Water Contamination

Any treatise you've ever read on caring for horses probably includes the line, "Provide access to plenty of fresh, clean water." Although we all understand that this is good advice--all living things need this simple, essential liquid--we don't really tend to give water a lot of consideration as part of the equine diet. But, just any water source won't do--it must be clean and palatable to the horse if he's going to drink enough.

Water is the most important nutrient in the equine diet, bar none. Without water, almost all of your horse's systems cease to function. It would be virtually impossible to list all the ways in which water is essential--but just to name a few, it:

  • Aids in thermoregulation (maintenance of the horse's body temperature);
  • Lubricates the joints;
  • Helps cushion the central nervous system;
  • Is involved in both sight and hearing;
  • Aids in digestion;
  • Acts as a solvent for toxins and helps eliminate them through urine and sweat; and
  • Helps maintain an elastic skin tone.

To give you another perspective on water’s importance, consider that horses can survive without food for up to three weeks, but they can only survive without water for a maximum of five to six days. Although water intake varies according to the horse's exertion level, the ambient temperature, the components of his diet (more on this later), and whether or not the animal is pregnant or lactating, the average 1,000-pound horse needs a bare minimum of three to eight gallons a day to function at a maintenance level.

When water intake is restricted--whether because water isn't made available, the horse finds it difficult to drink or swallow (for example, if he is suffering from a broken jaw or any of a number of diseases), or the available water isn't very palatable, a horse quickly becomes dehydrated. Within 24 hours of water deprivation, a horse can lose about 4% of his body weight. After 48 hours without water, 6.8% of his body weight will be lost, and after 72 hours it's about 9%. If summer heat is involved, that number can skyrocket to 16%.

The symptoms of dehydration--dry mucous membranes, sunken eyes, a tucked-up appearance, skin that has lost its elasticity, and a slowed capillary refill time--only become obvious when the horse has already lost 6% of his body weight or more, by which time dehydration has already begun devastating athletic performance and digestive efficiency. Both functions take a nosedive in the absence of water, and decreased digestive function can quickly lead to colic. In fact, the main reason the incidence of colic increases from December to March is that many horses don't drink enough water in the winter months (often because their water supply has been allowed to freeze).

However, winter isn't the only time horses are at risk for colic due to restricted water intake. Any time a horse faces a rapid decrease in water consumption, he’ll be more prone to impaction colic, especially if a good part of his diet is dried forage. Horses grazing on fresh, juicy, spring pasture can extract much, but not all, of their water needs from their grass intake, but those eating hay or roughage cubes need to drink significantly more so that their gastrointestinal systems can churn the dried forage into a digestible slurry.

In-foal mares or lactating (or both) have an increased need for water, largely because they are satisfying their increased energy and protein needs by taking in more feed (requiring more water to digest the additional feed), but also because they lose some water in the placental fluids and in their milk. Although foals satisfy most of their liquid requirements by nursing, most will begin to drink water at the age of only one to two weeks. It's a requirement that begins early and lasts a lifetime.

The other reason horses become dehydrated is excessive water loss through sweating, as can happen in conditions of extreme heat and humidity, especially when strenous exercise is involved. Water needs can increase by three to four times with work when temperatures are high.

Horses with diarrhea become dehydrated quite rapidly, and the water loss in those cases makes thermoregulation difficult and contributes to a rise in body temperature.

Whatever the reason behind it, dehydration is a situation best prevented. The easiest way to ensure your horse never gets dehydrated is to make sure he always has access to clean, fresh water, regardless of the weather. (To learn how to check for dehydration, see below: "Is Your Horse Drinking Enough?")

Straight From the Source

Making clean water available sounds like a very basic thing, but it’s not always as simple as it sounds. Water that is completely untouched by chemicals or minerals doesn’t exist in nature. Water is, after all, the universal solvent, with a unique ability to pick up and dissolve virtually everything it encounters. Substances contained in drinking water aren't necessarily bad; after all, minerals dissolved in water impart much of its flavor, and many are even beneficial (such as fluoride in city water supplies). The issue with dissolved substances isn’t so much purity as it is safety. In other words, it's not whether they are present, but whether they are present in toxic amounts.

