Horses autistic? Doubtful...
They are sociable -- they run in herds and have a social order among themselves. They enjoy each other's company.
They make eye contact -- they do try to look at what's around them, but they are generally far-sighted and can't see what's directly in from of their faces out to about 2 to 3 feet.
They communicate -- They are even verbal at times, although most of their "language" seems to rely on body language and scent (as it does with most animals).
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The mere fact that science may not yet adequately explain an object, event, or experience does not mean the immediate explanation should automatically default to a conspiratorial, extraterrestrial, paranormal, or supernatural cause.