Poisoning guide
Macadamia nuts and dogs: the strange syndrome that passes
Two or three nuts can make a small dog wobble, tremble and run a fever. It looks frightening, it is rarely fatal, and it usually resolves in 48 hours.
The short version
- Toxic dose: signs are reported from around 2 g of nut per kg of body weight — roughly 2–3 nuts for a small dog.
- What happens: weakness, tremors, wobbling, vomiting and a raised body temperature. It looks alarming and is rarely fatal.
- Timeline: signs within 3–12 hours, resolving over 24–48 hours with supportive care.
- Why: the mechanism is still not fully understood, which is unusual and worth knowing.
A toxicity that is genuinely strange
Macadamia nuts cause a syndrome that veterinary toxicologists still cannot fully explain. Dogs develop hind-limb weakness, tremors, a stiff-legged gait and sometimes a fever, usually within twelve hours of eating the nuts. Then, with supportive care, they recover — almost always completely, within two days.
What makes it unusual is that the mechanism is unidentified. Unlike chocolate (theobromine) or grapes (tartaric acid), there is no agreed toxic compound. Some researchers have proposed a neurotoxin affecting ion channels in muscle and nerve tissue; others suggest a metabolic effect. The practical consequence is that treatment is supportive rather than specific.
The other unusual feature is the species gap. Macadamia nuts are a normal food for people and are not known to cause this syndrome in cats. Dogs are specifically affected, which is a useful reminder that "safe for humans" tells you nothing about dogs.
What to expect, hour by hour
- 0–3 hours: usually nothing. The dog may seem fine, which is normal.
- 3–12 hours: hind-limb weakness, reluctance to walk, tremors, wobbling, vomiting, lethargy. Some dogs develop a raised temperature.
- 12–24 hours: peak severity in most cases. This is when a vet visit is most likely.
- 24–48 hours: gradual resolution. Full recovery is the usual outcome.
The exception is a dog that eats a very large quantity, or a dog with another condition. Severe cases can develop pancreatitis from the fat load, and that is a different and more serious problem.
What treatment involves
For a dog seen within a couple of hours, inducing vomiting may reduce the dose. After that, care is supportive: intravenous fluids, anti-nausea medication if vomiting is persistent, and a quiet, cool environment for the tremors. Most dogs are sent home the same day or the next morning.
The fat content is the reason not to shrug it off entirely. Macadamia nuts are around 75% fat, and a large ingestion can trigger pancreatitis even when the neurological signs are mild.
Other nuts: why the whole category is a "no" by default
Macadamias are the only nuts that produce this specific syndrome, but they are not the only nuts worth avoiding. The general case against nuts is fat, salt and choking risk rather than toxicity.
| Nut | Risk | Why |
|---|---|---|
| Macadamia | High | Weakness and tremors; mechanism unknown |
| Black walnut | High | Mould contamination can cause seizures |
| Pecan / walnut | Moderate | Very high fat; stomach upset and pancreatitis risk |
| Almond / cashew / pistachio | Low–moderate | Choking, salt, fat; not toxic in small amounts |
| Peanut (plain, unsalted) | Low | Safe in tiny amounts; watch for aflatoxin in mouldy nuts |
Peanut butter deserves its own warning: it is one of the best treat vehicles there is, and one of the most common sources of xylitol in a dog's diet. Always read the label. If it lists xylitol, birch sugar or E967, it is not a dog treat.
What about the shells?
Nut shells are a mechanical hazard rather than a toxic one. They are hard, sharp and indigestible, and a dog that eats a handful of pistachio shells may end up with a blockage or a gut perforation. Keep shells out of reach as carefully as the nuts themselves.