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Food Trials for Dogs

Learn about food trials in dogs.

If your veterinarian ever suggests a food trial for your dog, you may have some questions about how and why they're done. Of course, your veterinarian is the best source of answers for your dog's specific situation, but this article should help you understand the general mechanics of food trials for dogs.

When Is a Food Trial Done?

Your veterinarian may recommend a food trial for your dog if he or she is concerned about a food allergy. The signs of food allergies can overlap with those of other types of allergies, like inhalant allergies (atopy).

Food allergies in dogs are caused by an overreaction of the body's immune system to components of the diet, especially the protein source.

Signs of a food allergy in dogs can include:

  • Excessive licking and chewing at the paws, flank, groin, and ears. Chronic otitis externa is extremely common in dogs with food allergies.
  • Hair loss, thickened skin, and secondary skin infections.
  • Vomiting, excessive flatulence, and diarrhea (GI signs are less common than skin symptoms).

In order to diagnose the cause of a skin allergy, a veterinarian may do various tests, including serum or skin allergy testing, which are good for helping to diagnose inhalant allergies.

Skin and blood testing are not accurate for food allergies. Instead, a food trial is necessary for diagnosing food allergy in a dog.

If a food allergy is suspected, the veterinarian may suggest a food trial, which is the gold standard test for diagnosing food allergies.

How Is a Food Trial Performed?

A food trial consists of taking the dog off the diet she's been on and instead, giving her a diet that she's unlikely to be allergic to. There are a couple different options that fall into the following categories:

  • Novel protein diets. These diets use a protein source that isn't in over-the-counter dog foods. Examples are salmon, kangaroo, and rabbit.
  • Hydrolyzed diets. These diets are low-antigen, which means the proteins have been formulated to be too small to trigger an immune response.
  • Homemade diets. These generally also use a novel protein source. It's crucial that the owner prepares the diet based on a recipe created by a board certified veterinary nutrition specialist, so the dog is certain to get all the required nutrients. A homemade diet is often chosen when the dog won't eat one of the other types of food trial diets or they don't agree with her.

Once the veterinarian chooses the type of diet for the trial, the owner should mix the two diets together, gradually adding more of the new diet and less of the old until the dog is completely on the new diet. This can take a week or two and is meant to decrease the chances of vomiting or diarrhea related to a fast diet change.

Once the dog is completely on the hypoallergenic diet, the clock starts. A dog should be on the diet for at least eight to twelve weeks, and the owner will monitor closely for improvement in the original signs of allergy.

The Biggest Pitfall of Food Trials

The biggest pitfall involved with food trials is the dog getting some other type of food. When that happens, the clock must be reset on the food trial. The dog must not get anything besides the recommended diet, including treats, human food, flavored medications, vitamins, supplements, and preventatives (like heartworm preventative). Even flavored dog toothpaste has to be avoided.

If your dog is on a food trial, you must be diligent about making sure your dog doesn't have access to anything that isn't the therapeutic diet. That may mean limiting his access to the kitchen or dining area during meals and making sure visitors know the rules. Additionally, if you have other pets, your dog must not be able to get to their food or, in the case of cats, the litter box because the allergic dog will get proteins from the cat's diet if they eat cat stool. Be sure your dog can't get into the garbage and leash walk her so she doesn't scarf up something outside.

Instead of treats, while your dog is an a food trial, you can use bits of the food trial kibble. Or, if there is a canned version of the food trial diet you can bake thin slices until they're crispy to use as treats.

Remember, any time your dog eats something that isn't the food trial diet, it could re-trigger the allergy and make the food trial invalid. You will have to do the food trial longer in those cases, so being diligent about making sure your dog can't get anything else will save you time and money.

What Happens After a Positive Food Trial

If the food trial is positive, it means that the dog's allergy symptoms disappeared while she was on the food trial diet. In that case, there will be two options for you to consider going forward: staying on the food trial diet long-term or conducting food challenges.

During a food challenge, a new ingredient is added to the dog's diet individually, and the dog is monitored for return of allergy symptoms for six to eight weeks. If signs occur, that ingredient is off-limits. If not, you can look for an over-the-counter food that contains those ingredients. This can be time-consuming, as you can only add one ingredient at a time and must wait to monitor the response.

You May Also Like These Articles:

Dealing With Canine Scratching and Licking

Food Allergies in Dogs

Atopy: Inhalant Allergies in Dogs

Contact Dermatitis in Dogs

Otitis Externa: Ear Infections in Dogs

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