Safe, non-toxic varieties include the Chilean wine palm (Jubaea chilensis Baill.), which grows in U.S. Department of Agriculture plant hardiness zones 9 to 10a, the apricot-flavored jelly palm (Butia capitata Becc.), grown in USDA zones 8b to 10b, the areca palm (Dypsis lutescens), grown in USDA zones 10 to 11, and the Canary Island date palm (Phoenix canariensis), grown in USDA zones 9a to 11. Another popular palm with orange berries grown in USDA zones 9b to 11, the queen palm (Syagrus romanzoffiana), hasn't built up toxicology data in either direction.
Two varieties of palm trees that produce some orange color in their fruit are significantly dangerous to both dogs and humans. The bamboo palm (Chamaedorea seifrizii), grown mainly in USDA zones 10 to 12, produces highly toxic orange fruit and should never be ingested. The second variety, the sago palm (Cycas revoluta), produces bright orange seeds that protrude from scalelike leaves in USDA zones 8 to 10. All parts of the sago palm are inedible, but the seeds contain the highest concentration of toxins.
In cycads like the sago palm, three toxins affect animals. Cycasin irritates the intestines and stomach and causes liver injury. A neurotoxic amino acid, beta-methylamino-L-alanine, causes neurological diseases that affect memory and muscle movement. The last toxin, as yet unidentified, causes damage to the central nervous system, including limb paralysis in some animals.
Dogs that ingest toxic palm fruit may develop symptoms between 24 and 48 hours following ingestion. Possible signs include often-bloody vomiting, black stool, yellowing membranes in the eyes and mouth, excessive thirst, diarrhea, bruising, impaired blood clotting and loss of appetite. Symptoms last up to nine days, and liver damage, liver failure and death can follow if they are untreated. Some dogs may be asymptomatic, but if fruit ingestion was witnessed, treatment is necessary.
If a dog ingests orange fruit from a toxic palm tree, whether or not he shows symptoms, contact a veterinarian immediately. There is no antidote for palm tree toxins, so the doctor will mainly attempt to alleviate symptoms and flush the toxins out of the system. Asymptomatic dogs are typically at a higher risk; however, if treatment begins early, a full recovery is possible.