What's in Your Horse's Water?

How to keep your horse’s life source pathogen- and debris-free

For Florida boarding barn operator Clarissa Cupolo, a good, steady rain is a welcome sight. It means the 14 horses residing on her property have lush paddocks to graze. But excessive rainfall can present a set of horsekeeping challenges, particularly when it comes to horses’ drinking water and any standing water in their environment. So each morning Cupolo inspects every trough in every paddock to make sure it’s free of algae and debris—cleaning it if it’s not—and filled to the brim. Then she examines the waterlines and spigots that feed the troughs to make sure they are in place and in good working order. Finally, she peruses the pond in one paddock for algae blooms and insect activity.

“There is either too little rainfall or too much of it, so we’re always compensating for something,” she says.

Cupolo is mindful of water availability and vulnerability to environmental pressure, but most horse owners generally only think about these factors in a crisis—such as after a natural disaster. But they should pay them more attention, says Rebecca McConnico, DVM, PhD, professor of Agricultural Sciences and Forestry at Louisiana Tech University, in Ruston, and a member of the Louisiana State Animal Response Team (LSART).

“Basically, water is essential,” she says. It’s an irreplaceable nutrient that aids digestion, helps maintain body temperature, keeps joints lubricated, helps cushion a horse’s nervous system, and maintains an elastic skin tone.

And horses need lots of it every day. Authors of a PennState Extension publication note that the average-sized 1,100-pound horse consumes 5-10 gallons of water daily. Horses that work harder, especially during periods of warm weather, might require more water to stay properly hydrated. Meanwhile, lactating mares might consume 20-25 gallons of water a day.

Water is so critical that horses deprived of food but not access to drinking water can survive up to 20 or even 25 days, the PennState authors note. By contrast, horses without access to water might survive only three to six days. After two days they might refuse to eat and show signs of dehydration, colic, or kidney failure.

Therefore, it’s crucial that owners provide horses with free-choice access to fresh, clean water. And depending on where they live, they might face unique challenges in doing so.

What's in Your Horse's Water?

Keeping Water Sources Clean

In U.S. climates that experience long winters, owners grapple with frigid temperatures that freeze pasture ponds and troughs. They struggle to keep waterers and troughs well-filled and ice-free. Then there are the warmer months of the year, where all manner of things might bloom or contaminate water, whether surface water or buckets and troughs.

For instance, cyanobacteria generated by blue-green algae blooms on the surface of pasture ponds and in streams and creeks that flow through or near pastures can threaten natural water resources. Also known as pond scum, the blooms produce natural toxins that, if ingested, can poison horses.

In general, most horses will choose clean, fresh water—that is, water in man-made containers—over pond, stream, or creek water that might contain algae, bugs, or bacteria from dead animals decomposing upstream, says Liz Steele, DVM, of Steele Equine Veterinary Services, in Zolfo Springs, Florida. “But some horses will choose to drink water from natural water sources for whatever reason,” she adds.

In those cases Steele recommends owners erect fences to separate horses from natural water sources. She suggests giving horses an alternative to natural water sources by placing troughs filled with fresh, clean water in their paddocks. But those can create water issues of their own, she says.

“I think that the everyday factors, such as keeping critters out of water troughs and keeping them free of (algae), are owners’ biggest water concerns,” she says.

Troughs are also vulnerable to algae infestations (blue-green as well as more harmless varieties), making the water less desirable to your horse and potentially reducing his intake.

Then, of course, there are the disease threats that can lurk in troughs and buckets if they aren’t cleaned and refilled frequently.

“The bacteria from decaying mice, birds, even raccoons can contaminate water in open troughs,” says D. George Anderson, of Bar-Bar-A automatic ­livestock waterers, referring to the Clostridium botulinum neurotoxin that causes often-fatal botulism.

“Putting a nonpressurized wooden post or rail in the tank with one end up against the rim provides an escape route for small animals that fall in the trough,” suggests Ragan Adams, DVM, MA, veterinary extension specialist at Colorado State University’s College of Veterinary Medicine & Biomedical Sciences, in Fort Collins.

Troughs also provide disease-spreading mosquitoes with the standing water they prefer for breeding. Mayflies or caddisflies attracted to lights in the barn can fall into water buckets and troughs, possibly introducing the organism that causes Potomac horse fever (a disease caused by a bacterium found in some parasites that infect aquatic snails and these flies). And if urine of a leptospirosis-infected animal contaminates water sources, it can put horses at risk for contracting this bacterial infection that can result in abortion, chronic uveitis (eye inflammation), and/or kidney failure (though horses are more likely to pick this up from standing water on the ground—ponds or floodwaters, for instance).

Keeping troughs free of contaminants takes a combination of vigilance and effort. Steele says owners should inspect water troughs daily for debris, algae, or rodent and other small animal remains. She recommends cleaning troughs weekly simply using elbow grease and sunshine.

“I’m not in favor of using chemicals or bleach to clean troughs because there might be some kind of chemical residue left from using them,” she says.

