Winter time brings this on. You need to protect your pets from attractive snail food/poison. AND you need to keep it well stored at other times. Usually after a short burst of rain at night the snails have made a mess of your broccoli seedlings and you rush into Roberts for something to kill them. Again you've acted without planning. We all do sometimes and the seedlings were coming on nicely.
Dogs and cats love it much more than slugs and snails do. Snails are actually alcoholics by nature and love beer. That kills them but only a few dogs like grog. Take no notice of the additives written on the snail poison pack that the makers say are are supposed to make your pet avoid it. They don't work. Your garbage-guts Labrador will eat the snails too and then the packet if that's the way he's found it. I've even seen dogs eat the whole "pet proof" container that is supposed to prevent pet access and then end up with a gut blockage with plastic as well as poisoning.
Apart from beer and sawdust there are two main sorts of toxic snail killer ...Blue sort and Green sort. They both effectively kill dogs and cats as well as other species. They do it in pretty horrible nervous convulsions. There is one maker that has broken the colour rule but knowing the colour of your poison as well as its name can help me because... most green ones are METALDEHYDE and that is a real doggy nasty and needs a heavy programme of early therapy and most blue ones are ORGANOPHOSPHATE which are bad enough but we have a quick antidote. I forgot to say cattle sheep goats and horses all love snail baits too and it affects them all. Especially horses.
Bring in the empty packet (or your memory of the name). Don't overstress if you can't find it quickly or remember. The treatment for each is quite different but those of us with enough experience can usually pick the slight differences in the type and nature of the convulsions to take a fair guess at which of the two types is involved.
What can you do at home? ... almost nothing unless you can induce vomiting very soon after taking the poison (with very concentrated salty water). You are best to get to the vet as soon as possible rather than waste time trying to vomit the dog or cat. The vet will vomit your dog with a reliable drug if you get it there soon enough.
If it is one of the blue ones (usually but not always organophosphates eg. Baysol) we will give atropine as antidote and may have to repeat it as often as needed for as long as needed.
If it is metaldehyde (eg defender or one of the spin-out farm products)then sometimes stomach flushing is needed as well as anti-convulsive therapy. Anaesthesia, sometimes for several days with supportive therapy is needed in bad cases but survival seems to be the rule rather than the exception. We once saved a Labrador that had eaten 8 to 10 kg of farm strength metaldehyde, when only a few gram is enough to kill a dog...but we earned our fee that time.

