EQUINE VETERINARY EDUCATION / AE / JANUARY 2017


conditions, it may or may not work under field conditions. Discussed below are several feed supplements that have had some scientific testing or have ingredients that have been shown to have effects on gastric ulcer scores in experimental conditions.


Sea buckthorn berry extract There is an increasing interest in the use of herbs and berries that may have therapeutic application in man and animals. Berries and pulp from the sea buckthorn plant (Hippophae rhamnoides) are high in vitamins, trace minerals, amino acids, antioxidants and other bioactive substances, and have been used in man (Beveridge et al. 1999; Geetha et al. 2002; Xu et al. 2007). In addition, sea buckthorn berries have been shown successfully to treat and prevent acetic acid-induced glandular gastric ulcers in rats (Xing et al. 2002). Two previous studies failed to show efficacy in treatment or prevention of squamous ulcers in horses fed supplements containing sea buckthorn berry pulp and extract (SeaBuck Complete)1; however, glandular ulcer scores were significantly improved when compared to untreated controls in a later study using another supplement containing sea buckthorn berry pulp (SeaBuck Gastro Plus)1 (Reese et al. 2008; Huff et al. 2012).


Calcium carbonate and gastroprotectants Many supplements on the market contain varying concentrations of calcium and sodium bicarbonate, various herbs and coating agents. The first author (F.M.A.) performed a small study with an antacid preparation containing calcium carbonate (Neigh-Lox; 124.5 g top-dressed on feed, q. 12 h, for 3 weeks)2 and found no effect on squamous ulcer scores (unpublished data, 2001); however, gastric juice pH, as measured by an indwelling pH meter was increased (≥4) 2 h after feeding. Calcium carbonate has been shown to enhance recovery of VFA-induced sodium transport in squamous mucosa in vitro Ussings chambers (Andrews et al. 2006). These data suggest that calcium carbonate preparations may have some efficacy in maintaining mucosal integrity, but because of the short duration effect on gastric juice pH, more frequent feedings may be necessary to help prevent squamous ulcers. Two other commercially available supplements (Egusin


250; E-250 and Egusin SLH)3 containing sodium bicarbonate, calcium carbonate, pectin and lecithin showed improvement in squamous ulcer scores after 35 days of treatment in stall- confined horses compared to untreated controls (Woodward et al. 2014). In addition to buffering agents, the Egusin supplements


contain surface acting compounds, pectin and lecithin. In horses, dense osmophilic surface-active phospholipids, similar to the structure of pulmonary surfactant, coat the surface of the squamous mucosa (Ethell et al. 2000); however, the mucus layer is thin to nonexistent (Bullimore et al. 2001) and lacks bicarbonate secretion compared to the glandular mucosa. Hydrophobic surface-active phospholipids might provide the primary defense mechanism against HCl and organic acids (Ethell et al. 2000). Pectin is a soluble complex polysaccharide derived from


the cell wall of fruits and vegetables. Lecithin is a phospholipid derived from soy beans. It is an emulsifying, lubricating surfactant. Pectin acts with lecithin to form a hydrophobic (water repellent) barrier on the gastric mucosal membranes, protecting it against the corrosive effects of


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gastric acids. The pectin and lecithin in the Egusin supplements might have been responsible for reducing squamous ulcer scores. In addition, two other studies using supplements containing pectin and lecithin (Pronutrin)4 improved squamous and glandular ulcer scores in horses with clinical disease after feeding (Venner et al.1999; Sykes et al. 2014a,b). However, other feed supplements containing pectin and lecithin have showed limited effects on improvement of ulcers in experimental models (Murray and Grady 2002; Ferrucci et al. 2003; Sanz et al. 2014). In a recent study, a commercially available supplement (SmartGut Ultra, 40 g)5 containing a proprietary blend of sea buckthorn, pectin, lecithin, and other ingredients (GastraVert)5 when mixed with the grain feed, q. 12 h, decreased the number of squamous ulcers 14 days after omeprazole treatment was discontinued and during a week of intermittent feed- deprivation (Andrews et al. 2016). Such supplements might be an alternative to long-term use of pharmaceutical agents to protect the squamous mucosa from acid injury. In addition to botanicals and coating agents, chelated


minerals containing zinc have been evaluated in horses with squamous ulcers. Zinc has been recognised as an important trace mineral for healing epithelial tissue in multiple species, and essential for the immune system including antioxidant protections against free radicals (Sturniolo et al. 2000; McDowell 2003). A recent study, feeding a mineral/vitamin supplement containing complexed mineral sources (ZINPRO zinc methionine, CuPLEX copper lysine, MANPRO manganese methionine and COPRO, cobalt glucoheptonate)6, resulted in lower squamous ulcer scores in horses after omeprazole treatment and during an alternating feed-deprivation model compared to the control containing all inorganic trace minerals. This difference was observed in Period 2, when a good nutritional plane was provided (Loftin et al. 2012). While the mechanism is yet to be clearly defined, other studies have shown gastroprotective action of Zn through involvement with gastric mucosa integrity (Watanabe et al. 1995; Sharma et al. 2003; Opoka et al. 2010; Sharir et al. 2010). Zinc evaluated in a cell culture model, appears to promote signalling for epithelial repair. In work with rat models, zinc compounds have been shown to be effective for healing ulcerated glandular gastric mucosa (Watanabe et al. 1995).


Oils (corn oil, rice bran oil) Dietary fats delay gastric emptying time in man and other species (Sidery et al. 1994). In contrast to most species, in one study, gastric emptying rates were slower in horses fed a high- carbohydrate diet, compared with horses fed a high-fat diet, although these rates were not statistically significant (Lorenzo- Figueras et al. 2005). In an earlier study, however, the addition of 10% corn oil resulted in a significant decrease in solid phase gastric emptying and blunted the glycaemic response to the diet (Geor et al. 2001). In another study, ponies fitted with gastric canulas fed dietary corn oil (45 ml, orally, once daily) had a significantly lower gastric acid output and increased prostaglandin concentration in gastric juice (Cargile et al. 2004). Corn oil supplementation could be an economical adjunct approach to the therapeutic and prophylactic management of glandular ulcers in horses. In contrast to the previous study, corn oil, refined rice bran oil and crude rice bran oil (240 ml, once daily, mixed in grain) failed to improve squamous ulcer scores (Frank et al. 2005).


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