"Irregularity" is a politely inadequate euphemism for what you know as diarrhea, constipation, and flatulence. In all cases, these symptoms are accompanied by changes in an animal’s gastrointestinal bacteria. That’s why probiotics are often recommended for these pets as a way of boosting good gut bacteria to counteract the bad.

But what are these probiotics and how do they work? Should you be careful with them? Are you missing out if you don’t use them?

Here’s some background:

Probiotics are as timeless as Abraham and his sour goat milk, yet these therapeutic food additives are a relatively new field of study for most nutritionists.

Part of the problem has always been the mystery that is the unplumbed depth of the intestinal tract. Just as our vast oceans are unknown to us at their most unfathomable depths, the lowly intestinal tract is teeming with populations of creatures that outnumber our own cells ten to one. While their populations and diversity astound us, it’s their complex biological machinations that really find us scratching our heads in amazement.

According to the proceedings from a recent veterinary conference, here’s a sampling of what intestinal populations do:

"Microbes impact the maturation and maintenance of the intestinal immune system, influence cell proliferation and facilitate energy salvage (e.g., through conversion of nutrients to short chain fatty acids). The catalytic potential of the microbiota may contribute to (or detract from) health through production of beneficial (or detrimental) metabolites."

If that sounds complex, that’s because it is. Suffice to say, bacteria aid in more than simple digestion and absorption of foodstuffs and nutrients, respectively. Though they do that, too, of course.

Now that you have an inkling as to the role of intestinal bacteria, let's move on to the explanation of therapeutic intestinal probiotics for pets. First up, the current working definition of a probiotic, according to the World Health Organization (WHO):

"[Probiotics are] live microorganisms, which when administered in adequate amounts confer a health benefit on the host."

The idea is that adding “good” bacteria will stimulate the production of more good bacteria (the ones that are presumed to be associated with health benefits). In this way, the entire balance of the intestinal flora will be shifted toward the beneficial bacteria. Makes sense, right?

Lots of veterinarians think so. Many are recommending probiotics for any pet showing symptoms of a bacterial imbalance that is associated with unhappy symptoms of the aforementioned irregularities: diarrhea, constipation, flatulence, and sometimes vomiting.

On occasion, probiotics are offered on a short-term basis for short-term symptoms. For others with more chronic or chronically intermittent symptoms, however, probiotics may serve well as a lifetime stop-gap for whatever underlying intestinal malady is ailing the animal.

They’ve been so successful — in many cases displacing the need for antibiotics and food trials — that the trend towards using probiotics in veterinary medicine is ramping up. And now that more companies are stepping forward with their own versions of probiotic supplements, the pet food reps are out in full force with their explanations and exhortations refined to make sure that all veterinarians consider their routine use. It’s a new probiotic world out there and we’re just beginning to scratch the surface of it.

Intestinal probiotics are usually formulated as oral supplements. Some come as capsules, others as tasty chews. Still others are powdered and packaged in single-dose envelopes.

But there’s a catch — as there always is. As the CVC proceedings (referenced above) explain:

"Probiotics and related compounds are not approved drugs and undergo no premarket approval process. As such, data supporting quality assurance, safety and efficacy for each product may not exist."

Manufacturers, however, are quick to point out that theirs are safe, effective, quality-controlled, and subject to the same rigorous standards we’ve come to expect from their other products. But not all products are created equal. That’s why I stick to the most well-distributed ones, whose manufacturers have a long-held reputation to protect.

Then there’s the other issue my clients have asked about: If this probiotic works, am I just masking the symptoms of a larger disease process? Do I risk killing bad bacteria arising from a chronic problem we should be addressing?

To any client who poses such intelligent questions I only have this to say: I don’t know for sure, but we can always stop the probiotics and start looking for the true source of your pet’s ills. Food trials, blood tests, endoscopies, biopsies, etc. may be in order.

That’s about the time they start thanking the probiotics and administering them to their pets like communion wafers. Are they a good thing? They're better than a whole lot of other alternatives, I say.

Dr. Patty Khuly