Instead, she advises owners to scrub the inside of troughs using water and a stiff brush, turning them upside down to drain and leaving them in the sun for several hours to dry before refilling.

“That should kill just about everything,” she says.

Installing automatic watering systems in paddocks provides another alternative, says Alayne Blickle, founder and president of Horses for Clean Water, an Idaho-based program that helps owners manage their land for better horse and ­environmental health. While automatic watering systems still require routine cleaning, Blickle believes they can be more efficient and ecologically friendly than troughs.

“Automatic watering systems conserve water because they only use as much water as your horse can drink,” Blickle says. “Another advantage is that since water is circulating and not stagnant, it won’t provide a habitat for mosquitoes—and you don’t waste large volumes of water when you clean them as you might when dumping a stock tank.”

Anderson recommends placing automatic watering systems near paddock fence gates so caretakers can access the systems easily for efficient maintenance.

Meanwhile, Blickle says owners can facilitate cleaning by choosing systems with moderate-sized water pans.

“A large one will quickly get dirty and full of algae, requiring you to clean and dump it frequently,” she says.

Standing Water: Fertile Ground for Mosquitoes

In most areas of the country, mosquitoes come on the scene during summer to deposit their eggs in standing water—in ponds, along the edges of streams, and in any water-harboring receptacle. This puts horses at risk for viral insect-borne diseases such as the nearly always fatal Eastern equine encephalitis (EEE) and West Nile virus (WNV), which has about a 30% fatality rate. Both attack a horse’s central nervous system and are transmitted when a mosquito bites a horse after feeding on an infected animal, usually a bird.

While the American Association of Equine Practitioners (AAEP) has included both EEE and WNV among the group of core vaccinations it recommends all horses receive, you should still take steps to limit vaccinated horses’ mosquito exposure by eliminating breeding grounds. Some owners try to reduce their horses’ risk of contracting a mosquito-borne illness by stocking natural ponds with mosquito-eating fish, such as koi or bluegills; introducing beneficial insects such as dragonflies that also feast on mosquitoes and their larvae; and establishing riparian zones (boundaries containing shrubs and grasses) that keep water-borne pests and their larvae in ponds and away from areas used by horses.

“I prefer a multiprong approach: Decrease the mosquitoes in the environment, protect your horse with fly sheets and masks, and follow the AAEP core vaccination recommendations,” says Ragan Adams, DVM, MA, veterinary extension specialist group coordinator at Colorado State University’s College of Veterinary Medicine & Biomedical Sciences, in Fort Collins.

—Pat Raia

Weather’s Effects on Water

Most often, owners’ concerns about water revolve around day-to-day resource management and pest control. But when they involve flooding and drought, those concerns become critical.

For Cupolo the effects of drought are ongoing. Lack of rain frustrates her efforts to keep paddocks green with moisture-packed grass, so her horses are more likely to consume the sandy soil; this increases their risk for colic.

“We use sprinklers to keep grass growing in the paddocks, but the horses can’t help but pick up the sand when they graze,” she says. “That’s why they get a psyllium supplement every Friday.”

Steele says such a supplement helps prevent sand impaction colic by collecting sand and moving it though the digestive tract.

“The psyllium actually binds with the sand, turns it into a kind of Jell-O blob, and pushes it through the gastrointestinal system and out the back end,” she says.

Horses must have free access to clean, fresh water, for psyllium to work, Steele adds.

While drought has challenged horse owners on the East Coast, West Coast, and everywhere between, others have struggled to keep their horses healthy when floodwaters rise. Among those is McConnico, who along with other LSART members helped rescue horses during the Baton Rouge, Louisiana, floods in 2016.

“There are all kinds of things that pop up in floodwaters, including tires, vehicles, diesel fuel, oil, and algae,” she says. “And horses are standing in this water sometimes for an hour, sometimes for a day or more, and they are drinking it. Storm-surge associated flooding can contain saltwater, along with many other hazardous materials which should not be ingested by horses or other livestock.”

In these scenarios you might need to bring in an outside source of clean water for horses. “Generally, the alternative is bottled water,” McConnico says. “That’s why if you are in a flood zone, you want to hook up with someone who supplies bottled water by the truckload.”

Whether in a flood or drought zone, McConnico recommends horse owners have local or county health authorities or a university extension service test their water sources for pollutants—­ideally, routinely, but definitely post-flood, fire, or other natural disaster. Testing measures the amount of dissolved solids (TDS) present in a water sample. The U.S. Environmental Protection Agency (EPA) considers levels below 1,000 parts per million (ppm) TDS to be excellent for livestock, and levels between 1,000 and 5,000 ppm to be satisfactory.

Meanwhile, McConnico has her own rule of thumb concerning the integrity of water resources.

“Basically, if you won’t drink it, your horse shouldn’t drink it, either,” she says.

Ultimately, Adams believes the key to owners’ concerns about water is simple: “The No. 1 thing about water is that horses get enough,” she says. “And that it is fresh and clean.”