Is geranium pusillum l. Toxic to horses?
This looks like the more common Dove's Foot Geranium, Geranium molle. G. pusillum is similar with fine hairs covering its fruit. Regardless, many cultivars of geranium are toxic to horses. I cannot find specific information about the above mentioned species, however. Looking at reliable publications from W. I do not see any mention of any geranium. See Protect Your Horses from Toxic Plants: https://www.nwcb.wa.gov/pdfs/Final-WSNWCB-toxic-booklet_low_res.pdf I think you're safe.
Thank you for your help. Thanks for the information on plants that are toxic to horses. I've downloaded it for future reference.