What Is a Limited Ingredient Dog Food?

Limited ingredient dog food is formulated to reduce the number of ingredients that your dog is exposed to within their diet. These diets are used in hypoallergenic dog food trials to diagnose and treat food allergies (adverse food reactions).

There’s conflicting evidence about how common food allergies are in dogs. In a dog with allergic symptoms, about 15-20% of those are related to food allergies. The principle with food allergies and limited ingredient dog food is that a dog cannot be allergic to an ingredient that it has not been exposed to before.  

Beef, dairy, chicken, and wheat account for 79% of food allergies in dogs. It is uncommon for a dog to have a food allergy to a grain other than wheat. 

Here’s what you need to know about limited ingredient dog foods and what they can do to help dogs.

What Does “Limited Ingredient Dog Food” Mean?

“Limited ingredient dog food” is not a regulated term. The term “limited ingredient” or “limited ingredient diet” (LID) is used loosely, and although there may be fewer ingredients in the food, those ingredients may or may not be appropriate for your dog.

If you are looking for a dog food with limited ingredients, you should still always check the ingredient label to see what’s in it. There can be surprising “hidden” ingredients in these diets that are potential problems for dogs with food allergies.

LID dog food should have been evaluated for contamination with unwanted ingredients. Studies show that prescription versions of limited ingredient dog food diets are less likely to have contamination with unwanted ingredients.  A recent review of several studies showed that 33%-83% of nonprescription “limited ingredient” pet food diets had ingredients in them that were not listed on the label.

To determine if a particular diet is right for your dog, consult with your regular veterinarian.

How Many Ingredients Is “Limited”?

There are no set regulations for how many ingredients are in a limited ingredient dog food. This term indicates that the number of ingredients in the food is reduced from the number in your average dog food formula, but the important consideration is what the ingredients are, not the actual number of ingredients. 

What’s Usually in a Limited Ingredient Dog Food?

Generally, a limited ingredient dog food diet has a novel protein (one that’s not common in other dog foods), and sometimes, a carbohydrate source that is out of the ordinary. LID dog foods may contain a carbohydrate source that is an unlikely cause for food allergies, such as rice. 

Protein in Limited-Ingredient Dog Food

Limited ingredient diets list proteins such as:

• Rabbit

• Fish (salmon, trout, whitefish, herring)

• Alligator

• Kangaroo

• Venison

• Bison

• Duck

• Pork

• Turkey

• Lamb

• Chicken

It is important to note that just because a nonprescription dog food is labeled as limited ingredient, it does not mean that it is appropriate for a hypoallergenic food trial to diagnose food allergies in dogs.

Many of these ingredients, like lamb, turkey, and chicken, are very commonly used in regular dog foods, and therefore, most dogs have been exposed to them.

Carbohydrates in Limited-Ingredient Dog Food

Common carbohydrate sources used in limited ingredient dog foods are:

• Potatoes

• Rice

• Sweet potatoes

• Peas

• Brown rice

• Lentils

• Oatmeal

What’s the Difference Between Grain-Free and LID Dog Food?

A grain-free diet is not the same as a limited ingredient diet. 

A grain-free diet does not contain any of the grains that are commonly used in dog foods:

• Wheat

• Rice

• Barley

• Oats

• Rye

• Corn

• Quinoa

But some limited ingredient dog foods do contain certain grains, although you might not find grains like corn and wheat.

A limited ingredient diet typically contains one or two protein sources and one or two carbohydrate sources. Grain-free diets may contain many other food sources, so they are not necessarily what you would call a limited ingredient food.

Does My Dog Need an LID Dog Food?

A limited ingredient diet is not necessary for healthy dogs with no medical issues.

The most common reason to feed a limited ingredient dog food is to diagnose a food allergy (adverse food reaction). This is currently the only way to diagnose a food allergy in dogs. Skin tests, hair or saliva tests, and blood tests are not accurate for diagnosing food allergies.

Food-allergic dogs can have symptoms involving the ears, feet, inner thighs, armpits, face, and area around the anus. Itchy ears, with or without infection, may be the only symptom in up to 25% of dogs with food allergy.

Some dogs may only have recurrent skin infections, with or without itching. Some dogs with chronic diarrhea may have an underlying food allergy, as 10-15% of dogs with a food allergy have GI symptoms.

Using LID Dog Food to Diagnose Allergies

The principle with a hypoallergenic food trial to diagnose a food allergy is to feed foods that a dog has not been exposed to before. Limited ingredient diets are often the first choice of veterinary dermatologists for diagnosing food allergies.

Another type of diet that is commonly used is a hydrolyzed diet. These are diets in which the protein is broken down into very small particle sizes, with the goal being that the body cannot recognize it as an allergy causing substance.

Food trials are conducted for 8-12 weeks and require strict adherence. Flavored medications, flavored chews and toys, human foods and treats must be discontinued and/or substituted with acceptable alternatives.

Any infections that are present in the skin or ears must be treated at the same time to be able to tell if the food trial is successful.

Is Limited Ingredient Dog Food Better?

You may think that just having fewer ingredients makes LID dog food better than other dog food, even if you don’t suspect that your dog has allergies.

But having fewer ingredients doesn’t mean much on its own, unless those ingredients are high-quality ingredients. You could have a human food that only has three ingredients, but those might be corn syrup, food coloring, and an artificial preservative.

If you suspect that your dog might have food allergies, you might be wondering which dog food is best out of limited ingredient, grain-free, and gluten-free dog food. Veterinarians do use limited ingredient diets for food trials to diagnose allergies, so you should talk to your vet about starting a food trial and determining which formula is best for this.

While grain-free and gluten-free diets may be beneficial to some dogs, the reported percentage of dogs that have adverse reactions to grains is low, relative to proteins. A diet that is labeled grain-free or gluten-free may or may not be a limited-ingredient diet.

Your veterinarian is the best person to help you choose which type of diet is the best choice for your particular dog, whether or not you are worried about dog food allergies.

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