Vet Advice

Equine Gastric Ulcer Syndrome – a hidden problem

Case Study

Star is a 12 year old Irish Sports Horse who has been with her current owner for 5 years. She was regularly exercised and competed in local dressage classes and the occasional hunter-trial. The owner was happy with her condition and believed her to be healthy at the time she was presented for vaccination.

When attending Star for routine vaccination the veterinary surgeon noted that the mare was quite slim (she looked more like a fit Thoroughbred racehorse than a Sports Horse!).

In her manger there was a considerable amount of her morning feed left over and she was taking great delight at demonstrating her skill in crib biting. It was advised that these were some of the symptoms of EGUS and that it would be worth gastroscoping her to investigate further.

The image above shows the extensive grade 2 ulcers found in Star’s stomach on gastroscopy. She was place on a 4 week course of omeprazole and her diet altered to allow adlib access to hay.

She was re-examined 4 weeks later and the ulcers were found to have completely resolved. The owner observed that Star now finished all her hard feeds straight away and the frequency of her crib biting had reduced. It was also noted that she had now stopped bucking every time she jumped a fence. As this had been a habit for 5 years it had always been assumed that Star was just a little over exuberant! Six months later Star had also gained nearly 150Kg in weight.

This real case doesn’t illustrate every aspect of equine gastric ulcer syndrome but it does give you an idea of what a major impact it can have on your horse. Studies have shown prevalence rates of up to 95% in flat racehorses, 60 to 70% in showjumpers and eventers and even 30% of children’s ponies.

What causes Gastric Ulcers?

Gastric ulcers are caused by the action of stomach acid and other corrosive elements overwhelming the normal protective mechanisms and damaging the cells lining the stomach. Protective factors include:

· Bicarbonate released in saliva counteracts stomach acidity

· High roughage content in the diet buffers stomach acidity

· Lack of movement reduces the contents splashing around – they would rarely do little more than walk in the wild.

· Frequent eating ensures frequent gastric emptying

Exmoor ponies on the moor are close to how a horse should naturally live.

In a natural situation a native pony would spend up to 16 hours per day eating a mainly fibrous diet. This produces lots of saliva and causes frequent gastric emptying.

They would spend most of the rest of the day sleeping with movements generally being slow as they do not have many natural predators.

When we domesticate horses we dramatically change their management:

· Change of diet – we feed large quantities of hard feed reducing the time they spend eating and reducing the buffering effect of the diet.

· Grazing horses – Grass fields are generally a manmade creation and do not provide a diet nearly as fibrous as that which is natural.

· Riding horses – this causes the stomach contents to splash around and reduces blood supply to the stomach wall that is essential for cells to repair.

What are the symptoms of Gastric Ulcers?

The symptoms of gastric ulcers vary between horses with some horses with severe ulceration showing no symptoms at all and some horses with only minor ulceration being severely affected. The symptoms seen include:

· Weight loss

· Colic

· Dull coat

· Poor performance

· Crib biting and windsucking

· Back pain – e.g. bucking, dislike having the girth tightened

· Teeth grinding

· Poor appetite – slow to eat hard feed

· Bucking, rearing, reluctance to go forward

Studies have now shown EGUS is a trigger factor for the behavioural vices crib-biting and windsucking. However these vices will often continue even when the ulcers have resolved.

How to diagnose EGUS

There are no reliable diagnostic laboratory tests for EGUS. Some horses with gastric ulcers may have a mild anaemia or elevations in liver enzymes but this is not consistent. One company has attempted to market a faecal test for EGUS but it is merely a test for the presence of a red blood cell constituent in the faeces and is not diagnostic for any ulceration of the gastrointestinal tract. The only accurate and reliable way of diagnosing EGUS is to perform a gastroscopy where a 3M endoscope is passed into the stomach and the upper intestines to perform a visual examination.

Image showing the margo plicatus (division between the upper and lower parts of the stomach) via a 3M endoscope. In the upper part of the stomach there are 2 grade 3 ulcers.

EGUS is generally graded between a score of 0 to 4 where 0 is a normal stomach lining and grade 4 is extensive deep lesions involving large areas.

Ulcers can be found in both the upper parts of the stomach (above the margo plicatus) and at the pylorus (the exit into the small intestine).

Image showing deep ulcers around the pylorus. The pylorus is at the top of the image (a narrow slit)

Treatment and Prevention

The main effective treatment for EGUS is the use of a drug called omeprazole. This drug was originally developed for treating gastric ulcers in humans. It acts as a proton pump inhibitor in the stomach which reduces the acidity of the stomach contents. Unfortunately we cannot use the human form as equine saliva will deactivate it (and it is against the law!). The equine form comes as a paste which contains coated microgranules. It is extremely effective and will nearly always reduce the severity of ulcers or eliminate them altogether. Sometimes it is used with sucralfate which can be used to coat the surface of the ulcer to aid resolution.

In combination with the medical treatment, it is equally vital to change the management of the horse to assist with healing and prevent recurrence. Thus it is important to try to mimic natural conditions for the horse as much as possible.

1. Attempt to allow free access to forage at all times. This can be unlimited hay or haylage or reasonable quality grazing. If there is inadequate grass in a paddock, this in itself can cause ulcers. If there is a concern that the horse is getting too fat then the hay can be soaked for 16 hours which reduces its nutritional value but maintains a source of roughage.

2. Ensure feeding hay before riding. This forms a mat on the surface of the gastric contents, stopping them splashing around and buffering the stomach acidity.

3. Reduce the size of hard feeds but their frequency can be increased.

4. Hard feeds should be altered to include as much roughage as possible. Some diets are specially formulated as high fibre pelleted feeds and there also high fibre alfalfa feeds. These are not a treatment, but will aid prevention and recovery.

In conclusion, this is one of the most important conditions to affect horses and ponies in a modern domestic situation. Its effect on the performance and welfare of your horse is significant. It is not always obvious to detect but treatment is usually extremely effective and simple stable management changes will often prevent recurrence.

By Mark Cubberley BVetMed CertEM(IntMed) MRCVS

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Equine Gastric Ulcer Syndrome – a hidden problem