An Auckland family have been left heartbroken after their family dog died of suspected 1080 poisoning.

Cara Popping said her father took their dog for a walk in the Hunua Ranges on Saturday but it started vomiting about 1.5 hours later and a local vet was unable to stop the seizures.

The dog was eventually put down.

Auckland Council started on an aerial poison drop after a legal bid to prevent it dropping 1080 poison in the Hunua Ranges failed last month.

The council said the dog's death was an "unfortunate situation" but had advised people to avoid taking dogs into the operational area until the caution period was over and warning signs removed.

Popping said her father had checked the council's website to see if they had reopened tracks for walking.

In a post on the Franklin community Facebook page she said the dog never strayed from the track, but somehow managed to ingest a lethal dose.

"It wasn't a poisoned animal, but the actual pellets. She started vomiting these up 1.5 hours after starting the walk and the vets were unable to stop the seizures that followed."

The dog was then put to sleep.

She said they had spoken to council staff who apologised for what happened but said they had waited several weeks before, checked the trails and waited for heavy rain before reopening the tracks.

"Please be careful if you are walking our dog in the ranges - even if the tracks are open and the signs have been taken down, there is still this risk."

Auckland Council regional parks manager and operational lead Rachel Kelleher said the incident "highlighted the importance of thinking carefully about exercising dogs in this area".

"We have advised people to avoid taking dogs into the operational area until the caution period is over and warning signs are removed. Those who choose to bring their dogs into the area must always supervise them closely and ensure they keep them on-lead at all times, this is a requirement of bringing dogs into the park at all times."

Kelleher said they communicated "extensively" with the public and landowners or occupiers living in close proximity to the operational area on the risk to dogs as a result of direct contact with toxic 1080 baits or through secondary poisoning as a result of scavenging carcasses.

The parklands re-opened in the weekend, after being closed for the operation and a rigorous track clearance programme was completed.

Warning signs would remain in place until the caution period had been lifted – likely to be in 2019.

"As part of the operational programme, the breakdown of baits and carcasses is being monitored to inform when the risk to dogs no longer exists and the caution period can be lifted," she said.

Kelleher said she sympathised with the family being a dog owner herself.