food (Limited Ingredient Diet - LID) does not have a standard definition. It generally means the food is limited to one animal protein. Some manufactures state that their food is limited to one animal protein and one carbohydrate. And still others define it further as having an overall lower number of ingredients. Selecting a food with a single identified animal protein is a desirable goal since it is recommended to rotate and feed a variety of differing proteins and brands of food over time to help correct for any excesses, insufficiencies, or imbalances. Another advantage is that dogs fed the same food over time are more likely to develop particular food sensitivity and food allergies.
Many owners select a limited ingredient food in an attempt to avoid foods that may be the cause of food allergies or food intolerance/sensitivities. Food elimination diets are often used to test for adverse food reactions (AFR). “The elimination diet trial should be performed for a minimum of 6 to 8 weeks and ideally 10 to 12 weeks… Although maximum improvement may take up to 10 to 13 weeks,” [Applied Veterinary Clinical Nutrition] “It is noteworthy that dietary trials confirm or rule out adverse reactions to food but do not indicate the underlying mechanism (allergy or intolerance).” [Small Animal Clinical Nutrition 5th edition]
A problem found with several limited ingredient diets is that they often contain additional food ingredients not listed on the label.
” ten of twelve pet foods tested herein as limited antigen diets may not reliably rule out a diagnosis of AFR, and the use of homecooked diets should be considered whenever the dog fails to respond to dietary restriction” https://onlinelibrary.wiley.com/doi/epdf/10.1111/jpn.12045
“ten of the twelve selected commercial dry limited antigen diets, all novel protein diets, were unsuitable for use in diagnostic food elimination trials because they contained ingredients belonging to one or two zoological classes (mammalian, avian or fish) not listed on the label.” https://onlinelibrary.wiley.com/doi/epdf/10.1111/jpn.12045
The U.S. Food and Drug Administration has issued an alert about reports of canine dilated cardiomyopathy (DCM) in dogs eating pet foods containing peas, lentils, other legume seeds, or potatoes as main ingredients. “These reports are unusual because DCM is occurring in breeds not typically genetically prone to the disease.” DCM is a disease of the heart muscle and results in an enlarged heart that often results in congestive heart failure.
“Breeds that are typically more frequently affected by DCM include large and giant breed dogs, such as Great Danes, Boxers, Newfoundlands, Irish Wolfhounds, Saint Bernards and Doberman Pinschers. It is less common in small and medium breed dogs, except American and English Cocker Spaniels. However, the cases that have been reported to the FDA have included Golden and Labrador Retrievers, Whippets, a Shih Tzu, a Bulldog and Miniature Schnauzers, as well as mixed breeds.”
“Taurine deficiency is well-documented as potentially leading to DCM.” This was a problem with cats in the 1980s. Cats require taurine in their food and it is considered essential in their diet. Taurine has not been considered essential for dogs since they can synthesize taurine from the amino acids cysteine and methionine. The FDA issued their alert after a significant number of dogs developed DCM that were on foods containing high levels of peas, lentils, legumes, or potatoes. These dogs were found to have low levels of taurine in their blood. The exact cause is not known and is currently being studied. It may be that certain dogs have a higher requirement for taurine in their diets. The cause may be low or poor quality proteins in the diet, or be caused by ingredient interactions. DCM in dogs has been studied for years although the cause is not certain there have been low taurine levels in dogs that are associated with lamb meal and rice foods, rice bran, cellulose, beet pulp, and high fiber diets.
“Unfortunately, some processed pet food advocates are using the link between grain-free dog foods and DCM to try to push pet parents back in the direction of grain-based diets. Don't be fooled. The problem with grain-free formulas isn't the lack of grains!”
“Mycotoxin contamination in pet food poses a serious health threat to pets. Cereal grains and nuts are used as ingredients in commercial pet food for companion animals such as cats, dogs, birds, fish, reptiles and rodents. Cereal by-products may be diverted to animal feed even though they can contain mycotoxins at concentrations greater than raw cereals due to processing (Moss, 1996; Brera et al., 2006).”
“Given what we do know, a recommendation is to feed a food that contains sufficient levels high quality, animal-source protein, does not include plant-source proteins as its primary protein source, and does not contain high levels of dietary fiber.”