http://www.aspca.org/pet-care/animal-poison-control/horse-plant-list
http://poisonousplants.ansci.cornell.edu/php/plants.php?action=display&ispecies=horses
http://www.omafra.gov.on.ca/english/livestock/horses/facts/poison.htm
https://njaes.rutgers.edu/pubs/fs938/
