Once you have selected a good quality dog food, that’s all you need to feed, right? Not really. You should vary your dog’s food periodically. There are many good reasons for this:

_ Dogs (actually all mammals) are designed to consume a range of different foods, and to obtain differing vitamins and minerals from each. They are not designed to eat “only chicken” or “only lamb” or any other food item for eternity. Rotating foods, importantly the contents of those foods, every so often helps to give them the variety their bodies were designed to thrive on.

_ There is no one dog food in existence that “has it all”. And remember, the feeding trials that foods go through only last for six months (and not all foods are examined the same way). Rotating foods periodically helps to ensure that no dietary deficiencies or excesses build up over time.

_ Variety is the spice of life. Who wants to eat the same food day in and day out? Could you do it? For months or years? Feeding your dog something different helps to ensure that he does not become bored and frustrated with his food. This will not make your dog picky - we are talking about periodic changes here, not serving up something different or adding goodies to tempt him every time he doesn’t like his dinner. 
And most importantly of all:

_ It helps to avoid the development of allergies. In a few extreme cases, you (or your dog) may be instantly and violently allergic to something. But that is a few extreme cases only - the vast majority of allergies are things that build up over time and with constant exposure. The surest way to develop an allergy to chicken, for example, is to consume it daily for an extended period. It is no coincidence that the most common allergens are things that have commonly been used in dog foods for many years. The (modern) advice given by nutritionists is that feeding a wide variety of different foods, preferably from a young age, can help to avoid the development of allergies in the first place (that's the advice given for humans too). 

Common signs of allergies are itchy skin, red itchy paws, chewing paws, yeast infections, ear infections, and skin infections that may respond to antibiotics but reappear as soon as the antibiotics are discontinued.

That all adds up to rotating the food you feed every once in a while. That means rotatinging to a food with different main ingredients. There is very little benefit to switching from one chicken/rice food to another, for example. If you have been feeding a food with chicken as the main ingredient, then it is far better that the next food is based on lamb, or turkey, or fish, or beef, etc and that the other main ingredients are also varied.

Do I have to change brands every time I rotate food?

No, not necessarily. Look at the ingredients in the different formulas made by your brand. What is different? If it is only the main meat ingredient, then you should change to a different brand when you rotate foods. If many of the ingredients, including the main meat, are different then there is no need to change brands if you don’t want to. The point here is to ensure that your dog gets a good variety of different food items in his diet. Not brand loyalty.

How often should I rotate foods?

Minimally, at least every three months. But you can rotate more frequently than that. If your dog does not suffer from digestive upsets when his food is rotated, then you might even consider changing foods every time the bag runs out.

How many different foods do I need? Can I use a food again?

At least three or four different foods (different main meat source and different main ingredients). More is better. You can certainly reuse a good food though, especially if your dog does particularly well on it. You could choose, for example, to feed food A for one bag then rotate to food B – go back to food A, then to food C and so on. This satisfies the criteria of avoiding constant or prolonged exposure to a particular set of ingredients.

What about just mixing foods together?

Mixing foods together can certainly help to ensure nutritional adequacy for the long term. But it does nothing to provide your dog with variety (something different to eat!) and it does not satisfy the criteria of avoiding constant or prolonged exposure to a particular set of ingredients. So this practice will do nothing to help avoid the development of food allergies – it just means that there are a greater number of things the dog is being exposed to on a constant basis. It also means that there is a wider range of possible culprits should a food allergy develop. You can mix foods if you choose, but you should vary the foods that you mix together, just as if you were feeding a single food.

Do I need to rotate the food gradually?

It is usually wise to effect a change gradually. Not every dog is sensitive to food changes, and many will handle cold turkey changes without issue. But many won’t, and the upset tummies and loose stools that can come with rotating foods too fast are such an annoyance (for the dog too!) that it makes sense just to rotate gradually, unless you know for certain that your dog has the sort of cast iron stomach that won’t be upset by a sudden change.

The simplest way to rotate foods is to blend the old and new foods together for a week or so. Start with a mix that is 25% new food and 75% old. Feed that for two or three days, and if there are no upset tummies or loose stools, increase the blend to a 50/50 mix. Again, feed that for a couple of days, then increase to a 75/25 blend, and finally to 100% new food. If at any stage there is a tummy upset or the dog’s stools become loose, then hold off on increasing the amount of new food in the blend until that problem resolves. If there are no problems at all, it will take a week to ten days to accomplish the switch.

Won’t rotating foods make my dog picky?

No, it won’t. It’s more likely to have the opposite effect, and keep the dog interested in his food. How long could you stay interested in eating exactly the same thing? A food rotation once a month, or every two or three months is not going to give you a picky dog. What creates pickiness is serving up something different any time the dog shows no interest in his meal. Just like little kids, a dog will learn very quickly that refusing to eat a meal results in Mom producing something better – if you constantly produce something better. Instead, you should give the dog his food at set meal times, and pick it up if it is not eaten within about 20 minutes. Don’t offer anything else (i.e. don’t fill him up on treats) until the next meal time.

Are there any other benefits to rotating foods?

YES! Rotating foods every so often means that you keep yourself aware of what is available. Dog food is not a static science and it is very pleasing to be able to note that constant improvements are being made. Foods that may have once been amongst the best available are constantly being surpassed (this is a good thing! Dog food has not historically been a high quality product). 

We’ve all met people who swear “brand x” is the best you can get – and have been feeding it for the last 15 years, completely unaware of advances that have been made. Well, that may have been true 15 years ago, but now “brand x” may be one of the lower quality foods available (though it’s unlikely to be reflected in cost).

We fully expect the foods we currently recommend here to be surpassed or improved in the coming years. This is good news for you and your dog. Don’t fall into the trap of assuming that what is the best available now will always be the best you can get. It won’t be (or at least, we sincerely hope that it won’t be).