Flex+Max wins this comparison. It’s the better product for most horses, despite Cosequin’s genuine advantage in quality documentation.
The deciding factor is Dosing Adequacy (15/20 vs 12/20). Flex+Max delivers 10,000 mg of glucosamine at full therapeutic threshold plus 150 mg of hyaluronic acid. Cosequin delivers 7,200 mg of glucosamine and no HA at all.
Cosequin’s real edge is Quality Assurance (6/15 vs 2/15) — the best documented manufacturing program of any product in our Joint Health database.
If your horse works regularly, trail rides or does lessons, and you want the most glucosamine and HA per dollar, Flex+Max is the buy. Two cents a day more than Cosequin, 2,800 mg more glucosamine per scoop.
Skip Flex+Max only if you show under FEI or USEF rules where a contaminated supplement ends your season. Cosequin’s documented QC program is the strongest contamination-risk mitigation in our Joint Health database, and that single concern overrides dose math when the stakes are a positive test.
Full audit reports linked at the bottom of this page.
The Scores
| Flex+Max | Cosequin ASU | |
|---|---|---|
| Overall | 6.9 | 6.5 |
| Label Transparency | 12 / 15 | 12 / 15 |
| Ingredient Form | 15 / 20 | 15 / 20 |
| Dosing Adequacy | 15 / 20 | 12 / 20 |
| Formula Design | 13 / 15 | 10 / 15 |
| Quality Assurance | 2 / 15 | 6 / 15 |
| Value | 12 / 15 | 10 / 15 |
| Badge | Recommended | Recommended |
| Cost/day | $1.75 | $1.73 |
In our 15-product Joint Health database, Flex+Max is #1 overall and Cosequin ASU is #3. SmartFlex Ultra at 6.8 sits between them. All three carry the Recommended badge and cluster inside a 0.4-point band at the top of the category.
2,800 mg of Glucosamine Per Scoop — That’s the Whole Story
Flex+Max delivers 10,000 mg of glucosamine HCl per serving. Full therapeutic threshold. Cosequin ASU delivers 7,200 mg, about 72% of the way there. The 2,800 mg gap is the single reason Flex+Max earns the overall win.
Glucosamine is the substrate your horse’s body uses to build cartilage and glycosaminoglycans. Every other ingredient in these formulas plays a supporting role. When the foundation is short by 28%, the supporting cast can’t make up the gap. They work through different mechanisms on different timelines.
Cosequin partially compensates with ASU at 1,050 mg, slightly above the 1,000 mg research threshold. ASU reduces inflammatory mediators rather than building cartilage directly (Henrotin et al., 2003). That’s a useful mechanism Flex+Max doesn’t address. But it complements glucosamine; it doesn’t replace it, and there’s less glucosamine here for ASU to complement.
Flex+Max also delivers 150 mg of hyaluronic acid (threshold: 100 mg) where Cosequin has none. HA supports synovial fluid viscosity, the lubricant inside the joint capsule. Combined with the glucosamine gap, this puts Flex+Max at 15/20 on Dosing Adequacy versus Cosequin’s 12/20.
Translate the 28% glucosamine shortfall into outcome timing. At 10,000 mg/day on a 500 kg horse, synovial fluid concentrations reach a therapeutic plateau in roughly 30-45 days. At 7,200 mg/day the same horse needs 60 days or longer to reach a steady state closer to the threshold of measurable effect. For an owner starting a supplement because of early stiffness, that’s an additional month of observation before knowing whether the product is helping. On a 600 kg warmblood the math gets worse: Cosequin’s dose drops to 60% of threshold, Flex+Max stays above 80%.
Why this gap outweighs the 4-point Formula Design edge Cosequin holds on paper. Formula Design rewards boswellia and ASU presence; both exist in Cosequin at meaningful doses. But those ingredients sit on top of the glucosamine-chondroitin foundation, not beside it. The literature treats them as adjuncts, not replacements. Strip out the adjuncts and what’s left is a product delivering 72% of primary active versus a product delivering 100%. Flex+Max earns a 4-point Formula Design disadvantage and recovers it twice over on Dosing Adequacy.
Flex+Max and SmartFlex Ultra are the only products in our 15-product Joint Health database that deliver glucosamine at full 10,000 mg threshold. Cosequin’s 7,200 mg, while the best dose from a pharma-grade source, leaves it 5th on this dimension.
Where Cosequin’s QA Documentation Actually Matters
Cosequin scores 6/15 on Quality Assurance — the highest in our Joint Health database. Nutramax uses trademarked ingredient specifications (FCHG49 for glucosamine, TRH122 for chondroitin, NMX1000 for MSM), describes 80+ quality checks per batch in public documentation, and explicitly states contaminant testing. Flex+Max scores 2/15: “Made in the USA” and not much else.
