Horse
In Ezekiel 26:11, this signifies the love of learning or intellectual things. (Arcana Coelestia 3727)
In Revelation 6:2, this signifies the love of understanding the Word. (Apocalypse Revealed 298)
In Zechariah 12:4, this signifies that the intellectual should be filled with falsities. (Arcana Coelestia 2383[2])
In general, 'a horse' signifies knowledge or understanding of the Word. In an opposite sense it signifies the understanding of the Word falsified by reasonings, and likewise destroyed from self-derived intelligence. 'A dead horse' signifies no understanding of truth from the Word.
Jeremiah 12:8-10
8
My heritage is become to me as a lion in the forest: she has uttered her voice against me; therefore I have hated her.
9
Is my heritage to me as a speckled bird of prey? are the birds of prey against her all around? Go, assemble all the animals of the field, bring them to devour.
10
Many shepherds have destroyed my vineyard, they have trodden my portion under foot, they have made my pleasant portion a desolate wilderness.