Supplementing your dog’s diet with probiotics is an important part of boosting her immune system and overall health. It can also help manage irritable bowel disease and gastrointestinal upset…

… But not all probiotics are equal.

FortiFlora is a probiotic supplement that many conventional veterinarians recommend. In fact, Purina claims that it’s the #1 probiotic that vets recommend…

… So what if I told you I’d never give it to my dogs or cats?

Let me tell you why.

Ingredients In FortiFlora

The ingredients in ForiFlora:

  • Animal Digest
  • Enterococcus Faecium
  • L-Ascorbyl-2-Polyphosphate (source of Vitamin C)
  • Brewers Dried Yeast
  • Vitamin E Supplement
  • Zinc Proteinate
  • Beta-Carotene
  • Salt
  • Manganese Proteinate
  • Ferrous Sulfate
  • Copper Proteinate
  • Calcium Iodate
  • Sodium Selenite

That’s a long list of things, so let’s just look at the ones with the most issues, like animal digest.

What The Heck Is Animal Digest?

Animal Digest is a concentrated flavoring agent made up of hydrolyzed animal protein. It’s not actually the contents of the digestive tract. It’s a reference to the way the manufacturer processes the animal protein  and it means that the protein is hydrolyzed with heat, enzymes and/or acids to break it down into its subsequent amino acids.

FortiFloraIn many cases, changing the chemical structure of a protein (hydrolyzing it) can void or minimize its nutritional value.

The wording is intentionally vague, as we’re not told what type of animal is used to make this component of the supplement. Purina claims that the digest is made up of animal protein supplied by a USDA-inspected facility.

However, they don’t state that the animal protein itself is USDA-inspected. This is a problem because USDA-inspected facilities include rendering facilities that process euthanized animals and “4-D” livestock. 4-D = dead, dying, diseased, and downed.

According to the Environmental Protection Agency, these facilities can get “meat” from all kinds of places including:

  • Butcher shops
  • Supermarkets
  • Restaurants
  • Fast-food chains
  • Animal shelters

Fast-food chains? Animal shelters?

It’s pretty easy to understand why the company chooses to keep their wording ill-defined.

To make matters worse, before these ingredients are rendered they have to be denatured. This means they get a coating of carbolic acid or cresylic disinfectant, which are both known toxins that will cause chemical burns and can even be fatal.

[Related: FortiFlora isn’t the only vet recommended food that contains toxins. Here are some of the others]

Probiotics: The More The Merrier?

In the case of probiotics, more is better.

Your dog needs probiotics to defend the gut. When there are more good bacteria, the gut can fight off anything it sees as a threat. That’s why you want more probiotics.


Ironically, the second ingredient in FortiFlora, Enterococcus Faecium, is the only bacteria strain in the entire ingredient panel. The problem with having only one bacteria strain in a probiotic supplement is that the gastrointestinal tract is home to hundreds of different types of bacteria all of which thrive in different sections of the digestive system.

The dog’s stomach houses a relatively low bacterial count made up of two primary bacteria strains. Slightly farther along the digestive tract, however, in the first part of the small intestine, one study found six different phyla of bacteria. Another study in 2008, found four bacteria strains in the jejunum that were not previously known to live there.

A supplement with only one bacteria strain will likely not serve the whole GI tract.

How To Spot A Quality Probiotic

An easy way to spot a quality probiotic is to look at its Colony-Forming Unit (CFU) count. CFU count refers to the number of viable bacteria cells in a sample amount. We measure the CFU count in probiotics per gram and the higher the CFU count, the better, since some of the bacteria will not survive the digestive process.

FortiFlora has a moderate CFU count of one hundred million CFU per gram. In comparison, my probiotic supplement of choice has a CFU count of 30 billion per gram.

The Problem With Synthetic Vitamins And Minerals

The majority of the ingredients in FortiFlora are synthetic vitamins and minerals (9 of the 13 ingredients to be exact) and the body can’t use these inorganic mineral forms such as oxides, sulfates and carbonates as well as whole foods.

So, one of the FortiFlora side effects is that you’re limiting your dog’s ability to absorb the nutrients she really needs.

FortiFloraIn fact, using synthetic antioxidants like the beta-carotene listed in FortiFlora’s ingredients can block the antioxidant activity of other carotenoids supplied from whole food sources.

Some claim that chelated minerals (those ending in proteinate) are easier for the body to digest, but their quality can vary greatly. Cheaper chelates often come from extracting a mineral from crushed industrial rock with one or more acids then attaching it to a hydrolyzed soy protein.


Glyphosate’s another problem. Over 90% of the soy crop grown in the US is from genetically modified seed from Monsanto. Monsanto seeds are created to be resistant to glyphosate based weed killers like Roundup. This study found that good bacteria are negatively impacted by the presence of glyphosate but “bad” bacteria like Salmonella are highly resistant.

FortiFlora contains chelated minerals which are created by attaching a hydrolyzed soy particle to a mineral in the hopes of making it more digestible. Because at least 90% of the soy crop grown in the US is from that Monsanto seed, it’s likely that this is the type of soy used during chelation. This soy is modified so it doesn’t die when sprayed with glyphosate based weed killers. However, after being sprayed there are traces of glyphosate in the plant itself meaning it could be present in the supplement.

[Related: What’s the big deal about GMOs? Find out here]

So, what’s the alternative? Natural probiotics.

Feed Natural Probiotics Instead

So, don’t rely on synthetic supplements. Instead, add some natural probiotics to your dog’s diet.

Here are some good ones to try:

Raw green tripe

  • Made from the lining of a ruminant’s stomach. It’s full of the same digestive enzymes and beneficial bacteria that help dogs break down food.
  • Start your pet off with a few tablespoons and work your way up to a ¼ cup per 50 lbs of your dog’s weight.


  • Kefir is a cultured, fermented liquid that’s made from dairy milk, goat’s milk, coconut milk or water. It’s full of healthy bacteria and protein. You can buy kefir (make sure it’s unsweetened) or make your own.
  • Give about 1 tbsp per 25 lbs of your dog’s body weight.

Fermented Vegetables

  • These are foods like sauerkraut or kimchi. You can buy them or make your own.
  • Mimic the gut contents of prey animals, have beneficial bacteria and serve as a prebiotic.
  • Feed 1 tsp per 30 lbs.

Raw Goat’s Milk

  • Full of natural probiotics and is more digestible than cow’s milk.
  • Give about 2 oz per 25 lbs of your dog’s weight. Add 1 tsp of a probiotic supplement into your goat’s milk to make it extra potent.


And remember, if you do want to give your pet a probiotic supplement look for one with a high CFU count and no fillers. If your probiotic doesn’t already include a prebiotic, it’s a good idea to add one to make your probiotic more effective. Read why here.

Probiotic foods or supplements can work wonders for your dog’s gut health … and because 80% of your dog’s immune system is based her gut, probiotics boost her overall health too. So skip the FortiFlora and go natural.