Best cat supplements.

The strongest-evidence omega active, fully disclosed in triglyceride form and third-party tested; a partial per-softgel dose for a larger dog keeps it just under the top.

A disclosed, well-dosed salmon and pollock omega oil, NASC-sealed and inexpensive per day; strong execution puts it near the top. The Feb 2025 Zesty Paws recall covered soft chews, not this oil.

High disclosed EPA and DHA per pump in natural triglyceride form, NASC-audited, and inexpensive per day; strong execution lands it at the top of Good.

The studied SAMe and silybin combination at the dose used in the canine trial, fully disclosed; moderate evidence and a high cost per day keep it Good.

A triglyceride-form fish oil third-party tested for purity and keyed to the feline skin and coat evidence; a typical cat reaches only a partial share of the studied EPA and DHA dose at the labeled serving, which keeps it Good rather than Strong.

A fully-disclosed glucosamine, chondroitin, and ASU joint capsule for cats at the studied forms and a weight-scaled dose; the active's osteoarthritis evidence is contested and Nutramax is not an NASC member, so it lands Good rather than Strong.

A disclosed fish-oil liquid delivering an EPA and DHA dose near the feline dermatology target, keyed to the cat skin and coat evidence; well made, though the fish-oil form is not stated and the scoop count is derived.

A fully disclosed, per-ingredient cat joint chew from a NASC, own-facility maker, with green-lipped mussel alongside glucosamine and chondroitin and a hedged support claim; the catch is the same as every glucosamine product, the evidence for the active is weak and contested, so it lands Good on execution rather than Strong on proof.

A transparent, well-priced feline joint capsule from a batch-testing owner-operator, held to Good by the contested glucosamine and chondroitin evidence base.

Discloses EPA and DHA separately in an NASC gel cap from a maker that owns its cGMP plant, but the weight-scaled label dose delivers only about 20 mg/kg/day of EPA plus DHA, below the studied skin and coat range, and there is no independent testing.

The canonical alpha-casozepine calming supplement, a milk-protein hydrolysate with modest but real randomized-trial support for situational stress in cats and dogs, NASC-sealed with a restrained non-sedating claim. It scores on a moderate evidence tier, not a strong one, and at over a dollar a day it runs expensive for the category.

The studied L-theanine form, fully disclosed and very cheap per day, but at 5 mg it is well under the studied dose; weak evidence and a low dose hold it to Mixed.

A fully disclosed dog-and-cat joint chew from an NASC founding member that owns its Vermont plant, with glucosamine, chondroitin, and green-lipped mussel and a hedged support claim, and it is very cheap per day; the catch is the familiar one, the glucosamine evidence is weak and the per-serving dose is modest, so it lands Good on execution rather than Strong on proof.

A calming chew scored on its disclosed L-theanine (the studied Suntheanine form); the C3 colostrum complex is not in our evidence library and at 21 mg the L-theanine is below the studied dose, so it lands Mixed.

The veterinary-strength Composure, scored like the regular version on its disclosed Suntheanine L-theanine, with added L-tryptophan and a higher thiamine load; at 25 mg the L-theanine is still below the studied dose and the C3 colostrum complex is not in our evidence library, so despite the clinical-onset marketing it lands Mixed, the same band as the standard Composure.

The feline twin of FortiFlora: one studied strain from an owner-operator manufacturer, but no NASC seal, no independent testing, and a high cost per day; Mixed.

A fully disclosed, NASC-sealed L-lysine chew for cats at a studied dose, from a maker that owns its facility and frames lysine as a mechanism rather than a cure; like every lysine product the catch is the same, the controlled evidence is against lysine for feline herpesvirus, so good execution and a fair price cannot lift it past the evidence ceiling.

The one hairball product built on fiber, which is the only hairball approach with controlled cat evidence: a randomized trial found a dose-dependent drop in trichobezoars from a specific fiber, and a second study found psyllium plus higher dietary fiber raised fecal hair excretion in long-haired cats. The label is clean, NASC-sealed, and weight-scaled, with psyllium disclosed at 490 mg per capsule. The catch is dose: the trials raised total dietary fiber to 11 to 15 percent of the diet, and a single 490 mg capsule is far smaller than that, so the label does not prove a daily capsule delivers a studied-effective amount, and Value is flagged approximate. Still the best-evidenced option in a category whose alternative is petroleum gel with no efficacy trial.

A fully disclosed, NASC-sealed cat urinary chew with a restrained support claim; the problem is the evidence, not the execution. A placebo-controlled trial of oral glucosamine for feline idiopathic cystitis found no benefit, and the 2025 feline consensus says glycosaminoglycans have no significant benefit, so a cranberry-and-glucosamine urinary supplement scores low on evidence no matter how cleanly it is made.

A cleanly disclosed, NASC cat urinary chew built on cranberry; the support claim is restrained, but cranberry has no controlled efficacy evidence in cats and most feline lower-urinary disease is sterile, so the anti-adhesion rationale does not even apply. Well made, weakly evidenced.

A well-made, NASC-sealed, properly dosed L-lysine paste from an owner-operator manufacturer, but the controlled evidence is against lysine for feline herpesvirus, which lands it in Limited; to its credit the label stays restrained and does not over-claim a cure.

An NASC-sealed, fully-disclosed feline multivitamin from an owned cGMP facility; well made and cheap, but a general-wellness multivitamin for a healthy cat on a complete diet has weak evidence, which is what holds it down.

A petroleum-free hairball gel that licks off the paw, built on vegetable oils rather than petrolatum, with every active disclosed and an NASC seal. The catch is that petroleum-free is a sourcing story, not an efficacy one: a vegetable-oil lubricant gel rests on the same absent evidence as the traditional petroleum kind, because a peer-reviewed review found none of the commonly recommended hairball-prevention strategies have been tested in cats. The label stays modest, claiming to lubricate and minimize shedding rather than to eliminate hairballs, which is why it edges just above the petrolatum gel on honesty while landing in the same low band. Fiber is the only hairball approach with trial support.

The classic petroleum-jelly hairball gel, NASC-sealed and clearly labeled, but it has no controlled efficacy trial in cats; a peer-reviewed review notes no study has evaluated the common hairball-prevention strategies. The lubricant mechanism is plausible and low-risk, but the 'eliminate and prevent' claim runs ahead of the evidence, so it scores at the floor. Fiber, not lubricant gels, is the hairball approach with actual trial support.

A 7-strain probiotic that names its strains but discloses only a combined 7.5 billion CFU, so we cannot confirm an effective per-strain dose and the Active Dose score is capped; the marketing also reaches past the acute-diarrhea evidence into allergy, immune, and behavior claims. Well made and inexpensive per day, but the hidden per-strain dose and claim breadth land it low.

A seven-strain probiotic from a batch-testing maker at the studied strain set, well priced; the multi-strain evidence is modest and per-strain CFU is hidden behind a proprietary blend, so it lands Limited.

The studied De Simone (former VSL#3) multi-strain formulation, NASC-sealed, but it discloses only a combined 112.5 billion CFU rather than per-strain amounts, so under our rules it is a proprietary blend (Active Dose capped) and at over a dollar a day it lands in Limited.