Dog Ate Dead Mouse

dog ate dead mouse
Photo by andy carter on Flickr

When you discover that your dog just ate a dead mouse, try to get over the gross aspect as quickly as possible and focus on your pet’s safety. 

Your biggest worry should be whether or not the mouse had been poisoned to death, as this is a medical emergency. 

We’ll have a look at the most common poisoning symptoms, but if you or your neighbors have been using rat poison on your properties, heading to the vet right away might be the wisest choice. 

On the other hand, even if the mouse was not poisoned, it might still make your dog sick if it was carrying some parasite or harmful bacteria. 

That’s not a medical emergency, but you’ll have to see a vet over the next few days, just to be on the safe side.

If you have rodent problems in your area, try to use other means of getting rid of them than poison.

Why might a dead mouse be a threat to a dog?

Even if you’ve never had a problem with rodents and there are none to be found on your property, there’s always a chance your dog might find a dead mouse on your routine evening walk. 

In most cases, he’ll want to investigate the dead animal and see what it tastes like. Remember that most household pets today were once hunting dogs or at least retrievers of dead prey. 

They don’t find it revolting to put a dead animal in their mouth. It’s a hardwired instinct for most dogs and the stench doesn’t seem at all revolting to them.

If your dog does that, the first thing you need to consider is whether or not that mouse had been poisoned. 

You don’t know the amount of poison in that mouse so it’s hard to say if it’s enough to kill a dog. 

The fact is that it can kill a dog so you cannot afford to take any chances.

There’s also the risk of disease. 

Mice can carry various bacteria and parasites, especially roundworms

These can cause severe health issues so you should see a vet even if the dog appears to be just fine after eating the yummy dead mouse.

What does a poisoned mouse look like?

If your dog happens to find a dead mouse, you probably won’t have much of a chance to examine it before he puts it in his mouth. 

Also, for the untrained eye it can be very difficult to determine if the mouse was poisoned or died of other causes.

The best you can do is look for external wounds or punctures. 

If there aren’t any and the mouse seems to be intact there’s a higher risk it was poison that killed him. 

Some types of rodenticides are in fact anticoagulants and they kill by causing internal bleeding. Check out the mouse’s mouth to see if you can spot any blood.

What are common poisons (chemicals) used to kill mice?

The chemicals used to poison mice and rats are known as rodenticides and they fall into four categories:

Anticoagulants – This type of rodenticide works like your basic blood-thinner, only in much higher dosage. The rodent ingesting this type of poison will die of internal bleeding. It’s a slow and painful death, and it might take days. During this time, the mouse will grow progressively weaker and stumble on his feet, which makes it an easy prey for predators, your dog included.

Cholecalciferol – Actually, that’s vitamin D3, the one your pediatrician might prescribe to your toddler. In high doses, it’s a powerful rat and mouse poison. It acts by causing kidney failure. It is also one of the most popular rodenticides on the market and one of the most difficult to treat if your pet gets secondary poisoning by eating a dead mouse.

Bromethalin – This type of poison kills a rodent by causing brain swelling. If your dog ingests a large amount of bromethalin it can be lethal, with symptoms becoming apparent in 2 – 24 hours.

Phosphides – Zinc, calcium, and aluminum phosphides are not primarily used for rat and mice extermination, but they can be found in certain rodenticides. Phosphides work by causing the release of a toxic gas in the animal’s stomach.

What are the symptoms for a dog that has eaten a mouse that has been poisoned?

The symptoms exhibited by a dog that has eaten a poisoned mouse will depend on the type of poison the rodent ingested.

If the poison contained anticoagulants, you need to watch out for signs of internal bleeding, such as:

  • General weaknes
  • Vomiting or coughing up blood
  • Nose or gim bleeds
  • Blood in stools or while peeing
  • Breathing difficulties caused by bleeding in the lungs

The antidote for this type of poisoning is vitamin K, but the dog will have to be taken to the vet as it needs massive doses, plus other treatment to support failing organs.

If the dog was poisoned with cholecalciferol the symptoms are excessive thirst and frequent urination, followed by lethargy as the animal’s kidneys are shutting down.

