FortiFlora vs Proviable: which probiotic should you buy?
For most dogs, FortiFlora: one packet a day gives 100 million CFU of one strain, SF68, for $1.03 a day, and a 2011 lab test found 2.6 times the bacteria on its label, one of 2 of 25 products to pass every check.1 Pick Proviable instead for 5 billion CFU from 7 named strains plus a prebiotic (50 times the CFU) at $0.67 a day, $0.36 less.
Best for most dogs
Purina Pro Plan FortiFlora Probiotic Powder
100 million CFU a day (1 packet)one strain (SF68)$1.03 a day at any weight2
Best value
Nutramax Proviable Chewable Tablets
5 billion CFU a day (1 tablet)7 strains, each with a strain code$0.67 a day at any weight3
How we pick: FortiFlora is the vet brand with the NASC seal and a lab-checked count; Proviable gives the most bacteria for the least cost. Both labels give one dose for every dog size. Prices on Amazon, October 28, 2026.4, 5
Per day, any size dog
Purina Pro Plan FortiFlora Probiotic Powder vs Nutramax Proviable Chewable Tablets
From each label. Prices on Amazon, October 28, 2026.
Which one to buy
- Buy FortiFlora for the easiest dose. It is a flavored powder: one packet a day on food, 100 million CFU of Enterococcus SF68, $1.03 a day.2, 6 It is the one we pick for most dogs in the best probiotic for dogs, and the maker holds the NASC Quality Seal.5
- Buy Proviable for the most bacteria for the money. One chewable tablet a day gives 5 billion CFU from 7 strains, each printed with its strain code, for $0.67 a day: about 35% less than FortiFlora, or about $134 a year, and it adds a prebiotic.3, 7 Cornell's canine health center says vets tend to recommend a product with a variety of bacteria rather than a single strain.8
- Same dose for every size. Neither label has weight bands, so a 10 lb dog and a 100 lb dog pay the same per day.
FortiFlora and Proviable side by side
The dose is the label's own, the same for every dog size.
CFU = colony-forming units, the count of live bacteria on the label. Cost a day = one dose at the Amazon price read October 28, 2026.
| Product | Strains on the label | CFU a day | Prebiotic | NASC seal | Cost a day |
|---|---|---|---|---|---|
| Purina Pro Plan FortiFlora Probiotic Powder | One strain: E. lactis (faecium) SF68 | 100 million CFU (1 packet) | Not listed | Yes | $1.03 a day |
| Nutramax Proviable Chewable Tablets | 7 strains: E. faecium, B. bifidum, S. thermophilus, L. helveticus, L. delbrueckii, L. casei, L. plantarum, each with an NCIMB code | 5 billion CFU (1 tablet) | Yes: gum arabic in the tablet | No | $0.67 a day |
Source: Each brand's label; Amazon prices read October 28, 20264, 5
Other versions of each
| Version | What you get | Cost |
|---|---|---|
| Purina Pro Plan FortiFlora Chewable Tablets | 100 million CFU of SF68 in one chewable tablet a day, 45 tablets | $1.00 a day |
| Nutramax Proviable Digestive Health Supplement Kit | 10 sprinkle capsules (5 billion CFU each) and a 30 mL paste (500 million CFU per gram), for loose stool. Paste: 1 to 2 ml under 20 lb, 3 to 4 ml for 21 to 50 lb, 5 ml over 50 lb, 2 to 3 times a day for 48 to 72 hours9 | $29.97 kit |
Proviable-DC capsules have the same 7 strains at 5 billion CFU per capsule, with FOS (a prebiotic that feeds the bacteria).10 Nutramax also sells Proviable-Forte as its most advanced formula.7 The numbers on this page are for the FortiFlora powder packet, the same as in the best probiotic for dogs, and the Proviable chewable tablet.
