Q&A: When a Dog Meets a Garter Snake

Christine’s dog had an encounter with what she thinks was a garter snake, and wonders whether either animal came away unscathed:

Two days ago I was wandering around in a bush lot and came across what I believe is an Eastern Ribbon snake (dark grey with light yellow stripes, very long tail and no patterning) taking up some sun on a leaf-covered rock pile. While I was busy admiring this fellow who seemed content to let me do so I didn’t notice that my dog had found another snake a few feet away and was ashamedly harassing it. By the time I got hold of his collar and pulled him off, the poor snake was sort of balled up with mostly belly showing, half covered in the leaves.
I didn’t want to handle the snake and add insult to injury but I did at least want to make sure he was still alive. I gently rolled him over (he was still all balled up, belly up) and he slowly unwound and headed for cover under the leaves.  At first I thought it was another ribbon snake but the belly was a very bright yellow-green color, more like a garter snake.
My question is threefold. Firstly, do you think it was a garter snake or a ribbon snake that suffered at the nose of my dog? Secondly, given how long it took him to right himself do you think he was OK? I’d hate to think my dog caused him any harm. And lastly, the snake did get a chomp in on my dogs nose. I’ve been told that garter snakes can emit a mild toxin when they bite and/or eliminate a musky fluid. Could either of these cause a dog or any other animal to become mildly ill?
My bad boy sort of came down with what I can only equate to mild flu symptoms later that evening. (Yep — serves him right.)

The short answer is that it does not seem likely that either the snake or your dog came to harm as a result of the encounter. I could be wrong, but if your dog got sick later that evening, it’s probably not a result of anything a garter snake did.

But to answer your three questions in turn:

1. Was it a garter snake or a ribbon snake? I’ve already written an article on how to tell the two of them apart, but, in my experience, belly scales aren’t something you can use to tell the two kinds of snake apart. I’ve seen garter snakes whose belly scales are almost black, and others that have belly scales as bright as what you describe — and these were the exact same kind of garter snake!

Garter Snake vs. Ribbon Snake (2003) In the same area, garter snakes and ribbon snakes have the same kind of colouration: the two snakes I used to show the difference between garter snakes and ribbon snakes were only found a few feet apart. Similarly, in Florida, Blue-striped Ribbon Snakes, Thamnophis sauritus nitae, and Blue-striped Garter Snakes, Thamnophis sirtalis similis, are found in the same area. Their local habitat has a big impact on their colouration: it’s why so many snakes in the mangrove swamps of the Everglades are bright orange, and why snakes on the prairies are all in similar shades of browns and greys. In a word, camouflage.

In the end, though, garter snakes and ribbon snakes are closely related enough that it doesn’t matter for the purposes of your other questions.

2. Was the snake okay? I think so: the fact that it crawled away is a positive sign. I’ve encountered snakes in the wild with huge gashes in their sides or who are missing half their tails (unlike lizards, snakes don’t grow their tails back) — snakes that have had run-ins with birds or other large predators and have still managed to survive. If you didn’t see a significant dog-inflicted wound on the snake, my guess is that it will probably live to musk another day.

So what was it doing when it was “sort of balled up with mostly belly showing”? It was playing dead. Biting and excreting musk aren’t the only defenses in a snake’s arsenal: sometimes they curl up to protect their head while offering their tails as a lure; sometimes they flop over and play dead. Eastern Hognose Snakes, Heterodon platirhinos, are the most famous for doing this, and they do it better than any other species of snake; take a look at this short video of a hognose snake playing dead by Benny Mazur:

Garter snakes have also been known to do this (Gibbons and Dorcas 2005, p. 80); it has been quite well documented, for example, in the Plains Garter Snake, Thamnophis radix (Ernst and Ernst 2003, p. 415). My guess is that this, or some other kind of defensive behaviour, is what was going on.

3. Could a snake’s bite or musk cause a dog or other animal to become mildly ill? Only mildly, if that. Garter snake musk is pretty pungent, enough that it could make you gag a bit if you’re a bit sensitive to it. (I’ve been exposed to it since I was eight years old, so I’m pretty blasé about it, but yeah, it’s kind of strong.) But it’s not engineered to be toxic, just foul. Getting zapped by a skunk would almost certainly be worse.

As for a garter snake’s bite, their saliva has been described as slightly venomous, but that’s not normally a cause for concern. Ernst and Ernst (2003) have documented reactions to garter snake bites that they describe as “envenomation”: one boy suffered swelling in the hand and lymph nodes and required hospitalization; Carl Ernst himself has developed a hyperallergic reaction to garter snake saliva (Ernst and Ernst 2003, p. 436).

But it’s important to keep that in perspective: most people who have been bitten by a garter snake have suffered no ill effects whatsoever. My girlfriend gets bitten by garters all the time, and was once bitten by our female Wandering Garter Snake, Thamnophis elegans vagrans, considered one of the more “venomous” garter snakes. I watched — a little too eagerly, she said — to see if any reactions occurred at the bite wound; none did.

The bottom line is probably that some people can have an allergic reaction to the bite of even harmless snakes — and even if their saliva has some toxic properties, garter snakes are still harmless to the vast majority of the population.

Still more perspective: Tennant and Bartlett (2000) report that “animals as small as cats” survive envenomation by copperheads (p. 478), which, even if they have the mildest venom of any North American pit viper, are still several orders of magnitude more dangerous than garter snakes.

I’m not a veterinarian, and I can’t be 100 percent sure, but my guess is that your dog is probably fine — at least as far as his encounter with the snake is concerned.


Ernst, Carl H. and Evelyn M. Ernst. 2003. Snakes of the United States and Canada. Washington and London: Smithsonian Press.

Gibbons, Whit and Mike Dorcas. 2005. Snakes of the Southeast. Athens and London: University of Georgia Press.

Tennant, Alan and R. D. Bartlett. 2000. Snakes of North America: Eastern and Central Regions. Houston: Gulf.

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