Macadamia nut toxicosis is a syndrome that occurs in dogs after ingesting macadamia nuts. It is characterized by vomiting, weakness, hyperthermia, and CNS depression. No specific treatment is typically required because clinical signs generally are mild and self-limiting; dogs with more severe clinical signs may benefit from administration of IV fluids, analgesics, or antipyretics.
Ingestion of macadamia nuts by dogs typically causes a nonfatal syndrome characterized by vomiting, ataxia, weakness, hyperthermia, and CNS depression. Dogs are the only species in which clinical signs have been reported.
Etiology of Macadamia Nut Toxicosis in Dogs
Macadamia nuts are cultivated from Macadamia integrifolia in the continental US and M tetraphylla in Hawaii and Australia. The mechanism of toxicity is not known. Dogs have developed clinical signs after ingesting macadamia nuts at 2.4 g/kg. Dogs experimentally dosed with commercially prepared macadamia nuts at 20 g/kg developed clinical signs within 12 hours and were clinically normal without treatment within 48 hours.
Clinical Findings of Macadamia Nut Toxicosis in Dogs
Within 12 hours after ingestion, dogs with macadamia nut toxicosis typically develop weakness, CNS depression, vomiting, ataxia, tremors, or hyperthermia. Tremors may be secondary to muscle weakness. Macadamia nuts may be identified in vomitus or feces.
Mild, transient increases in serum triglyceride concentrations, lipase activity, and alkaline phosphatase activity were reported in some dogs experimentally dosed with macadamia nuts; these values quickly returned to baseline.
Clinical signs generally resolve within 12–48 hours.
Diagnosis of Macadamia Nut Toxicosis in Dogs
Clinical evaluation
History of exposure
Diagnosis of macadamia nut toxicosis is based on history of exposure and clinical signs.
Differential diagnoses include bromethalin rodenticide toxicosis, ivermectin toxicosis, ethylene glycol toxicosis, and infectious diseases (eg, viral enteritis).
Treatment of Macadamia Nut Toxicosis in Dogs
Supportive care in more severe cases
For dogs with recent ingestion of macadamia nuts at > 1–2 g/kg, provided that patients remain clinically normal, emesis should be induced using one of the following drugs:
ropinirole (2.7–5.4 mg/m2, in the conjunctival sac, repeated in 20 minutes)
apomorphine (0.03–0.04 mg/kg, IM, IV, SC, or in the conjunctival sac, although IV is preferred due to its rapid onset of effect)
3% hydrogen peroxide (1–2 mL/kg, PO, maximum of 45 mL)
Note: Use of emetic drugs licensed for use in dogs should be prioritized over extra-label use of other drugs to ensure emesis and to avoid unintended adverse events.
The efficacy of activated charcoal is unknown and is generally not recommended.
Most clinically affected dogs recover without any specific treatment.
Severely affected patients may be administered supportive treatment, such as IV fluid therapy, antiemetics, analgesics, or antipyretics.
Key Points
Macadamia nut ingestion by dogs can lead to muscle weakness, CNS depression, vomiting, and hyperthermia.
Clinical signs are usually mild and self-limiting, requiring no treatment; supportive care may benefit dogs experiencing more intense clinical effects.
For More Information
Also see pet owner content regarding macadamia nut poisoning.
