Winter Coat Prevention

Why is my horse still growing a winter coat?
I keep a light (200 Watt bulbs) on my horse from 5PM-11PM and 5AM-7AM. I live in Alabama and the weather is still warm. Why is his winter coat coming in thick like last year?

Additional Details
Why would the light not help? And what could be wrong with the lights? He's not sick... all of the horses are starting to grow their winter coats. He had a summer coat, and his winter one is just now growing in, just like last year when I did not have a light on him. He has been in the pasture all day this summer, and is 10 years old.

Is there a reason you don't want him to have a winter coat?

The light might be too far up on the wall, or maybe his stall is big enough it isn't enough? I also blanket mine even though it's still warm - you want him to be toasty and bright lights - enough you can read in the stall easily. My lights are on 6 am to 8 am, then they go out... they are in and lights go on 6 pm to 10 pm, but as it gets dark earlier they will go in and under lights earlier...

Good luck!

I'm pretty sure the light would have to be a full spectrum bulb to simulate natural daylight. I don't think you can fool a horse's coat with a regular light bulb. Only other thing you can do is blanket early to keep it from getting any longer.

By the way, blanketing will not help slow/stop the hair growth. It's a common misconception. :) The only thing blanketing does is smooth down the hair so it looks shorter.

Obviously, if you're keeping your horse under lights, you do need to blanket once it gets cold enough but until then, blanketing and the heat from the blanket isn't going to stop hair from growing in.

I've never kept a horse under lights, but I'd assume, like MyBoyPuck said, that it'd need to be a full spectrum light.

It doesn't stop the growth, but it does help shorten the overall length of the hairs. It'll be more thick/fuzzy than wooly bear.

I don't use full spectrum lights, my mare's coat is summer glossy and short. She has finer skin and so a nicer coat that my paint gelding who has a lot of white - he already has a much thicker coat than her and they are both under lights. His isn't nearly what it was last year without lights though... so I'll take it. It is harder with some horses who have thicker coats anyway...

Hmm... I guess some horses just grow more hair than others, light or no light.