Adequan Dosage For Horses: Calculator, Chart & Safe Guide

When your veterinarian mentions Adequan Dosage for your horse’s joints, you’re likely to have one question first—how many and how often? The simple answer is that Adequan i.m. is not like other drugs — it is not dosed based on the body weight of your horse. Same dosage (500 mg) on the same schedule for all horses regardless of size.

This surprises many owners, so let’s take the time to try to understand where the number comes from, what the complete schedule should look like, how much this costs, and where the true safety limits lie (all from the FDA approved label and the manufacturer’s own veterinary dosing materials, of course).

Key Takeaways

• Standard dose: 500mg/injection, irrespective of horse weight.
• The length of the loading schedule depends on how fast the IVC is removed. This is the official 1•4•7 (1 dose, every 4 days, 7 times).
• Administration: Intramuscular (I.M.) only; do not intra-articular (into the joint) with this particular product.
• The concentration is 100 mg/mL, which means that each dose of 500 mg is 5 mL.
• Maintenance: More and more vets are suggesting to repeat the entire 7 injection loading course approximately twice a year, instead of reducing to monthly shots.
• Not weight based – FDA label does not vary dosage by weight like most equine drugs.
• Prescription-Only: Adequan can only be used by or on the order of a licensed veterinarian.

What Is Adequan Dosage For Horses?

Adequan i.m. is the trade name for a joint medication produced by American Regent, called polysulfated glycosaminoglycan (PSGAG). It is approved by the FDA for intramuscular injection for non-infectious degenerative and/or traumatic joint dysfunction (aka arthritis and joint wear) for horses in the carpal (knee) and hock joints.

There is no generic PSGAG on the market and it is the only FDA approved equine PSGAG product.

Quick facts:

Detail	Information
Active ingredient	Polysulfated glycosaminoglycan (PSGAG)
Brand	Adequan i.m.
Manufacturer	American Regent, Inc.
Concentration	100 mg/mL
Route	Intramuscular (I.M.) only
Approved for	Carpal and hock joint dysfunction/lameness
Prescription status	Rx only, veterinarian-directed

Adequan Dosage Chart for Horses

This is the number that owners are looking for. The dose is set — it is the same for all horses, regardless of their weight, breed or size (as per the FDA approved label).

Parameter	Standard Dose
Dose per injection	500 mg
Injection volume	5 mL (at 100 mg/mL)
Frequency	Every 4 days
Loading course length	28 days
Total injections in loading course	7
Total mg delivered in loading course	3,500 mg
Total volume delivered in loading course	35 mL
Route	Intramuscular only

Why isn’t Adequan dosed by weight?

People are thrown off by the way most equine drugs are prescribed per kg of body weight. Dose titration studies were performed by Adequan (on mature Quarter Horses and Thoroughbreds) and 500 mg was found to be effective for the study population, with the dose being fixed and not based on a weight formula. In practice, that equates to giving a 900 lb pony-sized horse and a 1400 lb warmblood the same 500 mg dose, at the same time.

If your horse is well outside of the typical adult range (around 900-1400 lb), your vet might take that into consideration in his/her overall treatment strategy, but it would not be considered in the label dosing calculations.

Adequan® i.m. for Horses

Adequan® i.m. dosage for Horses is one of the most popular joint treatments for horses, treating non-infectious degenerative joint disease (DJD) in the hock and knee (carpal) joints. It can be used as a standalone product or in conjunction with a regime of exercise management, physical therapy and other joint supplements for a complete joint health program, and is popular in all sports, performance and pleasure racing applications.

Medication is given through a series of intramuscular injections usually every four days for four weeks and is repeated if symptoms return. Adequan® can also be given as an intra-articular injection (directly into the affected joint).

Its active ingredient is polysulfated glycosaminoglycan (PSGAG), which acts as a disease-modifying osteoarthritis drug (DMOAD) and has been found to decrease inflammatory mediators and increase collagen production in the joint.

Even though Adequan has been used for decades as a front-line treatment for joint diseases, its mechanisms of action are still relatively unexplored. Your veterinarian will always be the best person to determine if Adequan® is an appropriate treatment option for your horse.

Use the Adequan Dosage Calculator

Rather than doing the mg-to-mL math by hand, you can use our Adequan Dosage Calculator for Horses Instead of manually calculating the mg to mL conversion, use our Adequan Dosage Calculator for Horses to view the mg to mL conversion in seconds:

• Number of doses per injection
• All 7 loading-course injections in a 28-day period
• Course total mg and mL used
• A maintenance-schedule note, if you are using a twice-a-year repeating maintenance schedule for your horse

One doesn’t have to change the dosage, but the calculator still requires the input of the horse’s weight for reference purposes in your records and as a simple precaution to alert you to a weight that is out of a realistic range for a horse.

