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Stomach Ulcers and Gastroscopy

Mike Fitzgerald BVSc.

Stomach ulcers (gastric ulcers) are a hot topic! Stomach ulceration is a somewhat confusing syndrome – the syndrome can have a multitude of clinical signs, ranging from very subtle performance issues, or picky eating, to weight loss and colic. There is also a multitude of products on the market which claim to help with ulcers, not all being equal. The recent advancement and availability of gastroscopy (stomach scoping) has moved the diagnosis from a guessing game, to black and white.

How do you know if your horse or pony has stomach ulcers?

Until recently, the only way we could diagnose ulcers was on behavioural and physical signs – this includes an array of symptoms that can be associated with ulcers, including; poor coat, difficulty gaining weight, recurrent colic, temperament or behavioural changes, reduced appetite, picky eating, girthiness, sensitivity around the abdomen, poor performance, crib biting, etc.  

 This is all and well, as all of the above can be caused by ulcers; however recent studies have shown the accuracy of these ‘classic symptoms’ to be poor in the diagnosis of ulcers. Tolerance and outward signs of gastric ulcers will vary immensely between horses – some with mild ulcers may show obvious outward signs, whereas other stoic horses (or “silent sufferers”) may only show mild and transient symptoms (e.g. nervousness, picky eating), despite having severe ulcers.

Some practitioners use the presence of reactive acupuncture points to diagnose ulcers. While this can raise suspicions of their presence, it is nonspecific and has not been confirmed as an accurate or valid diagnostic test for ulcers.

Gastroscopy – the use of a 3 metre endoscope to directly visualise the stomach lining, is the only definitive and accurate method to assess the presence and importantly, the severity, of gastric ulcers.

How common are ulcers?

The prevalence of ulcers varies with breed, the type of exercise the horse does, and how they are managed. In thoroughbred racehorses, it is reported that 80-100% of horses in training and 37% of spelled horses are affected. Rates of 54% in pleasure horses, 93% in endurance, and 64% in sport horses, have been reported in the literature. Ponies that are on feed restriction for weight loss are at a high risk if they are not able to graze continuously.

What causes ulcers?

The horse’s stomach is divided into two main areas, each with a different lining (mucosa). The top part, called the squamous or non-glandular portion, has a lining similar to skin, lacking adequate defence against stomach acid. The bottom section is the glandular area, which is responsible for acid secretion. It secretes a thick layer of mucous, as well as bicarbonate to buffer acid, and protect its lining.

Gastric ulceration in horses can be divided into two kinds, squamous ulceration (equine squamous gastric disease - ESGD) and ulceration of the glandular region (equine glandular gastric disease - EGGD). ESGD is the ‘classic’ stomach ulcers we know the most about, whereas EGGD is a relatively new finding. It appears to be more prevalent in NZ compared to other countries, and can be more difficult to treat. It’s causes are less well understood, but are assumed to be similar to ESGD.

Horses, unlike humans, secrete gastric acid continuously. The horse evolved to graze high fibre feed for around 18 hours per day - when horses have continuous access to feed, particularly roughage, the presence of feed in the stomach buffers the acid, and acts as a mat, protecting the vulnerable squamous portion. Chewing causes saliva to be produced -this is high in bicarbonate which also helps to neutralise acid. Exposure to acid, or acid splashing, is thought to be the cause of ulcers in the squamous part of the stomach. Also, certain feeds are broken down into acidic by-products. High starch feeds (grains) create more acidic conditions, than roughage or fat. 

When horses exercise, the pressure in the stomach increases, and causes acid to splash onto the squamous mucosa, causing damage. The more strenuous the exercise, the more pronounced this effect is. Added to this, is the fact that many horses have traditionally been held off feed before exercise, so there is more acid, and less feed and saliva to neutralize it. Even when horses aren’t exercising, periods of feed restriction put them at high risk of ulcers.

The type of diet can contribute to ulcer risk. High starch, grain diets increase acid production and can directly injure cells in the squamous part of the stomach, as well as being lower in fibre and overall bulk. Higher fibre feeds are eaten more slowly, and form a ‘mat’ that sits on the acid to reduce splashing. Lucerne is a particularly good feed because the high calcium content assists in buffering the acid. 

Any factors that increase stress levels, for example, transport, box confinement, and competition, increase the likelihood of ulcers developing. 

Gastroscopy for ulcer diagnosis

Gastroscopy is the only way to conclusively diagnose ulcers, and tell how severe they are. This enables an instant diagnosis, compared with a treatment trial. Importantly, it guides the duration of treatment needed to get a complete resolution. It also allows for the diagnosis of glandular (pyloric) ulceration, which requires an extended course of treatment and the addition of another medication. Gastroscopy can be very useful in differentiating between pain and true behavioural issues – for those cases that are not obviously clear cut.

Treatment of ulcers

It has been shown that turnout alone is poor at resolving gastric ulcers. I scoped a horse late last year that had been turned out for 8 months, due to rearing and behavioural issues – he still had severe ulcers present.

There are a huge number of products and supplements available that claim to heal or prevent stomach ulcers – however most of these products are lacking any robust scientific trials to support their claims. Currently, the only treatment with widespread scientific validation is the suppression of stomach acid, using omeprazole.

The duration of treatment required varies depending on the gastroscopy findings, but at least 30 days at the full dose of omeprazole is required. Some glandular ulcers may take 6 months of treatment to fully resolve.

Once a treatment course is finished, prevention of recurrence is important. There is an array of management and feeding changes that can be implemented to limit the chance of recurrence – that is another article in itself!

We are now fortunate to have the ability to perform gastroscopy. We have access to a scope that we can hire periodically and we performed 3 days of scoping late last year which was very well received, with some great cases and good outcomes. We plan to organise scoping clinics once every couple of months – please contact your local clinic with any questions or enquiries!!




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