What the research says
FortiFlora's strain, SF68, was tested in a shelter trial of 182 dogs and 217 cats: in dogs, statistical differences between the groups were not detected, and diarrhea was uncommon in both; in cats SF68 cut diarrhea lasting two days or more from 20.7% to 7.4%.11 Purina also describes a Colorado State University study in which shelter dogs with diarrhea improved faster on metronidazole plus SF68 than on metronidazole alone.6 Nutramax says Proviable has 6 published studies in dogs and cats, and that in one of them at least one of its 7 strains was detected in 91% of dogs, against 45% for a single strain.7 A 2011 lab test of 25 pet probiotics found FortiFlora held 2.6 times the bacteria on its label, and it was one of 2 of 25 products to pass every check; Proviable was not in that test.1
Questions people ask
- FortiFlora vs Proviable: which is better?
- For most dogs, FortiFlora: a sprinkle-on-food powder with the NASC seal (100 million CFU of SF68, $1.03 a day). Pick Proviable for 7 strains, a prebiotic and 5 billion CFU (50 times the CFU) at $0.67 a day.
- What is the difference between FortiFlora and Proviable?
- FortiFlora is one strain, Enterococcus SF68, in a powder packet. Proviable has 7 strains and a prebiotic: gum arabic in the tablet, FOS in the capsules and kit. It comes as capsules, chewable tablets and kits. Nutramax makes Proviable; Purina makes FortiFlora.
- Is Proviable cheaper than FortiFlora?
- Yes. The Proviable chewable tablet is $0.67 a day and the FortiFlora powder packet is $1.03 a day, a gap of about $134 a year, at the Amazon prices read October 28, 2026.
- Which is better for a picky eater?
- FortiFlora. It is a flavored powder you sprinkle on food, and its label lists a liver flavor.
- How much FortiFlora or Proviable do I give?
- The FortiFlora label says one packet a day. The Proviable chewable tablet label says one tablet a day. Neither has weight bands. Proviable kit paste is dosed by weight on its label.
- Can I give FortiFlora and Proviable together?
- Most owners pick one, because both do the same job. If your vet suggests using both, follow the vet.
- Does Proviable have the NASC seal?
- No. Nutramax is not on NASC's member list. FortiFlora's maker, Purina, is, and FortiFlora also held its label count in a 2011 lab test.1, 5
Notes and sources
- Strains, CFU per dose and directions come from each brand's label, read October 2026. See how we do the math.
- The NASC seal is listed by maker, from NASC's own member list.
- For more brands, see the best probiotic for dogs.
- Product photos come from Amazon.
- Prices checked on Amazon October 28, 2026. Published .
Sources
- Weese JS, Martin H, "Assessment of commercial probiotic bacterial contents and label accuracy," Canadian Veterinary Journal, 2011 (25 products; Proviable was not tested), read October 28, 2026.
- Purina Pro Plan label: Veterinary Supplements FortiFlora Canine Probiotic, read October 2026.
- Nutramax label: Proviable Probiotics + Prebiotics, Chewable Tablets, read October 2026.
- Prices: Amazon product data, read October 28, 2026. Cost per serving = listing price divided by the servings in the container.
- National Animal Supplement Council, member list (green check = may show the NASC Quality Seal), read October 28, 2026.
- Purina Pro Club, "FortiFlora Supplements for Dog Digestion" (SF68; sprinkled on food; sachets and chewable tablets; Purina's account of a Colorado State University shelter study), read October 28, 2026.
- Nutramax, proviable.com home page (product lines, 7 strains, prebiotics, 6 published studies), read October 28, 2026.
- Cornell University College of Veterinary Medicine, Riney Canine Health Center, "Diets to boost immunity" (from the DogWatch newsletter), read October 28, 2026.
- Nutramax label: Proviable Digestive Health Supplement Kit, read October 2026.
- 1800PetMeds, "Nutramax Proviable-DC" label (5 billion CFU per capsule, 7 strains with NCIMB codes, FOS prebiotic), read October 28, 2026.
- Bybee SN, Scorza AV, Lappin MR, "Effect of the Probiotic Enterococcus faecium SF68 on Presence of Diarrhea in Cats and Dogs Housed in an Animal Shelter," Journal of Veterinary Internal Medicine, 2011 (Colorado State University; funded by Nestlé Purina), read October 28, 2026.
Labels for the products in the tables
- Nutramax: Proviable Probiotics + Prebiotics, Chewable Tablets.
- Purina Pro Plan: Veterinary Supplements FortiFlora Canine Probiotic.