Why do mammals bleed out of the mouth and nose after death ?

When things die (assuming a lack of traumatic injury), they bleed from their mouth and nose.

Where is this blood coming from?

Is it ruptured capillaries in the pharynx? Bleeding within the GI tract?

Why does this happen?

I see it in people and animals, mostly mammals, I haven’t seen it in birds reptiles and fish.
Is this a uniquely mammalian phenomenon?

When does this happen?
Like right away or after a few hours?

I wasn’t really aware of this phenomenon. That’s kinda interesting.

Can you provide some evidence that this happens regularly, because I’m astounded that I’ve never witnessed such a thing. I’ve seen a lot of dead mammals in my life, certainly hundreds, possibly thousands. And they’ve died in all sorts of ways: car accidents, bullet wounds, drowning, poison, starvation, disease and thirst. And the only time I’ve seen a dead animal bleed from the mouth or nose is as a result of either head of chest trauma. Even head wounds don’t usually result in blood form the mouth/nose.

Can you possibly provide more details? What were these non-traumatic death that you witnessed? How did the animal/person actually die? That will probably help explain what you saw.

If when human blood hydraulics cease to function the head is in the lowest position… The body is now a bag with holes in it (ears, nostrils, mouth) and the fluid leaks out.

Maybe if they were upside down… but what about people who die standing/sitting up?
I don’t think they just leak out their arses.

The body is just a “bag with holes in it” isn’t really quite the situation either. It’s more like a bag filled with tubes filled with fluids. Each of the tubes themselves are leaky yes, but it’s not like there’s a gushing of fluids that are just going to come pouring out of the body. I don’t really think your statement is quite correct.

Again, I gotta go with the “need more information” request as I think more information is needed other than “non-trauma” - cardiac failure? Stroke? Choking to Death? Respiratory failure? There’s lots of non-traumatic reasons for people to die, and not all of them will cause the leaking of blood out the nose/mouth specifically. Though it has been done quite a bit in Hollywood films and such, but usually that’s for dramatic effect and to better show “he’s dead, Jim” rather than just having the body gasp and wheeze and then ceasing to breath any more.

This is possible, but there needs to be some vessel breakage for this to happen right?

Some examples… Well, the mice and rats that we feed to our snakes often have blood on the snout area or bleed from the mouth and nose when thawed.

I worked at a museum at one point, and the animal carcasses we got from beavers, to raccoons and other things often (but not always) have blood coming out of the nose. We got in a moose at one point that had collapsed and died in some one’s yard, and as it worked on it blood pooled out of it’s nose and mouth.

Ive had a few hamsters that died of natural causes that did this. In people, Ive seen it in cardiac failure and stroke.
These cant all be head and chest trauma.

I don’t know how regularly it happens, but it happens regularly enough for me to notice it.

Ive read forensics reports that uses the blood flow direction from the nose and mouth to determine the position of the head at death.

Im not sure how soon after death it happens. I had a turtle that died that began bleeding from the mouth overnight.

Blake: Do you work in some sort of wildlife management or zoo type thing to see thousands of animals die? I don’t think it’s anywhere near the moment of death, probably hours later.
Im not talking about some huge outpouring, just the bloody muzzle effect that you see.

My question is why does this happen? and where is the blood coming from?

I’m no expert but I saw a corpse once where the guy overdosed on the toilet, then fell on his head. His head was the lowest point in the final position. When I saw him he had been there for a few days and his face was dark purple - full of blood. His arm, which was higher up, was completely pale. There was large (3 foot across?) pool of dried cracked blood on the floor and it had obviously come out the nostrils mainly. There was no head trauma.

Also, when people are strangled, like in The Godfather, don’t they shi*?

I’m thinking its a gravity thing, but again I’m no expert.

When animals get their lungs pierced they spit blood out the mouth and nose for obvious reasons but I don’t think that’s what OPs asking about.

