A pasture in northern New Zealand yields an odd sight: 45 horses dressed in identical one-size-fits-all canvas New Zealand rugs, grazing together on a rainy spring night. The scene is as startling as turning up to a holiday party to find all of your friends dressed in matching size-8 party frocks.

Utilitarian polo barns aside, it’s rare to see two horses in a field wearing identical blankets, never mind an entire herd. In part, that’s due to owners’ personal preference. A proper blanketing regime requires constant maintenance and the willingness to wrestle with unwieldy, manure-covered fabrics—so if it’s going to be a daily chore, most figure that it might as well be one that looks good. More importantly, the wide variety of winter blankets available reflects an equally wide range of horses’ needs, measurements, and readiness for weather patterns in their region.

So it’s not surprising that the unisize New Zealand rugs left some horses adrift in canvas and others with maxed-out adjustment straps. Avoid some common blanket mishaps by doing careful research and measuring first—and remember these factors when you decide how heavily to blanket your horse (if at all).

Tipping the Body Scale

Here in Vermont, many owners take a laissez-faire approach to blanketing. It’s not the “Live Free or Die” state—that’s New Hampshire—but the motto crosses state lines and, as a result, most horses sprout thick, hairy coats in lieu of blankets. If your horse grows a wooly coat naturally, great. But before you leave him au naturel for the season, first evaluate what’s underneath his hair.

“One of the most important things to consider is a horse’s body condition,” notes Scott Leibsle, DVM, Dipl. ABVP, deputy state veterinarian at the Idaho State Department of Agriculture. “The Henneke body condition system measures general physique of the horse and, indirectly, body fat. Horses with a lower body condition score simply are not as capable of insulating themselves as horses with a higher score.”

Horses are graded on a scale of one to nine, with one being emaciated and nine being obese. While a lower score represents a lesser body condition and lower fat content, it doesn’t necessarily mean a horse is underweight. Certain breeds might never score above a five and are in fine condition, but the number still represents a horse’s insulating ability.

“Horses scoring a three compared to horses scoring a seven can conceivably both maintain body heat effectively to stay warm in the winter—but the seven will have a greater ability to insulate than the three,” Leibsle says. “Foals and senior horses often need a little extra attention and a thicker blanket, as both tend to have very low body condition scores.”

Cold, Hard Facts: Temperature

Carleen Matson, a sales associate at a tack shop in Bellevue, Washington, doesn’t have to consider below-freezing temps when recommending winter blankets to customers. In this Seattle suburb, “waterproofing is the top priority,” she says. The temperature rarely dips below the 40s, but the gray, drizzly weather provides the perfect conditions for equine hypothermia.

“The most important weather-related factor to consider is the dampness in the air,” says Carey Williams, PhD, extension specialist and professor in Rutgers University’s Department of Animal Sciences, in Brunswick, New Jersey. “If it’s a dry cold, most horses will be just fine (without a blanket) as long as they have access to shelter. But if it’s 40 degrees and raining, it’s imperative to keep a horse dry.”

Keep an eye out for physical signs of prehypothermia, such as shivering, she says. If a horse is shaking—or if he’s soaked through—it’s time to bring him into shelter. And as tempting as it might be to throw the thickest blanket you have over his shivering shoulders, resist the urge.

“If you put a dry blanket on a wet horse, you’re just trapping the cold and moisture inside and preventing air from circulating underneath, making it difficult for him to dry off and warm up,” Leibsle says. “Bring him into the barn and start toweling him off next to a space heater (one that is safe and never left unattended, of course). At the very least, you need to bring him in out of the elements.”

Of course, it’s a lot easier to keep a horse warm and dry in the first place than it is to hand-towel a 1,200-pound shivering animal. All horses need an opportunity to escape the elements while turned out, and choosing not to blanket your horse (or not purchasing a suitable blanket) makes that all the more important.

Once You Start, You Can’t Stop

A horse’s natural response to shorter days and colder temperatures is to grow a thick hair coat with insulating “loft.” For this reason, riders who show their horses late into the fall often extend the hours of “daylight” through full-spectrum lighting in the barn to discourage autumn hair growth. Other owners simply start blanketing earlier in the season.

