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Understanding Gut Health

What Evidence And Research Is There That Probiotics Work?

What Evidence And Research Is There That Probiotics Work?

There’s enormous interest in gut health in veterinary medicine. In recent years, the research looking at the impact of gut microbiome on the health of our pups (as well as their human companions) has exploded.

We now understand that the microscopic population of trillions of microbes within the gut has far-reaching impacts on our dogs’ health[1]. We also know that changes to this population are associated with diseases such as chronic inflammatory enteropathy in dogs (previously referred to as inflammatory bowel disease)[2] and have implications for other diseases, as mentioned below.

With this increase in knowledge, there has also been a rise in the number of products on the market that claim to support your dog’s microbiome, including probiotic supplements. As a pet parent, you might be wondering whether probiotics for dogs really work. Let’s review the evidence!

What Are Probiotics?

Before we start, it’s helpful to understand exactly what we mean by probiotics. Probiotics are defined as ‘live microorganisms that, when taken in adequate amounts, confer health benefits’ for your pup[3].

What’s The Evidence For Giving Probiotics To Dogs?

When it comes to the evidence base to support probiotic use in dogs, the vast majority of studies to date look specifically into cases of gastrointestinal or digestive disease. This is because gut disease is a logical research model, and these diseases are the third most frequent reason for pet insurance claims[4].

For conditions that are less researched, your veterinarian’s recommendation for probiotics may be extrapolated from human studies, or our understanding of how the microbiome influences your pup’s body as a whole[1].

Here’s the evidence for probiotic use in dogs in some specific circumstances:

Healthy Dogs

Several studies have looked at the effect of giving probiotics to healthy dogs, but at this time, there are no studies that look into the long-term health benefits.

Probiotics are safe for, and well-tolerated by, healthy dogs[5-6]. In one study, these healthy dogs also showed significant changes in the composition of their gut microbiome, with an increase in beneficial bacteria and an enhancement of some immune system functions[6]. In another study, only some dogs had a change in microbiome composition—highlighting that not every dog has the same response to probiotics[5].

Gastrointestinal Disease

Several studies support using probiotics in managing acute canine uncomplicated diarrhea[7-11]. Studies also show probiotics are beneficial in the management of chronic inflammatory enteropathy (inflammatory bowel disease)[2,12], parvovirus infection[13], and acute hemorrhagic diarrhea syndrome[14].

Probiotics should only make up one part of your dog’s treatment plan for these more severe conditions, because conventional therapies are almost always essential for successful treatment. Don’t delay seeking veterinary care if your dog has a significant gastrointestinal illness.

After Antibiotics

Antibiotics are important for fighting serious infections, but unfortunately, they can also harm your pup’s gut microbiome[15]. If your dog needs antibiotics, evidence supports using probiotics during and after the course to support their gut microbiome[16].

Urogenital Disease

While we don’t have evidence in veterinary research for probiotic benefits in urogenital disease, there’s a suggestion in human studies that probiotics may benefit women with recurrent urinary tract infections (UTIs)[17]. Your veterinarian may choose to add probiotics to the mix if your dog suffers from recurrent UTIs (assuming there are no contraindications)[18], as they may have an unconfirmed benefit in animals too.

Neurological And Behavioural Diseases

There are no studies investigating the use of probiotics in neurological disease in animals at the time of writing. However, studies show that fecal microbiota may be associated with some neurological and behavioral disorders in dogs[19-23].

There’s significant research on the importance of the gut microbiome in mental health, anxiety, and degenerative brain disease in people, including the suggestion that probiotics may be a valuable addition to treatment plans[24-26]. As a result of this human research, your veterinarian might suggest adding a probiotic to your dog’s treatment for behavioral or neurological conditions.

Stress-related diarrhea is a recognized condition in animals, so adding probiotics ahead of a stressful event (such as travel or a kennel stay) is known to be effective[27-28].

The link between a dog’s gut and their brain is an area of active research in the veterinary industry, so watch this space for more developments.

How Long Do Dog Probiotics Take To Work?

If your veterinarian has prescribed a course of probiotics, you may find yourself wondering how long they’ll take to work. There’s minimal research to answer this question, but let’s look at what we do know:

  • A 2019 study looking at the treatment of acute diarrhea with either probiotics, antibiotics, or a placebo treatment found that an ‘acceptable’ fecal consistency was recorded in 3.5 days (+/- 2.2 days) in the probiotic treatment group[11]—faster than the other treatment groups
  • Another 2019 study comparing Pro-Kolin advanced paste with a placebo group found diarrhea resolved within around 36 hours, 1.6 times faster than the placebo group[10]

So, it’s fair to assume improvement should be seen in around three to five days if your pup has been prescribed probiotics for a sudden case of diarrhea.

Why Aren’t My Dog’s Probiotics Working?

If you’re finding that probiotics aren’t working for your dog, it could be due to several reasons, including:

  • They’ve Got The Wrong Probiotic For The Job

There are many different kinds of probiotic organisms. For example, there’s evidence that human and canine inflammatory bowel disease (now called chronic inflammatory enteropathy in dogs) have different patterns of microbial disturbance (or dysbiosis) within the gut[29]. Due to the differences in the microbes, it’s advisable to use probiotic products made especially for dogs, not humans.

  • They Have A More Severe Disease

Despite the ways they support the gut, probiotics shouldn’t be considered a cure-all treatment. Some conditions, such as chronic inflammatory enteropathy, will usually require additional treatment to get them under control. If your dog’s symptoms aren’t clearing up with probiotics, it’s time to make an appointment with your veterinarian.

  • There Are Individual Variations

As we’ve discussed, not every dog will respond to probiotic products in the same way due to their individual needs.

Final Thoughts

We have good evidence to support the use of probiotics for several medical conditions in dogs. Studies looking at the use of probiotics in healthy dogs also show them to be safe, and to benefit gut microbiome composition and immune system function. At this time, no scientific studies are looking at whether routine probiotic use has long-term health benefits, but watch this space.

Many studies into human health—and increasing numbers in the veterinary sector—are highlighting the importance of the gut microbiome for health, so it stands to reason that supporting this microscopic ecosystem should be beneficial. The most important thing to remember when choosing a probiotic supplement is to pick one that is specifically for dogs, and that guarantees a certain probiotic dose at the end of its shelf life.

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  2. Jergens and Heilmann (2022) Canine chronic enteropathy – Current state-of-the-art and emerging concepts. Frontiers in Veterinary Science. DOI https://doi.org/10.3389/fvets.2022.923013
  3. Hill et al. (2014) The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature Reviews: Gastroenterology and Hepatology. DOI https://doi.org/10.1038/nrgastro.2014.66
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