Benefits of Adequan® i.m. for Horses

Adequan® i.m. can provide veterinarian recommended and trusted support for the health of horse joints with benefits on which horse owners can count:

• Effective Joint Health: Addresses and treats the root of degenerative joint disease (DJD) instead of just painting the symptoms.
• Enhanced Mobility: Supports horses attaining better mobility and comfort.
• Veterinarian Recommended: Reliable and effective as trusted by equine health professionals.

How Does Adequan® i.m. Work?

Adequan® i.m. falls into the category of chondroprotective (cartilage-protective) drugs, but the exact mechanism of action in the joint is not well understood and there is limited research on the effectiveness of this drug in horses.

Its active ingredient PSGAG has been found to inhibit the enzymes that break down cartilage and stimulate the synthesis of cartilage in in vitro (cell culture) experiments and has also been shown to have anti-inflammatory properties.

It should be noted, though, that the concentration of PSGAGs used in these in vitro tests is much greater than the concentration that could possibly be achieved in a horse’s joint after a typical i.m. injection, which is a limitation in the interpretation of the results.

The 1•4•7 Protocol, Step by Step

Adequan’s own literature cites the proper loading protocol as the 1•4•7: 1 dose, every 4 days, for 7 doses.

1. Day 1: First 500 mg (5 mL) I.M. injection.
2. Day 5: Second injection (4 days after the first).
3. Day 9: Third injection.
4. Day 13: Fourth injection.
5. Day 17: Fifth injection.
6. Day 21: Sixth injection.
7. Day 25: Seventh and final injection of the loading course.

That makes the entire course a total of 28 days from the first dose to the last (day 1 + 6 doses at 4-day intervals = day 25; day 28 is the end of the full course of treatment).

Administration notes straight from the label:

• The injection site should be carefully cleaned prior to each shot.
• Adequan horse medication should NOT be mixed with other drugs or solvents in the same syringe.
• Do not reuse a needle for injection; the stopper of the multi-dose vial may only be punched 10 times.
• The product is only to be used for intramuscular injection and not for intra-articular (joint) injection.
• The injections are usually into the neck or chest muscle.

Adequan Maintenance Dosing After the Loading Course

In the past, many veterinarians administered the loading dose followed by monthly single shots, indefinitely. That is now no longer the case. Recent veterinary experience indicates that it is more advisable to give the full 7-injection loading dose (perhaps in the spring and again in the fall for a performance or aging horse) than smaller doses spaced out monthly.

Practicing vets say that two complete “pulses” a year seem to be more effective than a “trickle” of a single dose each month.

Important distinction: this is a common veterinary practice pattern and not actual FDA label language. The label refers to the first 28 day/7 injection treatment; whether and how to continue is at the discretion of your veterinarian based on your horse’s response, workload and joint condition.

How Long Does Adequan Take to Work?

Unlike an anti-inflammatory painkiller Adequan does not have an immediate single dose effect. It’s based on what happens throughout the entire loading course:

• This 4-day interval was based on the pharmacokinetics data which demonstrated that PSGAG peaks in the joint around 48 hours after an I.M. injection, and that it has a duration of action of about 96 hours.
• In the dose-titration efficacy study that led to the FDA approval, horses receiving the 500 mg dose experienced a mean efficacy of 19% after the 4th injection and 71% after the 7th injection.
• This means that for most owners, there should be a progressive and cumulative benefit throughout the entire 28-day regimen and not a huge difference after the first vaccination.

Does Adequan® i.m. Reach the Joint? 

Evidence of Adequan®’s bioavailability in the treatment of joint disease: after injection into the muscle, PSGAG enters bloodstream and is carried to the synovial fluid where it is absorbed in the articular cartilage.

The highest concentration of PSGAG in the synovial fluid occurs at 2 hours after injection, with detectable amounts persisting in synovial fluid, cartilage, and subchondral bone for 4 days. During all of this time, PSGAG levels remain well above the therapeutic level required to suppress cartilage degrading enzymes and promote proteoglycan synthesis — suggesting a possible mechanism by which Adequan® treatment could help maintain and improve cartilage health.

Adequan vs. Legend vs. Pentosan: How Do They Compare?

Adequan dosage for horses is frequently referred to with Legend (hyaluronic acid) and Pentosan (pentosan polysulfate) as treatment options for equine joint problems. They are NOT the same; they work in different ways and have different dosing routes.

