I live in a climate where the weather is below freezing from October to April or May (Rocky Mountains!!) and i have never blanketed my horse. My horse lives in a pasture with a shelter during the winter where it is very windy and cold. My comment is that horses are smart and will get out of the cold, their bodies will aclamate to the weather by growing fur and putting a blanket on them only shelters them from the cold and prevents hair growth. I agree with Dr. Darien that human intervention means extra measures should be taken, but if you let a horse do what his body naturally does then he will weather the weather even in the extremes.
My horse grows in a good coat, has hay available most of the day, and has a paddock attached to her stall but still get cold enough to shiver. Had her throughly checked by the vet & all he could think of is because she's a t.bred mix she's more suseptible to the cold and damp. So I am constantly making the twice/day trip to take off or reduce her blanketing in the morning and putting whatever layers are needed for the night on after dinner. Someday we'll have enough land to have her at home and this will be easier.
I don't blanket and temps in the winter can/will reach below zero. I let my horses tell me. If they shiver, they get the lightest weight blanket neccesary to keep them warm. I haven't had to yet. They all go in a stall at night but the barn is well vetilated.
I have a 5 yr old anglo-arab mare that does not grow a coat at all! She shivers at 60* and below. Every year I try to hold off as long as I can, but she just gets to cold. I am afraid she will colic at 50* if I don't get her warm. when the temps get into the 30* she can have three heavy blankets on and still be shivering! She is in excl. health, is a bit chubby, and always has good free choice hay, her own run in stall, and heated water. Anyone else??
I have never blanketed my Haflinger, but I do own a blanket just in case. He always grows a good winter coat which this year he started growing in September. He is stalled at night with plenty to drink and if the temps really drop well below 30 degrees like the teens and below I give him alot of extra hay to munch on during the cold nights.
I have two 16 yr. old horses, both paints and two mini horses. They all grow heavy coats for winter. They all live outside with access to the barn at all times. I give extra hay when it's really cold. They run around the fields and play at night and I've never had a problem with cold horses. I also have a heated water bucket in case their other buckets freeze.
I have 2 beloved TB's. My mare is 27yrs old and my gelding is 25. They are outside all day then up in their 2 stall barn not enclosed at night. They get very fuzzy in the winter. Plus My gelding had Cushings so is fuzzy anyway. I still use "stable blankets" on nights whend its below 40 degrees and "turn-out blankets" when outside if below 4o degrees also. I hope I'm doing it right. I've had my mare 25 yrs. and my gld. 19 years.
Generally I don't use blankets but I have taken a liking to having a clean horse when I arrive to ride and have little time to spend scraping mud off my horse. I purchased blankets in 4 weights last spring so I'm ready to go for the winter.