So I've decided to try my hand at anthropomorphic clop. I need insight on what an anthropomorphized mare would go through while in heat.

3826412
Well, since they are Anthropomorphic, I guess the first question that needs to be answered to answer yours is: How much 'pony-like' do you what this mare to be vs 'non-pony-like/human-like?'

As an author, you do have the choice of the sliding scale of "boy, do I feel horny today. Better get back to work." to "Grab the first stallion you see and lock the doors."

3827030
I have an idea of the psychological aspects. I need help in describing the physical sensations. The reproductive side leans more toward the pony-like side of things.

3827544
Well typically there's a "tightening sensation"/jolt that runs through the mares entire body that makes them feel needy, and makes each inch of their body want to be touch/felt to the point it hurts. And at the increase heart rate at the sight/thoughts of something they find attractive. And of course, after a moment of intimacy with person/or after a long period of loneliness, a need to feel something that can fill the 'unfilled, aching, empty space' inside them.

Some things that should help from the The Erotic Clop Thesaurus:

DESCRIPTIONS OF ESTRUS
warmth/heat/burning/aching/ in nethers
intense desire for a mate/sex
lust/arousal/desperation
behaving irrationally/aggressive
instinctual/primal urges
fantasizing
whining
hormonal
spikes/surges of arousal
moodswings
sweating
panting/gasping/blushing
frazzled look
wild/dazed/clouded/distracted/inebriated feeling
world enveloped in a fog/haze
winking
thick, damp, cloying scent of arousal in air
increased vaginal secretions (to various levels depending on situation)
flushed, swollen labia
twitching/thrashing tail
increased sensitivity in vagina
extreme relief upon male ejaculation/feeling of a fire being quenched

3827620
Thanks.

3827787
No problem.
If you find yourself needing any more help with your clopfic, I'm sure I or someone else in this group would be happy to help.