We tend to notice this in periods where there is snow on the ground. Our horse’s urine turns red or a rust color once in the snow. Typically there is no need to panic (but if your horse has health concerns or you want to be sure – always reach out to your vet). However, if the stream of urine coming out of your horse is orange or red, call your vet immediately.
Horse pee often changes color, to a red, rust, or dark orange color, after being expelled due to the presence of pyrocatechines (plant metabolites) when mixed with oxygen. You may notice this year-round, but it is especially noticeable in snow or light colored shavings.