Karaka berries have been poisoning some dogs in Wellington western suburbs, the New Zealand Veterinary Association says.
Kelburn vet and association spokesman Brendan Bullen said he had treated one case of berry poisoning.
Two other cases, one suspected and one confirmed, were treated in nearby Karori.
"[The berries] are a major food source for kereru, but the fresh kernels contain the alkaloid karakin which is highly toxic to other animals."
Owing to their foraging nature, dogs often hunt out and consume berry kernels, which are currently plentiful across bushy areas in Wellington suburbs, Dr Bullen said.
The veterinary association advised dog owners to take extreme care when walking their dogs, as even older berry kernels carried toxic risk.
"Berries remain toxic for a long time, and animals can be poisoned by previous year's fruit," he said.
Karaka is native to New Zealand and found spread throughout both the North Island and northern South Island.
Its berries are orange, about 25-45mm long and produced between January and April.
Signs of karaka poisoning include:
* Weakness
* Behind leg paralysis
* Convulsions which can lead to death
Symptoms are often delayed by 24-48 hours after ingestion of the berries.