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Equine Aggression

Aggressive mare

Sometimes there is more to it than just Ulcers!

Juliet said “This is something I have been struggling with for two whole years, trying anything and everything so sticking with the plan for a number of weeks is not really long in the scheme of things. The confusing part is his presentation is exactly the same as having ulcers and it wasn’t until they were fixed and he was STILL having issues that I had to start to look further.

I have a 10 year old 16hh Connemara/Irish Sport Horse gelding called Ailbhe. His primary discipline is dressage. We live in Tirau in the Waikato.

For the last 18+ months he has been grumpy to brush, cover and saddle up. Not girthy as such, just the putting of the saddle on and adjusting of the blanket. Grumpy to the point of swinging at me with his mouth open, never connecting because he is too polite. Ailbhe is one of the happiest most easy going horses I’ve ever had so not this was not at all normal. It started with being grumpy being brushed on his neck..."


"I did all the usual, changed brushes, checked regularly for soreness, regular saddle fit checks, talked to the vet. Never found anything of note. I suspected ulcers but everyone including my vet said he was highly unlikely to have them.
He’s a very good doer and doesn’t have the lifestyle of the typical ulcer prone horse.

Then he got really bad and I thought ‘stuff it’ and put him on a course of Gastropell. Different horse in 3 days. Thought I’d cracked it.

Didn’t last long. I tried more Gastropell, various gut conditioners, Equishure, removed as much sugar and starch from the diet as I could (excluding grass), anything I could think of. Some made a difference initially but nothing improved him for long.

Then I took him to Matamata Veterinary Services for scoping. This revealed healing squamous ulcers, not serious enough to cause his current extremely aggressive behaviours.

He went on a course of sucralfate and ulcershield and showed brief improvement. Again thought I’d cracked it. But when I rode him he was still very grumpy. I read that glandular ulcers can be exacerbated by riding so vet advised not to ride for a couple of weeks to let everything settle down.

He has had blood tests for everything including Cushings and metabolic syndrome. Apparently everything was ‘normal'".

After reading the info on the CHH website Juliet was convinced there was more to his issues than just ulcers and contacted us with the story to date.

We spoke to Juliet and recommended some changes to his feeding regime along with ad lib hay:

The Fibrepro (Lucerne) was swapped out for oaten chaff instead, his previous mineral mix was replaced with the more helpfully formulated Premium MVA, he was given 40gms twice a day of Alleviate Gold (he is a big horse at 640kgs) as well as a heaped tablespoon twice a day of AlleviateC.

His salt was increased to 60gms/day which was more appropriate for his weight than the 10gms or so he had been on. (Interestingly the blood results actually showed signs of dehydration).

The purpose of these recommendations was to reduce the hyper-sensitivity of the nerve endings in his skin. Due to the fact he was particularly sensitive to being touched/brushed on his neck and chest area, whereas with ulcers they are more sensitive around their girth and flanks, we deduced that this was a separate issue going on for Ailbhe aside from the original ulcers.

It took at least 3 weeks to see any difference – Julie reported “He’s coming right again and has progressively improved over the week.
Last Sunday I had him in and he was hardly reactive at all to brush but when I put the saddle to see what would happen he told me, and got progressively louder, that he wasn’t ready for that!".
But just a couple of days later ... “His reaction factor to brushing and the saddle was zero!"

Then Juliet could finally ride him again after many months:

" Thanks to your help If he has any relapses I will know why and I know he will recover from them. Gosh I’ve learnt a lot through this process! While it’s been a bit distressing at times, not knowing what to do to help him but knowing something is very wrong. The learning has been hugely valuable".

Thanks to Juliet for sharing her arduous experience! She should be out and about enjoying her horse again this season.

BTW Juliet runs a fabulous website store: check it out here:

Horses are Not Born Aggressive!

They can become aggressive due to any of the factors listed below.

Physical injury, ill-fitting tack or a dental issue which is causing them discomfort or pain

Usually these are obvious and the appropriate professional should be engaged to attend and eliminate

Mineral Imbalances causing Aggression

The horse’s entire skin is densely populated with sensory nerves enabling him to respond to the sensations of touch, pain, itch, heat, and cold. Mineral imbalances in the grass can affect these peripheral nerve endings in a way that causes aversion to touch, grooming, covering, saddling and girthing up.

When the sub-cutaneous muscles are affected you may observe quivering or twitching when you touch them.

Phyto-estrogens causing Aggression

Phyto-estrogens in Legumes –lucerne and/or clover

Aggressive behaviour is often associated with pastures which contain clover, especially red clover. Legumes such as clover and Lucerne contain ‘hormonally active compounds’ which can adversely affect normal hormone production.

These can cause geldings to exhibit stallion-like behaviour which can be mistaken as the horse being ‘a rig’. Or that the horse ‘has not being gelded properly’.  The vet is called, bloods are drawn but results turn out to be clear. The solution can be as simple as removing all legumes from the horse’s diet.

This same forage can cause mares to be ‘hormonal’ or ‘moody’, have ‘raging’ seasons and fail to cycle properly.

Dairy Grass and Aggression

Dairy grass or any grass fertilised with high octane chemicals

Such pasture is completely unsuitable for horses and can cause any horse to exhibit ‘aggressive’ behaviours.



The communication between you and you horse is not good enough, he isn’t sure what you mean and you are making him feel wrong when you weren’t clear in the first place.


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