Does Poison Make a Mouse Thirsty?

We’ve read and heard this myth so many times, we’re almost starting to believe it ourselves, but, sadly, mouse poison, also known as rodenticide, does not make mice thirsty. We’re not quite sure where that myth came from in the first place.

The idea is that mice get thirsty, head outside, and then die somewhere far away from your home, but the reality of this situation is usually quite different.

To start with, mice need to eat the poison pellets repeatedly in order to get sick. One dose or nibble isn’t going to be enough to have any effect on them, and it works on a bit-by-bit basis. The poison bait station is often flavored or scented so that it is appealing to mice, hoping that they will keep coming back to it and getting more of a poison dose each time.

If the mouse needs to eat MORE of the poison in order for it to have effect and kill them, the last thing you’d want is for the mouse to eat a bit and then leave to find water. You’d want the mouse to eat a bit and eat a lot more. The more it eats, the faster the poison will work and the higher the chance it will work at all.

Moving aside from the logistics for a second, mice don’t actually get their water content from water. They get a lot of it from their food. If the rodent were to get thirsty as a result of eating the poison pellets, they would simply more in the hope that it would quench their thirst. They wouldn’t head outside to die.

Of course, poison doesn’t work immediately. We’ve already covered that point; the rodent needs to eat more and more of it for it to take effect. Most rodenticides contain anticoagulants, and this makes the blood thin. Other compounds cause the blood vessels to start to decay, and this, with the thinned blood, causes blood to leak inside the body. This is called internal bleeding and it does not cause a quick or painless death. Quite the opposite, in fact.

Rat and mouse poison can take weeks to work — many doses. Some rodents have shown to have a staggering immunity to the poison, too, which makes them walking time bombs to other animals. If a cat were to chase and then capture a poison-immune rodent, consuming some of the flesh in the process, it would consume some of that poison. An immune rodent will have many times the recommended dose of poison in their body because they repeatedly ate from the bait station but the poison had no effect, and that can actually kill the predatory animal — in this case, the cat. This process is called secondary poisoning and is happening all over the world, usually with pest animals like foxes, as a direct result of rodenticide immunity.

Does poison make a mouse thirsty? No, it does not. In reality, it might take weeks for the mouse to die, and some of them are immune so it won’t work at all.