Hello and welcome to just answer.
Most Slugs and snails are not poisonous to dogs however if they like to eat the snails this can pose a risk for intestinal blockage.
The safest way to kill them is to just cover them with table salt. This will kill and dissolve the slug or snail. If your dog eats a salted slug it may cause vomiting but is not harmful.
frank a german shaphard, has been with us for a few monthes. he was under weight (40 lbs) or so. he owned didn't feed him well, now we are trying to put sdme pounds back on him. he's fhrowing up and he's poop is loose. now there are snalis all over his food and porch. he is also not very stable when walking or running.
Some fresh water snails can carry the Nanophyteus salmincolaI bacteria, if he ate a large amount of snail infected with this bacteria it can lead to salmon poisoning.
This will cause vomiting diarrhea and weakness. This is normally seen 2-3 day after ingesting a large quanity of snails or infected fish.Since he is showing all of these symptoms he should be seen immediatly.
Please have your boy seen by your vet as soon as possible preferably tonight if possible.
Do not give food tonight but try to get him to drink some water.
Please let me know how he is doing.