What does it mean if a horse isn’t alert in his eyes?

I've heard its a bad thing when talking conformation wise but what does it mean if a horse isn't looking alert?

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Answer:
Fever and hormone imbalances are two major causes for a dull eyed appearance. Even in the absence of fever, some illnesses will cause the horse such distraction that you'll see that look in the eyes. Dehydration is a cause, but fever usually accompanies dehydration, so the cause of the appearance might be the fever. Some metabolic disorders other than hormone related can also affect the appearance of the eyes, which involves the body chemistry being out of whack.

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Answer:
in my experience, alert eyes refer to health. alert eyes are clear, bright, and interested looking, not cloudy or listless. dull eyes can be a sign of a health problem. your horse should always have alert eyes, and if he doesn't, start looking for other signs of sickness right away

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Answer:
The horse will just be staring blankly and it will look like it isn't really “there”. A horse might look unalert in his eyes if he is fatigued, old, sick, mentally slow, or if he has been given a sedative….ok, well I hope this helps!!

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Answer:
Not paying attention, dull