In the past decade, probiotics have become increasingly accepted as an adjunct therapy for acute and chronic gastrointestinal conditions in both humans and animals.
Owners often inquire about placing their pets on probiotics because they take them themselves; however, misperceptions regarding use and efficacy may require clarification and education from veterinarians, experts note.
“Probiotics are formulations of live bacteria considered to be beneficial that are administered to a patient for a perceived benefit,” says Jody Gookin, DVM, PhD, DACVIM, Fluoroscience Distinguished Professor of Veterinary Scholars Research Education at the North Carolina State University College of Veterinary Medicine.
“We don’t really understand completely how probiotics work, but there are some general mechanisms that explain the benefit,” Dr. Gookin continues. “One is they can compete with less beneficial or even pathogenic bacteria in the intestinal tract. They occupy a niche in the GI tract that impairs pathogenic bacteria from becoming inhabitants.
“[Probiotics] metabolize components of our diet and generate compounds that are beneficial to the GI tract and can be used as energy sources. They also can elaborate substances, such as antimicrobial peptides, that can directly impact other bacteria.”
Probiotics have been in general use since around the mid-2000s, notes Al Jergens, DVM, PhD, DACVIM, Donn E. and Beth M. Bacon Professor in Small Animal Medicine and Surgery and Associate Chair for Research and Graduate Studies at the Iowa State University College of Veterinary Medicine.
“The earliest studies were done in shelter environments, generally using single-strain probiotics to treat acute diarrhea,” he says.
Mysterious, but beneficial
Since then, a wide variety of probiotic products have become available to veterinarians. Some are single-strain, others are multi-strain, and some contain probiotics combined with prebiotics and, therefore, are symbiotic preparations.
A variety of bacteria strains are used in probiotics, including Lactobacillus, Bifidobacterium, and Enterococcus species. Other products are made using a strain of yeast called Saccharomyces, which one small study found effective in treating chronic gastrointestinal signs in dogs, Dr. Jergens says.
Probiotics have been under the investigative microscope for many years, with several studies indicating a benefit for specific gastrointestinal conditions. Two such studies, conducted at Iowa State University, investigated the potential benefits of probiotics alone or in combination with a hydrolyzed diet for treatment of inflammatory bowel disease in dogs.1,2
“When we compared probiotics side by side to another therapy, the probiotics did better in one study, and were equivalent in the other,” Jergens says. “When we asked how probiotics work to reduce intestinal inflammation, we were able to show the probiotic enhanced intestinal immunity and barrier integrity. In one study, it reduced intestinal inflammation by decreasing inflammatory immune cells, and, in both studies, it increased the intestinal epithelial barrier by upregulating tight junction proteins that help to maintain intestinal health.”
Most studies have investigated the benefit of probiotics to gut health; however, other possible uses are also under investigation. For example, a 2017 meta-analysis of animal research published in the European Journal of Pharmaceutical Sciences looked at the efficacy of probiotics as a pharmacological treatment of cutaneous wounds.3 The results indicate probiotics administration is an effective treatment for this purpose, but additional studies are required due the heterogeneity among studies.
Another paper, published in the January 2019 issue of the Journal of Functional Foods, reviewed animal studies and clinical trials regarding probiotics supplementation for obesity management.4 It found probiotic supplementation may help manage obesity by modulating gut microbiota, and is species- and strain-specific.
“Other potential areas of use are proving quite interesting,” Dr. Gookin says. “I think the best example might be chronic urinary tract infections. There has been intriguing work in the microbiome wondering if animals receiving a probiotic might be less likely to get an E. coli urinary tract infection, for example. If fecal contamination leads to urinary tract infections and we can enrich the feces with certain types of bacteria that might compete with those uropathogens, perhaps we could decrease incidents of recurring urinary tract infections. Dermatology is another interesting area, looking at probiotics that might populate the skin with healthy bacteria to help prevent superficial pyoderma and other types of bacterial infections of the skin.”
