(this drawing is a rough, i might come back later and re-paint it if i have time ;)

Untying his reins Annie let her stallion loose, now unleashed he immediately set about the zebra's luscious cheeks licking his hole while snorting uncontrollably. Down below the zebra's dangling cock throbbed harder and harder until it hung horizontal, the horse's hands wondered as he lubricated his partners hole. Suddenly grasping the zebra's hard heavy cock the horse's body jolted and shuddered as his hanging cock hardened and pulsed upwards.
With his anus drenched the zebra felt a thick finger slide over his clenched meaty hole, feeling that finger slip in, his muscles quivered and relaxed around it, it slid further in, suddenly another finger joined the other stretching his anus wider.
The fingers were drawn out, and a far larger and thicker limb forced its way in filling their place, for the first time the zebra whinnied, as the cock slid further and further the zebra panted and grunted seemingly loosing control of his breath. As the throbbing limb reached the end of his rectum it burst though the sphincter and slid even further. The zebra's eyes rolled back in ecstasy as he allowed the cock to plunge back and forth, after a brief while a great convulsing feeling took over his body his vision blurred and his head swam in the heat of the motion. unable to control himself he began moaning and snorting With every breath his spread hips buckling and swaying back and forth to the rhythm.
The horse began to feel his cock throb as a fantastic burning itch worked its way from his balls to the very tip of his thrusting member, the feeling blazed deeper and deeper until at last! it burst forth pumping its hot slippery juice directly into the very fathoms of the Zebra's body.
The two of them shared a moan as the zebra slumped over finally able to gather his breath. unsheathing his cock the horse moved away allowing the zebra to recover, to her surprise Annie couldn't help but notice it was still as solid and vertical as it was before it entered its hole.
Thinking to herself she stared longingly at it. "good boy" she said in a breath, looking at the glistening cum flowing forth from the zebra's puckered gaping anus, she knew that she had started truly something substantial...