Most chronic tying up is genetic — PSSM, MFM, or RER. Selenium and Vitamin E aren't a cure (the research has refuted that). The right workup goes diagnostic-first: bloodwork, then genetic testing, then nutrition. Here's how to do it in the right order.
Tying up — clinically called exertional rhabdomyolysis (ER) — is a syndrome of muscle pain, stiffness, cramping, and tissue damage during or after exercise. The horse's hindquarters become rigid and painful. Muscle fibers actually break down, releasing myoglobin into the bloodstream and turning urine dark. It is a real veterinary emergency at the moment it's happening.
The single biggest mistake in tying-up management is treating chronic ER like sporadic ER. The horse who keeps tying up doesn't need different turnout or another supplement. That horse needs a genetic test and a diagnosis.
Old names you might still hear: Monday morning disease, azoturia, blackwater, set-fast, tied-up, shipping fever-related cramping. They're all describing the same general syndrome — exertional rhabdomyolysis — but with different underlying causes that modern genetics can now identify specifically.
Three distinct inherited conditions account for most chronic tying up. They look similar from the outside. They are not the same disease. Treatment that helps one can do nothing for another.
CK and AST muscle enzyme panel during or shortly after an episode confirms ER and quantifies severity. Critical baseline.
GYS1 for PSSM1, P-variant panel for PSSM2/MFM, breed-history assessment for RER. Tells you which disease you're managing.
Diet (low-NSC + fat for PSSM1), consistent daily exercise, controlled excitement (especially RER), electrolyte management.
Hair mineral analysis to rule out selenium deficiency, electrolyte imbalance, heavy-metal contributors. One input among the workup, not a substitute.
The published research has refuted this claim. Most horses with chronic ER already have adequate or more-than-adequate selenium and vitamin E status, and further supplementation has not been shown to prevent or cure tying up. Adequate selenium status is necessary for normal muscle function — but you cannot supplement past adequate. Test before you supplement; don't assume.
The right relationship between hair mineral analysis and tying up: it tells you whether selenium status is in range, whether magnesium and electrolytes are balanced, and whether heavy metals are contributing background load. It does not diagnose PSSM, MFM, or RER. Genetic testing does that.
$49.99 kit. ICP-MS analysis. Selenium status, Ca/Mg ratio, electrolyte panel, heavy metals.
Hair mineral analysis is one input in a complete tying-up workup. It identifies the mineral and heavy-metal contributors. It does not diagnose the underlying muscle disease.
| Tier | What It Measures | Why It Matters For Tying Up |
|---|---|---|
| Essential Minerals | Selenium, Magnesium, Calcium, Sodium, Potassium, Phosphorus, Sulfur, Copper, Zinc, Iron, Manganese, Cobalt, Chromium, Boron, Molybdenum | Selenium status (deficiency OR toxicity both relevant). Magnesium for muscle function. Sodium/potassium/calcium for electrolyte balance during work. |
| Mineral Ratios | Sodium/Potassium, Calcium/Magnesium, Sodium/Magnesium, Calcium/Phosphorus, Calcium/Potassium, Zinc/Copper, Iron/Copper | The Na/K and Ca/Mg ratios are the muscle-function ratios. Iron overload status reveals indirect oxidative stress contributors. |
| Toxic Heavy Metals | Lead, Mercury, Arsenic, Cadmium, Aluminum, Antimony, Beryllium, Uranium | Cadmium has documented impacts on equine musculoskeletal function. Chronic exposure to lead, mercury, arsenic can contribute oxidative stress to already-vulnerable muscle. |
Be honest with yourself about the limits — they matter:
Four steps. About a week of total elapsed time. No needles, no extra vet visit required for the hair sample.
Order the $49.99 hair & mineral analysis kit from Mane Metrics. Resealable bag, pre-labeled return envelope, plain instructions.
2 business days to arriveSnip about 1.5 inches of mane hair close to the crest. Total time at the barn: under 5 minutes. Drop the sealed envelope in any mailbox.
~5 minutesPartner laboratory runs ICP-MS analysis across 42+ elements — including selenium, magnesium, the electrolyte panel, and the heavy-metal panel.
5–7 days at the labEmail-delivered report with color-coded findings, plus a follow-up phone consultation focused on the mineral picture and what to bring to your vet.
Email + voice debriefList "tying up" or "exertional rhabdomyolysis" as your main concern at checkout. The lab interpretation focuses on selenium, magnesium, the electrolyte ratios, and the heavy-metal panel when they know that's the investigation. Bring breed, age, episode history, current diet, and any genetic test results to the follow-up consultation.
