The most often reported birth defects are cleft palate and spinal abnormalities. The birth defects resemble those seen with lupine, with lupine being the more dangerous plant. If animals are seen ingesting poison hemlock, call a veterinarian immediately. Treatment consists of eliminating the toxin from the gastrointestinal tract and providing supportive care. If the animals become comatose but do not die, they will require intense nursing care until they recover.
Recommendations are to feed little or no hay that contains poison hemlock.
Seeds may contaminate grain-type feeds, making these feeds unsafe for consumption. Most animals will avoid poison hemlock if other forages are available. Tiny amounts may be consumed with little problems resulting, but significant consumption, especially of the seeds, will produce clinical signs and possibly death. Be sure all plants are dead prior to re-introduction of animals, since treated plants may be more palatable. Poison hemlock may be difficult to eradicate.