Brain swelling caused by bromethalin will manifest itself by lack of coordination, tremors and seizures.

Phosphide poisoning causes a bloated and tender abdomen and vomiting, and the dog might go into shock.

The most important thing to keep in mind is that the symptoms might take a few days to appear. Don’t assume your dog will be fine if he seems pretty much his usual self by the following day.

If there’s any poison in his system the doctor will prescribe an antidote your pet should take before any symptoms appear. 

What diseases do live mice carry that might harm dogs?

If your dog ate a mouse that was not poisoned, but died of other causes, he won’t be in immediate danger.

Still, the dead rodent might carry harmful bacteria, such as clostridium botulinum, a neurotoxin that causes botulism. This is rare however.

Another dangerous bacteria commonly carried by rodents is Leptospira, which causes leptospirosis.

Early symptoms are vomiting, diarrhea and lethargy, and since they’re common to many diseases the owners might not realize the severity of the issue until the dog goes into kidney and liver failure.

Left untreated, leptospirosis can be lethal.

A dog that ate a dead mouse is at risk of developing toxoplasmosis.

This disease is caused by a parasite, Toxoplasma gondii, that lives in mice and other rodents.

This disease also starts with vomiting and diarrhea, so the vet will have to run some tests to make a diagnosis.

Finally, there’s also the risk of your dog getting roundworms from the dead mouse.

This parasite hatches in the mouse’s stomach then the larvae hide in muscles and tissue, waiting for their chance to infect another host, like your dog.

A dog infested with roundworms will develop all the usual gastrointestinal symptoms, plus unexplained weight loss, as the parasites in his belly take up all the nutrients.

The vet will have to examine the dog’s stool to look for roundworm eggs.

Will washing a dog’s mouth out help?

When you see your dog gulping down a dead animal, your first reaction is to clean his mouth thoroughly.

You can use a small cloth dipped in a solution made with water and baking soda, or even simple salt, and rub the inside of your pet’s mouth with it.

That will make you feel better, but won’t help the dog in any way if he just ate a poisoned mouse.

If you catch your dog eating a dead mouse, oral hygiene should be the least of your worries.

The poison might already be in his stomach so don’t waste time cleaning his mouth.

Call the vet already! Or the poison helpline!

Is there such a thing as a “dog friendly” mouse poison?

No, there’s no such thing as dog-friendly rodenticide.

If you have pets you shouldn’t use toxic chemicals to get rid of mice or rats.

Some pet owners say their animal is not curious and he’s never expressed any interest in the rat poison they’ve used before.

Never assume your dog won’t touch something simply because he’s never done that before.

There’s a first time for anything, only in this case it might also be the last time.

How should a dog owner kill mice on their property?

The safest way of killing mice is to use traps, preferably live traps that don’t kill the rodents either.

Once you catch a rodent inside such a trap you can take it and release the unfortunate animal somewhere into the wild, at least one mile away from your house.

Another pet-friendly way to rid your property of mice is to use tiny electrical traps that are only big enough for a mouse to crawl in.

If you don’t want to electrocute the mice, you can install ultrasonic emitters which scare the rodents off your property with their high-frequency sounds. Thankfully, neither humans, nor dogs can hear these sounds.

To make sure mice don’t come back, seal any holes they might use to get inside and, most important, make sure there’s no food available to them.

If they can not munch on your food, they’ll go elsewhere on their own.

Why is a poisoned rat more dangerous than a poisoned mouse?

The same type of poison is used whether you need to get rid of mice or rats. The difference is that rats are bigger and so it takes more poison to kill one than it takes to kill a much smaller mouse.

Obviously, if a dog eats a dead rat he might ingest a larger amount of poison, so there’s a higher risk of a lethal secondary poisoning. 

Sarah Pulsen

Hello, I have been in love with dogs since I was a little girl. I became even more infatuated with them when I was told by my Mum that I couldn't own one. Since I left home there has rarely been a time in my life when I have lived without a dog. My current dog is a Collie Terrier cross, called Ian.