Gastroscopy and Upper Airway

Gastroscopy (Equine Gastric Endoscopy)

Stomach ulcers or EGUS (Equine Gastric Ulcer Syndrome) is one of the most common causes of poor performance in horses and can also cause poor condition, weight loss, colic, and behavioural issues. Evaluating sport horses for EGUS is particularly important, as a horse’s performance is often significantly improved after successful treatment.

There are two main types of ulcers:

1. Equine Squamous Gastric Disease (ESGD) – this affects the squamous mucosa, the upper part of the horse’s stomach. The squamous mucosa does not secrete acid and is normally protected from the acidic stomach contents by a layer of keratinsed cells similar to skin cells.
2. Equine Glandular Gastric Disease (EGGD) – this affects the glandular mucosa, the lower part of the horse’s stomach. Some cells in the glandular mucosa secrete acid to help digest food, while other cells secrete mucous to help protect the surface of the glandular mucosa from the acidic stomach contents.

How are stomach ulcers diagnosed?

Stomach ulcers are diagnosed via gastroscopy. During gastroscopy, we pass a 3-meter long fiber optic camera up the horse’s nose, into the oesophagus, and then into the stomach. This allows for direct visualization of the stomach lining to diagnose ulcers and other upper gastrointestinal disorders. We do the procedure under standing sedation at your barn. It is normally performed in the morning, as horses must be starved overnight so that food material in the stomach does not block the path or view of the camera. The results of the gastroscopy allow for targeted medical treatment as well as diet and management changes that promote ulcer healing and reduce their likelihood of recurrence.

What are the signs of stomach ulcers?

Horses can show a variety of signs of stomach ulcers (or none at all!), making this condition sometimes difficult to identify. Sometimes horses have been showing signs of ulcers for a long time, through behaviours that are considered ‘normal’ for that horse. Notable signs of stomach ulcers include cribbing, windsucking, being girthy/cinchy, bucking, having a poor or picky appetite, weight loss, poor condition, and discomfort or reactivity (including biting) during grooming, particularly around the girth area. Subtler signs of stomach ulcers can include a drop in performance, an irritable, nervous, or dull horse (even if a horse has ‘always been that way’ – ulcers can be chronic), or a horse that ‘just isn’t right’.

What causes stomach ulcers?

We do not yet fully understand the etiology of EGUS in horses, but several factors are known to contribute to the development of stomach ulcers:

1. Diet – High starch and high sugar foods, as well as excessive protein intake, can make the contents in a horse’s gastrointestinal system more acidic, contributing to the formation of stomach ulcers. A typical scenario might be a performance horse who is being fed a high ration of grain or competition/conditioning feed.
2. Management – Periods of starvation, e.g. during travel or between feeding times, allow acid levels to increase in the horse’s stomach. Because horses are grazing animals, their stomachs continuously release acid (unlike humans, whose stomachs release acid in response to food). Without regularly ‘diluting’ this acid with food material, the acid levels in a horse’s stomach become too high, contributing to the formation of ulcers. Exercising a horse on an empty stomach can be particularly damaging to the upper (squamous) portion of a horse’s stomach. As the horse moves, acid splashes this area, which is not normally in contact with gastric juices, and slowly wears away the skin-like lining.
3. Stress – although we do not know the exact mechanism, we know that horses are more likely to develop stomach ulcers during periods of stress, including travel, competition, and changes to their environment or management. Horses can also develop ulcers secondarily to an illness or injury such as chronic lameness. In these cases, not only do we have to treat the ulcers, but we must also diagnose and treat the underlying condition to prevent their recurrence.

How are stomach ulcers treated?

Stomach ulcers are treated through medication, diet, and management change.

1. Medication – we mainly use two types of medication to treat ulcers: omeprazole, an acid suppressant that is given as an oral paste or intramuscular injection, and misoprostol, a drug that promotes the healing of the stomach lining, given as an oral liquid. The exact treatment protocol depends on the type, location, and severity of the ulcers, which is why gastroscopy plays an indispensable role in the successful treatment of Equine Gastric Ulcer Syndrome.
2. Diet – diet is key to the long-term management and prevention of ulcers and must be tailored to the individual horse based on body condition, level of work, and other health conditions. Our aim is to:

• Reduce sugar and starch levels
• Provide energy from fat and fibre
• Ensure a good diversity of forage types to encourage a healthy gut microbiome
• Provide enough protein for the horse’s level of athletic performance

It takes the horse’s body 3-4 weeks to adjust to this type of diet, but even sport horses generally perform well on a high fat/high fibre diet and benefit from improved stamina without extra ‘fizz’.

Certain supplements are also useful to support a healthy gastrointestinal system. These contain probiotics and prebiotic fiber to support a healthy gastrointestinal tract, and buffering agents to help protect the stomach lining. Our vets will make appropriate recommendations for diet and supplements on a case-by-case basis.

1. Management:

• Avoid periods of starvation, especially before exercise. While it is not advisable to give horses hard feed before exercise, ensuring they consume some forage (grass, hay, or a chopped forage) about 30 minutes before exercise will protect their stomach without negatively impacting performance.
• Use hay nets during travel.
• For horses on a restricted amount of forage, e.g. for weight loss, use slow-feeders or small-holed hay nets to ensure the horse gradually consumes forage throughout the day.
• Predict times of stress and treat prophylactically with targeted or low-dose acid suppressants. This can include giving oral omeprazole before and during travel, competition, moving to a new farm, or being turned out with new or different horses.

Respiratory disorders are a significant cause of poor performance in sport horses, and can impact any horse’s day to day life and training. Common performance-limiting conditions include Equine Asthma and laryngeal hemiplegia (“roaring”). Horses can also be affected by a variety of inflammatory or infectious respiratory diseases.

Notable signs of respiratory disease include coughing at rest or during exercise, abnormal respiratory noise during exercise, increased respiratory effort at rest (“heaves”), nasal discharge, fever, or inappetence. Subtler signs can include occasional coughing, often at the start of exercise, exercise intolerance or a general drop in performance.

Upper airway endoscopy allows us to visually inspect the upper respiratory tract, as well as collect samples as indicated from the upper and lower respiratory tract. During upper airway endoscopy, we pass a 1.5 meter scope up the horse’s nose and into the trachea, making stops along the way to inspect parts of the sinuses, nasal turbinates, pharynx, larynx, guttural pouches and trachea. We may also follow up an upper respiratory endoscopy by taking samples from the horse’s lower respiratory tract via bronchoalveolar lavage.