If you live in suburbia, your barn might draw its water from a public or municipal system that provides extensive purification and filtration services, and also regularly tests its water for contaminants such as disease-causing bacteria, toxic chemicals, and even radioactive elements such as radon. Worries are few with this sort of system, but that doesn't mean there’s no possibility of contamination. The testing is done at the source, and if there is damage to the delivery line, or a problem with the plumbing on your property, your water could still be compromised.

More diligence is required if, like the majority of horse owners, you draw your barn's water from a well. Many wells provide beautifully clean water, but there is also the potential for contamination. The same is true if your horse gets his water from a natural source, such as a stream or pond in your pasture. Fortunately, as herbivores, horses are well-adapted to dealing with less-than-pristine water sources. Unlike us, they're fairly resilient when it comes to most bacterial (and other) contaminants.

Like us, however, their water intake can quickly be adversely affected if the water's taste is unpleasant. Horses which refuse to drink from unfamiliar-tasting water sources are distressingly common (so much so that most of us are familiar with the trick of flavoring water with anything from peppermint oil to powdered kids' drinks in order to disguise the taste when these finicky horses are away from home).

The most reliable indicator of water quality in your barn is the total amount of dissolved solids (TDS), a number that can easily be determined with a water test run by your county or state health laboratory, your local agricultural extension agent, or the Environmental Protection Agency. TDS is the sum of the concentrations of all organic and inorganic substances dissolved in the water, including mineral salts, algae, bacteria, nitrates, and solid particles of debris. Levels below 1,000 parts per million (ppm) TDS is considered satisfactory for livestock. Levels between 1,000-5,000 ppm are considered satisfactory, although they might cause a mild, temporary diarrhea or refusal of drinking water. Levels over 5,000 ppm should not be used for lactating animals or for animals in late gestation. At levels over 3,000 ppm, your water might have an offensive smell, taste, or color.

Testing your well's water for bacterial contamination on an annual basis is another sound practice. A total coliform test checks the water for bacteria that are normally found in the soil, surface water, and human and animal waste. Coliform bacteria are not, in themselves, considered harmful, but their presence in your water supply is an indication that your well might be contaminated either from run-off from your manure pile, from a nearby septic bed or tank, or from fertilizer or manure spread on a nearby farmer's field. Coliform levels can rise in drought conditions, or when there's a sudden heavy rainfall or any unusual change in weather patterns. It’s also possible to have high coliform levels when the well has developed physical defects, such as a broken or missing cap that could allow debris, surface water, insects, or rodents inside. At this time, there is no information as to what level of coliform is safe; however, the absence of coliform would be ideal.

Doing bacterial testing is a good idea whenever there is a noticeable change in the color, odor, or taste of your water, when any animal or person on your farm becomes sick from a water-borne disease such as Salmonella, when the water supply system on your farm has been disassembled for repairs, after spring flooding occurs near your well, or when the cap or the interior of the well has been damaged.

Wells which are correctly drilled, sealed, and more than 50 feet deep generally have less chance of becoming contaminated with bacteria. Water from an old or shallow well should be tested more frequently. Don't rely on "clean" tests from a neighbor's well; even two wells side by side can draw water from separate aquifers (underground water sources) and yield very different results.

Other Contaminants

Well water often contains significant concentrations of dissolved minerals, which can influence the taste, smell, and palatability of your water. (The classic example is "sulfur water," which has that unmistakable rotten egg stench.) Your local lab can test your water for levels of calcium, magnesium, manganese, iron, copper, zinc, sodium, chloride, and lead, as well as sulfates and nitrates (nitrate contamination is particularly common on horse farms; its likely source is your manure pile). Concentrations of these minerals, if sufficiently high, can also have an impact on your horse's dietary balance, since levels of one mineral in his gut can often influence his ability to absorb another.

Some minerals, such as iron, calcium, and magnesium, are chiefly concerns because they can clog your plumbing with scale and deposits, and change the water's color and taste. Other minerals, such as lead, are more worrisome because they can build up to toxic levels.

