Vets are warning dog owners to be vigilant after a spate of dog poisonings, including at least one incident believed to be deliberate.
President of the New Zealand Veterinary Association's Companion Animal Society, Dr Cath Watson, said the incidents were a reminder for dog owners to be aware of the environment and what their dogs could access both at home and while out and about.
Last month a dog in Palmerston North was put down after eating meat laced with rat poison on a riverside walkway, Dr Watson said.
"There may be people that will maliciously place poisons in public places like parks, beaches, and walking tracks with the goal of deterring dogs (and their owners) from these places."
The association advised people to contact their local council or police if they suspected poison had been maliciously laid in a public place.
Dog owners needed to be careful and stay alert when taking dogs to public places, Dr Watson said.
"Do not allow your dogs to rummage or to pick up and eat anything they find.
"Preferably keep your dog on a lead in all public places. Basket-type muzzles can also be useful to prevent your dog picking things up in their mouths, while still allowing them to pant, drink, and behave normally."
Owing to their naturally inquisitive nature, effective sense of smell, and often indiscriminate tastes, dogs can be very effective at finding poisons, she said.
"This, combined with a dogs' relatively small size, often means that only a small amount of a poison needs to be ingested to have some very serious consequences, even death."
The signs of poisoning depended on the toxin, however common symptoms included gastrointestinal problems like vomiting and diarrhoea, or excessive drooling.
Other symptoms included uncontrolled shaking, seizures and reduced levels of consciousness.
It was helpful to collect any of the suspected poison and take it to the veterinarian, Dr Watson said.
At least seven dogs have become sick and suffered seizures in the past month after walking at beaches in Auckland's eastern suburbs.
Marine ecologist Dr David Taylor of the Cawthron Institute said it was likely the dogs had eaten sea slug egg sacs.
Both the slugs and sacs contain tetrodotoxin, which has been found in high concentrations on beaches in Auckland and Coromandel and was blamed for the deaths of nine dogs in 2009.
September and October is the danger season for slugs and their eggs, and it was during this period in 2009 that the dog deaths occurred.
Dog poisonings this year:
October: At least seven dogs become sick after eating toxic sea slug eggs.
September: Palmerston North dog had to be put down after eating meat laced with rat poison in a park.
September: Auckland woman's Japanese chin dog became so sick it could barely move after poisoning from pyrethrum insecticide spray.
January: A Hawke's Bay dog had to be put down after being affected by toxic algae poisoning on a river bank walk.