604


NOVEMBER 2022


prognosis for treating horses with sand accumulation and related colic in recent studies has been good; up to 90–95% of horses survive with medical or surgical treatment, compared with 75% short-term survival after surgery some decades ago (Granot et al., 2008; Hart et al., 2013; Kilcoyne et al., 2017; Ragle et al., 1989a; Specht & Colahan, 1988). Some horses have been described to have recurrent sand colic during the follow-up period, considered most likely due to ongoing sand ingestion (Kilcoyne et al., 2017; Ragle et al., 1989a), and the authors have observed reaccumulating of large amounts of sand in as little as 3 weeks when intake has not been controlled. In the authors’ opinion, if surgery is successful, the long-term prognosis is comparable with other non-strangulating diseases of the large colon.


Prevention


Research on prevention of sand accumulation is scarce, and there are no controlled studies evaluating methods of prevention. Authors from previous studies have suggested ensuring adequate food and mineral supplementation (Bertone et al., 1988; Ragle et al., 1989a; Ramey & Reinertson, 1984; Rollins & Clement, 1979) and preventing food from dropping onto the sandy ground (Ragle et al., 1989a). Other recommendations include ensuring that there is sufficient feed for horses at pasture, either by rotation of fields or feeding sand-free hay indoors, before letting the horse out to pasture to reduce the intensity of grazing activity and subsequent exposure to accidental sand ingestion (Hanson, 2002). The provision of additional roughage sources to horses on sandy pastures may also decrease the risk of sand ingestion (Husted et al., 2005). Some horses might seek the salty taste in soil, and therefore, sodium supplementation may stop geophagia in these individuals (McIntyre, 1917). Placing rubber mats under feeding containers and


keeping them clean of sand should help unless the horse is intentionally seeking to ingest sand. In extreme cases, if sand eating cannot be otherwise prevented, confinement to a stall or dry lot, or muzzling while at pasture may be required. Although unproven, supplementation of iron and copper may reduce geophagia in some animals based on the behavioural patterns described above (Aytekin et al., 2011; McGreevy et al., 2001). Based on recent findings (Niinist€


o


et al., 2019), separate feeding of submissive animals in herds may reduce their risk.


Conclusions


Sand enteropathy is an important disease condition in the horse, particularly in geographically predisposed regions. The reasons why horses eat sand, or why some horses accumulate sand when exposed and others do not are poorly understood. Diagnosis in the field is challenging, and current evidence does not support the use of the faecal glove sedimentation test for screening horses at risk of sand accumulation. Instead, ultrasound is a useful screening test under such conditions. In contrast, ultrasound appears to be of limited value in the assessment of sand accumulations in acute disease; radiography remains the reference standard for diagnosis. Current evidence does not support the feeding of psyllium for the removal of sand accumulation. Instead, daily administration of psyllium and MgSO4, both at 1 g/kg bwt via nasogastric tube, has been reported to be effective


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in removing the majority of sand accumulations over a 3– 7 day period in a number of studies. Prevention remains challenging in horses at risk due to ongoing exposure to sandy pastures but, based on epidemiological evidence, small management changes may be beneficial in reducing disease risk.


Conflict of interests K. Niinist€


o has no interests to declare other than supports for


the original research performed by the author(s) discussed in the current manuscript was supported by the Finnish Foundation of Veterinary Research and Vetman Finland. B.W. Sykes has previously received research support or consultancy payments from a range of companies with relevant products in their portfolio including Abler, Axon Animal Health, Bova Australia, Bova UK, Dechra, Boehringer Ingelheim, Duggan Vet, Freedom Animal Health, Luoda Pharma, Prydes Australia, Purina, Vetcare Finland and Virbac Australia. B.W. Sykes is currently engaged in consultancy agreements with Kelato and Equestra Australia. None of the aforementioned entities had any input into the manuscript and the opinions expressed are solely those of the authors.


Ethical animal research Not applicable to this review article.


Funding information


No specific source of funding was required for the preparation of this manuscript.


Author contributions Both authors contributed to all aspects of the manuscript’s preparation. Both authors have approved the final version for submission.


References


Abrahams, P.W. (2012) Involuntary soil ingestion and geophagia: A source and sink of mineral nutrients and potentially harmful elements to consumers of earth materials. Applied Geochemistry, 27, 954-968.


Alonso, J.M., Schmitt, F.P., Sousa, F.A.L., Rosa, G.S., Esper, C.S., Neto, G.B.M. et al. (2020) Carboxymethylcellulose and psyllium effects in sand output of horses with asymptomatic sand accumulation. Arquivo Brasileiro de Medicina Veterin 1617.


aria e Zootecnia, 72, 1609-


Aytekin, I., Onmaz, A.C., Aypak, S.U., Gunes, V. and Kucuk, O. (2011) Changes in serum mineral concentrations, biochemical and hematological parameters in horses with pica. Biological Trace Element Research, 139, 301-307.


Bergstrom, T.C., Sakai, R.R. and Nieto, J.E. (2018) Catastrophic gastric rupture in a horse secondary to psyllium pharmacobezoars. Canadian Veterinary Journal, 59, 249-253.


Bertone, J.J., Traub-Dargatz, J.L., Wrigley, R.W., Bennett, D.G. and Williams, R.J. (1988) Diarrhea associated with sand in the gastrointestinal tract of horses. Journal of the American Veterinary Medical Association, 193, 1409-1412.


Colahan, P. (1987) Sand colic. In: Current Therapy in Equine Medicine 2, Ed.: N.E. Robinson, Philadelphia: Saunders. pp 55-58.


Ferraro, G.L. (1973) Diagnosis and treatment of sand colic in the horse. Veterinary Medicine, Small Animal Clinician, 68, 736.


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