COLT is applied in the Bible not to the young horse, but to the young ass, and once (Gen_32:15) to the young camel. Outside the Bible it is not applied to the young of any animal but the horse.
Hastings' Dictionary of the Bible
Edited by James Hastings, D.D. Published in 1909
Gen_49:11 (b) This picture is presented to teach us that GOD's people, especially young Christians, are to be bound to the Lord and to His words. The vine represents the Lord. They are bound to the vine so they will be well nourished and become fruitful.
Mar_11:2 (c) This type represents a young Christian who is loosed from the world and its evil habits in order to be the servants of the Lord JESUS, to take Him wherever He wants to go.
Wilson's Dictionary of Bible Types
press 1957.
Colt
(prop. Per, עִיִר, a young ass, Jdg_10:4; Jdg_13:14; Job_11:12; Zec_9:9; πῶλος, Mat_21:2, etc.), spoken of the young of the horse, ass, or camel. SEE FOAL.
CYCLOPEDIA OF BIBLICAL, THEOLOGICAL AND ECCLESIASTICAL
press 1895.