Is Azolla filiculoides toxic to dogs?

Mildly. The ASPCA lists azolla filiculoides 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. Azolla filiculoides is not individually listed on the ASPCA Toxic and Non-Toxic Plants database, so a pet-safety claim cannot be confirmed; treat with caution and verify with a vet. Its symbiotic cyanobacterium has largely lost the genes for classic cyanotoxins, but as a cyanobacteria-hosting floating mat it can degrade water quality, so a pet drinking from an Azolla-covered pond is the practical hazard to monitor.

Azolla filiculoides is not individually listed on the ASPCA Toxic and Non-Toxic Plants database, so a pet-safety claim cannot be confirmed; treat with caution and verify with a vet. Its symbiotic cyanobacterium has largely lost the genes for classic cyanotoxins, but as a cyanobacteria-hosting floating mat it can degrade water quality, so a pet drinking from an Azolla-covered pond is the practical hazard to monitor. 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 azolla filiculoides.

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: Azolla filiculoides is mildly toxic to cats as well. See the full azolla filiculoides 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.