Whether processed or fresh, macadamia nuts can cause problems for your pet. Dogs are the only species in which toxicity has been reported.

Signs and symptoms of toxicity: weakness, depression, vomiting, lack of muscle control, tremors, joint pain, difficulty walking, hind limb weakness, elevated body temperature, and mild abdominal pain. These signs usually occur within 12 hours of ingestion.

Toxic Consumption: Typically clinical signs of toxicity are seen at > 2 g/kg (0.8 g/lb) . However, as little as 0.7 g/kg (0.3 g/lb) may cause signs of toxicosis.

For all considerations below, an approximation of 12 nuts in 1 ounce of macadamia nuts was used.

Dogs: Macadamia Nut Toxic Consumption
X-Small Yorkie, Chihuahua	Small Pug, Boston Terrier, Poodle	Medium Beagle, Scottish Terrier	Large Boxer, Cocker Spaniel	X-Large Retriever, German Shepherd	XX-Large Great Dane, St. Bernard
1 – 10 lbs. (0.45 – 4.6 kg)	11 – 25 lbs. (5 – 11.4 kg)	26 – 40 lbs. (11.8 – 18.2 kg)	41 – 70 lbs. (18.6 – 31.8 kg)	71 – 90 lbs. (32.3 – 40.9 kg)	91 – 110 lbs. (41.4 – 50 kg)
> 0.1 nuts	> 1 nut	> 3 nuts	> 5 nuts	> 9 nuts	> 12 nuts

References:
– Osweiler, G, et al. (2011). Blackwell’s five-minute veterinary consult clinical companion. Small Animal Toxicology. [Kindle version]. Retrieved from Amazon.com
– The Merck Veterinary Manual. Macadamia Nuts. Available at: http://www.merckmanuals.com/vet/toxicology/food_hazards/macadamia_nuts.html. Accessed August 31, 2014.