Ingestion of macadamia nuts by dogs has been associated with a
nonfatal syndrome characterized by vomiting, ataxia, weakness, hyperthermia, and
depression. Dogs are the only species in which signs have been reported.
Macadamia nuts are cultivated from Macadamia
integrifolia in the continental USA and M
tetraphylla in Hawaii and Australia. The mechanism of toxicity is
not known. Dogs have shown signs after ingesting 2.4 g of nuts/kg body weight.
Dogs experimentally dosed with commercially prepared macadamia nuts at 20 g/kg
developed clinical signs within 12 hr and were clinically normal without
treatment within 48 hr.
Within 12 hr of ingestion, dogs develop weakness,
depression, vomiting, ataxia, tremors, and/or hyperthermia. Tremors may be
secondary to muscle weakness. Macadamia nuts may be identified in vomitus or
feces. Mild transient increases in serum triglycerides, lipases, and alkaline
phosphatase were reported in some dogs experimentally dosed with macadamia nuts;
these values quickly returned to baseline. Signs generally resolve within 12–48
Diagnosis is based on history of exposure and clinical
signs. Differential diagnoses include ethylene glycol toxicosis, ingestion of
hypotensive agents, and infectious diseases (eg, viral enteritis).
For asymptomatic dogs with recent ingestion of more than
1–2 g/kg, emesis should be induced; activated charcoal may be of benefit with
large ingestions. Fortunately, most symptomatic dogs recover without any
specific treatment. Severely affected dogs may be given supportive treatment
such as fluids, analgesics, or antipyretics.
Last full review/revision May 2013 by Sharon M. Gwaltney-Brant, DVM, PhD, DABVT, DABT