Onion
Not listed does not mean safe.
Colin · CC BY-SA 3.0 · Photo source · shows: Onion
Evidence by animal
| Animal | Verdict | Basis | Plant parts | Sources | Evidence link |
|---|---|---|---|---|---|
| Companion mammals | |||||
| Cats | Cats: ⚠ Toxic | Not specified | ASPCA Toxic and Non-Toxic Plants Poison control | evidence | |
| Dogs | Dogs: ⚠ Toxic | Not specified | ASPCA Toxic and Non-Toxic Plants Poison control | evidence | |
| Horses & livestock | |||||
| Horses | Horses: ⚠ Toxic | Not specified | ASPCA Toxic and Non-Toxic Plants Poison control | evidence | |
| Small mammals | |||||
| Guinea pigs | Guinea pigs: ⚠ Toxic | Oxbow: on the "never feed" list | Not specified | Oxbow Animal Health Veterinary reference | evidence |
| Birds | |||||
| Pet birds (general) | Pet birds (general): ⚠ Toxic | AAV: listed as toxic to pet birds; VCA: on the may-be-poisonous list (not specifically reported) | Not specified | Association of Avian Veterinarians Veterinary reference VCA Animal Hospitals Veterinary reference | evidence |
| Finches | Finches: ⚠ Toxic | VCA: reported toxic to birds (finch guide) | Not specified | VCA Animal Hospitals Veterinary reference | evidence |
Source excerpts
ASPCA Toxic and Non-Toxic Plants — Cats, Dogs, Horses
poison-control
Toxic to Dogs, Toxic to Cats, Toxic to Horses
Source checked 2026-10-27
Read original sourceOxbow Animal Health — Foods Guinea Pigs Should Never Eat — Guinea pigs
veterinary-reference
Oxbow: on the "never feed" list · Oxbow Animal Health "foods guinea pigs should never eat" (veterinary-reviewed article from a pet-food maker, not a poison-control centre).
Allium spp of plants include garlic, onions, chives, and leeks with garlic and onions being most reported for toxicosis.
Source checked 2026-10-27 (source updated September 5, 2025)
Read original sourceAssociation of Avian Veterinarians — Protecting Your Pet Birds From Household Dangers — Pet birds (general)
veterinary-reference
AAV: listed as toxic to pet birds · AAV leaflet: Allium family "such as onions and garlic".
Plants in the Allium family such as onions and garlic are toxic to many species, and ingestion can lead to anemia and liver damage.
Source checked 2026-10-27
Read original sourceVCA Animal Hospitals — Plants That Are Toxic to Birds — Pet birds (general)
veterinary-reference
VCA: on the may-be-poisonous list (not specifically reported) · VCA: on the list of "many plants which may be poisonous to birds, although it is not exhaustive"; no asterisk, so not specifically reported harmful in birds. VCA notes information is often inferred from other species.
Onion
Source checked 2026-10-27 (source updated Aug 14, 2026)
Read original sourceVCA Animal Hospitals — Feeding Finches — Finches
veterinary-reference
VCA: reported toxic to birds (finch guide) · VCA finch feeding guide: foods "reported to be toxic" to birds. About the food (avocado, onion) as written for birds in general.
Avocado and onions have been reported to be toxic and should never be fed to a bird.
Source checked 2026-10-27
Read original sourceNo evidence collected in this database yet for 17 animals
No evidence collected in this database yet for: Rabbits, Hamsters, Rats, Mice, Chinchillas, Ferrets, Parrots (macaws, Amazons, African greys…), Budgerigars (budgies), Cockatiels, Lovebirds, Canaries, Pigeons & doves, Tortoises, Bearded dragons, Iguanas, Goats, Chickens & other poultry
No supported claim has been collected for these animals. Not listed does not mean safe; do not infer suitability from another species.
Toxic principles
ASPCA, as published: N-propyl disulfide Source
Clinical signs
ASPCA, as published: Vomiting, breakdown of red blood cells (hemolytic anemia, Heinz body anemia), blood in urine, weakness, high heart rate, panting Source
Last verified (ASPCA record): 2026-10-27. Source access dates and limitations.
Similar plants (same family)
Shared family is not a shared verdict. Check each plant separately.