The mineral test is one of three things you should be doing at the same time. Run them in parallel — don't wait one out before starting the next.
| When | What's happening | What you do |
|---|---|---|
| Day 0 | Decide on a real workup, not more guessing | Order kit on manemetrics.io. Schedule vet bloodwork. Order genetic test panel. |
| Day 1–2 | Kit ships. Vet appointment scheduled. | Watch your mailbox. Confirm vet appointment for CK/AST workup. |
| Day 2–3 | Collect mane sample, send genetic panel | Single sample collection can serve both — take one for hair analysis, separate sample for genetic lab per their instructions. |
| Day 7–14 | Vet bloodwork results back | Review CK/AST trends with vet. Confirm ER vs. other muscle issue. |
| Day 9–12 | Mineral panel results delivered | Read the report. Schedule the voice debrief. |
| Day 14–28 | Genetic test results return | Diagnosis: PSSM1? PSSM2/MFM? RER? Negative? Plan management accordingly. |
| Month 2+ | Combined workup informs management plan | Diet (low-NSC + fat if PSSM), work program, electrolyte support, mineral correction if indicated. |
The honest truth from the racing world: trainers who get tying up under control are the ones who do the diagnostic work. Trainers who keep losing days at the track to recurring episodes are usually the ones still running through their fifth or sixth supplement protocol without ever genetically testing the horse.
Order the kit now. We'll handle the rest. Questions? Call (972) 284-1878.
The literature on PSSM and RER is one of the better-developed areas of equine muscle physiology. The supplement claims are weaker than the marketing suggests. Here are the references worth reading.
The questions trainers and owners ask most often before they finally do the diagnostic work.
Tying up — clinically called exertional rhabdomyolysis (ER) — is a syndrome causing muscle pain, stiffness, cramping, and damaged muscle tissue during or after exercise. The horse may sweat, refuse to move, urinate dark coffee-colored urine (myoglobin), and have visibly hard, painful hindquarter muscles. Most chronic cases are caused by inherited muscle conditions, particularly polysaccharide storage myopathy (PSSM1, PSSM2/MFM) or recurrent exertional rhabdomyolysis (RER).
PSSM1 is a glycogen storage disorder caused by a single gene (GYS1) mutation, common in Quarter Horses, Paints, Appaloosas, and Draft breeds. PSSM2 / MFM (Myofibrillar Myopathy) is a disorder of muscle fiber organization, common in Warmbloods and Arabians, with multiple suspected genetic variants. RER (Recurrent Exertional Rhabdomyolysis) is a disorder of intracellular calcium regulation triggered by excitement, common in Thoroughbreds, Standardbreds, and Arabians. All three present clinically as "tying up" but the underlying causes — and the right management — are different.
No. The claim that vitamin E and selenium prevent or cure equine rhabdomyolysis has been refuted in published research. Most horses with chronic ER already have adequate or more-than-adequate selenium and vitamin E status, and further supplementation has not been shown to improve outcomes. Selenium is important for normal muscle function — but supplementing a horse who is already replete provides no benefit and can risk toxicity.
The right diagnostic order is: (1) vet bloodwork during or shortly after an episode to confirm muscle enzyme elevation (CK, AST); (2) genetic testing for PSSM1 (GYS1 mutation) and MFM/PSSM2 variants — multiple labs offer reliable panels; (3) RER assessment based on breed, history, and clinical presentation; (4) nutritional and environmental workup including diet analysis and hair mineral analysis. Skipping ahead to supplements without the diagnostic foundation is the most common mistake.
No. Hair mineral analysis cannot diagnose tying up, PSSM, MFM, or RER. Those diagnoses require genetic testing and vet bloodwork. What hair analysis can do is reveal selenium status (over OR under), magnesium and Ca/Mg ratio, electrolyte balance, and chronic heavy-metal exposure that may be contributing factors. The right framing is: hair analysis is one input alongside the genetic and clinical workup, never a substitute for it.
PSSM1 horses benefit from a low-NSC (non-structural carbohydrate) diet with minimal starch and sugar, plus high-quality fat as the primary calorie source, plus daily consistent exercise. RER horses benefit from controlled excitement, consistent routine, and similar low-NSC feeding. MFM horses may benefit from increased amino acid support. Specific protocols depend on the genetic diagnosis — which is why testing comes first.
Heavy metals are not a primary cause of inherited tying up syndromes (PSSM, MFM, RER). However, cadmium has documented impacts on equine musculoskeletal function, and chronic low-level lead, mercury, or arsenic exposure can contribute to oxidative stress and overall muscle dysfunction. Ruling out heavy-metal exposure is a reasonable part of a complete workup, especially in horses on older properties or in industrial-proximity environments.
Approximately 9-12 calendar days from order to results: 2 days for kit shipping, 5 minutes to collect, 5-7 days at the lab. You receive an emailed report plus a follow-up phone consultation focused on the mineral picture and what to bring to your vet alongside genetic testing and bloodwork.
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