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The Silent Killer: Sand!

A healthy, happy, and fit horse is what every horse owner desires. For a horse, their digestive system is essential for their health. Compared to other species, horses are unfortunately very sensitive to digestive issues. One significant reason for this is the relatively long length of their gastrointestinal tract. In an adult horse, food must travel a journey of at least 35 meters. If it were a straight path, things might be less complicated. However, due to the horse's intestines' sharp turns, they are prone to blockages.


Colic is one of the greatest nightmares for many horse owners. When a horse experiences abdominal discomfort (in its intestines), the expression of the pain is referred to as colic. It's a collective term for when a horse doesn't feel well, and it's related to its digestive system. Like any pain, it can range from mild to severe, and its manifestations can vary for each horse. A horse with abdominal pain often appears restless: alternately standing and lying down, rolling, swishing its tail, scraping its front legs, sweating heavily. However, some horses don't display restlessness but rather internalize their discomfort: reduced appetite, faster breathing, enlarged nostrils, standing stretched out (as if urinating), a general apathetic impression.

For some horses, it's easy to recognize their pain and that something is amiss. For others, it might not be as immediately apparent. Therefore, it's essential to remain alert if your horse exhibits different behavior; this could be a sign that something is wrong.

Causes of Colic

One of the most common questions directed to a veterinarian when a horse experiences colic is, "But how does this come about?" Sometimes there's a very clear reason for colic, such as a drastic change in feed (horses are highly sensitive to this and changes should always be gradual). However, in many cases, the answer goes something like this: "We often don't know. The digestive system of horses is poorly designed compared to other animals, so we should wonder more about why it doesn't occur more frequently."

For many, this is a frustrating answer and can cause anxiety. Does it mean that there's zero control over whether a horse gets colic? Does it mean that there's nothing we can do? Thankfully, no! Although there are various forms of colic, I will focus on sand colic.

Sand in the intestines

Sand colic arises when there's a significant amount of sand in the intestines. Horses of all ages can encounter sand in their intestines, and it doesn't immediately mean they'll be affected by it. Every horse occasionally ingests some sand, and for a healthy horse, this isn't a problem. Healthy horses effortlessly expel small amounts of sand as long as they:

  1. Receive sufficient fiber-rich forage to stimulate their intestines.

  2. Have ample opportunity to move, 24/7 (note that confinement in a stable limits movement).

  3. Have a healthy intestinal function.

When horses ingest too much sand, it's not a matter of a few grams; we're talking about dozens of kilograms. Due to gravity, the sand often accumulates at the bottom of the abdomen, creating a sandbank. When there's a significant amount of sand in the intestines, it impairs their function and hinders the movement of sand. Before you notice clear symptoms in a horse, you're often already years and many kilograms of sand into the situation. You shouldn't underestimate that it has restricted nutrient absorption and potentially caused damage to the intestinal lining. Once there's a substantial amount of sand, it's not easy and often painful to expel it. When large quantities of sand shift in the intestines, it can cause pain and discomfort in a horse, which can manifest as colic.

The issue can arise if a horse's intestinal function isn't optimal. This could be due to a physical restriction or its environment (insufficient poor-quality forage or inadequate movement). Another common problem observed in housing is that horses are offered forage in sandy or muddy areas. Even if you provide hay in a feeder, ensure that there's a solid surface around the feeding area and clean it from sand regularly. Prevent horses from consuming hay remnants from sand/mud. This prevents a horse from ingesting more sand than it can expel. In some cases, horses ingest sand due to deficiencies in their diet. If you observe this behavior, try to identify why your horse is doing it as quickly as possible.

Early Recognition

Unfortunately, attention is often only given to this problem when it's too late, and a horse needs to be taken to a clinic for further treatment. What can you, as a horse owner, look out for as indications that your horse might be suffering from excessive sand in its intestines? We've noticed that horses tend to display quite a few indications that sand is building up in their intestines before things take a serious turn. These are mostly vague and non-specific symptoms. A horse with excessive sand in its intestines might exhibit one or a combination of these symptoms:

  • Depression.

