Probiotics: How to choose a product? (Proceedings)


For decades, scientific research has focused on fighting "bad" bacteria in the body, primarily through the use of antibiotics. Antibiotics are often effective at killing "bad" bacteria in the body, but unfortunately they are not without problems.

For decades, scientific research has focused on fighting "bad" bacteria in the body, primarily through the use of antibiotics. Antibiotics are often effective at killing "bad" bacteria in the body, but unfortunately they are not without problems. For example, antibiotics are not selective in the kinds of bacteria they kill; "good" bacteria are killed along with "bad" bacteria. In addition, "bad" bacteria are becoming "super" bugs and developing resistance to many commonly prescribed antibiotics. Antibiotics can also cause numerous adverse side effects.

More recently, there has been a shift away from fighting "bad" bacteria in the body in favor of promoting "good" bacteria primarily through the use of the "biotics" which include prebiotics, probiotics and synbiotics. Promoting beneficial bacteria in the GI tract by using "biotics" offer several distinct advantages over the use of antibiotics to kill bacteria. The "biotics" can be incorporated into the diet and provide a proactive way of maintaining health on a daily basis, whereas antibiotics are generally used only after a problem has occurred. "Biotics" can be used on a long-term basis without encountering the side effects seen with antibiotics, and "biotics" are viewed as a more holistic approach to maintaining health in the animal than are antibiotics. A healthy bacterial flora in the intestines is important for not only health of the GI tract, but overall health. "Biotics" enhance and support a healthy bacterial population, whereas antibiotics disrupt this balance. The bacterial flora in the gut are so important that they have a collective metabolic activity equal to a virtual organ within an organ and have been referred to as a forgotten organ.

What are probiotics?

Probiotics are defined as (a) live (viable) beneficial bacteria, which upon ingestion in sufficient numbers (b) exert health benefits to the host. It is very important that both parts of the definition are met in order to call a product a probiotic.

The gastrointestinal tract in dogs and cats

The gastrointestinal (GI) tract in dogs and cats is a very dynamic organ that performs numerous functions essential for health and well-being. Critical roles of the GI tract include digestion and absorption of nutrients and elimination of potentially harmful substances and waste products. In addition, the GI tract is the most voluminous immunologic organ in the body and also functions as an endocrine organ.

Companion animals have extensive gastrointestinal bacterial ecosystems. For example, the mammalian digestive system contains more than 1,000 different species of bacteria and comprises approximately 95% of the cells in the gastrointestinal tract. The balance between the beneficial bacteria and the pathogenic bacteria have an effect on overall health of the animal. For example, enteric bacteria contribute significantly to the function of the host's immune system as well as resistance to infectious disease. Furthermore, changes in the composition of the intestinal flora can be associated with disease and may, in some cases, be a precipitating factor. "Biotics" can be used to maintain a healthy gut flora.

Important characteristics of successful probiotics

Probiotics are a rapidly emerging area in veterinary medicine, and more and more companies are selling products labeled as probiotics for dogs and cats. However, not all these products meet the definition of probiotics. How does the practitioner know whether a product is worth spending their client's money on it? In addition to meeting the criteria for the definition of a probiotics, any company selling a probiotic product for dogs or cats should be able to document that their product meets the characteristics of a successful probiotic which include:

1. Stability of the product

2. The ability of the product to survive passage through the stomach and resist damage from bile salts as it passes through the small intestines.

3. The ability of the bacteria to colonize the gut

4. The ability of the probiotic organism to ferment prebiotics

5. Species specificity

6. Antipathogen effects

7. Safety of the product

8. Clinical efficacy of the product for the intended species. This is one of the most important characteristics of any probiotic product.

The use of probiotics to enhance intestinal health

The mechanisms by which probiotics benefit the host are not completely understood, but may involve immune-enhancing and anti-inflammatory activities, modifications to intestinal pH, suppression of pathogenic bacteria through production of inhibitory substances, and competition with pathogens for nutrients and mucosal attachment sites. Bacteria in the gut may also influence the number and distribution of cell types in the gut-associated lymphoid tissue and modulate immune response. It is through a combination of these activities that the full range of probiotic benefits is achieved.

