This information is from our visit with a vet dermatologist and from an NWVDS Information Handout written by Dr. Vincent Defalque and Dr. Tyler Udenberg in 2017.
Why do a Food Trial?
Casper came to us with itchy skin and scarring/scabbing. This improved somewhat with basic care, but he remained an itchy cat with the occasional flare up causing him to become uncomfortable. A food trial is a way to ascertain if a food allergy is a cause of a Casper’s skin issues (aka, a cutaneous adverse food reaction). We started this trial in winter: an ideal time as their are less potential allergens in the air.
What is a Food Trial?
A food trial to test for a cutaneous adverse food reaction requires maintaining a strict diet for several weeks. There are two vet prescribed diets that can be used: A Novel Diet and a Hydrolysed Diet. The theory behind the novel diet is to feed a protein source that the cat would not have been previously exposed to (and therefor not have developed a prior immune response). This may vary depending on your location. The theory behind the hydrolysed diet is that the protein in the food is broken down to be so small that the immune system is not stimulated. A homemade diet may be needed if the vet is concerned that additives may be the issue.
The hand out we received listed possible acceptable treats for Casper…these included: dried or boiled sweet potato, carrots, broccoli and apples. It’s possible this list was meant more for dogs.
Why so long?
Cat food reactions aren’t like people food allergies, and usually take days to weeks to show symptoms. Our vet specialist suggested an 8 week food trial.
How to Proceed?
Step 1: Buy the special vet prescribed food, making sure to have enough that you don’t run out. Fortunately prescription food is returnable if your cat won’t eat it.
Step 2: Realize you will be surviving on pasta and Shreddies to pay for the prescription food.
Step 3: Slowly transition your cat to the new food:
- Day 1-2: 75% old food and 25% new food.
- Day 3-4: 50% old food and 50% new food.
- Day 5-6: 25% old food and 75% new food.
- Day 7: the pet should be 100% on the new food.
Step 4: Monitor the cat’s wellbeing: checking “itch score”. Maintain the diet for a minimum of 8 weeks and rebook with the vet.
Step 5: Potentially, the cat can now start a food challenge to test food allergies more specifically. If however the food is not resulting in a significant improvement, tests for environmental allergies or a different food trial may be warranted.
An added complication to doing a food trial is if you have a multi-pet household. It is important that the patient does not have access to any non prescription food or treats during the trial. Fortunately our dog gets fed in our barn, but we do have four other cats that live in our house. For simplicity sake, we have opted to transition all the indoor cats to the prescription food. They are not thrilled.