Can I blanket a wet horse?

No. Dry him first. Extension specialists agree on this one. Rutgers' Equine Science Center says you don't want to put a blanket on a wet horse, because wet blankets trap moisture, leave the horse colder and can lead to skin fungus if the blanket doesn't dry. Penn State Extension says to wait until the horse is dry and to take off a wet blanket so he doesn't chill. The University of Maine's blanketing bulletin says never to blanket a wet horse, whether the wet comes from riding or from rain, and to towel him dry or use a blow dryer first.

The reason is the coat. Penn State notes that a horse's coat loses its insulating value when it is wet or muddy. A blanket on top does not bring that insulation back. It just holds the dampness in.

A waterproof turnout over a damp horse in bad weather is a judgment call. A turnout is built to shed rain from outside; it isn't built to dry a coat that is already wet underneath. None of the extension sources we read recommends putting any blanket on a wet or sweaty horse, and they all point to drying first. If conditions are miserable, give him time to cool and dry in shelter, then reassess. When you are unsure, ask your vet or an experienced barn manager.

Weight matters too, and so does the cut. See what weight blanket your horse needs and which cut fits his build once he is dry and ready for one.

Walk him until his breathing is close to normal, then use a cooler if he is still sweaty. A cooler is made from breathable, moisture-wicking fabric that moves moisture away from the coat so it can evaporate. Rutgers recommends fleece or wool coolers because they wick moisture away while keeping the horse warm as his coat dries. Once he is dry, a heavier blanket can go on.

Horseware describes coolers as lightweight, breathable blankets used after exercise to wick moisture from the coat and slow cooling, and cooling sheets as helping prevent chilling while a horse dries after hard work or a bath. Check under it now and then. If the cooler becomes saturated, swap in a dry one so the drying keeps going.

Check the coat near the skin, not just the top. Long winter coats can feel dry on the surface and still be damp underneath. Run your hand under the hair behind the ears, along the neck, over the chest and shoulders, under the mane, around the girth and across the flanks.

Get him out of the wind and rain, take off the excess water, and use towels and a cooler. For rain or snow, move the horse to shelter, remove the excess water and use a cooler if needed. After a bath, a sweat scraper and towels take off most of the water, then a breathable cooler in cooler weather, with extra attention to thick-haired areas such as the chest, belly and between the hind legs. The University of Maine suggests a towel or a blow dryer.

Wet is a bigger deal in cold weather than many riders expect. Penn State Extension says wet conditions are the main concern: rain, ice and freezing rain are much more of a problem than snow, and as little as 0.1 inch of rain can cause cold stress. Rutgers adds that snow melting on a horse's back means he is losing heat, while snow that stays on his back suggests he is holding his warmth.

Call your vet if he seems off. Shivering and a horse that will not leave his shelter are the signs of too cold that the University of Maine lists. If a horse seems unusually cold, lethargic, weak or unwell, contact your veterinarian.

A rain sheet blocks water and adds little warmth. A turnout can add fill for cold as well. A rain sheet is a waterproof blanket with no fill or very little, while turnout blankets are waterproof and breathable and come in different fill weights. Horseware says a light, unfilled turnout can keep a horse clean and dry, and that a waterproof outer helps keep core body temperature steady and can protect against rain scald.

Do not send a stable blanket out in the rain. Stable blankets are not waterproof. The University of Georgia's equine program warns that a horse turned out in a stable blanket and rained on may be colder than with no blanket at all.

Waterproof ratings are not one number. Our horse blanket guide describes about 1,000 mm as handling light rain and 1,500 to 2,000 mm as handling sustained rain, our guide to keeping your horse dry says to look for 1,200 mm and up for genuine wet-weather protection, and Horseware rates every one of its turnouts waterproof to over 3,000 mm and breathable to 3,000 g/m². Check the rating on the label. Breathability matters as much as waterproofing, because a blanket that holds sweat in leaves him wet from the inside.

Rain alone does not automatically mean a horse needs a blanket, especially in spring, according to Rutgers. Check the temperature and wind chill first.

Wet and wind push up the temperature at which a horse gets cold. Rutgers cites beef cattle studies that put the lowest comfortable temperature at about 18°F for an animal with a full, dry winter coat and about 59°F if the animal is wet, clipped or in a summer coat, and the authors say it is likely similar in horses. They also note critical temperature varies with fat cover, hair thickness, acclimatization, wetness and wind chill.

None of the sources we read gives one wet-weather number for horses. They agree on the direction. Shelter matters, a dry coat insulates and a wet one does not, and age, body condition, clip and acclimation change the answer. Penn State lists a very young or very old horse, a horse that has not acclimated and a body condition score of 3 or less as reasons to blanket sooner.

Check whether water beads on the outer shell. If it doesn't, the waterproofing may need cleaning or re-treating. Sweat from over-blanketing is a common cause of dampness underneath, so a horse that feels hot may need a lighter blanket. Poor fit at the neck or shoulders can also let rain in; our blanket cut guide covers that.

Our guide to keeping your horse dry describes a simple water test. Lay the blanket flat and pour a cup of water on the shell. It should bead and hold for several minutes. If it soaks in within about 30 seconds, it is time to reproof. Follow the care label for washing and drying; our Horseware blanket guide notes the label calls for a cool wash and no tumble dryer.

Take the blanket off regularly. Penn State suggests removing a continuously worn blanket to inspect it and straighten it if it has twisted, then drying the horse's coat and airing the blanket when it comes off. A spare blanket helps through a wet week, since you can rotate instead of fighting a damp one.