Horses are hard-wired for a Fight or Flight Response to real or perceived threats. Being a prey animal, this primitive, automatic response is necessary. When threatened or afraid, the autonomic nervous system (the one that controls bodily functions without conscience effort, such as breathing and heartbeat) immediately activates causing a sudden response. Then the sympathetic nervous system initiates a jolt of adrenaline, this is in preparation of a confrontation or to flee danger. Often the response is brief–a false alarm if you will–and only a moment of heightened reaction occurs.These mares were startled and briefly concerned, but they determined the danger to be false and went back to the business of grazing.
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