Read a dog probiotic label in this order: named strains, guaranteed live count at the end of shelf life, prebiotic content, then everything else. Most labels in this category, Ark Naturals Gentle Digest included, do not publish all of that online. The printed pack and the manufacturer are your real sources.
Strain names, and why genus alone tells you nothing
A probiotic organism has three parts to its name. Genus, species, and strain designation. Something like Enterococcus faecium SF68 gives you all three. A label that says only "Lactobacillus" has given you the first part and stopped.
That matters because behaviour differs at the strain level, not the genus level. Two strains from the same species can survive stomach acid very differently, colonise very differently, and have been studied very differently. A label naming strains is telling you the manufacturer knows precisely what is in the tub. A label naming a genus is telling you considerably less than it appears to.
When you find a strain designation, you can look it up. When you find only a genus, there is nothing to look up. That asymmetry is the whole reason strain naming is the first thing to check.
None of this means an unnamed blend is worthless. Plenty of well made products use a proprietary blend and do not disclose it. It means you cannot independently verify anything about it, and you should price that uncertainty into your decision rather than ignore it.
Live counts, and the number that actually matters
Live organism counts are usually printed as CFU, short for colony forming units. You will see figures in the millions or billions per serving.
Two things go wrong when owners read that number.
The first is treating bigger as automatically better. A higher count is not a quality grade. Different strains are studied at very different levels, and a huge number of a poorly suited organism is not an improvement on a modest number of a well suited one.
The second, and more important, is the difference between count at time of manufacture and count at the end of shelf life. Live organisms die off in storage. A product guaranteeing its count through the printed expiry date is making a meaningfully stronger commitment than one quoting what went in on the production line. If a label does not say which figure it is quoting, assume the weaker one and ask.
There is also a labelling convention worth knowing. Some products state a count per chew, others per serving, and a serving can be more than one chew depending on the dog's weight. Comparing a per chew figure on one pack against a per serving figure on another produces a nonsense result. Check the unit before you compare anything, and if the pack does not make the unit explicit, that ambiguity is itself a mark against the label.
Storage conditions interact with this. Heat and humidity shorten the life of live cultures, which is why a tub left in a hot car or a steamy kitchen cupboard is not doing what the label promises. Cool, dry and sealed is the baseline, and the pack should tell you if anything more specific is needed.
Prebiotics, and what they are doing on the same label
A prebiotic is not a probiotic. It is a fibre that the beneficial organisms already present in the gut can use. You will see names like inulin, fructooligosaccharides, often shortened to FOS, and chicory root.
A product combining both is sometimes called a synbiotic. The logic is straightforward enough: supply the organisms, and supply something for them to work with. Ark takes this approach with Gentle Digest, which pairs probiotics with prebiotics and is positioned as helping to balance intestinal microflora to support proper digestion and bowel health.
What you generally will not find on a label is how much prebiotic is in there. Fibre ingredients often appear in the ingredient list with no quantity attached, which makes comparison across products effectively impossible. That is a limitation of the category rather than of any one brand.
What is usually missing, and what to do about it
Here is where the category disappoints. Across pet probiotic labelling, the gaps are consistent and predictable.
The practical response to a gap is not to abandon the product. It is to ask. A brand that answers a direct question about strains and shelf life counts is telling you something useful. A brand that cannot or will not is also telling you something.
For broader background on how supplements fit into canine nutrition, the American Kennel Club maintains a general reference at akc.org that is written for owners rather than clinicians.
Where Ark Naturals Gentle Digest lands
Gentle Digest is a soft chew that combines probiotics and prebiotics. Ark states it helps balance intestinal microflora to support proper digestion and bowel health, and suggests it for dogs switching foods, dogs fed a raw diet, and dogs travelling. It is crafted in the USA with no artificial flavors or colors, and it sells for $13.30.
Held against the checklist above, Ark's published product information does not name individual strains, does not state a live organism count, does not say whether any count is guaranteed at manufacture or at expiry, and does not give calories per chew. That is the same shape of gap most of the category has, and it is worth being plain about rather than glossing over.
None of that makes Gentle Digest a poor product. The format is easy to give, and the positioning is sensible: a food switch, a raw diet and a trip are three of the most common moments an owner starts looking for digestive support in the first place. The point is that you cannot compare it strain for strain against anything else, because the strain information is not published, and you should not pretend otherwise when deciding.
So use the pack. The printed label carries the ingredient declaration and the feeding directions, and it is the only source that should determine how much you give. If the pack does not answer a question that matters to you, contact Ark before buying rather than after. You can check the current format and price on the Gentle Digest product page.
When to stop reading labels and call your vet
Label literacy is useful right up to the point where it becomes a substitute for a diagnosis, and then it becomes a problem.
Persistent diarrhoea, vomiting that does not settle, blood in the stool, weight loss, lethargy, or a dog who stops eating are all veterinary matters. So is any digestive change in a puppy, a senior, or a dog with an existing health condition, because those dogs have less margin. A probiotic chew is not the right first response to any of them.
Talk to your veterinarian before starting a probiotic if your dog is on medication of any kind, is immunocompromised, or has a diagnosed gastrointestinal condition. Your vet can also tell you whether the timing of a supplement relative to other medication matters in your dog's case, which is not something a label will cover.
And follow the feeding directions on the pack rather than a number from anywhere else. Ark does not publish a dosing chart on its website, so the packaging is the authority.
Frequently asked questions
What does CFU mean on a dog probiotic label?
CFU stands for colony forming units, and it is a count of live organisms per serving. The number by itself is less informative than owners assume. What matters more is whether the count is guaranteed through the end of the shelf life or only measured at the time of manufacture, and whether the organisms being counted are strains suited to dogs.
Is a higher CFU count better?
Not automatically. A larger count of a poorly matched organism does not beat a smaller count of a well matched one, and there is no universal threshold that makes a product good. Use the count as one data point alongside strain naming, shelf life guarantees and your veterinarian's view of what your particular dog needs.
What is the difference between a probiotic and a prebiotic?
A probiotic supplies live beneficial organisms. A prebiotic supplies fibre that beneficial organisms in the gut can use. Products containing both are sometimes described as synbiotics. Ark Naturals Gentle Digest combines probiotics and prebiotics in a soft chew format.
Does Ark Naturals publish the strains in Gentle Digest?
Ark's online product information describes Gentle Digest as combining probiotics and prebiotics but does not list individual strain designations or a live organism count. The printed ingredient declaration on the pack is the source to check, and Ark can be contacted directly if the pack does not answer your question.
Can I give a probiotic to a puppy?
Ask your veterinarian first. Puppies have less reserve than adult dogs when digestion goes wrong, and a change in stool quality in a young puppy is worth a phone call rather than a supplement. If your vet does recommend one, follow the feeding directions printed on the pack for your puppy's weight.
Related reading: Ark Naturals Gentle Digest: What Helps a Dog Switching Foods?