Warning: toxic to horses

One important point to raise about catsear is its potential toxicity to horses. Catsear has been linked (although not proven) to cases of stringhalt, a neurological issue in horses that causes the muscles in the rear legs to contract so excessively an affected animal can kick itself in the stomach.

I’m not the best person to provide animal health advice, especially about horses (they terrify me), but I would be very careful about allowing horses to graze in paddocks with high levels of catsear.