Helpful, but not traditional
Probiotics come in a variety of forms, including powder, capsules, and paste, notes Gookin, who has used probiotics on her own pets. In addition, many pet food companies now offer products containing probiotics as an essential ingredient.
When used as directed, probiotics have been shown to be safe, with minimal side effects. “I’m not aware of any published adverse complications of treating dogs or cats with probiotics,” Gookin says.
Another important question, of course, is whether a probiotic product provides a benefit.
“As we understand more about the microbiome in the gut, we will find some species of bacteria in a probiotic may be better in some circumstances than in others. So, it might come down to the actual bacteria in the probiotic,” Gookin says. “In some cases, it is going to be beneficial, and, in others, it won’t be.”
As probiotics are considered dietary supplements, they do not fall under traditional U.S. Food and Drug Administration (FDA) regulations. Indeed, as long as outlandish medical claims are not made on the label, anyone can produce and market a probiotic product. So, how can clients determine which products are best for their pets?
“They should consult with their veterinarians,” Jergens says. “In the early days of probiotics, there was a seminal study that evaluated several products for their bacterial content and potency. Long story short, the specific bacteria and the quantity of organisms that were labeled did not match the scientific evidence. Across the board, there is a lack of consistent regulation and guidelines, so you’re at the mercy of the manufacturers, and you hope they are responsible, ethical companies.”
It is understandable, then, that pet owners should turn to their veterinarians for guidance on probiotic use; however, there are also certain issues owners often do not know or do not understand. For one, probiotics must be given continuously to be effective.
“Most studies for chronic gastrointestinal disease verify probiotics need to be administered continuously for four to six weeks, and perhaps longer,” Jergens says, “but sometimes the client will give their pet probiotics for a couple of days and expect the animal to get well, which can be a problem.”
It is also important for pet owners to understand the beneficial effects of probiotics are modest at best, which is why they are commonly used as adjunct therapies. Further, they can be expensive, Jergens says, which may cause some owners to stop their use prematurely.
The third issue clients should understand is not all probiotics are created equal. In fact, as noted, products can vary wildly in terms of number and type of bacterial strains, as well as being combined with other ingredients, such as supplements.
“It can be confusing to individuals,” Jergens says. “If you conduct an internet search of probiotics, you see numerous products out there. I personally favor multi-strain probiotics since different probiotic strains benefit different hosts. I think the odds are better using a multi-strain product that you’re going to receive some bacterial species that benefit your pet.”
As more people turn to probiotics for their own health and their pets, researchers continue to investigate their potential benefits.
“With the gut, I think we’re really making strides in characterizing underlying diseases, and I think in the next five years we will be able to take measurements from patients and look at their microbiome, look at the metabolites in their fecal sample, for example, and determine whether or not we think it is likely they will benefit from probiotics,” Gookin says. “Our evidence base is growing and it’s going to get a lot better.”
Don Vaughan is an award-winning writer who frequently writes about veterinary-related topics.
- Rossi Giacomo, Graziano Pengo, et al. “Comparison of Microbiological, Histological, and Immunomodullatory Parameteers 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, April 2014, Vol. 9, Issue 4.
- White Robin, Robin White, Todd Atherly, et al. “Randomized, controlled trial evaluating the effect of multi-strain probiotic on the mucosal microbiota in canine idiopathic inflammatory bowel disease.” Gut Microbes, 2017, Vol. 8, No. 5, 451-466.
- Tsiouris Christos G., Martha Kelesi, et al. “The efficacy of probiotics as pharmacological treatment of cutaneous wounds: Meta-analysis of animal studies.” European Journal of Pharmaceutical Sciences, Vol. 104, 15 June 2017, Pages 230-239.
- Ejtahed Hanieh-Sada, Pooneh Angoorani, et al. “Probiotics supplementation for the obesity management; A systematic review of animal studies and clinical trials.” Journal of Functional Foods, Vol. 52, January 2019, Pages 228-242.