Skip to Content

6 Reasons Purina Pro Plan Causes Loose Stools!

With dogs being such a popular pet choice in the western world where the vast majority of our readers live, we constantly see a wide range of different questions being asked from the dog keeping community about various issues with their dogs.

With there being so many dog food options on the market these days, we commonly see a wide range of questions about all of the different dog food products out there and although we have answered many of these questions already, we want to focus on one of these questions today.

Over the last few months, there have been a large number of people reaching out and asking questions about why Purina Pro Plan causes loose stools in their dog.

With Purina Pro Plan having such an excellent reputation within the dog keeping community as well as so many people reaching out about this each month, we have decided to publish this article to try and help as many of our readers as possible.

Please note that before we go any further with the article, this is general information and not intended to be a replacement for professional advice form a qualified veterinarian. If you do suspect that your dog has a serious issue, you should take it to a vet as soon as possible!

Why Purina Pro Plan Causes Loose Stools!

Here is our show list of potential reasons that Purina Pro Plan is causing loose stools in your dog:-

  • Allergies!
  • Switching Foods Too Fast!
  • A Lack Of Fiber In The Diet!
  • Unsuitable Dog Treats!
  • Digestive Upset!
  • Old Age!

In some situations, your dog may be having issues with more than one of these at the same time so keep that in mind.


The most common reason that Purina Pro Plan will cause loose stools in your dog is due to your dog having allergies to at least one of the ingredients in the food mix.

We would guess that over two thirds of all problems with dog food is due to allergies and most dog owners don’t realize just how many allergies dogs can have!

We have other articles online going over various dog food brands below and the number one cause is always allergies:-

In fact, there are so many common allergies that dogs have to some of the most common ingredients in dog food that we have made our custom table below to try and help our readers.

As you can see from the table, there is a high chance that most dogs having a potential allergy to at least one ingredient in their dog food and a common symptom of these allergies is a loose stool or actual diarrhea.

You can go with a limited ingredient dog food option as these tend to have the lowest number of potential allergens in them but in most cases, these dog foods are more expensive.

The majority of dog food brands, Purina included will offer a fish and rice food mix that is usually the same price as their other options within the line.

We would highly recommend that you try this food mix if possible as most dogs can eat it without issue.

It is surprising how many people switch from a Purina food mix with beef or chicken in it over to the fish and rice food mix and have no issues with their dog.

The issue is not the dog food brand, it is usually the ingredients.

Switching Foods Too Fast!

This is such a common issue that we see with dog owners and it is so easy to do!

When you first get your dog, they will be eating the food that their breeder or previous owner has been feeding them.

The vast majority of the time, this food will not be Purina and in fact, it is often a lower quality food brand.

This is not an issue as most dogs will do just fine on a lower quality food but the problem occurs when people switch their dog over to Purina too fast.

What tends to happen is that people see all of the great things that Purina offers and they want their dog to have the best possible food.

The switch their dog over to purina instantly and their dog ends up having loose stool for a week or so until their gut bacteria switches over to being able to digest the new food mix optimally.

You can do a gradual switch of food by slowly switching the food you give your dog over to the new mix.

We usually recommend that you start with the old food mix if possible and then switch a quarter of the food mix in your dog’s bowl over to the new one every three to four days.

This gradual approach will usually reduce any digestive issues while also making it easier to get your dog to eat its new food mix without issue too.

A Lack Of Fiber In The Diet!

This is a common issue that we see in dogs that are eating a high protein diet or a diet that has a higher than average fat content.

The problem with these types of diets is that they can cause your dog to have loose stools if there is not enough fiber in the food mix.

The fix for this is usually pretty simple and that is to just add some fiber to your dog’s diet.

You can do this by adding a small amount of canned pumpkin to their food mix or even some sweet potato.

Now, this is not actually due to the Purina Pro Plan dog food mix as in most cases, it contains plenty of fiber but the dog treats that you use to supplement your dog’s diet can cause the issue.

For example, things like Bully Sticks are very popular right now and they can work great as dog treats but the spike the protein macronutrient up and can cause issues with there being enough fiber in your dog’s diet.

Unsuitable Dog Treats!

As we touched on above, many people give their dog unsuitable dog treats that can cause issues with its stool and then unfairly blame the primary dog food that they feed their dog.

As we mentioned earlier in the article, many dogs have allergies to many common food ingredients and these can often be found in dog treats too.

It doesn’t matter how good your primary dog food is, if you use low quality dog treats, it can still result in a loose stool or other issues.

Digestive Upset!

Dogs like to eat random things while they are out on their walks and many dogs will end up causing themselves digestive upset due to these random things that they eat.

Just like with treats, the primary dog food that the dog eats often gets the blame for this but in many cases, the dog will have eaten something it shouldn’t and caused the issue.

A good example is when dogs eat seaweed or crab shells if they walk along a beach, these can both cause digestive issues in the dog due to their high salt content resulting in a loose stool.

Old Age!

As dogs get older, their bodies start to slow down and this can often lead to them having a loose stool.

This is not always the case but in many instances, an elderly dog will have a hard time digesting its food as well as it used to and this can result in a loose stool and there is usually little to nothing that you can do.

There are some senior dog food mixes with slightly different macronutrient ratios that may help but this is not guaranteed.