Why is my dog itchy?
Allergies are a very common cause of itchy skin in dogs. Your dog might be allergic to certain protein molecules in food ingredients, grass, dust mites or many other common things found in its environment. Trying to determine exactly what your dog is allergic to can be challenging. Diet trials are designed to find out if your dog has an allergy to something in its food, and to figure out exactly what food item it is allergic to.
What is a diet trial? – aka ‘elimination diet’
A diet trial aims to find out which protein(s) your dog is having an allergic reaction to. The trial starts with a diet which contains no or very few allergenic proteins. Then, one at a time we ‘challenge’ the body by adding in a small amount of a single protein source and seeing if the dog reacts to it. If your dog does not react to the protein challenge, the protein is ‘safe’ and can be added back into the dogs diet.
Ideally, a diet trial should last 8-12 weeks in total.
Remember, every type of food contains ‘proteins’ of some type, not just meats. Grains, potatoes and dairy products all contain proteins too.
Where do I start?
The starting point for a diet trial is with an an-allergenic or hydrolysed diet. These diets are produced by specialist veterinary nutrition companies. They use a process called hydrolysis to break down the proteins into small molecules that the immune system doesn’t react to. These diets are nutritionally balanced so can be fed long term.
Hypo-allergenic diets contain lower levels of proteins which can cause allergic reactions. However, they may still cause a skin reaction in your dog because the proteins they contain haven’t been processed in the same way as hydrolysed diets.
An-allergenic or hypo-allergenic dog foods can be ordered through the vet practice.
It is important to store the food in a clean, dry place. Keep the bag sealed and do not pour the food into another container. The food has been packaged in a contaminant free conditions so it is important to prevent any other allergens getting into it!
What do I do next?
Feed ONLY the an-allergenic or hydrolysed diet to your dog for 2 weeks. NO TREATS, dental chews, flavoured toothpastes or ‘palatable’ medications should be fed at all. If treats are needed for training, use the trial diet.
If there are other animals in the house, use different feeding bowls/scoops for the dog you are doing the diet trial for. Wash all bowls/scoops/cups regularly.
Challenge 1: continue to feed the above diet. Add in a small amount of a single type of protein that was previously in your dogs diet (e.g. chicken, turkey, white fish) each day for up to 2 weeks. If your dogs skin flares up, stop feeding the protein source. If there is no reaction, you can continue to feed the protein. Keeping a diary is a great way to keep track of what foods your dog can tolerate and what causes a reaction
Challenge 2: repeat step 4 but add in a different type of protein, for up to 2 weeks.
You can challenge your dogs diet with as many protein sources as you would like in order to find out what is ok to feed.
Maintenance: once you have found out which foods your dog can eat without having a skin flare up, continue to feed only a diet containing those foods.
What if my dog is still itchy after feeding the an-allergenic diet?
If your dog is still itchy despite feeding the diet for 2 weeks, it is likely that something other than a food allergy is causing the itch. This may be an allergen in the environment, external parasites or a skin infection. Please contact your vet for further investigations.