Macadamia nuts are an odd entry on the toxic list. The mechanism is genuinely unknown, the dose that causes signs is unusually low for a food, and the sight of a dog affected by them is alarming enough that owners think they are watching something neurological and permanent. And then, in most cases, it passes on its own within a day or two. Both halves of that are true, and an article that only tells you one of them isn't much use.
- No. Dogs have developed clinical signs after as little as 2.4 g/kg of bodyweight.
- Nobody knows why. MSD: "The mechanism of toxicity is not known."
- Signs appear within 12 hours and usually resolve within 12-48.
- The prognosis is good. Signs are "generally mild and self-limiting", and most affected dogs recover without specific treatment.
- Dogs only. MSD: "Dogs are the only species in which clinical signs have been reported."
- Still ring your vet - partly for the nut, mostly for what it came wrapped in. See below.
The dose, which is lower than you'd guess
MSD gives two figures. The clinically useful one: "Dogs have developed clinical signs after ingesting macadamia nuts at 2.4 g/kg." And an experimental one that shows what a large dose does: "Dogs experimentally dosed with commercially prepared macadamia nuts at 20 g/kg developed clinical signs within 12 hours."
For treatment decisions, MSD puts the bar lower still, suggesting emesis be induced for ingestions above 1-2 g/kg.
Translating 2.4 g/kg into nuts. This table is our arithmetic, applying MSD's g/kg figure to an assumed 2.5 g kernel - MSD publishes the g/kg and says nothing about how much a nut weighs:
| Dog | Rough weight | 2.4 g/kg works out to | Roughly |
|---|---|---|---|
| Chihuahua, Yorkshire terrier | 3 kg | 7 g | 3 nuts |
| Miniature dachshund, Pomeranian | 5 kg | 12 g | 5 nuts |
| French bulldog, cocker spaniel | 12 kg | 29 g | 12 nuts |
| Border collie, springer spaniel | 20 kg | 48 g | 19 nuts |
| Labrador, German shepherd | 32 kg | 77 g | 31 nuts |
A small bag of macadamias is 100 g or so, which puts every dog in that table comfortably over the line if it finds one. As with every dose figure on this site: this is the amount at which signs have been reported, not a safe allowance beneath it.
What it looks like
MSD's clinical findings, appearing "within 12 hours after ingestion":
- Weakness
- CNS depression - dull, flat, unresponsive
- Vomiting
- Ataxia (wobbliness, an unsteady gait)
- Tremors
- Hyperthermia (a raised temperature)
On bloodwork, MSD also notes "mild, transient increases in serum triglyceride concentrations, lipase activity, and alkaline phosphatase activity".
The combination of wobbliness, weakness and a dog who has gone quiet is what frightens people, because it looks neurological. It is worth knowing in advance that this particular presentation has a good outlook.
MSD: "Clinical signs generally resolve within 12-48 hours", they are "generally mild and self-limiting", and "Most clinically affected dogs recover without any specific treatment." For severely affected dogs, supportive care may include IV fluids, antiemetics, analgesics or antipyretics.
This is genuinely different from grapes or onion, where the damage is cumulative and the treatment is a race. It does not mean don't call. It means that if you do call, the conversation is likely to be a manageable one.
The bigger risk is usually what the nut came in
This is the part most articles skip, and in practice it's the part that changes outcomes. Macadamia nuts are rarely eaten by a dog as plain nuts from a jar. They arrive:
- Covered in chocolate. Now you have two toxins with two different timelines, and the chocolate one is the more serious. The chocolate dose thresholds are what your vet will want to work from.
- Baked into cookies. White chocolate macadamia cookies are the classic. Add butter, sugar and sometimes raisins - and raisins are a far bigger problem than the nuts.
- Salted, in a mixed nut bowl. Which means the real question is what else was in the bowl.
- In the shell. Macadamia shells are notoriously hard, and a swallowed shell is an obstruction and a dental-fracture risk rather than a poisoning one.
Nuts in general are also very high in fat, and a sudden large fat load can trigger pancreatitis in susceptible dogs. So even for a nut with no recognised toxicity, a dog that eats a bagful has a problem worth a phone call.
What to do if they've eaten some
- Work out what else was in it before you ring, if you can do that in thirty seconds. Chocolate, raisins or a sugar-free product changes the urgency completely.
- Ring your vet. MSD supports inducing emesis above 1-2 g/kg, which for most dogs is a small handful - but that is a decision for the practice, not the kitchen.
- Note the time. Signs come on within 12 hours, so when it happened tells your vet what to expect and when.
- Don't panic if they go wobbly. It is the expected picture, and it usually passes in 12-48 hours. Keep them somewhere quiet where they can't fall down stairs, and keep your vet updated.
- Do go in if there is a tremor, a high temperature, or no improvement. "Usually self-limiting" is a statement about most dogs, not a promise about yours.
In the UK, Animal PoisonLine (01202 509 000) is a 24-hour service for owners, run by the Veterinary Poisons Information Service; there's a per-call fee. In the US, the ASPCA Animal Poison Control Center is on (888) 426-4435, 24 hours, also for a fee.
What about cats?
MSD is specific: "Dogs are the only species in which clinical signs have been reported." The topic itself is titled Macadamia Nut Toxicosis in Dogs.
As with grapes, absence of reports is not proof of safety, and it is heavily confounded by the fact that cats are obligate carnivores with no particular interest in a nut. The fat content and the choking risk apply to a cat as much as a dog. There is simply no recognised macadamia toxicity in cats to report.
Not sure about something else your pet got into?
Check any food instantly in the Supernormal app's food safety checker - or try the Pet Food Safety Checker for the foods we've covered so far.
Related guides: Pet Food Safety Checker · How Much Chocolate Can a Dog Eat? · Can Dogs Eat Grapes or Raisins? · Is Xylitol Toxic to Dogs?