Snail and slug control from a veterinary perspectiveBy Geoff Stein (palmbob)
April 12, 2008
In a previous article I discussed some of the possible toxic ramifications of trying to eradicate rodents from ones yard, at least to one's pets. Not all of us have rodent problems, but it is clear the toxins sold to get rid of those pests are extremely hazardous to your pets and should not be used if one has any pets- the risk is just not worth it. But what about getting rid of snails and slugs? Are the hazards similar, or are there some ‘safe' products for use in our gardens, should we have pets? After all, most gardeners have snails and slugs in their gardens. In this article I will go over a few of the products used to keep these slimey creatures at bay and how their use could impact our own pets.
Banana slugs in the garden
Banana slug chewing on leaf (an actual audible sound) A slug-fest
Metaldehyde is the most commonly sold product used to help the gardener in their literally endless battle against these pests. Snails are of a particular interest to me as there are a number of palms that are easily decimated by these creatures. And Metaldehyde is a somewhat effective product against snails. However, it is also extremely toxic to mammals as well, and is probably the most common cause of pest poisoning seen by veterinarians, barely surpassing the anticoagulant rodenticides. Snail bait, for some reason, is formulated to be particularly attractive to dogs (some forms taste a lot like dog food), though some granular and flake formulas seem less so. But dogs love some of this stuff (I have yet to see a cat with this toxicity, but I am sure it has happened). And dogs that survive one episode of poisoning from snail bait will happily seek it out again apparently not learning from their nearly fatal mistake the first time. If you have a dog, do NOT use this stuff! It can easily kill your beloved pet in a very short time. Many dogs die every year from Metaldehyde poisoning.
different Metaldehyde products in a nursery
Metaldehyde poisoning results in constant seizures and untreated pets die of either hyperthermia or respiratory or cardiac collapse from the endless seizure activity. These affected pets often have to literally be anesthetized until the poison leaves their systems (can take up to 2 full days sometimes). Fortunately most dogs that get treated early on have no lasting effects and most recover fully. But it can cost many hundreds, if not thousands, to treat these pets until they are able to be released. It is far better to just avoid the occurrence and not ever use the stuff. There are many other ways to control snails, from using copper wires, sinking glasses of beer or salt in the ground, and using much safer commercial snail repellents.
Metaldehyde in combo with Carbaryl for a broad spectrum killing effect, as if one product wasn't dangerous enough for your pets
Iron Phosphate is, in my personal experience, a less effective product than metaldehyde but it is a LOT safer to use around dogs. My dogs didn't seem to notice its application and never touched it, but one must assume ANYTHING one puts down will be ingested, just in case. And iron, it turns out, is toxic, too. If ingested by your dog, iron will be stored in your pet's body naturally. Unfortunately iron is released very slowly by the body, so excessive amounts of iron can build up quickly to toxic levels. Excess iron, either from snail baits, or from fertilizers, (or multivitamins, which is the most common way dogs poison themselves) can lead to vomiting and diarrhea initially, then a pet may seem to improve only to then get lethargic, go into shock, collapse and develop liver failure and/or heart failure, hemorrhage, seizures, coma and death. And if they should survive, subsequent intestinal strictures can result from the bleeding earlier and further complications can ensue. There is an antidote, but it has to be started early, and iron toxicity is not an easy diagnosis to make unless the veterinarians are told the dog was exposed to large amounts of iron. A dog has to eat a of iron snail bait to get this ill and few recorded instances of serious iron poisoning from snail bait exist (iron poisoning is common in dogs, but is usually from vitamin or fertilizer ingestion), but, still, it may not be worth it to see what that actual amount a ingested snail bait might be. I have used it carelessly in the past, but now I will be a tad more cautious.
'safe' product for controlling snails made of Iron phosphate
Though an internet search has come up with many anecdotal reports of Arsenic being used in slug and snail products, I could not find the actual snail or slug products themselves that had arsenic in them. But if they exist, these should also be used with caution, or avoided completely, as arsenic is a highly toxic substance used to kill many forms of life from insects to rats, and even as an herbicide and wood preservative. Arsenic poisoning is serious and there are no antidotes for it. Acute arsenic poisoning can result in bloody vomit and bloody diarrhea as well as abdominal pain. It can also cause neurological problems including spasms, seizures and coma. It takes a lot more arsenic to make a dog ill than it does to make a slug ill, and most products that contain arsenic tend to have tiny amounts of it in them... but some arsenical products taste good to dogs and if they eat enough they could get seriously poisoned. Additionally this product also can build up in the system and cause chronic toxicities (unlike most pesticides which are only dangerous immediately but do not build up in the system), so years of use of this product could be dangerous as well, even if only small amounts are used at a time.
Another technique discussed in some websites discussing slug and snail control suggest using coffee grounds, though the effectiveness of this material at actually keeping slugs and snails away is debatable. However, the potential toxicity of coffee grounds to dogs is not debatable, and though normally not voluntarily ingested by dogs, if eaten, coffee can be a potent and deadly cardiac toxin. If you have dogs, I would not try this slug treatment.
Garlic oils and products have also been touted as ‘natural' slug and snail repellents. Though I am not sure how much garlic it would take to make a snail or slug to turn away, garlic products are also quite toxic to dogs and cats and their ‘natural' origins should not convince one of their safety around pets. I would not be surprised to discover that garlic is more toxic to a dog or cat than it is to a snail. Garlic can lead to liver failure as well as a form of anemia in which your pet's blood turns a brown color and cannot carry oxygen as well. Garlic does taste good to dogs (and sometimes cats as well) and they may seek this toxin out and eat too much of it. Garlic also can cause chronic toxicity problems, as well as immediate problems. Do not use garlic products around dogs and cats!
Beer is an oft used snail and slug killer, and I have tried this myself on a number of occasions. I was actually surprised how many slugs and snails ended up in the cups of beer I sunk into the ground. Yet it made hardly a dent in the overall slug/snail population. Many dogs, and even some cats like beer. Dogs and cats have a lower tolerance for alcohol than most humans do, and it can make them pretty ill, just as it can us. Though beer has a fairly low alcohol content, a dog can easily drink enough beer to get serious alcohol poisoning. I have not personally seen a fatal case of alcohol poisoning in a dog, but there are plenty of examples in the literature. Non-alcoholic beer seems to work equally well in killing slugs and snails and this product does seem to be harmless to pets, so it would certainly be the way to go if this method of snail control was to be attempted by pet owners.
Slugs and snails can be serious and annoying garden pests, but do not pursue eradication methods that endanger the health of your own pets. Perhaps try carnivorous snails (they live on garden snails), copper bands, application of ashes, hand-picking and other safe deterrent materials.