Ulcers are a big concern to horse owners. External symptoms vary a great deal – with riders reporting girthiness, behavioural problems, issues with fence chewing, and soil eating and their horses being poor do-ers.
However, research has shown that that the only way to truly diagnose ulceration in horses is by endoscopy.
Modern horse management and feeding programmes can predispose horse to gastric problems. The horse’s stomach is highly susceptible to ulceration, as it continuously secretes acid, unlike we humans, who only produce stomach secretions when a meal is ingested. This is because the horse has evolved to have continuous forage throughout the day.
Additionally, the equine stomach is very different to that of humans. Although the lower hemisphere of the stomach is protected by mucous sections, the upper part, which acts as an expansion vessel for high levels of forage intake, is not. As the horse has evolved to survive primarily on a high fibre, forage-based diet, this would naturally form a mat across the top of the liquid secreted into the stomach, prevent acid splashing which is the primary cause of ulceration, according to current research. A horse left without fibre for any lengths of time (during travel or competition, for example) is at risk of acid splashing the unprotected upper region, causing gastric ulcers.
Although drugs should be used in severe clinical cases, where large and eroded ulcers can pose a risk of stomach perforation, appropriate feeding management can prevent or control ulceration in the long term, and allow the stomach to heal naturally once the acid-damaging factors have been removed.
This can be achieved by ensuring the horse has a regular and adequate supply of forage fibre in their feed. High grain diets tend to sit in the bottom of the stomach, so still allow the ‘splashing’ effect of the acid surface. They should be served with high fibre forage (such as chaff) included in the feed, to reduce these effects.
Acid is not the bad guy in this picture; rather, it has an important role in the stomach. It facilitates the first part of enzyme activation and protein digestion. Removing acid entirely can reduce this initial digestion step, limiting the amount of protein available to the horse for muscle and other essential processes and tissues in the body, manifested typically as loss in topline and condition score.
Calcium is well known to have a role in the natural control and reduction of acidity in the gut. It acts as a buffer, neutralising the acid to prevent potential burns in the unprotected upper area of the stomach. However, the form of the calcium provided is important, as it need to be slow-acting, allowing for protein digestion whilst the meal is in the stomach, but then being neutralised when no longer needed.
Natural forms from plant material are considered to be the best types to use, as they don’t interfere as much with the initial acid hydrolysis of protein, but slowly increase acidic buffering (neutralisation) as digestion proceeds, to reduce the risk of ulceration from acid splashing as the stomach empties. Currently, it appears that inorganic calcium and anti-ulcer drugs that block acid production when used long-term may inhibit protein digestion.
Recent trials have just been published (Moir et al. 2016 in the Journal of Applied Animal Nutrition) which investigated the role of a natural form of calcium supplementation from algae. Algae combine minerals within their tissues, and can be a very useful feed ingredient. In this trial, 10 horses were selected based on the presence of ulcers in their stomachs. The average ulceration score was 2.2 (from a range of 0-4, whereby 0 is no ulcers and 4 is large, eroded ulcers) before the trial started.
Owners were told not to change the diet, but to add 40g of the high calcium algae supplement into the daily feed. After 30 days on this regime, seven of the 10 horses had no evidence of any ulceration, and three had only mild inflammation with significant ulcer healing. This change in ulcer score was attributed to the neutralising effect of the calcium on the acid in the stomach, reducing the opportunity for ulcers being caused by the burn damage, allowing them to heal naturally.
This initial small research study has shown that feeding higher levels of natural calcium from algae can help buffer stomach acid, reducing the risk of damage to the stomach wall, which is the primary cause of ulcer development. Over time, reducing acidity allows existing ulcers in the upper stomach lining to heal. Even though these horses were fed a variety of diets and used in a variety of different ways (racing, trotting and other equine sports), the simple addition of this natural calcium had a major impact on ulceration.
More research into the role of natural calcium in horse nutrition is now planned to investigate its impact on mineral digestion, and how this may also be useful to horses.
For example, in New Zealand, extra calcium intake is important for horses fed kikuyu grasses in the northern regions, as this pasture contains compounds that bind calcium and results in leaching from bones, leading to weakness and soft spots. A natural form which is well digested and absorbed can have multiple benefits.
- This article was first published in the November 2016 issue of NZ Horse & Pony