Macadamia Nuts Poisoning in Dogs

Macadamia nut trees belong to the Proteaceae family, a group of flowering trees found mainly in the southern hemisphere. Several species, Macadamia integrifolia and treaphylla, are cultivated for their nuts which are frequently used in cookies and candy, or eaten by themselves. Macadamia nuts have been found to be poisonous to dogs. It’s not known what causes this toxicity, which does not seem to affect cats or humans. The Animal Poison Control received 48 calls from 1987-2001 with dogs presenting similar symptoms after macadamia nut ingestion and the results were replicated in a study. The symptoms of macadamia nut poisoning are typically non-fatal and resolve within 48 hours. Weakness is the most common sign, followed by lethargy, lack of muscle control, tremors, and fever.

Doses as low as 2.4 grams per kilograms of the dog’s weight have been found to affect muscle strength, with other symptoms such as vomiting and fever being more apparent with larger amounts. Doses as high as 62.4 grams per kilogram have been recorded. Immediate treatment can reduce absorption and hasten the passage of the nuts through the dog’s system. If a large amount was ingested, supportive treatment may also be needed to limit the severity of the symptoms and make the dog more comfortable. In most instances the condition will pass by itself, however if other toxic foods have been ingested at the same time (such as raisins or chocolate), there can be further complications.

Macadamia nuts cause symptoms of weakness and lethargy when they are ingested by dogs. This is called macadamia nut toxicity or toxicosis. Most symptoms will resolve in about 48 hours.

These symptoms could suggest your dog has eaten macadamia nuts.

• Pieces of macadamia nut in the stool
• Weakness
• Back legs collapsing
• Inability to walk
• Lethargy
• Vomiting
• Uncoordinated muscles (ataxia)
• Fever
• Tremors

Types 

Keep these products away from your dog.

• Macadamia nuts
• Chocolate covered macadamia nuts
• Trail mix
• Macadamia nut cookies
• Any other product containing macadamia nuts

These are some of the risk factors associated with macadamia nut toxicity.

• Cookies left out to cool
• Open containers of trail mix at a party
• Dogs chewing through a bag
• Owner feeding nuts to their dog
• Dogs that like to eat sweet or salty foods

Diagnosis of macadamia nut poisoning is based on the symptoms and a history of macadamia nut ingestion. If you didn’t see the incident, missing food, chewed containers, or pieces of undigested nuts in the stool can be a good indication. With macadamia nut poisoning, dogs will often have an elevated serum lipase activity on a blood test, as well as hyperthermia (higher than normal body temperature) and signs of muscle weakness are obvious on a physical examination. Further testing may be needed to check for infection or more serious poisoning like ethylene glycol toxicity, especially if there is no known history of macadamia nut ingestion. Chocolate and raisins are also toxic to dogs and more likely to be fatal than macadamia nuts, so ingestion of products like trail-mix with raisins, chocolate covered macadamia nuts, or cookies with raisins and/or chocolate could result in several concurrent toxicities.

Vomiting may be induced with cases of recent poisoning and activated charcoal may be given to reduce further absorption in the stomach. A cathartic medication like sorbitol will help to induce bowel movements and eliminate the nuts faster. Other treatments will be based on the symptoms. Medication may be given to reduce fever and make your dog more comfortable. In rare cases intravenous fluids may be necessary. If a large amount was ingested, the veterinarian may want to keep your dog for 48 hours to monitor the symptoms. Other concurrent poisoning like chocolate or raisin toxicity might need more aggressive treatment.

Almost all known cases where macadamia nut was the only toxin ingested have resulted in a full recovery. It’s still a good idea to seek treatment however, especially with large doses. Combination with another substance that is more toxic could result in a different prognosis. Chocolate or grape poisoning can both be fatal without treatment. Prevention is the best way to manage macadamia nut poisoning. Don’t leave cookies out to cool in a place your dog can reach. Keep bags on a high shelf or in a dog-proof plastic container. Dispose of old or spoiled nuts in a sealed garbage can and, if possible, train your dog to avoid unknown foods.