By Jenny Paterson, B.Sc.

 

Back in early spring (2009), I received a call from a very worried Denise. She had leased out Primo in May to some competent, competitive people who wanted to do some showing and dressage. All went well until late August when Primo, completely out of the blue after five to ten minutes of going perfectly, would rear! Something he had never done before. At first it was a nappy sort of a rear, but after a few days it was 'right up'!!

 

Naturally, this was causing great concern and it posed a mystery to everybody. WHY? I asked Denise if he was showing any other signs like being touchy or grouchy but at this stage, no, he would go along quite happily and then all of a sudden throw in a rearing tantrum! Then he would get over it and go along happily again.

 

This sort of behaviour arising early spring 'smacked' of being some kind of grass issue. It was therefore logical to yard him on ad lib hay with a twice daily feed of beet containing a heaped tablespoon of salt and highly absorbable organic magnesium with boron.

 

Well, at first it was like he got worse, becoming very aggressive and dangerous to be around in the yard. So the vet was called and bloods were taken. As I had mentioned he was probably high in potassium they asked for a potassium reading to be included in the blood test. Primo's potassium came back at 8.6 (it should be 3-5). This is an extremely high, life threatening reading! The highest the attending vet had ever seen!

 

How had it got so high? Easily! Primo had been grazing lush spring pasture, 'rich' Clover hay and Lucerne. He was therefore eating about 10Kgs/day of high potassium forage, literally flooding his system (consuming hundreds of grams of potassium when his daily requirement is around twenty five).

 

Out of the same 10Kgs of forage, Primo was only getting about two grams of sodium! All the literature says that excess potassium in the diet is not a problem so long as the kidneys are functioning normally. Potassium is normally excreted in the urine but not in the absence of sufficient sodium. As soon as salt (sodium chloride) is added to the diet, the horse drinks more and then excretes more potassium.

 

The reason 'getting them off the grass' works is because it is the quickest way to drop the potassium content of their diet. Actually, it is necessary to temporarily remove all green from the diet, i.e. no Lucerne either. This gets potassium DOWN and adding salt (sodium chloride), highly absorbable organic magnesium with boron plus extra organic calcium to get these other minerals UP.

 

Within a week on this regime Primo was much improved. Another blood test showed his potassium levels were back to normal. But at first it didn't take much to send him over the edge again. At one point, he was fed some comfrey leaves which caused an immediate relapse. Comfrey and many herbs are also very high in potassium.

 

The good news is that Primo was back to normal for the Ashburton A&P Show in November, where he won County Open Hack, won Open Best Mannered and placed 2^nd in Best Paced Hack.

 

Primo was extremely well behaved, not batting an eye at all the goings on including helicopters, Clydesdales, etc and it was quite an achievement to win the Manners Class in open company on the Saturday. I know Amanda and Craig Wiggins did a lot of ground and ridden work to get him there in addition to the strict diet he was on.

 

Primo's story is a classic example of how a serious behavioural problem can be caused by feeding a diet that seemed the 'best' for the horse but which was in fact the opposite. A big thank you to Amanda and her mum for allowing us to share Primo's story in the hope it will save others the exasperation, expense, lost time and risk of a serious accident. Primo is back to being a great show hack!