Sand colic, or sand enteropathy, is most commonly seen in coastal areas of the UK where a higher percentage of sand in the soil can be found.

It is also observed more frequently in winter months when the grass is poor and horses accidentally ingest sandy soil as they graze much closer to ground level, especially if supplementary forage is not provided. Some horses also may choose to deliberately eat sand (geophagia) and it is unclear why.

In sheep, ingestion of sand may help with copper, iron, iodine, manganese, sodium and selenium deficiencies, so ensuring a vitamin and mineral supplement is provided to horses on poorer pasture may help prevent cases.

Sand accumulation appears to be problematic in only some horses and the reason is unclear. It can occur in all breeds but Shetland ponies and miniature horses may be predisposed. The type and quality of pasture has the biggest impact with, unsurprisingly, sandy soil being the highest risk, even when longer grass is present. Clay soil was found to have the lowest risk.

Read more: Horse feeding: Don't make colic a winter woes – Harbro specialist

Diagnosis is challenging, with some horses not showing any clinical signs of sand accumulation. For others, they show signs of acute colic with or without a large colon impaction detected on rectal examination.

However, for the majority of horses, clinical signs are often vague with a mix of symptoms including diarrhoea, weight loss, recurrent colic and poor performance.

Diagnosis

Auscultation of a characteristic ‘seashell’ sounds have been described in some when using a stethoscope to listen to the lowest part of the abdomen. The test has a high specificity but low sensitivity and one study found that 6.3-10.5 kg of sand was required before ventral sounds were obvious.

Glove faecal floatation test can be easily performed by adding water to faeces and allowing any sand to sediment out (Image 1). However, the presence of sand does not necessarily mean there is a problem with accumulation and it is merely just passing through (Picture 1).

However, radiology (Picture 2) remains the best method of diagnosis and ultrasound may be useful as a screening test.

Treatment

Treatment in the first instance should be pain relief and the nasogastric fluids if an impaction is felt or the horse is dehydrated. Once the horse is stabilised, the next step is to remove the sand.

Psyllium, either in feed or via nasogastric intubation, has been the most commonly used treatment for a number of years. However, more recent studies have questioned its efficacy and found the best treatment was to use it in combination with magnesium sulphate salt (both at 1mg/kg) once daily via nasogastric intubation.

Horses are best starved prior to tubing as psyllium can swell in the stomach and may cause mild colic. Magnesium sulphate should also not be used in causes with kidney disease.

Removing the horse from sand paddocks or pastures with sandy soil is also crucial. In rare cases, some require surgery. The prognosis is overall very good.

• References: K. Niinisto and B. W. Sykes (2021) Review Article: ‘Diagnosis and management of sand enteropathy in the horse.’ Equine Veterinary Education, DOI: 10.1111/eve.13562