Both options can help owners avoid clipping their horses, but take care: Williams says it doesn’t take long for a horse to lose loft in his hair coat—only a few days. So if you throw a blanket on during a September cold snap, prepare yourself for a winter’s worth of blanketing. The same applies if you keep a horse stabled around the clock and only ride in an indoor arena, thus resetting his tolerance (or lack thereof) to winter weather. Once you’ve altered a horse’s natural defense against cold weather, it’s up to you to keep him warm.

“The biggest determining factor with the hair coat production is where the horse is accustomed to being housed,” Williams notes. “For example, take a horse from Northern Wisconsin and put him in Florida for the winter and he will still grow a long heavy coat for a few years. This also holds true going from South to North. Those horses will have to be treated with care because they will not produce a heavy hair coat in the first year.”

Blanket Maintenance 101

Personal preference and the factors mentioned will ultimately dictate whether you blanket your horse, but once committed to blanketing, you can’t just leave him and his pretty rug be—it’s important to check the horse and his blankets and revisit the regime regularly.

“There’s a lot of variability in deciding whether to blanket, but one thing we really try to enforce is the importance of daily maintenance,” says Krishona Martinson, PhD, University of Minnesota professor-equine specialist and extension program leader. “If you put a blanket on and never take it off until spring, you could find a horse that’s morbidly obese or a rack of bones.”

To that end, she advocates the practice of assessing body condition weekly to stay on top of weight changes.

She also recommends inspecting blanket fit and checking for rub marks daily. Brush the horse thoroughly to eliminate any dried dirt or sweat, she says, and launder blankets regularly; in her home state of Minnesota, lingering mud and other debris can cause skin irritation and rubs.

In warmer and wetter climates, like Williams’ home state of New Jersey, sweating under a too-thick blanket is a concern.

“Overheating, sweating, and damp conditions are the cause of skin fungi and conditions like rain rot or chafing,” she notes. “Horses can’t thermoregulate with a blanket on, so you need to check to be sure they don’t feel clammy or sweaty and sticky underneath. In many ways, a hot horse is much worse than a cold horse.”

Many horse owners mitigate overheating by full or partial clipping—a sound option, provided the owner is willing to invest in a variety of blanket weights for different weather conditions. And the blanketed horse’s need for warmth doesn’t stop once he’s tacked; remember to cover a clipped horse during the walk from the barn to the arena, Williams says. Warm up with a quarter-sheet, she suggests, and bring a cooler to ward off the post-workout chill.

A Full-Service Winter Wardrobe

Many horse owners approach winter blankets with the same enthusiasm with which they approach their personal shoe collections: You can never have too many.

Maria Trout, a director of merchandising at SmartPak, understands what customers are looking for when purchasing a blanket for their horse: A product that fits well and is a good value.

A horse’s wardrobe essentials will depend on where the customer lives, she says. Owners that live in colder climates might purchase a light, medium, and heavyweight turnout blanket, stable blankets, and sheets, as well as some anti-sweat sheets and coolers. Those in a warmer climates might only need a lightweight turnout blanket and stable sheets, if anything at all. Owners of ponies prone to rough pasture play often elect for blankets backed by an “indestructible” guarantee or warranty.

And, says Kara Judge, a buyer at Dover Saddlery, customers are getting savvier about blankets’ technical specs. “Customers are really doing their research about the different types of fabrics and cuts,” she says. “They’re more aware of denier numbers (a measure of thread thickness) and fill weight and, as a result, manufacturers are really having to step it up to supply the information people want to know.”

Blankets have also become more sophisticated over the past few years; unlike the old-fashioned oiled canvas New Zealand rugs, new lines include options with extended pleats and gussets designed to “self-right” the blanket after a horse rolls, interchangeable layers, and variegated insulation to prevent heat from escaping.

Despite increased owner interest in loft, Cordura (a durable synthetic fabric), and denier counts, Judge notes that sizing and proper fit still remain important. Different brands fit differently, as some are designed to accommodate the broader shoulders and rumps of Quarter Horses or Warmbloods, while others fit long, slim Thoroughbreds.

Take-Home Message

The extensive “library” of blankets available means that eventually most horse owners will find the ideal fit and weight for their horse. Most end up buying spare blankets so they can launder one while their horse wears the other; strategic layering can help reduce the number of blankets required if the insulating layer also doubles as a stable blanket. Other owners simply keep close tabs on the elements and bring their unblanketed horses inside when weather threatens.

But regardless of whether your equine is a clotheshorse that wears many blankets or a hairy specimen who grazes in the buff, remember that it’s up to you to keep him comfortable and warm.