March is Pet Poison Prevention Awareness Month, and in keeping with this month's theme of toxins in dogs, let's discuss snails and snail bait (and other outdoor toxins) as they relate to dog health.
People often wonder whether snails are poisonous to dogs. It's a good question, because many dogs enjoy hoovering up the crunchy molluscs. And reports exist of dogs developing tremors or even severe seizures after having been in the area of snails.
Let's jump straight to the punch line. The snails found in temperate countries (such as the U.S. or Europe) are not poisonous. There are some venomous (which is different from poisonous) snails out there, but not in the U.S. or Europe. Cone snails are among the most deadly venomous creatures on Earth. Fortunately, cone snails live underwater on tropical coral reefs around Australasia, so they aren't likely to pose much of a risk to dogs. When it comes to eating snails, they generally are non-toxic.
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But that's not to say snails can't cause problems. In fact, snail consumption can cause a major health issue in dogs: lungworm infestation. Lungworms can cause coughing as well as more severe respiratory problems, such as bronchitis or difficulty breathing. The type of lungworm spread by eating snails is common in the UK and Europe. Lungworms in the United States, in my experience, typically are not spread by snails.
Snails have the potential to cause other problems in dogs as well. Their shells could conceivably cause gastrointestinal obstruction (although I've never seen it) or good old-fashioned gastrointestinal upset (which I certainly have seen). Snails are the intermediate host for the dreaded disease schistosomiasis, and dogs can contract the disease. However, the disease is not contracted by eating snails, but rather by swimming or wading in waters in which certain species of snails dwell. Those waters, by the way, tend to occur in the least developed portions of Asia, Africa, and South America.
In my experience, the biggest danger posed by snails is that they are often found in the area of snail and slug bait. Snail and slug bait contains an ingredient called metaldehyde. The bait pellets usually also contain bran, which makes them attractive to both snails and dogs. Dogs therefore are exposed to metaldehyde with great frequency. Metaldehyde is related to strychnine, and it is deadly toxic to dogs. Initial symptoms of metaldehyde ingestion include tremors and twitching, which is often exacerbated by noise. The symptoms can rapidly progress to severe, urgently life-threatening seizures. Any dog that develops these symptoms requires urgent veterinary care.
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As the spring gardening season approaches, dog owners must be aware that virtually all snail and slug baits are toxic to their pets. I prefer pet-safe control methods, such as placing saucers of beer in the garden. The beer attracts the snails, and they then (I imagine) drown drunk and happy.
Dog owners should remember that their neighbors may not be using a dog-safe snail control method. The risk of snail bait in the neighbor's yard is yet another reason to keep a watchful eye on, and good control over, your dog.
Snail bait isn't the only pest control agent that is poisonous to dogs. Rat and mouse baits, like snail baits, are attractive to and poisonous to dogs. There are two common types of rat and mouse baits. The so-called anticoagulant rodenticides cause fatal (but usually treatable) bleeding disorders. Bromethalin-containing rat and mouse baits can cause brain swelling and neurological symptoms. And then there's gopher bait, which may be similar to rat and mouse poison, or may contain strychnine or a product that releases deadly phosphine gas.
Again, all dog owners should avoid these dangerous products at all times. Don't even keep them in areas that you think your dog can't access. (I hear this one all the time: "But the rat bait was locked up in the garage! I don't know how he got to it!") And again, you may not be able to control what your neighbor does, so be vigilant.
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Finally, if the antifreeze in your car's radiator is leaking after doing a hard winter's work, remember that it is deadly toxic to your pet. Antifreeze contains ethylene glycol, which is sweet and attractive to dogs; ethylene glycol also can cause kidney failure. Fortunately, antifreeze manufacturers recently have begun to add bittering agents to their products in all 50 states. As these new, non-palatable products replace the old, attractive antifreeze formerly used in many places, the risk of antifreeze toxicity in dogs should be significantly reduced. Meanwhile, any dog that consumes antifreeze should see the vet immediately.
Spring is full of toxic hazards for dogs. Fortunately, most poisonings can be prevented with owner awareness and diligence.