For competition horses subject to drug testing, this matters in a specific, narrow way. If your horse shows under FEI or USEF rules and a positive test ends your season, the documented QC program gives you a contamination paper trail that Flex+Max doesn’t offer. That’s one real scenario where the 4-point QA gap translates into something you can put on a claim form.
Cosequin ASU’s 6/15 Quality Assurance is the highest in our 15-product Joint Health database. The next-closest scores are Joint 6-in-1 at 8/15 and Cosequin Optimized MSM at 6/15 (same manufacturer). Every other product scores 2/15 or below. On QA documentation, Nutramax stands alone.
What’s in Each Scoop
| Ingredient | Flex+Max (75 g) | Cosequin ASU (17.5 g) | Threshold |
|---|---|---|---|
| Glucosamine HCl | 10,000 mg | 7,200 mg (FCHG49) | 10,000 mg |
| MSM | 5,000 mg | 5,000 mg | 10,000 mg |
| Chondroitin sulfate | 1,200 mg | 1,200 mg (TRH122) | 2,500 mg |
| Hyaluronic acid | 150 mg | — | 100 mg |
| ASU | — | 1,050 mg | 1,000 mg |
| Boswellia | 130 mg | 300 mg | 300 mg |
| Flaxseed | 11,000 mg | — | — |
| Rice bran | 5,600 mg | — | — |
| Manganese | — | 250 mg | 50 mg |
| Cost/day | $1.75 | $1.73 |
Which One for Your Horse
Buy Flex+Max if: your horse is a trail horse, a lesson horse, an aging retiree with creaky hocks, or a weekend eventer below Prelim. The 10,000 mg glucosamine, 150% HA dose, and broader omega-3 profile from flaxseed and rice bran do more practical joint work than Cosequin’s pharma-grade glucosamine at 72% threshold. Two cents a day extra for 2,800 mg more of the primary active.
Buy Cosequin ASU only if: you show under FEI or USEF rules where a positive contamination test ends your season. Nutramax’s documented QC program (trademarked specs, 80+ batch checks, explicit contaminant testing) is the strongest contamination-risk mitigation in our Joint Health database. When the consequence of a bad batch is losing a ribbon season, the QA paper trail is worth the 2,800 mg dose shortfall.
For everyone else, Flex+Max is the buy.
Frequently Asked Questions
My vet recommended Cosequin. Should I ignore that and buy Flex+Max?
No. Your vet knows your horse. Cosequin ASU is a well-researched product backed by Nutramax’s clinical studies and trademarked ingredient specs. If your vet chose it for a specific reason (competition safety, a known condition, interaction with other medications), follow that advice. Our audit measures what’s on the label and at what dose. Your vet measures your horse.
Is ASU better than hyaluronic acid?
They do different things. ASU reduces inflammatory mediators that break down cartilage. HA supports the viscosity of synovial fluid that lubricates the joint. Neither replaces the other. No product in our Joint Health database delivers full-dose ASU and full-dose HA in one scoop. If forced to pick one, ASU has stronger equine research behind it. But Flex+Max’s HA at 150% of threshold isn’t negligible. It’s the closest any top-three product comes to that dimension.
I’m already using Cosequin ASU. Should I switch?
If you show at rated events, stay with Cosequin. The QA documentation is your best protection. If you’re not showing under FEI or USEF rules and you bought Cosequin for the brand name, Flex+Max at $0.02/day less with 2,800 mg more glucosamine is worth a 60-day trial. Taper over 7-10 days to avoid GI upset from the formulation change.
Sources
- Full audit report: Flex+Max Pellets — complete scoring calculations, label analysis, and sources.
- Full audit report: Cosequin ASU Pellets — complete scoring calculations, label analysis, and sources.
- Laverty S, Sandy JD, Celeste C, et al. Synovial fluid levels and serum pharmacokinetics in a large animal model following treatment with oral glucosamine at clinically relevant doses. Arthritis & Rheumatism. 2005;52(1):181-191. PubMed ID: 15641050. Establishes 10,000 mg/day glucosamine therapeutic threshold.
- Henrotin YE, Sanchez C, Deberg MA, et al. Avocado/soybean unsaponifiables increase aggrecan synthesis and reduce catabolic and proinflammatory mediator production by human osteoarthritic chondrocytes. J Rheumatol. 2003;30(8):1825-1834. PubMed ID: 12913942. Mechanism evidence for ASU at 1,000 mg dose.
- Nutramax Laboratories Veterinary Sciences. Cosequin ASU product documentation and ingredient specification page. cosequin.com/equine. Accessed April 2026. Source for FCHG49, TRH122, and NMX1000 trademark specifications and batch testing claims.
Read the full audits: Flex+Max (6.9) | Cosequin ASU (6.5)