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Is Your Horse Spooking? How Important is Electrolyte Balance for PSSM Horses and Other Nervous or Scared Horses?

PSSM horse spooking electrolyte imbalances

With your horse spooking at every small thing, life gets difficult – especially when you KNOW that horse can handle what’s being asked of him. Riding a scared horse is not only bad for the horse’s stress levels and ability to learn, it can be bad for your health. I call this behavior “scared horse syndrome,” as it’s not a natural way of being for most horses – there’s a trigger!

Jax has had yearly symptoms of high potassium since 2011 when I got him as a 4 year old. For my horse spooking and hyperexcitability are the early signs, and symptoms begin in late winter, progress throughout spring through shedding and grass growth season, and late May to early June he goes through low grade laminitis – this has happened every year for the past 9 years (he’s 13 now).  [Update Feb 2023: My horse is now 15 and has NOT had these symptoms for the past 2 years since writing this!]

He has had EVERY one of the potassium symptoms on this chart – many of the milder ones before he became symptomatic for PSSM!

I’m researching how shedding can affect the kidneys and potassium balance, and you can see some of my thoughts on that issue along with my tricks for managing high potassium and low calcium symptoms here: Can Shedding Affect a PSSM Horse?  I’ll keep these pages updated as I research, trial, and learn more.

Horse Spooking: A Simple Electrolyte Imbalance?

Take a look at the chart below to see how imbalances in potassium can cause issues that look like PSSM, including “scared horse syndrome”. Also keep in mind that kidney stress and high potassium, at least for some horses, go hand in hand – and see how the symptoms multiply when that happens! One thing to keep in mind is that Jax’s high potassium symptoms begin with “itching” – rubbing his face and neck incessantly – that’s not on the list below, but I use it as an early sign (along with his crazy horse spooking) that Jax’s potassium levels are getting high.

High Potassium SymptomsPSSM SymptomsKidney Issues
Muscle contraction 1, 8Stiff, sore, tight musclesBack soreness 4
Muscle cramping 1Muscle spasms, tying up*
Irregular heartbeat 1(PSSM shouldn’t affect the heart)
“Spring Fever” 2Some horse spooking and behavior is anecdotally blamed on PSSM
Acidosis 2Ulcers and stomach issues due to pain
Head shaking and flicking 2Anecdote on the PSSM forums show that quite a few PSSM horses have head shaking issues
Laminitic attacks 2Soreness in hooves and joints 4
Uncharacteristic aggression 2Behavior changes due to pain, with my horse spooking accompanies aggressionBehavior issues, aggression 4
Stiffness 2Stiffness
Bolting or running off, hypersensitivity 2, 8Won’t relax while ridden 4
Magnesium deficiency 2Muscle healing causes overuse and depletion of important minerals, proteins, etc.
Flank and ribcage twitching 2, 8Spasms and fasciculations
Colic 2Anecdotes from PSSM owners indicate some PSSM episodes can look like colicActs colicky and looks at sides 4
Labored breathing 2
Skin tingling 2, 3, 8Skin sensitivity, possibly related to magnesium deficiency
Face, Broncho- and laryngo- spasms
Trembling and muscle weakness 1Muscle weakness and loss
Lethargy and depression 1Lethargy and depressionLethargy and depression 5
Doesn’t trailer wellDoesn’t trailer well 4
Can’t round up or collect, or use hinds for hard stopsPerformance issues such as avoiding hard stops and turns 4
Increased urination 5
Low protein can cause edema 5 (Can particularly affect PSSM2 horses)Edema or swelling in legs and lower abdomen 5
* Note – electrolyte issues can cause tie ups in endurance horses.

Horse Spooking: Low Calcium?

For horses with PSSM, it’s difficult to tease out which symptoms are disorder (and possibly unmanageable) and which are a simple electrolyte imbalance (and potentially caused by PSSM management, since most protein sources are high potassium!).  Since potassium levels can affect calcium levels, let’s take a look at how low calcium and high potassium symptoms match up.  Here are some symptoms of hypocalcemia (low blood calcium) in horses:

  • ataxia 6, 7 (similar to PSSM ataxia)
  • seizures 6 (similar to grass tetany, related to potassium and magnesium imbalances)
  • hyperexcitability 6 (including horse spooking – similar to high potassium and kidney)
  • synchronous diaphragmatic flutter 6, 7 (thumps)
  • tachycardia 6 (rapid heartbeat – high potassium causes irregular rhythm)
  • tachypnea 6 (rapid breathing – high potassium causes labored breathing)
  • muscle fasciculation 6 (similar to high potassium and PSSM)
  • ileus 6 (obstruction of the ileum or other part of the intestine – can be a cause of colic, similar to high potassium, kidney, and sometimes PSSM)
  • anxiety 7 (including horse spooking – similar to high potassium, kidney, and sometimes PSSM/RER)
  • increased muscular tension 7 (similar to high potassium, kidney, and PSSM)

