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Pet probiotics: Are they really necessary?

I am a crazy pet parent. But not the kind who keeps a dog in their purse and has spa days with their Bijou. I’m the other kind — the kind that buys CBD dog treats and asks my cats how they feel about things. I don’t generally buy into supplements in general, but I do take a probiotic. I know that their purported health benefits are still up for debate, but they have been proven to strengthen digestive health. In other words, they help me poop. You know who else likes pooping? My dogs. Their small digestive systems sometimes need a little help — so do my pets need a probiotic supplement, too?

“There is no high-quality, consistent evidence for most of the suggested uses of probiotics in dogs and cats,” says Matthew McCarthy, an NYC-based veterinarian. Probiotic supplements, for humans and other animals, are meant to put “good” bacteria — microorganisms like acidophilus — into the gut biome, aka intestinal flora. Those “good” microorganisms are meant to eat the “bad” ones, and thereby create a healthy balance of bacteria in the body.

Just like for humans, having a healthy flora is beneficial for pets, McCarthy says, and imbalances in the flora are associated with disease, so the idea that manipulating the microbial ecology can affect health is reasonable. Sounds like an endorsement for probiotics, right?

Not so fast. The probiotic supplements on the market right now aren’t actually proven to help animals attain or maintain that healthy balance.

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Many doctors who treat humans are wary about the effectiveness of probiotic supplements. Veterinarians are too, it seems. “There are very few studies [on probiotics] in dogs and cats, and those that have been done have significant limitations — such as small sample size —and often conflicting conclusions,” McCarthy says. McCarthy points out that, while there does seem to be reasonable evidence for some clinical benefit in treating acute diarrhea due to stress or antibiotic use, there is simply no high-quality, consistent evidence for most of the suggested uses of probiotics in dogs and cats.

One of the problems with the research on pets and probiotics is that it is conducted by manufacturers of probiotics, says McCarthy, and therefore some bias must be assumed. Not because probiotics makers are jerks, they just want their products to work and that desire could taint their findings. But, McCarthy says, even though pet probiotics may not be effective, they probably aren’t actively dangerous.

“There does not seem to be significant risks associated with their use,” McCarthy says. But, again, because pet supplements are highly unregulated, it’s worth being suspicious. McCarthy thinks it’s worth noting that the European Union, which has stricter guidelines than the US for the use of dietary supplements, has banned the sale of certain veterinary probiotics over a concern that they could induce antibiotic resistance in pathogenic organisms — in other words the good bacteria make the bad bacteria even worse. “It does make you wonder if we should be playing with the complicated world of microbial flora until we understand more about the whole thing,” McCarthy says.

It makes sense to be wary of using probiotics as cure alls, but what about the ones that are meant to help pets' psychological health? My dogs — and I — are really stressed out about the state of the world, and some of the pet probiotics on the market claim they can ease pet anxiety.

“The notion that a probiotic may help with behavioral disorders may seem like a bit of a stretch,” says McCarthy, but adds that clinical trials of using probiotics to treat depression and anxiety in humans look promising, and that he has prescribed probiotics to pets for behavioral issues. McCarthy says that he’s suspicious of the limited clinical data on these calming probiotic products, but that his furry patients and their families have seen some success. “It does seem to help some patients become calmer as perceived by their owners,” McCarthy says.