Hannah Zulueta Fecal Transplants for Dogs: What the Evidence Actually Shows
Before you give your dog another dog’s stool, look at the terrain.
Fecal Microbiota Transplantation is getting popular in the dog world right now. It’s pitched as a fix for chronic diarrhea, allergies, and more. Before you give your dog another dog’s stool, even from a vet, let’s look at the evidence.
Adding bacteria at the end does not fix the root. The terrain has to come first.
To give you context, I’m a canine nutritionist and senior intern in acupuncture and Traditional Chinese Medicine. My take comes from human studies and TCM’s focus on internal terrain. In humans, FMT is not the miracle it’s called in the dog space. It’s riskier than it seems.
The FDA only allows FMT for one thing: recurrent Clostridioides difficile, or C. diff. It’s an investigational drug. It is not approved for IBS, Crohn’s, obesity, or anything else.
Why the limits? Bad outcomes happen.
For dog “poop pills,” screening isn’t foolproof. You’re trusting the source you got it from.
FMT looks at colon bacteria from stool samples. But that misses the full gut, including the stomach and small intestine.
Testing the stool is like testing the compost pile at the back of the property. I used to have one in the corner of my yard, back behind the apple tree. It tells you what died and fermented. The FMT then takes that compost and shoves it through the front door of the house, the mouth. Just because the compost is healthy for the backyard doesn’t mean you want it sitting in your kitchen, the small intestine.
In TCM, we focus on the Middle Jiao, the Spleen and Stomach. If digestion or absorption is off up top, the colon ends up stagnant. Adding bacteria at the end doesn’t fix the root issue. If the upper gut is inflamed, the new microbes often don’t survive or they cause problems. Bacteria that belong in the colon can cause havoc if they colonize the small intestine: gas, malabsorption, and leaky gut as the small intestine struggles with microbes it wasn’t designed to house.
The small intestine handles the Clear, the nutrients. The large intestine handles the Turbid, the waste.
By swallowing stool, you are forcing Turbid matter back through the Clear pathway.
In TCM, many diseases stem from External Pathogenic Factors. These disrupt harmony and weaken Wei Qi, the defensive energy. That’s why I’m cautious about introducing another dog’s stool into a sick animal. It risks introducing unknown pathogenic factors or donor disharmony, potentially overwhelming an already compromised system rather than strengthening its own terrain.
Another major issue with FMT is that it may transmit harmful bacteria that live in the donor without causing clinical symptoms, such as drug-resistant E. coli. (Tuniyazi, 2022)
FMT companies pick stool from dogs they deem healthy. Their entire model is based on making your dog look like their Average Healthy Dog database. In TCM, we treat the individual, not the average. Every animal has a unique body. What thrives in one dog’s gut might clash in your dog’s gut.
It reminds me of the one-size-fits-all approach. It’s like handing out a bag of kibble and saying it works for every dog.
A healthy gut is like rich, moist, tilled soil. Throw seeds onto it and they easily find a place to burrow, hydrate, and grow. They become part of the landscape. A gut stripped by chronic inflammation, antibiotics, or a poor diet is a different surface entirely.
Soil
Rich, moist, tilled. The mucosal lining gives bacteria somewhere to latch on, hide, and colonize. Seeds find parking spaces. They take root and become the landscape.
Concrete
Thin, hard, non-receptive after inflammation, antibiotics, or a poor diet. Bacteria land on concrete. There are no parking spaces. They can’t colonize. The gut can also become overly damp from a diet the dog cannot digest.
Doing FMT without fixing the diet sets it up to fail. Bacteria need the right conditions. If a report shows no Faecalibacterium, a key good guy, it’s usually because the diet starved them out. Transplant into the same food and they won’t stick. Any gains you see may be short-lived.