As you can see, high potassium and low calcium have a lot in common with both each other and PSSM symptoms, and horse spooking issues are on three of the four lists (I’ve not heard of kidney issues causing horse spooking issues).  Seizures, thumps, and ileus have never been on Jax’s list of symptoms thankfully (though he has colicked), but he has been through all of the other low calcium symptoms listed here. 

According to sites like Calm Healthy Horses 8 and a few others, high potassium is a low grade epidemic that many horses experience.  I feel PSSM horses are especially sensitive to any type of trigger, and with the possibility of already having stressed kidneys from their muscle disorders, they are prone to having a more exaggerated response to this common ailment.  It only takes one PSSM episode to lead to a spiral of issues from electrolyte imbalance.    

How Did I Fix “Scared Horse Syndrome” for Two of My Horses, and a Neurological Horse?

I’ve done so many things over the years to fix my horse spooking issues, and several things helped: Immubiome, different calming herbs, trialing different macronutrient and vitamin/mineral combinations, different tack

The thing that helped is Jax’s current dietary regimen of chelated calcium, B1, and reishi. And it not only helped him! After having good results with this mix, a friend moved her EPM horse here, and not only is his “scared horse syndrome” gone, he’s rideable again and his personality is starting to shine through. A couple months after, I bought a second horse who tended to be spooky at times, and this regimen also has him much calmer and doing well.

An interesting note is that Calm Healthy Horses uses chelated calcium in some of their supplements!

Click here to see notes on my trialing chelated calcium, and the immediate effects we had.


Sources for High Potassium, PSSM, and Kidney Stress Chart:

1. “Abnormally high concentration of potassium in the blood causes muscles to contract more than they should, resulting in cramping and irregular heartbeat. At a greater risk of hyperkalemia are horses with a history of hyperkalemic periodic paralysis (HYPP), compromised kidney function, or massive cellular destruction, such as after trauma, burns, or a severe episode of tying-up [emphasis mine].   Classic signs of hyperkalemia include muscle weakness, trembling, depression, and lethargy. While these symptoms are fairly general, when accompanied by changes in cardiac rhythm, hyperkalemia should be suspected. Cardiac changes are not always present in cases of hyperkalemia, so the absence of cardiac abnormalities should not rule out such a diagnosis.” –


3. I personally have experienced skin “tingling” with high potassium – even the lightest touch feels like your skin is being ripped from your bones, and is not something to be taken lightly.  The face and extremities are where I experienced this symptom the most – leaving me to wonder if that’s why head shaking and face rubbing is so prevalent with horses experiencing hyperkalemia.  When something brushed across my ear lobes it felt like fire ripping through them – maybe this is related to ear sensitivities with some horses?




Sources for Calcium List:



2 thoughts on “Is Your Horse Spooking? How Important is Electrolyte Balance for PSSM Horses and Other Nervous or Scared Horses?

  1. Hi what kind of electrolytes would your recommend for a horse that may have pssm 2 if there is some kind of potassium over load. Should I give her just salt? THank your for your time.

    1. A lot of people on the PSSM forums recommend salt and say it works for theirs, but it never helped Jax with this issue. Chelated calcium is the only thing that’s helped, other than calcium carbonate which had side effects (sediment buildup in kidneys). I tried calcium, then chelated calcium, after doing some research on endurance horses that tie up – usually a calcium deficiency is the issue for them (or at least part of it), and their episodes are very similar to “high potassium” type behavior and episodes. I’m actually in a high limestone (calcium) area and, after doing some research, found that oxalates can inhibit calcium absorption – and a lot of things in this area contain oxalates (including alfalfa, which is something Jax doesn’t handle at all). Malcolm at EquiFeast has talked about oxalates and high limestone areas being the worst for these types of horses, and that these horses can be helped with their supplements (which contain a high level of chelated calcium, and which were of huge benefit to Jax!).

      So like everything with these horses, I think it’s very individual, but considering that Calm, Healthy Horses (which pioneered the idea of potassium overload) also adds chelated calcium to their supplements, I think low chelated calcium levels is definitely an avenue worth investigating and trialing!

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