FortiFlora vs Proviable-DC: which has the better evidence?
The two veterinary probiotics most often recommended, side by side: one strain against seven, sachet against capsule, and the trials each can actually point to.
Quick answer
For cats, FortiFlora; for dogs, it is closer than the marketing suggests. FortiFlora’s single strain, Enterococcus faecium SF68, has a placebo-controlled shelter result in 217 cats (diarrhea in 7.4% vs 20.7%) and two antibiotic trials in cats; in dogs it helped alongside metronidazole but not on its own. Proviable-DC’s seven strains plus prebiotic have an open-label improvement in 53 cats with chronic diarrhea and a placebo-controlled result in cats on clindamycin; its dog evidence is a related product (Proviable-Forte) combined with a yeast. Both are one unit a day for any size of animal.
Side by side
| FortiFlora | Proviable-DC | |
|---|---|---|
| Organisms | E. faecium SF68, one strain, 1×108 CFU per 1 g sachet (canine label) | Seven species, 5 billion CFU per capsule, plus fructooligosaccharide |
| Strain named on the label | Yes (SF68) | Species only; no strain designations |
| Format and dose | Powder sachet, one a day, any weight; separate canine and feline SKUs | Sprinkle capsule, one a day, any weight; one SKU for dogs and cats |
| Best cat evidence | Placebo crossover, 217 shelter cats: diarrhea 2+ days in 7.4% vs 20.7% | Open-label, 53 cats with chronic diarrhea: fecal score 6.0 to 4.4, no placebo |
| Cats on antibiotics | 27 cats: lower diarrhea scores (P=0.0058); dysbiosis index normalized | 16 cats: all finished clindamycin vs half on placebo (P=0.04) |
| Best dog evidence | Added to metronidazole in shelter dogs: days with normal stool 65.6% vs 46.9%; alone in 182 dogs, no difference | None for DC itself; Proviable-Forte plus a S. boulardii product reduced food-intake loss in 22 dogs on antibiotics |
What each trial actually showed
FortiFlora in cats is the strongest pairing in this catalog. In the shelter crossover of 217 cats, 7.4% on SF68 had diarrhea of two days or more against 20.7% on placebo (P=.0297) (Bybee et al., 2011); in 27 cats on amoxicillin-clavulanate, diarrhea scores over days 1 to 11 were lower on FortiFlora (P=0.0058) (Torres-Henderson et al., 2017) and a 2026 trial of the same design found the dysbiosis index normalized by day 14 (Slaughter et al., 2026). In dogs, SF68 added to metronidazole raised the share of days with normal stools from 46.9% to 65.6% in shelter dogs (Fenimore et al., 2017), while on its own in 182 shelter dogs "statistical differences between groups of dogs were not detected" (Bybee et al., 2011).
Proviable-DC in cats: 53 cats with chronic diarrhea took one capsule a day for 21 days and the mean fecal score fell from 6.0 to 4.4 (P<0.001), with 72% of owners seeing improvement; there was no placebo group (Hart et al., 2012). In a randomized placebo-controlled crossover, 16 healthy cats given clindamycin all completed the course on the synbiotic against half on placebo (P=0.04) (Stokes et al., 2017). In dogs, the trial that is often cited used Proviable-Forte (a higher-count sibling) together with Mycequin, a Saccharomyces boulardii product, in 22 dogs on enrofloxacin and metronidazole: the food-intake derangement was smaller on the combination (P=.04), the diarrhea was not prevented (Whittemore et al., 2019). Proviable-DC itself has no dog trial.
Where they differ in practice
FortiFlora names its strain, which is what lets its trials be credited to the sachet in the box; Proviable-DC names species but not strains, so its own trials are the only evidence that transfers. FortiFlora comes as a flavored powder that most cats take on food; Proviable-DC is a capsule that can be sprinkled. Both are one unit a day regardless of weight, so cost per day is the pack price divided by the pack count and does not rise with a big dog. The product cards below carry the prices and the retailer each was read from.
Products in this catalog with the trials above
- Purina Pro Plan Veterinary Supplements FortiFlora Canine — dogs, $1.03 a day
- Purina Pro Plan Veterinary Supplements FortiFlora Feline — cats, $1.03 a day
- Nutramax Proviable-DC capsules — dogs and cats, $0.56 a day
Common questions
Is FortiFlora or Proviable better for cats?
FortiFlora has the placebo-controlled evidence: diarrhea of two days or more in 7.4% of 217 shelter cats against 20.7% on placebo, plus two antibiotic trials. Proviable-DC improved fecal scores in 53 cats with chronic diarrhea without a placebo group and helped cats tolerate clindamycin in a placebo-controlled crossover.
Is FortiFlora or Proviable better for dogs?
Neither has a standalone placebo-controlled win in dogs. FortiFlora helped alongside metronidazole in shelter dogs but not alone; Proviable-DC has no dog trial, and its sibling Proviable-Forte plus a S. boulardii product reduced appetite loss in 22 dogs on antibiotics.
Can I give FortiFlora and Proviable together?
No trial has tested the combination. Both labels are one unit a day for any weight; if a vet suggests both, that is their call to make, and the trials above are the evidence to weigh.
Does Proviable-DC name its strains?
No. The label lists seven species and a total of 5 billion CFU per capsule with a fructooligosaccharide prebiotic, without strain designations, so only its own trials count as evidence for it.
Sources
- Bybee SN, et al. Effect of the probiotic Enterococcus faecium SF68 on presence of diarrhea in cats and dogs housed in an animal shelter. J Vet Intern Med. 2011. pubmed.ncbi.nlm.nih.gov/21689152
- Torres-Henderson C, et al. SF68 in cats administered amoxicillin-clavulanate. 2017. pubmed.ncbi.nlm.nih.gov/29291771
- Slaughter A, et al. SF68 and the fecal microbiome of cats given amoxicillin-clavulanate. 2026. pubmed.ncbi.nlm.nih.gov/41923274
- Fenimore A, et al. Metronidazole with and without SF68 in shelter dogs with diarrhea. 2017. pubmed.ncbi.nlm.nih.gov/29291770
- Hart ML, et al. Open-label trial of a multi-strain synbiotic in cats with chronic diarrhea. 2012. pubmed.ncbi.nlm.nih.gov/22412160
- Stokes JE, et al. Prevention of clindamycin-induced gastrointestinal signs using a synbiotic in healthy research cats. 2017. pubmed.ncbi.nlm.nih.gov/28755457
- Whittemore JC, et al. Effects of a synbiotic on healthy research dogs administered antibiotics. 2019. pubmed.ncbi.nlm.nih.gov/31268578
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