Best Probiotic for Dogs (2026): What Works, and Cost per Day
For sudden diarrhea, the probiotic with the best trial is Pro-Kolin Advanced paste: dogs on it got better in a median 32 hours, against 47 on a placebo. Reviews of all the dog trials find probiotics help only a little. In that trial, dogs given a placebo got better in about 2 days too.
Our recommendation
For sudden diarrhea: Pro-Kolin Advanced paste
It holds the probiotic Enterococcus faecium 4b1707, with kaolin and pectin. Give it twice a day by weight: 2 mL under 11 lb, 3 mL from 11 to 33 lb, 5 mL from 33 to 66 lb. A 30 mL tube ($32.99) lasts about 5 days for a 30 lb dog.
Buy on Amazon- Blood, vomiting, not eating, or a puppy? See a vet first, not a probiotic.
- Your vet suggested a daily probiotic? Purina FortiFlora is one sachet a day for any size, $1.03 a day.
- Want every strain named on the label? Nutramax Proviable-DC lists all 7 with their codes: 5 billion live cultures for $0.67 a day, one capsule for any size.
Do probiotics help dogs?
A little, for sudden diarrhea. A 2019 review of the dog trials found the effect was "very limited and possibly clinically unimportant" (Jensen 2019). A 2024 review found probiotics did not shorten acute diarrhea by a meaningful amount (Scahill 2024).
- Pro-Kolin Advanced: in 148 dogs with sudden diarrhea, the paste cut the median time to recovery from 47 to 32 hours, and fewer dogs needed more treatment. The maker paid for the trial (Nixon 2019).
- FortiFlora's strain (SF68): in a shelter trial it lowered diarrhea in cats but made no difference in dogs (Bybee 2011).
- With antibiotics: a probiotic-and-yeast mix helped dogs keep eating but did not stop stomach upset (Whittemore 2019).
- High-dose mixes: one small study of a high-dose 8-strain mix (VSL#3) in 20 dogs with gut inflammation, with no placebo group (Rossi 2014).
More live cultures has not been shown to work better. The numbers below tell you what is in the bottle, not how well it works.
When should your dog see a vet instead?
Cornell's vet school says to get care if your dog stops eating, is weak, vomits, has black or tarry stool, or the diarrhea lasts more than 48 to 72 hours (Cornell). Take a puppy in right away if it is weak, will not eat, vomits, or has blood in its stool (VCA).
Dog probiotics compared: live cultures and cost a day (6)
At each label's dose for the dog's weight. Live cultures are what the label states.
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Best trial for sudden diarrhea
Pro-Kolin Advanced paste
Enterococcus faecium 4b1707, with kaolin and pectin.
A tube lasts 7 days (10 lb), 5 days (30 lb), 3 days (60 lb).
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Native Pet Probiotic powder
4 species (Bacillus coagulans, Enterococcus faecium, two Bifidobacterium), no strain codes. 6 billion live cultures a day for a 30 lb dog.
10 lb price not shown · 30 lb price not shown · 60 lb $1.00 a day.
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Nutramax Proviable-DC
7 strains with NCIMB codes, including Enterococcus faecium NCIMB 30183. 5 billion live cultures a day for a 30 lb dog.
10 lb $0.67 · 30 lb $0.67 · 60 lb $0.67 a day.
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Zesty Paws Probiotic Bites
Bacillus coagulans, Bacillus subtilis and Saccharomyces boulardii, no strain codes. 6 billion live cultures a day for a 30 lb dog.
10 lb $0.37 · 30 lb $0.74 · 60 lb $0.74 a day.
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Purina FortiFlora
Enterococcus faecium SF68. 100 million live cultures a day for a 30 lb dog.
10 lb $1.03 · 30 lb $1.03 · 60 lb $1.03 a day.
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Visbiome Vet
8 strains with DSM codes; keep refrigerated. 225 billion live cultures a day for a 30 lb dog.
10 lb $2.56 · 30 lb $2.56 · 60 lb $5.12 a day.
Costs are Amazon prices on November 4, 2026 divided by the servings in the container, at each label's dose. Visbiome Vet must be kept in the fridge.
Questions
How long does dog diarrhea last?
In the largest dog trial, dogs with sudden diarrhea given a placebo got better in a median of 47 hours (Nixon 2019). Cornell's vet school says to get care if it has not cleared in 48 to 72 hours, or sooner if your dog stops eating, is weak, vomits, or the stool is black or tarry.
Should my dog take a probiotic with antibiotics?
Ask your vet. In one trial, healthy dogs on two antibiotics that also got a probiotic-and-yeast mix ate better, but they still had stomach upset (Whittemore 2019).
Sources
- Jensen AP, Bjørnvad CR. Clinical effect of probiotics in prevention or treatment of gastrointestinal disease in dogs: A systematic review. J Vet Intern Med. 2019. PubMed 31313372
- Scahill K, et al. Efficacy of antimicrobial and nutraceutical treatment for canine acute diarrhoea: A systematic review and meta-analysis. Vet J. 2024. PubMed 38049062
- Nixon SL, et al. Efficacy of an orally administered anti-diarrheal probiotic paste (Pro-Kolin Advanced) in dogs with acute diarrhea. J Vet Intern Med. 2019. PubMed 30882953
- 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 21689152
- Whittemore JC, et al. Randomized, controlled, crossover trial of prevention of antibiotic-induced gastrointestinal signs using a synbiotic mixture in healthy research dogs. J Vet Intern Med. 2019. PubMed 31268578
- Rossi G, et al. Comparison of microbiological, histological, and immunomodulatory parameters in response to treatment with either combination therapy with prednisone and metronidazole or probiotic VSL#3 strains in dogs with idiopathic inflammatory bowel disease. PLoS One. 2014. PubMed 24722235
- Cornell University College of Veterinary Medicine, Riney Canine Health Center: Diarrhea. VCA Animal Hospitals: Puppy has diarrhea.
- Each product's label (strains, live cultures, dose by weight), read November 4, 2026; Pro-Kolin dose from Protexin's own page.