Review: Overview of the Scientific Evidence for Dog Probiotics

Many of us want only the best for our dogs. This includes finding ways to improve their health without the use of medications that can cause harmful long-term problems. One option that is gaining interest is dog probiotics.

Probiotics are defined as “live microorganisms that may confer a health benefit on the host.” They are becoming extremely popular, not only in alternative circles, but also within the scientific community. Scientists have discovered that the microbes that live within our intestines and on our bodies are important to our health. We host at least 1000 different species of bacteria and fungi, and maintaining the right populations of each species is essential. Therefore, adjusting one’s intestinal flora with probiotics is a logical step.

Research looking at the effectiveness of probiotics in dogs is not nearly so extensive as what has been done in humans. Still, there are studies that suggest that they can help the health of our best friends. The diseases that have been investigated so far have been acute diarrhea and contact dermatitis (skin allergy).

Preventing and Treating Acute Diarrhea in Dogs

Acute diarrhea is diarrhea that starts suddenly and usually resolves on its own. Probiotics have been tested on several types of acute diarrhea, specifically diarrhea caused by dietary sensitivity and through the ingestion of an intestinal pathogen. In dogs with a dietary sensitivity, treatment with Lactobacillus acidophilus in combination with the diarrhea-provoking food led to some improvement in bowel movements (1). Better results, however, were seen when probiotics were applied as treatments for acute diarrhea caused by a stomach virus. Dogs treated with a probiotic cocktail containing multiple species healed more quickly than dogs given a placebo (2).

Iams Prostora
Bifidobacterium animalis AHC7 has been studied more in detail. B. animalis AHC7 was specifically isolated from healthy canine feces. It was chosen for further research because initial studies showed that it had an above-average ability to bind to the gut, a characteristic often associated with beneficial bacteria. Initial studies in dogs showed that it could reduce the pathogenicity of Salmonella typhiurium and Clostridia difficile (3); bacteria known to induce acute diarrhea. And later during a treatment study, it was found that it could help acute diarrhea resolve faster (4). Bifidobacterium animalis AHC7 can be found in Iams Prostora probiotic for dogs.

Another probiotic species isolated from canine feces is Enterococcus faecium SF68. It was shown very early on to efficiently colonize the guts of dogs and lower amounts of harmful bacteria (5). However, there are no studies at this moment that support its use for diarrhea prevention in dogs (6). However, there is an indication that it could be good at preventing acute diarrhea in cats (7). This species can be found in Purina’s FortiFlora.

Preventing Dermatitis in Canines

Dermatitisis usually caused by a skin allergy. To treat the dermatitis, one needs to address the underlying immune problems. In allergy, the immune system considers a normally harmless substance as a threat. In dogs with a skin allergy, contact of the allergen on the skin causes an immune reaction leading to the classic symptoms of inflammation: itching, redness and heat. Unfortunately, dogs that develop allergy are usually genetically predisposed to the condition. This means that prevention has to happen at a young age or even when the pups are still in the womb.

Scientists looked at the ability of L. rhamnosus GG to change the course of allergy in dogs with a genetic pre-disposition towards allergy. The probiotic was given during pregnancy to the mother and to the puppies during weaning. Unfortunately, while they saw some significant changes in immunological parameters, the puppies had no real improvements (8). But a follow up study performed three years later in the grown-up pups showed that there were differences in the long-term. The immune system was geared towards anti-inflammatory reactions, and the dogs had less dermatitis (9).

Helping Your Own Best Friend

While these studies indicate that there may be a future for probiotic treatment, they do not show that they function as a silver bullet for acute diarrhea and dermatitis. More studies will have to be done.

Additionally, many products on the market are of dubious quality. A study testing 19 commercial pet foods, all claiming to contain probiotics, determined that none of the feeds contained what was written on the package. Only 53% actually contained at least one of the probiotics species listed, and 26% of the diets had no live bacteria (10). This would suggest that using pet food fortified with probiotics is not the wisest route for providing your dog with beneficial bacteria. The best bet would be to seek out a quality probiotic with the help of your veterinarian.


  1. Pascher M, Hellweg P, Khol-Parisini A, Zentek J. Effects of a probiotic Lactobacillus acidophilus strain on feed tolerance in dogs with non-specific dietary sensitivity. Arch Anim Nutr. 2008 Apr;62(2):107-16. doi: 10.1080/17450390801892583.
  2. Herstad HK, Nesheim BB, L’Abée-Lund T, Larsen S, Skancke E. Effects of a probiotic intervention in acute canine gastroenteritis–a controlled clinical trial. J Small Anim Pract. 2010 Jan;51(1):34-8. doi: 10.1111/j.1748-5827.2009.00853.x. Epub 2009 May 19.
  3. O’Mahony D, Murphy KB, MacSharry J, Boileau T, Sunvold G, Reinhart G, Kiely B, Shanahan F, O’Mahony L. Portrait of a canine probiotic Bifidobacterium–from gut to gut. Vet Microbiol. 2009 Oct 20;139(1-2):106-12. doi: 10.1016/j.vetmic.2009.05.002.
  4. Kelley RL, Minikhiem D, Kiely B, O’Mahony L, O’Sullivan D, Boileau T, Park JS. Clinical benefits of probiotic canine-derived Bifidobacterium animalis strain AHC7 in dogs with acute idiopathic diarrhea. Vet Ther. 2009 Fall;10(3):121-30.
  5. Vahjen W, Männer K. The effect of a probiotic Enterococcus faecium product in diets of healthy dogs on bacteriological counts of Salmonella spp., Campylobacter spp. and Clostridium spp. in faeces. Arch Tierernahr. 2003 Jun;57(3):229-33.
  6. Simpson KW, Rishniw M, Bellosa M, Liotta J, Lucio A, Baumgart M, Czarnecki-Maulden G, Benyacoub J, Bowman D. Influence of Enterococcus faecium SF68 probiotic on giardiasis in dogs. J Vet Intern Med. 2009 May-Jun;23(3):476-81. doi: 10.1111/j.1939-1676.2009.0283.x. Epub 2009 Mar 9.
  7. 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. J Vet Intern Med. 2011 Jul-Aug;25(4):856-60. doi: 10.1111/j.1939-1676.2011.0738.x. Epub 2011 Jun 20.
  8. Marsella R. Evaluation of Lactobacillus rhamnosus strain GG for the prevention of atopic dermatitis in dogs. Am J Vet Res. 2009 Jun;70(6):735-40. doi: 10.2460/ajvr.70.6.735.
  9. Marsella R, Santoro D, Ahrens K. Early exposure to probiotics in a canine model of atopic dermatitis has long-term clinical and immunological effects. Vet Immunol Immunopathol. 2012 Apr 15;146(2):185-9. doi: 10.1016/j.vetimm.2012.02.013. Epub 2012 Mar 1.
  10. Weese JS, Arroyo L.Bacteriological evaluation of dog and cat diets that claim to contain probiotics. Can Vet J. 2003 Mar;44(3):212-6.