TCM schools of thought have been passed down through generations for hundreds of years. The Spleen School, emphasizing digestion and transformation in the Middle Jiao, traces back to influential doctors like Li Dongyuan, who lived from 1180 to 1251. He argued that Spleen Qi deficiency underlies most chronic diseases, advocating warming, moistening tonics over harsh purging. Later physicians like Zhang Jiebin and Ye Tianshi built on this, shaping modern TCM practice.
Many TCM doctors today follow these systems. Note that we don’t have a Colon School or a Large Intestine School. We do look at the colon. But it is a result of what happens first in the Middle Jiao.
Treating the colon is literally like trying to get the tail to wag the dog.
Studies in dogs report side effects in 10 to 25% of cases, like diarrhea or vomiting within 48 hours, usually resolving in two to three days, along with flatulence, straining, or abdominal discomfort. In tough gut environments with pathogens, new bacteria can trigger inflammation such as SIRS. There is also the risk of passing on obesity, anxiety traits, or resistant bugs.
Fix the diet and internal balance first.
Stabilize the terrain before adding new bacteria. In TCM terms, that means warming the interior, expelling cold, or clearing heat and draining dampness, depending on the dog in front of you.
Stabilize the terrain before adding new bacteria. Otherwise, it’s money wasted.
Don’t let my opinion sway you from what your own intuition calls you to do. At the end of the day, you ultimately decide how to take care of your dog. An old mentor, Dr. Thomas, often said, “The truth always reveals itself.” If you have never done an FMT and you really want to try it, then by all means go for it. If you tried it and want to do it again, then do that too.
My own bias, full disclosure, is that I favor my Chinese Medicine approach. I’m more interested in restoring function to the Middle Jiao. That means we keep it warm and feed it a protein-rich diet with the appropriate plant matter to act as prebiotics that bring balance to the gut. I also love to use herbs.
FMT has a place, but not as a standalone cure. For my own dogs, it’s not a solution I find appealing.
Sources: U.S. FDA safety alert on fecal microbiota transplantation (2019), reporting deaths linked to drug-resistant E. coli in donor stool. Tuniyazi, 2022, on the risks of FMT in companion animals. Canine side-effect ranges drawn from published veterinary FMT research. This article is educational and reflects the author’s clinical perspective. It is not veterinary advice.
Resources:
Niina, T., Hasegawa, Y., & Tanaka, A. (2025). Impact of fecal microbiota transplantation in dogs. Frontiers in Veterinary Science, 12, Article 1505226. https://doi.org/10.3389/fvets.2025.1505226
Rodríguez-Palacios, A., et al. (2023). Clinical effects of faecal microbiota transplantation as adjunctive therapy in dogs with chronic enteropathy. Journal of Veterinary Internal Medicine. Advance online publication. https://pmc.ncbi.nlm.nih.gov/articles/PMC10145442/
Toresson, L., et al. (2025). Effect of faecal microbial transplantation on clinical outcome and fecal microbiota in dogs with chronic enteropathy. Scientific Reports, 15, Article 96906. https://doi.org/10.1038/s41598-025-96906-7
Tuniyazi, M., Hu, X., Fu, Y., & Zhang, N. (2022). Canine Fecal Microbiota Transplantation: Current Application and Possible Mechanisms. Veterinary sciences, 9(8), 396. https://doi.org/10.3390/vetsci9080396
Hannah Zulueta obtained her Certificate in Canine Nutrition from CASI Institute. She is also studying for her Doctorate in Acupuncture, Traditional Chinese Medicine, and Herbalism from the esteemed Pacific College of Health and Medicine. If you’re as keenly interested in health for yourself, visit her website for human health: Satori Acupuncture and Herbs.
She resides in San Diego with her three dogs, Maggie, Orbit, and Mr. Higgins.
She is available for one on one consultations. She develops evidence-based recipes that meet both NRC and AAFCO nutritional standards while integrating the therapeutic food principles of Traditional Chinese Veterinary Medicine into her formulations.
Additionally, you can find her sharing free content on Instagram.
