Label terms
CFU (colony-forming units)
A CFU, or colony-forming unit, is the unit used to count live micro-organisms that can multiply and form a visible colony in a laboratory test.
Also known as: colony-forming unit, CFU/g, CFU/mL, viable count
What it is
CFU comes from the viable plate count, a laboratory count of live cells. A sample is serially diluted and used to inoculate plates, which are then incubated; viable cells multiply and give rise to visible colonies, which are counted. Results are expressed in colony-forming units (for a liquid, CFU per millilitre) rather than in cells, because more than one cell may land on the same spot and grow into a single colony.[1]
- Bacteria that grow in clusters or chains are hard to separate, so one colony can represent several cells.
- Some cells are viable but non-culturable and will not form colonies, so they are not counted.
Source [1]
Where it’s found
CFU is the unit used to express amounts of live cultures in research and in feed regulation. Probiotics are defined as live micro-organisms that, when administered in adequate amounts, confer a health benefit on the host, so the amount is expressed as a CFU count. Human studies of one Bifidobacterium strain, for example, used daily amounts from 10⁷ to 10¹¹ CFU, and EFSA assessed an L. acidophilus feed additive for cats and dogs at a minimum of 5 × 10⁹ CFU per kg of feed.[2],[3],[4]
Why it’s used in dog supplements
A CFU figure tells you how many culturable live micro-organisms a product is declared to provide. It does not tell you everything: probiotic benefits are generally considered strain-specific, so which strains are present matters as well as the number. For a fuller explanation of reading CFU claims, see what CFU means.[2]
On the DIGEST+ label
The DIGEST+ label states that the five-strain Live Culture Blend provides 2 billion CFU per tablet (2 × 10⁹). That is the total for the whole blend, not a figure per strain. The feeding guide gives 1 to 4 tablets a day depending on your dog’s weight, so a day’s amount is 2 to 8 billion CFU in total. Find your dog’s number of tablets with the dose calculator.
| Tablets per day | Live Culture Blend, CFU per day |
|---|---|
| 1 | 2 billion |
| 2 | 4 billion |
| 3 | 6 billion |
| 4 | 8 billion |
| Body weight | Tablets per day | One bottle lasts |
|---|---|---|
| Up to 10 kg | 1 tablet/day | 120 days |
| 11–25 kg | 2 tablets/day | 60 days |
| 25–40 kg | 3 tablets/day | 40 days |
| Over 40 kg | 4 tablets/day | 30 days |
The label advises storing the bottle in a cool, dry place away from direct sunlight, and notes that refrigeration may help extend shelf life. More on that in storing dog supplements.
Questions people ask
What does CFU stand for?
Colony-forming units. It is a count of live micro-organisms that can multiply into a visible colony in a laboratory plate count.
Is 2 billion CFU per tablet per strain?
No. The DIGEST+ label gives 2 billion CFU per tablet as the total for the five-strain Live Culture Blend. It does not break that figure down by strain.
How many CFU does my dog get a day?
The feeding guide gives 1 to 4 tablets a day by body weight, which works out at 2 to 8 billion CFU a day from the Live Culture Blend in total.
Work out your exact supply
The calculator on the product page takes your dog’s weight band and how many dogs you have, then shows the daily dose, how long a bottle lasts and a sensible refill rhythm.
Sources
- 9.1 How Microbes Grow — Microbiology — OpenStax (Rice University). Checked 2026-10-15.
- Bifidobacterium animalis subsp. lactis HN019 Effects on Gut Health: A Review — Frontiers in Nutrition. Checked 2026-10-15.
- Safety and efficacy of Lactobacillus acidophilus D2/CSL (Lactobacillus acidophilus CECT 4529) as a feed additive for cats and dogs — EFSA Journal. Checked 2026-10-15.
- Clinical effect of probiotics in prevention or treatment of gastrointestinal disease in dogs: A systematic review — Journal of Veterinary Internal Medicine. Checked 2026-10-15.
Updated