Feeds and Feeding for Sand Colic
Sand colic is the accumulation of sand in the hindgut which can be caused when the horse eats feed from the ground or pasture that is cut too short, especially when the soil is of a high sand content. The build of sand is simply what is being ingested minus what is being passed. Large amounts of accumulated sand will require surgical intervention to remove the sand from the caecum. Often, untreated sand colic can be fatal.
Suggested Preventative Measures for Sand Colic
- Before sand colic reaches such a large accumulation, take the horse off the sandy area and let their body naturally remove the sand.
- Feed hay in hay racks, and not on the ground.
- If the horse is grazing short pastures on sandy soils, select feeds with a high water holding capacity (such as copra) to assist rate of passage of digesta (undigested food and water) through the gut
- Select feeds with a high fibre content that encourage passage of digesta through the gut. High carbohydrate (high NSC) feeds do nothing to remove sand.
- Feeding bran or psyllium can help remove some sand. Psyllium, made from the seed of the fleawort plant, swells and becomes gelatinous when moist. Psyllium is a proven laxative in humans and pigs, and many people feed it to their horses as well, in hopes that it will prevent sand colic. Psyllium is believed to help move small amounts of sand out of the horse's gut, but preliminary research calls into question its effectiveness in moving larger accumulations of sand from equine intestines ref Equus.
- Feeding oils is questionable because the oil is digested before they reach the lower gut.
What is Sand Colic?
Horses grazing short pastures, or hay from the ground, will often ingest sand. Sand colic is the accumulation of sand throughout the digestive tract, predominantly in the caecum and colon. The caecum is the blind ended sac (the same as the appendix in humans) so once the sand has accumulated at the bottom of the caecum it is hard to remove. Sand colic is slow to onset, and symptoms do not appear until such time as the amount of sand in the gut causes obstructive colic where the horse shows physical signs of discomfort and can lead to rupture of the intestine. Initially the build up of sand puts pressure upon the wall of the stomach or intestine causing the restriction of blood flow resulting in a dull constant pain. The horse will usually display no, or low grade symptoms at this stage.
Eventually the build up of sand will reach the stage where the amount of sand causes a physical blockage in the digestive tract. Digesta will accumulate in front of the sand causing distension, and acute pain. The accumulation will continue until such time as the blockage clears, or the hindgut ruptures, releasing digesta into the abdominal cavity, causing peritonitis, and death.
This image shows the layout of the equine digestive tract and the percentage of digestion that occurs within the foregut and hindgut
Symptoms of Sand Colic
- The first sign of sand colic is usually diarrhoea
- The horse spend a lot of time lying down and looking at its flank
- Poor appetite and low grade abdominal pain or colic.
Once the sand build up becomes too much and a physical blockage occurs the symptoms change to those of Obstructive colic.
Symptoms of Obstructive Colic
- Acute pain
- Horse goes into shock as a result of the release of endotoxins into the blood
- Heart rate is elevated and will not go down in even in the course of treatment
- Mucous membranes appear dark red and in the early stages the horses temperature may rise
- Just before the horse dies from the rupture of the intestine it will become cold and quiet.