Do Cats Need Probiotics? Here’s What the Science Says

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Whilst they sound great, probiotics aren’t proven to offer benefit to cats.

There is some evidence that certain strains of probiotics can help with diarrhea.

After more?

Probiotics are increasing in popularity by the year, as people search for ways to boost health. Some owners might consider using them on their cats.

But what do they do exactly? Which one’s work?

Do they even work at all? Are they risky?

In this article, I’ll answer the question of do cats need probiotics and break it down. Then I’ll offer recommendations about existing products.

I am not a veterinarian and I recommend seeking the advice of a vet for any further questions. This article is not intended as a replacement for medical advice.

What Are Probiotics

Probiotics are:

Live microorganisms that confer a health benefit to the host when administered in appropriate amounts.

There’s good and bad bacteria. Probiotics are the ‘good’ bacteria because they perform commensal roles.

Experts think probiotics form a symbiotic relationship with the host.

We (or our cat) provide the habitat (i.e. gut) and the bacteria help offer immune protection among other things.

Quick notes:

  • Probiotics are live micro-organisms
  • Provide health benefit
  • Symbiotic relationship with host

How Do Probiotics Work?

Researchers link probiotics with:

  • Boosted immune system
  • Reduced allergies
  • Less diarrhea
  • Less infections

Probiotics produce short-chain fatty acids from food material. This seems to inhibit pathogens.

Good bacteria seem to help improve gut wall permeability. This prevents bad bacteria from going into the blood and there’s less water loss (i.e. less diarrhea).

This can affect immune health, as there’s less need to fight invading bacteria. Probiotics may help reduce allergies.

Quick notes:

  • Probiotics affect gut health
  • May help reduce diarrhea
  • Linked with improved immune health

What are the Benefits of Probiotics for Cats?

Probiotics can help treat diarrhea in cats.

A 2012 study gave owners of 53 cats with diarrhea a probiotic (Proviable) to use for 21 days. 72% owners reported firmer stools, but the study didn’t use a control.

In a 2011 study, 217 cats received SF68 (probiotic containing E. Faecium) for 4 weeks.

No differences in diarrhea occurred. Incidents of diarrhea lasting over 2 days decreased in the probiotic group compared to placebo (7.4% vs 20.7%).

A recent 2022 randomized controlled trial looked at a probiotic (E. Hirae) in 130 kittens. The trial lasted 5 months.

The probiotic reduced cases of diarrhea (20 vs 6 in placebo).

Quick notes:

  • Probiotics can treat diarrhea
  • Several trials show benefit
  • Some limitations of research

What Are the Risks of Giving Cats Probiotics?

Probiotics appear safe.

There are no averse effects reported in trials at least in the short term.

However the industry isn’t tightly regulated. Probiotics are supplements, not drugs according to the Food and Drug Administration.

Research showed most probiotics aren’t accurate in what they report. A 2003 study showed 4 of 19 commercial products had Pediococcuss pp. – a pathogenic bacteria.

Human research cautions against the use of probiotics in critically ill people. Probiotics can increase the risk of sepsis in these groups.

In humans, probiotics are linked to brain fogginess and bloating, which are improved with antibiotics. How that affects cats isn’t clear, but could affect their quality of life.

Quick notes:

  • Industry not tightly regulated
  • Probiotics not accurate
  • Not advisable if critical ill

What Kind of Probiotics Can I Give My Cat?

Types include:

  • Powders
  • Chews
  • Kibble with added probiotic
  • Capsules

Freeze-drying and microencapsulation are the best forms of probiotic. Kibble is the worst form, since bacteria is destroyed via extrusion.

How Do I Give My Cat Probiotics?

Add them to wet cat food.

This is how most cat probiotics work. Chews are ready to eat as is.

How Often Should I Give My Cat Probiotics?


This is the standard frequency used in research experiments.

You might not need to use probiotics in your cat long term.

One study showed improved immune function using L. acidophilus (e.g. increased eosinophils) for five weeks.

This persisted four weeks after ceasing the probiotic in 15 adult cats.

Quick notes:

  • Use probiotic daily
  • Might not need to use long term
  • Check product guidelines

When Do Cats Need Probiotics?

Acute diarrhea.

This is generally the situation that probiotics seem to help treat based on research. Most acute diarrhea cases are common in cat shelters.

The evidence for use with general health and performance isn’t clear.

Other Factors To Consider When Choosing Cat Probiotics

Check what’s in the product.

What’s important is the type of bacteria used and the amount.

Dosage is given in colony reporting units (CFU). Experts believe 1 × 108 to 1 × 1010 CFU/d is required to exert benefit in humans.

Researched probiotics include:

Probiotic nameAmountBenefit
E. Feacium SF681g (2.1 × 109 CFU/g)Helps treat diarrhea in a cat shelter
Proviable5 × 109 CFUImproved fecal score (firmer stool)
VSL#3 probiotic225 × 109CFU/dayProbiotics absorbed into lungs (may help treat asthma)
SLAB512×1011 CFU/dayLowered gut inflammation
S. Boulardii and P. Acidilactici2.0 × 1010CFU/g (both)Lowered gut inflammation
A list of researched probiotics with benefits

Prebiotics vs. Probiotics: How are They Different?

Prebiotics are fuel for bacteria, whilst probiotics are the actual bacteria.

Types of prebiotics include:

  • Beet pulp
  • Inulin
  • Legume seeds
  • Fructo oligosaccharides
  • Xylo-oligosaccharides
  • Guar gum

How Long Does it Take Probiotics to Work in Cats?

Most studies report benefit after four weeks.

Are Human Probiotics Good for Cats?

I don’t think so.

Human probiotics often include yoghurt, which I don’t recommend using with cats.


The benefits of using probiotics for cats isn’t clear, although they can help treat acute diarrhea.

An older study showed most probiotics report inaccurate amounts of CFU. At least 1 × 108to 1 × 1010 CFU/d may be needed to see a benefit.

Check the product contains researched bacteria demonstrated to offer benefit.

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I'm qualified dietitian that's turned their attention to cat nutrition. My goal is to help tease out the science on how best to feed your cat.