For those who are interested the following is a summary of principal poisons used in pest control in NZ, and the risks to dogs taken into the bush
Cyanide paste is used to kill possums. It is green in colour and applied in 'pea sized' baits on rocks or tree turnks. It is normally used in conjunction with a lure, which will either be a white or transparent paste over the bait, or a small amount of scented flour / icing sugar. Cyanide paste baits are very difficult to spot - even if you know they're there.
One bait will kill 2 average (14kg) dogs - so the bait istelf is dangerous to any dog whilst the poison is still active.
Carcasses of animals killed with cyanide pose some risk. The amount of cyanide absorbed into the body of a possum should not kill a dog, and no dog deaths have been reported from dogs eating skilled and gutted poisoned possum carcasses (though I would not recommed trying this). However, the stomach may well still contain the full poison bait, and so some danger is present if dogs eat the intestines. 3 fatalities have also been reported from dogs licking cyanide paste from the mouths of dead possums.
Duration of risk
Cyanide paste remains dangerous for 3 months in dry conditions, or 3 days of heavy rain. Check the date of application on the signs: signs are often left up well after the danger period has passed. Since danger comes mainly from the bait, or exposed cyanide on recent carcasses, the risk after the area has received a good rain or after 3 months will be low: but keep dogs nearby to ensure they are not taking carcasses.
Symptoms / treatment
Dogs will become dizzy, and be seen staggering or lying down. Large doses will result in rapid loss of consciousness.
The antidote to cyanide (amyl nitrate), whilst effective is not publicly available without a license as it is open to abuse. The window to administer this is very short - under a minute - so seeking help is not an option. The best antidote to cyanide for people or dogs in the absence of amyl nitrate is to run up a hill. Get the heart beating as hard as possibe, and your dog (or you) will have the best chance of survival. Don't let your dog lie down: keep them running if possible.
Whilst carcasses pose some risk, the highest risk comes from the bait - incidents of poisoning can even occur when dogs step on exposed baits and then lick their feet. Avoid poisoned areas until they have had a good dose of rain, and even then keep dogs under close control. Areas can be considered safe 3 months after application.
Encapsulated cyanide (feratox):
Feratox is used for possum control. It is generally applied as single baits in blue bags stapled to trees, or multiple baits in plastic or cardboard bait stations. The baits are generally embedded in blocks of peanut butter, or cereal, often lured with sprays such as aniseed, five-spice etc - which are fortunately not attractive to dogs.
One bait contains 0.1g of cyanide, which is half of the lethal dose for a 14kg dog. As such, dogs are relatively safe from encapsulated cyanide baits. However, for small dogs the risk will be more significant - and even for larger dogs some risk remains from the bait - especially where bait stations have been used and contain multiple baits.
Feratox pellets generally get 'chewed' by possums, releasing their poison as cyinide gas, which disperses rapidly. In the event that they are swallowed intact, the full bait may be present in the stomach / intestines. As such, a low risk is presented by carcasses poisoned with encapsulated cyanide.
Encapsulated cyanide is more resistant to rain than cyanide paste, and will continue to contain poison for up to 4 months, even in wet conditions.
Symptoms / treatment
As per cyanide paste.
Encapsulated cyanide poses the lowest risk to dogs. Carcasses are very unlikely to kill dogs, so the main risk comes from the bait itself: a fresh bait may kill even a large dog, if consumed. NEVER feed your dog peanut butter: basic aversion training to peanut butter is advised if dogs are used frequently where feratox bait is present.
Risks will be further lowered after a long period of heavy rain, and areas can be considered safe after 4 months.
1080 (Sodium Fluoroacetate)
1080 is most commonly applied aerially as carrot, or ceral bait. Oats are also used. In such operations, poison is distributed evenly over large areas of ground, and will be found on the ground. All baits will be died green.
1080 jam is also applied by hand, and consists of a green died jam, generally applied to rocks or tree-trunks.
1080 pellets are also used in plastic and cardboard bait stations, and in white bait bags stapled to trees.
1080 is more dangerous to dogs than to almost any other animal - 10 times more so than a rabbit, and 4 times more so than a possum. This means that even at minumum doses, the poison in a 1.5kg rabbit carcass killed by 1080 is sufficient to kill a 15kg dog. The poison will be mostly in the intestines, so the biggest risk comes from that part of the carcass.
12mg is sufficent poison to kill a 15kg dog. At the dilution used for possum control, 8g of cereal bait (at 0.15% dilution) contains sufficient to kill at 15kg dog, as does 20g of carrot bait (at 0.06% dilution). Dilutions used in rabbit control are approx 3 times lower, but sill mean significant risk is posed by small amounts of bait.
Symtoms / treatment
1080 attacks the nervous system. Symptoms of poisoning are nausea, followed by twitching, convultions and death. Consumed 1080 must be digested before taking effect, and as such symptoms may not develop for up to 1.5 hours if the minimum lethal dose is consumed.
There is no antidote to 1080.
For humans the recommended treatment is to give water and induce vomiting until the vomit runs clear (i.e. contains only water). Medical help should be sought immediately. In a dog suffering the effects of 1080 poisoning, this treatment is probably both impractical and dangerous.
DO NOT TAKE DOGS INTO AREAS TREATED WITH 1080. Consider such areas dangerous for 6 months after poisoning. Even after that, low levels of danger may exist from carcasses. Keep dogs close to avoid consumption of carcasess, keep dogs well fed, and consider a muzzle or bite-chain. If you MUST take a dog into a 1080'd area, a muzzle is ESSENTISAL.
1080 is a very unpleasent way to die. Do not risk your dog.
New Zealand Food Safely Authority. CONTROLLED PESTICIDES Sodium Fluoroacetate (1080) in Pest Control, http://www.nzfsa.govt.nz/acvm/publications/notes/1080-study-notes.pdf
New Zealand Food Safely Authority. CONTROLLED PESTICIDES Sodium and Potassium Cyanide (‘Cyanide’) In Pest Control, http://www.nzfsa.govt.nz/acvm/publications/notes/cyanide-study-notes.pdf