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By Jenny Paterson, B.Sc.
Jane's story is particularly enlightening. The information that it reveals is extremely relevant. In Aspects of Pasture and Feeding that can Adversely Affect Your Horse you learn all about NSC's (sugar), fructans, fibre, photodynamic pigments, myco-toxins and mineral balances.
Since writing that article, it has become clear that of the minerals, electrolyte balances are absolutely critical to normal health and behaviour. In fact, I now believe, electrolyte imbalances caused by the cumulative effect of grass species, pasture management, the weather, plus various hard feeds, herbs and supplements are the cause of the wide array of problems experienced by owners, riders, trainers and breeders.
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Whilst Jane's horse is an extreme case, remember that for every extreme case there are many more mild to moderate cases. Maybe your horse only has a 'touch' of Jane's horse's problem and is mildly inflamed. That would still be enough to cause him not to be his true self, not perform to his true potential or to exhibit behavioural or saddle-fitting problems.
Fortunately, Jane had thermograph images taken of her horse Amigo before I spoke to her about the idea that the horses diet could be the cause of all his problems. This gave us a clear picture of what was going on prior to the dietary change, plus it clearly shows that the horse is not 'making it up'! With all that inflammation Amigo must have felt like he was 'on fire'!
- No wonder he didn't want to be touched, groomed, saddled or ridden,
- No wonder it seemed like the saddle didn't fit, despite it having been made to a mold of this horse's back,
- No wonder he couldn't move properly and didn't want to canter at all,
- No wonder he was sweating easily and agitated all the time.

Hi Jenny,
Thank you! I am so glad I ran into you and Emma at the clinic the other weekend. I was about to spend lots more money on further diagnostic processes for my horse's sore back and was desperate to get him sound for the coming show season. He was inflamed in all his muscles, as shown in the thermography report taken on the 14th of August. He was biting when being groomed, saddled and covered and was generally grumpy. Worst of all he was disuniting at the canter so badly that he could not be ridden at the canter at all. He ended up refusing to canter and reared and bucked instead.
The thermographer said it was the worst inflammation of the loin area that she had seen. His whole back was inflamed as well. The osteopath and vet could not pinpoint what was wrong apart from soreness in the sacroiliac area and muscle inflammation. The Bute he was given made no changes to his sore, swollen muscles or his demeanour. In fact, he had a severe adverse reaction to it and we are very lucky to still have him here with us today. That would have been tragic considering how easy this problem was solved in the end!
Following your advice on the day I saw you (and I then also read your article More Mysteries Solved on the effects of high potassium levels in horses) I immediately took him off all the grass and baleage he was getting at his livery. I eliminated the soya bean meal and upped his salt and highly absorbable organic magnesium with boron as you prescribed. He received only his usual blend of top quality, well balanced vitamins and minerals, ezy beet and meadow chaff, extruded barley and lots of brown top meadow hay. As you predicted, after ten days he was completely sound. The swelling in his muscles had disappeared, he no longer bites when being groomed, saddled or covered and he is cantering beautifully! Thank you SO much!
I will get another thermography report done to record the changes in the next week when the technician is in Auckland again. I would be happy for you to use this case and this thermography report in your articles and talks. This was a serious problem and would not only have cost me a lot more money but also the coming show season and my horse's well-being. I hope his case can help to educate others in similar situations.
Jane Valentine-Burt - Auckland, New Zealand.
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Above are the heat sensitive images taken by Hot Spots Thermal Imaging showing how inflamed poor Amigo was. Jane clearly wanted to do the right thing by her horse and sought excellent professional help. She even listed the various investigations and treatments for us:
Treatment costs in the past four months:
6 osteo treatments by two different equine osteopaths |
$480.00 |
1 chiropractic treatment |
$85.00 |
Vet treatment |
$1200.00 |
Back on Track rug |
$349.00 |
Devils Claw Free Mover |
$74.00 |
Equine massage "how to" DVD |
$65.00 |
Two different therapeutic pads |
$469.00 |
Sore NO more Liniment gel |
$49.00 |
2 x thermography images |
$40.00 |
Total: |
$2811.00 |
Unfortunately nothing seemed to work. It was at this point in early September I ran into Jane at a clinic. She described what was going on with her horse and having seen all these 'symptoms' before I explained that her horse was definitely 'grass-affected'. Some simple changes to his diet were suggested. Within ten days, her horse was back to normal and completely sound.
| Amigo's diet before: | Here are the changes we made: |
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Within ten days Amigo was back to normal and completely sound.

