Unravelling ulceration - The causes, treatment and prevention for squamous vs. glandular gastric ulceration

By Emma Hardy, PhD

Gastric ulcers remain a common condition facing competition horses. This poses an ongoing and persistent challenge to trainers who face the negative effects of ulcers in terms of training and performance. To address the issue, the typical trainer spends a small fortune on scores of omeprazole and other ulcer remedies, only to find the problem isn’t resolved or simply comes back.

Meanwhile, researchers have been testing the very notion of “what is an ulcer?” The data casts doubt on whether go-to treatment approaches will actually work. A look at what the research now tells us about equine gastric ulcers may provide some new guidance for how best to address this nearly ubiquitous concern.

The two faces of gastric ulceration

While many people think of gastric ulcers as one specific disease, equine vets and researchers refer to gastric ulcers as a “syndrome” (Equine Gastric Ulcer Syndrome, or EGUS). The medical definition of a syndrome describes a set of symptoms and signs that together represent a disease process. In practical terms, this means that ulcers are really a clinical signs—truly a symptom—of underlying disease conditions.

A few years ago, articles began to appear in the scientific press highlighting differences in the healing of ulcers in two distinct regions of the stomach—the upper “squamous” area on the one hand, as compared to the lower “glandular” portion on the other. In recent years, researchers in Australia published a series of articles (Sykes et al, 2014) to “clarify the distinction between diseases in different regions of the stomach” (i.e., to describe the differences between ulcers in the squamous area of the stomach from those in the lower glandular area). The articles described significant differences between the two conditions, including prevalence, risk factors and response to treatment.

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An example of a cherry ulcer

Squamous gastric ulceration

The upper region of the stomach is minimally protected from the corrosive effects of stomach acids. As such, squamous gastric ulceration (i.e., ulcers in the upper region of the stomach) is believed to result from the increased exposure to acid and other contents of the stomach. Ulcers in the squamous region are also more common, affecting upwards of 70% of Thoroughbred racehorses, as demonstrated in multiple studies over the past 20 years.

Glandular gastric ulceration

By contrast, ulcers in the lower glandular region of the stomach are believed to arise from a different set of conditions. The lower portion of the stomach is composed of numerous cell types including those that secrete gastric acid. Because horses secrete stomach acid continuously, the mucosal lining in this lower portion of the stomach is in direct contact with stomach acid at all times.

The lower portion of the stomach is also better protected—the glandular mucosa is lined with a thick layer of mucus that offers natural protection from acid. It is believed that glandular ulceration results from the breakdown of this protective lining. Although no research has conclusively shown exactly how this defence mechanism breaks down in horses, research in humans shows NSAID (non-steroidal anti-inflammatory drugs) use and bacterial agents are contributors.

Based on this, equine squamous gastric ulceration (ESGUS) is a specific condition distinct from equine glandular gastric ulceration (EGGUS).

Beyond the stomach….

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Feeding for weaning success

By Dr. Emma Hardy, PhD

The first 12 months in the life of a foal are pivotal in building the foundations for overall long-term health and optimal development. It is also during this initial year that the foal will face its first major life event in being weaned from his dam, and he must cope with the nutritional challenges this may bring.

There are many approaches to weaning and every breeder strives to make the right choices for the best outcome. The reproductive status of the mare, the cost and time available, the plans for the foal, and the physical practicalities of the yard will often dictate which type of weaning strategy should be employed. They all come with their own benefits and drawbacks.  Choosing the correct feeding and nutrition programme is key to your success.

Early growth

The dam’s milk is nutritionally complete, providing all the energy and nutrients required for a foal. However, at around three months of age, milk yield peaks, then naturally starts to decline, along with suckling frequency. At the same time the foal increases its intake of non-milk feedstuff such as grass, forage, and some concentrates as the his nutritional needs begin to overtake the mare’s own supply. This period coincides with rapid weight gain, with foals reaching around 30% of their adult weight by this point.

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Genetics, breed, seasonal temperature differences, and nutrient availability will all contribute to the growth rate of the foal. Small fluctuations in growth rates are normal and nothing to worry about. However, continuing or significant deviations from the National Research Council (NRC) 2007 growth recommendations can predispose the foal to health issues, most notably orthopaedic problems.  The structures and tissues of the foal’s body do not grow at the same rate: bone matures earliest, followed by muscle and then fat. Indeed at 12 months of age the yearling will have attained 90% of his mature adult height, which emphasises the importance of correct diet in supporting this rapid early bone growth.

Introducing creep feed

Although the foal supplements his milk intake with small quantities of the dam’s feed and forage, the introduction of a creep feed prior to weaning can help sustain normal growth rates. Highly digestible creep feed is formulated from milk proteins and micronised grain, and it’s fortified with vitamins and minerals. In addition to encouraging growth, it promotes gastrointestinal adaptation to the post-weaning diet and is also described as a significant factor in the reduction of weaning-associated stress.

