Squirrels almost certainly cannot vomit in the true sense of the word. As rodents, they belong to an order of mammals that lacks the neurological wiring and muscular coordination required for forceful vomiting. However, the story is more interesting than a flat “no,” because grey squirrels have been observed doing something that looks a lot like vomiting, even if it technically isn’t.
Why Rodents Can’t Vomit
Rodents make up roughly 42% of all living mammal species, and the inability to vomit appears to be a trait shared across the entire order. A comparative study tested members of all three major rodent groups, including squirrel-related species, with potent vomit-inducing chemicals. None of the animals produced retching or vomiting, even though the drugs caused other visible effects like changes in movement.
True vomiting is a surprisingly complex, coordinated event. It requires the esophagus to shorten, the muscular ring around the base of the esophagus to relax, the outer diaphragm to contract hard while the inner ring of diaphragm around the esophagus simultaneously relaxes, and the abdominal wall muscles to compress the stomach forcefully. All of this has to happen in sync, driven by a specific vomiting center in the brainstem. Rodents appear to be missing the brainstem circuitry that orchestrates this sequence, which researchers consider the most likely reason they can’t vomit. Even if a rodent’s body tried, its diaphragm is less muscular and its stomach geometry is poorly structured for pushing contents back up toward the esophagus.
What Grey Squirrels Have Been Seen Doing
Here’s where it gets interesting. A wild grey squirrel was recorded going through spontaneous episodes of retching (2 to 9 retches, each lasting about one second) followed by expelling a viscous white and brown liquid from its mouth. At first glance, this looks like vomiting. The researchers who published the observation in the Canadian Journal of Zoology noted that arboreal squirrels are neurologically and morphologically different from many other rodents, and suggested these differences might allow for emetic behavior that other rodents can’t perform.
But a critical review of the footage tells a different story. The squirrel expelled the liquid passively, chewing and then opening its mouth to let the material out rather than forcibly ejecting it. There was no sign of the powerful, synchronized diaphragm and abdominal contractions that define true vomiting. The conclusion from researchers who analyzed the behavior: what the squirrel did looks more like regurgitation or spitting than actual emesis.
Regurgitation vs. Vomiting
The distinction matters biologically. Vomiting is a forceful, reflexive expulsion where pressure builds simultaneously in the chest and abdomen to blast stomach contents upward. It’s preceded by retching, those rhythmic heaving contractions you’d recognize in a dog or a person about to be sick. Regurgitation, by contrast, is a more passive process. Material comes back up without the explosive muscular coordination, often from the esophagus or upper stomach rather than deep in the gut.
So when people see a squirrel gagging and producing liquid from its mouth, they’re likely witnessing regurgitation or gagging rather than vomiting. The squirrel may be dealing with something stuck in its throat, spitting out food that tastes wrong, or clearing irritants. But the full vomiting reflex, the kind that protects many mammals from poisoning, does not appear to be in its repertoire.
The One Possible Exception
The woodchuck, a ground-dwelling member of the squirrel family (Sciuridae), has shown possible vomiting behavior in response to red squill, a plant-based rodenticide. This observation dates back to the early 1980s and remains one of the only documented cases of anything resembling true emesis in a rodent. Whether woodchucks genuinely vomit or simply regurgitate more effectively than other rodents is still debated. No other squirrel species has shown comparable evidence.
What This Means if a Squirrel Eats Something Toxic
The inability to vomit is a real vulnerability. Most mammals that accidentally eat something poisonous can throw it up before absorbing a lethal dose. Squirrels and other rodents don’t have that safety net. Instead, they rely heavily on cautious eating behavior: sampling small amounts of unfamiliar foods, avoiding bitter tastes, and learning from negative experiences with particular foods (nausea, even without vomiting, still teaches them what to avoid).
For anyone caring for a pet or rescued squirrel, this has practical implications. If a squirrel ingests something harmful, it cannot expel the toxin on its own. Veterinary treatment for poisoning in animals that can’t vomit typically involves flushing the stomach through a tube or administering activated charcoal by mouth to bind the toxin and prevent further absorption. There is no equivalent of the “induce vomiting” step that works for dogs or cats.