Uncle takes the lead and you walking behind are naked but from having lived being a horse and naked the is no sense of feeling wrong. Three well meaning brave fellows walk along behind you, they the men trying to stop a draft horse from walking away from where its master/owner had placed the beast and his great wagon. Like what you were but in accordance to their family heritages, they being Europeans, became then as Belgian draft horse stallions. The trip through time had mellowed the three from their fearing of life and arriving, as they were then horses, each felt an odd sense of delight they would never fully understand.
Uncle hears a sound and he turns and you turn to see there the first stallion in the line of three to take a body stretched pose and is the masturbating his huge size cock.
As the cock spews its load, so then does the other two horses to begin what their pal did, as each is depleting their pent human semen, assuring they shall remain horses, stallions for the rest of their lives!