The appropriate age to introduce a creep feed depends on many factors. For the foal at pasture and doing well, there should be little need for any additional nutrition until two-to-three months of age, when milk supply begins to diminish. Earlier intervention may be necessary should the foal be orphaned or fail to thrive due to inadequate milk supply or other environmental influences.

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From fertility to foal - Considerations for digestive tract health

By Emma Hardy, PhD

The success or failure of any breeding program is dependent on the nutritional status and digestive tract health of foals, mares, and stallions alike. Although this aspect of the operation is often overlooked, it is only by ensuring that these considerations are optimised that foals are given the best chance to survive and thrive, from birth through weaning and on to sale.   

A weighty issue

There exists surprisingly little research surrounding the nutrient requirements of the breeding stallion. This may be in part complicated by the great variation in activity; some stallions may serve several mares a day during peak periods in the breeding season, while others may serve only that number in a year. Other influencing factors may include temperament, management routine, and competitive activities. However, it is generally agreed that energy demands are indeed above maintenance levels, and according to various National Research Council studies it has been suggested that active stallions require approximately a third more digestible energy than their non-breeding, sedentary counterparts.  

Research in other species has shown that a body condition that deviates greatly from the ideal can be associated with an increased risk of infertility (Nguyen et al. 2009). Nutritional content is also of great importance, with zinc and omega-3 fatty acids playing important roles in sperm motility, mobility, and viability.

Extremes in body weight and condition can also affect the fertility of broodmares. Low levels of body fat in mares can inhibit or delay ovarian activity, and obesity is often associated with insulin resistance (equine metabolic syndrome, or EMS), which can also disrupt cyclicity. Gentry et al. (2002) found that mares with a body score of 3-3.5 demonstrated a longer anaestrus than mares with a good body score (eg., 5) (Henneke et al. 1983) and was accompanied by lower plasma leptin, prolactin, and insulin-like growth factors.

It would therefore be sensible to carefully manage the weight and condition of both broodmares and stallions to optimise breeding potential.

Safely improving body condition and weight

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For horses struggling to maintain ideal body condition it is important to assess forage intake and quality, and to also increase concentrates. Energy-dense grains and fats are often employed in these situations; however, caution must be taken to avoid the digestive tract issues these can cause.

Adding fat-fortified feeds to the diet, or top dressing fats or oils, can be an effective way to increase caloric intake. However, oils can pose a palatability issue. For a significant caloric contribution, somewhere between 200-500 ml/day of vegetable oil would be required. This would also increase the need for additional vitamin E and selenium to counteract the greater antioxidant need of a horse on such levels of supplementation.

The horse is naturally limited in its capacity to digest large volumes of starch, so concentrations should be limited to about 2g starch/kg body weight per meal, which equates to 0.2% starch or 1.4kgs of grain per meal. Anything over this risks starch bypass through to the large intestine, which can cause a bacterial inversion and ultimately a range of issues from poor feed absorption and inflammation to colic and laminitis.     

While it is prudent to ensure that a diet is appropriate both in volume and quality, the health of the digestive tract itself can sometimes be overlooked.  Optimal absorption can only be maximised when the mucosal surface of the tract and its vascular supply is healthy, the structure facilitates effective nutrient uptake, and the transit rate allows adequate time for digestion.

Other factors known to affect fertility and gestation can include naturally occurring contaminants found in feed, bedding, and housing. It has been well established that exposure to toxins produced by moulds and yeast can have detrimental effects on many biological systems. Of particular interest to breeders are mycotoxins, such as ergotalcaloids (found in some species of grass) and zearalenone (occurring in cereals). Zearalenone disrupts the oestrous cycle leading to lower conception rates, and ergotalcaloids can induce late gestation fetal loss and placental abnormalities. Mycotoxin binding agents can be a beneficial addition to a broodmare’s diet in a bid to combat mycotoxicosis. Biological products such as yeast cell wall, containing polysaccharides such as glucan or mannan, are emerging as potent adsorbers, with multibinding properties to numerous chemically different mycotoxins (Diaz & Smith, 2005).

Clearly, risk management should be applied at all levels of the feed production and manufacture chain to minimise contamination. Correct storage and regular quality assessment are paramount but the addition of a mycotoxin absorbent to the diet is also likely to be beneficial.

Nutritional demands of the pregnant mare

The nutrient and energy requirements of the pregnant mare begin to increase from month five of gestation (as placental tissues significantly develop). Consequently, a carefully devised diet containing adequate protein, vitamins, and minerals (major and trace) is imperative.

The pregnant mare’s caloric intake should also be increased and, depending on climate, housing, etc., feed volume may need to be increased by up to 30% by the end of gestation. This may be complicated during late gestation when the foal occupies an increasing proportion of the mare’s abdominal cavity, thus making large volumes of feed difficult to ingest.

The foal will gain approximately 80% of its birth weight during the last trimester, and the most rapid growth period will be in the few days before or after birth (Staniar et al. 2004). Ensuring optimal gastrointestinal support helps to safeguard the health of both the mare and her foal.  

Colostrum IgG transfer crucial to foal health…

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