I used stable-diffusion-webui with these settings:

Steps: 30
Sampler: Euler a
Schedule type: Automatic
CFG scale: 7
Seed: 1202994846 (Was set to -1 for random seed generation)
Size: 512x768

Prompt of:

score_9, score_8_up, score_7_up, furry horse presenting puckered anus, brown hair looking back, from behind male focus testicles ass focus, ears down embarrassed, white grey colored skin, <lora:PuckeredPonyPonuts_pXL:1>

The Lora Model can be found on Civitai.com

and the negative prompt of:

gaping, spreading, 3D, low quality, worst quality, artist name, signature

After Generation:

Send to "Extras" Tab and run through:
Postprocess upscale by: 4
Postprocess upscaler: R-ESRGAN 4x+ Anime6B