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Since changing the diet 'cured' Jane's horse, it follows that diet caused the problems in the first place. Amigo was suffering from serious electrolyte imbalances, caused primarily by the grass he was consuming during the day.
What are electrolytes?
- Minerals dissolved in the blood stream which have the capacity to conduct electricity such as:
potassium | sodium + chloride (= salt) | calcium | magnesium,
- The brain, nervous system and muscles require electrical signals for communication,
- The exchange of potassium and sodium is critical in the generation of these electrical signals,
- Therefore they play a key role in normal nerve and muscle function, and
- They also help the body keep body fluids in a normal balance.
Factors contributing to the electrolyte imbalance.
- Species and stage of growth of the grass,
- Pasture management,
- The WEATHER, and
- Feeds and supplements.
All of which have a cumulative effect on ELECTROLYTE BALANCES.
Potassium in the grass.
Potassium is involved in cell division so it is always in the tips of growing grass. Rye Grass, Clover and Lucerne are normally 3-4% potassium. This can easily double when fertilisers are applied to enhance growth, especially potash (potassium), urea, superphosphate and nitrogen.
Horses consume approximately 2% of their body weight per day, therefore a 500Kg horse can consume 10Kgs of pasture/day meaning they can consume 300-400g of potassium/day. Their daily requirement is around 25g (up to 40 or 50 when in heavy work). At the same time, as grass gets high in potassium it is extremely LOW in sodium (0.02%). The same 10Kgs of pasture yields a mere 2g of sodium.
On actively growing pasture the horse is consuming too much potassium and too little sodium.
As potassium is always in the tips, short grass and grass just a few inches long may contain the same levels of potassium.
All the literature states that too much potassium is rarely a problem when the kidneys are functioning normally as any excess is excreted in urine, BUT:
- Horses on green, growing pasture are flooded in potassium (hundreds of grams) at the same time...
- As sodium levels are grossly inadequate (approx 2g).
When you add more salt (sodium chloride) to the diet they drink more and then they excrete more potassium.
It is the ratio that is important.
The grossly excessive potassium intake coupled with the grossly inadequate sodium intake is the problem. This is why temporarily eliminating potassium rich foods works immediately in most cases such as:
- Green, growing grass,
- Baleage,
- Lucerne/Alfalfa,
- Soya bean meal,
- Herbs (read Primo's Story and Lucky's Story),
- Kelp,
- Molasses.
Eliminating these and increasing sodium intake brings the potassium:sodium ratio back to normal.
Add in the Nitrate Factor.
Actively growing grass also gets high in nitrates which attach to potassium and go up into the plant with water. This is why your horse can be worse after rain. The horse (or any grazing animal) ingests potassium nitrate. The way the body gets rid of excess nitrates is via them attaching to calcium and magnesium and being excreted with these minerals in manure and urine.
The result is the horse's system being rapidly depleted of calcium and magnesium. Nitrates accumulate in cloudy weather and when night time temperatures are too cool for growth, especially in cold, frosty weather.
Correcting the electrolyte imbalances 'helped' Jane's horse.
Temporarily removing all green from Amigo's diet was the quickest way to get the potassium DOWN. Feeding large doses of organic magnesium and salt brought the other electrolytes UP.
NB. For these problems it is not a case of feeding commercial electrolytes but of making the basic changes to the diet.
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For the lack of understanding this SIMPLE information, thousands of horses:
- Are misdiagnosed and therefore mistreated,
- Are unfairly blamed and even punished,
- Don't reach their true potential,
- Go 'to the can',
- Cause accidents,
- Have reproductive problems,
- Cause loss of confidence in their riders,
- Cause unnecessary emotional stress to their owners.
The SIMPLE information being that pastures 'spike' in potassium nitrate under certain climatic conditions which occur mainly in spring and autumn but anytime of the year due to the weather, causing the electrolyte imbalance of too much potassium and too little sodium, calcium and magnesium (i.e. grass tetany).
This triggers a cascade of health, reproductive, growth and behaviour problems including Laminitis (read How Laminitis occurs when the Horse is not Obese), Head-flicking and Stringhalt.
The economic cost to the whole equine industry of not understanding this SIMPLE information is astronomical. The economic cost to the farming industry is even greater as this information applies to all livestock. See the 'After' thermograph images (pictured above). Both before and after images were taken at the same time of day, in the same stable. You can see the significant reduction in inflammation. See Jane below enjoying riding Amigo again, who is clearly now happy and relaxed with no more saddle-fitting issues. In fact, she is back out showing and doing really well winning lots of ribbons.
Hi Jenny,
I hope your talks are going well. You are doing such an important thing with your education! There are so many more people to reach about the effects of grass on their horses. I now see it everywhere at the shows I go to.
I thought you might like a further update on Amigo for your talks as a couple of big, positive changes have occurred. We went to Woodhill Forest last weekend and did the big hill tracks. This is the first time EVER that he has been able to go down ALL the hills without bucking or crabbing sideways! He was so relaxed and on a loose rein the whole time, what a pleasure it was! He and I both really enjoyed it.
Also, our show this weekend was a huge success. We won a horsemanship class which was great but I thought this horse would never be able to do Western Pleasure classes well (due to his previous show behaviour of hooning, bucking and throwing fizzy tantrums). This weekend we were placed in three out of three pleasure classes with large class numbers and placed over some consistent winners of pleasure! How amazing! He was relaxed, slow, soft and lovely to ride. He transitioned into the lope smoothly with no bucking.
I had lots of comments on how well he is going. The trail classes were very tough and any tight or challenging parts of the course were handled calmly and recovered from immediately without anxiety or tantrums! He really is so much happier, no longer sore or uncomfortable and is a pleasure to take out and show. I feel like I can finally really enjoy my horse at shows! Thanks again.
Smiles,
Jane.

References.
- Minerals "The Metabolic Miracle Workers" by Dr. Robert Erdman and Meirion Jones.
- Hyperkalemia by Joyce C. Hollander-Rodriguez, M.D. and James F. Calvert, JR., M.D. Oregon Health and Science University, Portland, Oregon.
- Potassium Ion and Anaesthetic Implications by S. Parthasarathy and M. Ravishankar.
- Nitrate Toxicity and Sodium Deficiency Associated with Hypomagnesemia, Hypocalcemia and the Grass Tetany Syndrome in Herbivores by T.W. Swerczek, DVM, PhD.
- Equi-Analytical Laboratories.
- National Research Council - Nutrient Requirements of Horses.