  • Reduced appetite.

  • Weight loss and difficulty gaining weight, regardless of the amount of food they're given.

  • Sudden changes in feces (watery, loose stools). Standing stretched out (as if urinating).

  • Unwillingness to work/move forward.

  • Reluctance to engage abdominal muscles during movement.

  • Drooping belly combined with a slightly sagging back.

  • Weak topline.

  • Various (vague) movement irregularities (especially in the hindquarters).

  • Sensitivity around the right groin and behind the saddle (sand often accumulates in the cecum and can form a dense layer at the bottom; the cecum is "hung" from the horse's skeleton via the right groin and behind the saddle).

  • Recurring vague (gas) colic. Often, 7 to 10 days before the onset of colic symptoms, loose, dark, sandy feces.

The accumulation of sand in the large intestine can cause irritation and hinder water absorption. This can result in inconsistent stool. The same theory explains why horses with a lot of sand tend to lose weight or struggle to gain it. The horse's intestinal lining is damaged, which affects nutrient absorption/production. Due to the damage caused by sand, discomfort and pain can arise, leading to depression, reduced appetite, or colic. During movement (including riding), sand can rub against the intestinal lining, which can be very painful. This might make horses less willing to work or exhibit evasive behavior.

It's essential to realize that the accumulation of sand in the intestines is not a matter of weeks but rather years! Many horses have suffered from this problem for years before we identify what's wrong when it's already quite serious. If you haven't had your horse from a young age, you also won't know where it has been and it's entirely possible that you've purchased a horse that already has excessive sand in its intestines without your knowledge.

How Can You Be Sure? Currently, the only sure way to know if your horse has excessive sand in its intestines is to have an X-ray taken. Nowadays, some veterinarians can take an X-ray at your stable, or many clinics have this capability. There's also a home test that many veterinarians recommend and perform themselves, but in my opinion, it's not reliable (see fecal test). If this test doesn't reveal any sand, it could mean that your horse isn't able to expel sand even though there might be a substantial accumulation. And if you do find a lot of sand in the feces, it certainly indicates that there's sand in the intestines, but it doesn't tell you how much. If you perform this test, it's important to do it multiple times a day and for several days in a row. Sand doesn't come out every time; it occurs intermittently. Consider the results as information, but you can't draw definitive conclusions from them.

Prevention Is Better Than Cure

How can you best prevent your beloved horse from developing problems with sand in its intestines? Many horses in the Netherlands spend extended periods in sand paddocks during winter (without forage) and in summer on short-grazed pastures. One of the highest priorities is to try to prevent your horse from ingesting (too much) sand and ensure it has a healthy intestinal function. Complete prevention isn't possible and isn't necessary for a healthy horse. However, you can consider the following factors in your horse's management to limit sand intake in the intestines:

  • Unlimited free movement (the digestion of horses depends on this).

  • Sufficient, high-quality fiber-rich forage (fiber is needed to transport sand and promote healthy intestinal function).

  • Never let your horse go without forage for longer than 4 hours.

  • Avoid feeding hay in sandy/muddy areas or on short pastures, and keep feeding areas clean (using hay nets in conjunction with feeding troughs is recommended, along with maintaining a firm surface around feeding areas).

Having proper horse housing is essential for minimizing sand intake, but if your horse already has excessive sand in its intestines, housing adjustments won't act as a cure.

The Silent Killer

The buildup of sand in the intestines is a process that occurs over years and doesn't happen overnight. If horses can't expel the sand effectively, it's dangerous, and it's crucial for us as horse owners to be aware of the potential symptoms. Before you chalk things up to "Well, my horse has always been like this," I hope that when it comes to the mentioned symptoms, you'll think twice. If your horse struggles to gain weight, don't only consider a worm infestation; also keep sand in mind as a possible cause. Horses are generally alert, willing, and present animals. If your horse isn't displaying these characteristics, it's not unwise to dig deeper for a possible underlying cause.


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