Is Equisetum hyemale toxic to dogs?

Mildly. The ASPCA lists equisetum hyemale as mildly toxic to dogs — a chewing dog typically gets mouth irritation, drooling, and vomiting rather than a medical emergency, but it is still best kept out of reach. The ASPCA lists Scouring Rush (Equisetum hyemale) and Field Horsetail as toxic to horses via thiaminase, which destroys thiamine and causes weakness, tremors, staggers and potentially death after prolonged grazing. Dogs and cats are not listed as affected, but because the plant contains an established toxic principle, treat ingestion with caution and verify with a vet.

The ASPCA lists Scouring Rush (Equisetum hyemale) and Field Horsetail as toxic to horses via thiaminase, which destroys thiamine and causes weakness, tremors, staggers and potentially death after prolonged grazing. Dogs and cats are not listed as affected, but because the plant contains an established toxic principle, treat ingestion with caution and verify with a vet. Signs usually appear soon after chewing rather than hours later — watch for drooling, pawing at the mouth, vomiting, loss of appetite, or unusual lethargy after your dog has had access to equisetum hyemale.

Stay calm. Remove any plant from your dog's mouth and take the plant away. Note how much was eaten and when, and do not induce vomiting unless told to. Call your vet or the ASPCA Animal Poison Control Center on (888) 426-4435 and follow their advice; a leaf or photo helps the vet treat it correctly.

The ASPCA classification Growli uses applies to both cats and dogs: Equisetum hyemale is mildly toxic to cats as well. See the full equisetum hyemale pet-safety guide for both species.

For a similar look without the risk, see the best dogs-safe plants list — every plant there is ASPCA non-toxic to cats and dogs.