Let’s assume horse guys would exist. They look like human guys, but have a tail, hoof hands and equine carpal joints on the lower thighs, so it looks like a horse leg under the lower thigh with hooves. Their genitalia also transforms, but they have no sheath. They participate in horse races where they stand on all fours and gallop like real horses, but they also move around in upright position. They are also taller than humans. Compared to the humans, they don’t need to wear shoes, and mostly run around with only very light clothing or no clothes at all. The name of the horse guy is Blaze and the story is nsfw. He gets checked out by his human trainer while he stands on all fours.

Trainer: So you’re the new horse guy? How did your transformation work out?
Blaze: It was a bit painful at first, but I’m getting used to my new body now.

Trainer: Well, you certainly look impressive. So, let’s start with your check-up. Can you get down on all fours for me?

Blaze complied, positioning himself in a horse-like stance while the trainer walked around him, inspecting his body.

Trainer: Everything seems to be in good condition. Your muscles are well developed, and your coat is shiny. How are your hooves?

Blaze: They’re a bit sore, but I’ve been taking care of them.

Trainer: Good. I’ll give you a quick hoof trimming after this. Now, let’s move on to your genitalia. Can you display it for me?

Blaze hesitated, feeling a bit embarrassed, but eventually complied, revealing his equine-like penis.

Trainer: Hmm, it’s definitely larger than a human’s. Does it function the same way, or have there been any changes?

Blaze flushed a deep red, feeling extremely exposed. “I…I’m not sure,” he stammered.

Trainer: Don’t worry, I’ll run some tests to make sure everything is working properly. Just relax and let me do my job.

Blaze closed his eyes and tried to focus on his breathing as the trainer ran his hands over his genitalia, checking for sensitivity and responsiveness. Despite his embarrassment, he couldn’t help feeling a surge of pleasure as the trainer explored his intimate areas.

Trainer: Everything checks out. You’re a healthy specimen, Blaze. Now, let’s get you cleaned up and ready for your next race.

Blaze couldn’t help feeling a bit disappointed as the trainer moved on to other tasks, wishing that the check-up could have gone on a bit longer. But he knew that as a horse guy, he had to focus on his training and performance, and not get distracted by his own sexual desires. He stood up on his hind legs and stretched, feeling the muscles in his equine legs flex and expand. Despite the challenges of his new body, he was proud to be a horse guy, and ready to take on the world.
Trainer: So you have no sheath? What is the length of your dick?
Blaze: Uh… I think it’s around 12 inches when fully erect.

Trainer: Wow, that’s quite impressive. And I suppose you don’t have to worry about a sheath getting in the way during races.

Blaze: Yes, that’s definitely a plus. It’s easier to move around and not have to worry about any extra appendages.

Trainer: Well, your unique anatomy certainly sets you apart from humans. Let’s get you cleaned up and ready for your next race.

Blaze nods, grateful for the trainer’s professional approach to the situation. Despite feeling embarrassed at times, he knew that this was just a part of his new life as a horse guy, and he was willing to do whatever it takes to perform at his best.
Trainer: What is your flaccid length?
Blaze: I’m not really sure, to be honest. It varies depending on the situation and temperature. 
Trainer: How did your dick transform? Give me a summary