Feature	Adequan i.m.	Legend	Pentosan
Active ingredient	Polysulfated glycosaminoglycan	Hyaluronic acid	Pentosan polysulfate
Route	Intramuscular	Intravenous (or intra-articular by a vet)	Intramuscular
Standard loading schedule	Every 4 days x 7	Once weekly x 4, then monthly	Varies by product/vet protocol
FDA-approved for horses	Yes	Yes	Not FDA-approved (often compounded/imported)
Typical cost per dose	~$40–$100	~$80–$130	Varies

That’s a true medical decision: Which joints are involved, how the horse is used, and what their soundness history is.

Is Adequan Safe? Side Effects & Precautions

Animal safety studies (FDA): Horses receiving twice-weekly injections for up to 12 weeks at doses up to 2,500 mg (five times the recommended dose) did not develop any signs of soreness or swelling, nor any clinical or laboratory signs of toxicity. There are also no known adverse reactions in the product’s EU veterinary label for normal use.

With that said, “safe in studies” does not mean “no precautions apply. The label and safety data warn of:

Precautions:

• Horses that are breeding, pregnant or lactating: Safety has not been established in these populations — use under veterinary supervision only.
• Not for human use: Do not use in horses intended for human consumption; not for use in humans.
• Injection site reactions: Always cleanse injection site and apply sterile technique to minimize occurrence of infection at site of injection.
• Drug interactions: There are a number of regulatory label statements of PSGAG’s potential to increase the effect of any anticoagulant medication, indicate if your horse is on any other medication to your vet.
• Never mix in the syringe: Don’t combine Adequan with other drugs or solvents before injecting.

Who should not receive Adequan without direct veterinary supervision:

• Horses known to be hypersensitive to the product (stop treatment if signs occur).
• Horses that are breeding, pregnant or lactating, for which there is no safety information.
• Without your vet considering the risk of the interaction, horses on anticoagulant therapy.

What Does Adequan Cost?

There are different prices depending on the source and if a veterinary farm call/injection fee is included:

• Bulk or distributor pricing: approximately $40 per dose when bulk ordered in the 7 dose loading-course box.
• Via the veterinarian: approximately $60-$100 per dose, which includes the costs of injection and farm visit.
• Full loading course (7 doses): This is more likely to be $300-$700 depending on your source, and if your vet gives the shots or you do.

There are times and places when prices change, so use these as a guide not a quotation – check your vet’s surgery or your local pharmacy for prices.

Common Adequan Dosing Mistakes

• Assuming that it is dosed by weight. No, it is not — providing a larger horse with an “extra” dose of Adequan is not indicated on the label and therefore should not be done without specific veterinary advice.
• Misses or skips doses during loading phase. The dosing every 4 days corresponds to the approximate 96-hour duration of Adequan’s effect in the joint; extending the dosing interval may be less than the cumulative effect demonstrated in the pivotal studies.
• Injecting into the joint. Adequan i.m. is indicated for use in intramuscular injection — it is not the same formulation as those intended for intra-articular injection.
• Mixing with other drugs in the syringe. This is clearly stated on the label.
• Re-use of needles and/or excessive puncturing of vial. The multi-dose vial stopper has 10 possible punctures – sterile technique is important to prevent infection.

Myth vs. Fact

Myth	Fact
“Bigger horses need a bigger dose.”	The FDA label sets a fixed 500 mg dose regardless of body weight.
“You inject it into the joint, like Legend.”	Adequan i.m. is intramuscular only — not intra-articular.
“Once a month forever is the standard protocol.”	Many vets now favor repeating the full 7-injection loading course about twice a year instead.
“It works instantly after one shot.”	Benefit builds cumulatively across the full 28-day, 7-injection course.
“Adequan for horse dosage and Legend are basically the same thing.”	Different active ingredients, different routes, different schedules — not interchangeable.

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FAQs

Final Thoughts

The single most important thing to remember about Adequan dosage for horses is this: it’s one dose for every horse. There’s no weight-based math to double-check, no per-pound formula to get wrong — just the 500 mg, every-4-days, 7-injection schedule the FDA approved back in 1989 and that veterinarians still rely on today.

Where the real decision-making happens is everything around that fixed number: whether your horse is a good candidate, how the loading course should fit into their training or competition calendar, and whether a twice-yearly repeat makes sense for their joint health long-term. That part is worth a real conversation with your veterinarian — this guide (and the calculator) is here to make sure you walk into that conversation already understanding the schedule, not guessing at it.