It is now recognized that the effects of these organisms extend well beyond the gastrointestinal tract. In addition, with increasing research, it is becoming clear that there are differences among various probiotic strains with respect to the types of benefits they are capable of providing. The range and depth of benefits of a probiotic can be species- and strain-specific. Different strains of the same species have been noted to differ in a number of ways, including stability, ability to colonize the GI tract, expression of enzymes and production of inhibitory substances, and perhaps most importantly, clinical efficacy.

New research is demonstrating probiotics can positively affect gastrointestinal conditions and skin function in dogs, and the potential use of probiotics in dogs is only just beginning to scratch the surface. It is known the microbial flora of the gut play a role in the normal function and maintenance of health of the gastrointestinal tract. Recent studies have shown the feeding of probiotics to dogs improves stool quality. In one study, young dogs (14 to 16 months old) were fed a probiotic (canine-derived Bifidobacteria animalis AHC7)* or placebo prior to traveling to a training kennel.(2) Fewer dogs who received the probiotic experienced loose stools during the transition to the kennel compared with dogs who received placebo. Another study examined the effects of feeding probiotics to dogs with diarrhea.(3) The time to resolution of diarrhea was approximately 40% less in dogs who received the probiotic. These studies indicate that feeding this organism may promote gastrointestinal tract health in dogs, even in the setting of acute diarrhea. Probiotics also have a beneficial effect on skin health. A randomized, placebo-controlled study in dogs found that transepidermal water loss, a measure of barrier function, was significantly reduced in dogs that received the probiotic compared with dogs that received placebo.(data on file. P&G Pet Care)

The use of synbiotics to enhance intestinal health

A two-point approach to maintaining gastrointestinal health can be achieved through the use of synbiotics. When prebiotics and probiotics are administered simultaneously, the prebiotic can be used to increase intestinal survival of the probiotic organism. Beneficial bacteria, such as Lactobacillus and Bifidobacteria, are able to utilize prebiotics as a source of nutrition, whereas pathogenic bacteria, such as Salmonella and E. coli, are not.

It is important to demonstrate that the prebiotic fiber selectively stimulates the growth and/or activity of the beneficial bacteria in the intestines because not all fiber sources are effective prebiotics. For example, the effects of various fiber sources were studied to determine their effects on the number of probiotic organisms Bifidobacterium animal AHC7.(data on file. P&G Pet Care) The fiber sources studied included cellulose, beet pulp and FOS. At baseline, there was no statistically significant difference in the number of Bifidobacterium animal AHC7 organism among fiber groups. However, 24 hours after administering the various fibers, there was a statistically significant difference in the number of Bifidobacterium animal AHC7 organisms among fiber groups. Cellulose resulted in the lowest number of Bifidobacterium animal AHC7* organisms, and beet pulp resulted in statistically significant increase in the number of Bifidobacterium animal AHC7 organisms when compared to the cellulose group. FOS resulted in the highest number of Bifidobacterium animal AHC7 organisms and was statistically higher than that seen with both the cellulose and beet pulp groups. As a result, this study demonstrated that there is a symbiotic relationship between the probiotic Bifidobacterium animal AHC7* organism and the prebiotic FOS, and there may be additional benefits of administering synbiotics over administering a prebiotic or probiotic alone.


There have been numerous clinical trials validating the use of prebiotics, probiotics and synbiotics for certain clinical conditions in humans. Although research on the use of the "biotics" in dogs and cats is lagging behind that performed in humans, it is becoming increasingly clear that many of the same health benefits that "biotics" provide to humans also occur in dogs and cats. As more studies are performed in dogs and cats, the potential use of "biotics" in dogs and cats will increase. Although the need for antibiotics will still exist in some patients, it is hopeful that the use of "biotics" will lessen our reliance on antibiotics for promoting and maintaining health in our companion animals.

*Iams Prostora Max


O'Hara AM and Shanahan F. The gut flora as a forgotten organ. EMBO reports 7:688-693, 2006.

Bifidobacterium animalis AHC7 moderates stress responses in dogs. Clinical abstract. P&G Pet Care, 2009.

Kelley RL, Minikhiem D, Kiely B, et al. Clinical benefits of probiotic canine-derived Bifidobacterium animals strain AHC7 in dogs with acute idiopathic diarrhea. Vet Ther 10:121-130, 2009.

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