An acidity/alkalinity test is another frequently performed water analysis. Water that tests below pH 6.5 is considered acidic, and can contribute to the corrosion of your pipes. On the other hand, if your water tests at pH 8.5 or higher, it’s alkaline, which means you probably have crusty mineral deposits on your pipes and fixtures. The pH levels in water usually fluctuate very little over time, so a sudden change can be a heads-up for damage to your well.

Blue-green algae occasionally bloom in ponds in hot, dry weather, and that can be a concern if your chief water source is above ground. Blue-green algae poisoning can cause muscle tremors, labored breathing, bloody diarrhea, liver damage, and even convulsions and death. Therefore, it’s best to remove horses immediately from a water source contaminated with algal blooms. Algal growth is usually associated with large amounts of organic material in the water, often as a result of runoff from nearby fertilized fields.

Pesticides and herbicides are another worry when it comes to water safety. Although testing for these chemicals is expensive, it might be worthwhile if you have concerns about agricultural sprays being used in your area. Likewise, if you suspect that solvents or other toxic chemicals might have leached into your water supply from a local industrial site, get your water tested.

Guidelines for Testing

If your water has an unpleasant smell or your horses refuse to drink it, test for pH, copper, lead, iron, zinc, sodium, chloride, TDS, and hydrogen sulfide.

If your water is cloudy and frothy, you should test for turbidity (cloudiness caused by mud, algae, and solids), TDS, and detergents.

If you live near a road salt storage site, a street that is heavily salted in winter, or the ocean shore, test for sodium and chloride levels.

What should you do if your water tests reveal an imbalance or contamination? Consult the lab that did your testing for their recommendations, and try these tactics:

  • Improve the protection for your well. Give it a weatherproof, sanitary seal and eliminate access for debris, insects, and rodents;
  • Eliminate the source of the contamination (i.e., remove or relocate the manure pile);
  • Treat the water with chemicals or filtration to improve its quality, if that's what your lab recommends.

When all else fails, you might have to drill a new well. Newer, deeper wells with good seals are far less problematic than older, shallower wells that might be chronically contaminated. Although the cost of a new well can be considerable, it will benefit you as well as your horses in the long run.

Two Tests for Dehydration

Two simple tests can help you determine whether your horse is suffering some degree of dehydration. The capillary refill test, which shows how well blood is flowing through the tiny blood vessels at the extremities, is performed by lifting your horse’s upper lip and pressing your thumb firmly into his gums above the incisors for a few seconds. Remove your thumb and watch how quickly the area turns from white back to a healthy pink. In a hydrated horse, the color will return within a second, but in a horse which is water-deficient, the capillary refill time will be two seconds or more. That's because when the body is short of water, red blood cell concentrations and proteins will become elevated relative to the plasma (in essence, the blood becomes "thicker"), and blood flows more slowly through the blood vessels.

The second test is often referred to as the "pinch test." It's also simple to do. Grasp a fold of your horse's skin on his shoulder, pinch and hold it between your fingers for a couple of seconds, release, and observe how long the skin takes to snap back to its normal appearance. In a horse with normal hydration, it should be normal nearly immediately, but a dehydrated horse's skin has less elasticity, so the pinched fold might remain visible for a few seconds before it slowly disappears. Note that many endurance riders (who have to keep close track of their horse’s hydration) find the shoulder to be a better place to perform this test than the skin of the neck. Remember, too, that this test might not produce accurate results in older horses, whose skin is less elastic than a younger horse’s at the best of times.

About the Author

Karen Briggs

Karen Briggs is the author of six books, including the recently updated Understanding Equine Nutrition as well as Understanding The Pony, both published by Eclipse Press. She's written a few thousand articles on subjects ranging from guttural pouch infections to how to compost your manure. She is also a Canadian certified riding coach, an equine nutritionist, and works in media relations for the harness racing industry. She lives with her band of off-the-track Thoroughbreds on a farm near Guelph, Ontario, and dabbles in eventing.

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