I don’t think hanged people bleed from the ears, nose, mouth…

For frozen animals, at least, it’s simple enough: We’re mostly water, and water expands when it freezes. That’d be enough to burst a bunch of capillaries.

Blood pooling to the lowest point after death is probably a factor. Is this becasue of vessel rupture or GI tract bleeding, or some other cause ?

Good point.

Trauma to the respiratory system or similar will certainly cause it - that video of that Iranian woman shot in the recent protests shows lots of blood coming out of her nose and mouth. I believe she was shot in the chest.

That’s exactly what Im talking about.

Since there’s no trauma, why does that happen?

Ive never see it to that degree in people, but I see it in animals.

When I was tending the animal house at my university, we killed mice by use of an “occipital crush”, which is a fancy way of saying we hit them over the back of the head with an iron bar. Of course mice killed in this fashion bled from the mouth. This is hardly a non-traumatic death

But you have no way of knowing how these animals were killed. The most common source of teaching materials for our students is roadkill. Your animals could have been collected in the same way, or they may have been killed in deadfall traps, or shot.

Do you actually know how any of these animals died? When you said there was a non-traumatic death, I assumed that meant you were present at the time of death, rather than receiving frozen/pickled corpses that could be years old and could have died in almost any way.

What was the natural cause? Lungworms? Tuberculosis? Did you have a vet perform an autopsy?

Al the animal examples except the hamster could very well be. You just don’t know how the died.

No doubt about that, but it relies on the fact that such blood flow exists. Where it doesn’t exist it can;t be used.

Again what did it die of? Turtles, especially wild caught turtles, are very prone to lungworms due to their diet. Lungworm infection causes, unsurpisingly, bleeding from the lungs.

I’ve grown up in the country and worked most of my life there. I’ve also worked pest control and crop protection amongst other many jobs. I used to be a keen hunter and still am a keen naturalist. Most country people are going to see a dozen or so animals die every year on average, which over a few decades adds up to hundreds of animals. Add in the hunting and job related deaths and I would make a WAG that I’ve seen 50 mammal deaths a year on average.

I’ve honestly never noticed it in the absence of trauma.

At this stage my question is whether it is happening at all in the absence of trauma.

I’m going to go out on a limb and say that your museum specimens and feed mice weren’t obtained by someone following animals around until they died of old age. Somebody killed those animals. The reason for the bleeding is probably revealed in how they were killed.

The feeder mice were killed humanly via asphyxiation or freezing.

The hamsters died from overheating.

The turtle (was not wild, it was a pet) died from being pulled out of hibernation and couldn’t tolerate the temperature change.

The man mentioned above died from overdose.

The specimens we got, some were road kill and it’s plausible, but alot were from the local zoo too, and those were documented natrual deaths. Theyre not years old as you say, nor are they pickled. Invariably they were a few days old at most, or prefrozen.

Your expertise is impressive though.

Asphyxiation how? CO2? CO2 is well known to cause lung hemorrhages.

Don’t know enough about this to comment, but since most mammals cool themselves by increasing blood flow to the lungs and nasal cavity, it doesn’t seem unlikely that hyperthermia would lead to nosebleed.

But where did it come from? Many (most?) pet turtles are wild caught.

That’s hardly non-traumatic. It’s organ systems were all out of whack with one another. It’s hard to think of a more traumatic death, except perhaps roasting over a slow fire. Hardly surprising that there was internal bleeding.

Of what? Assuming it was stimulant like cocaine then nosebleeds aren’t all that rare, even without death.

Natural death covers a lot of territory.
I think the point here is that you aren’t really dealing with a normal subsample of dead animals, or even a sample of animals that suffered no trauma. The lungs and nasal membranes have a very rich blood supply and are very thin. When systems get put of whack they are prone to rupture, which is why children, with their small bodies, are highly prone to nosebleeds. So it’s not surprising that animals under extreme, prolonged stress such as your turtle will similarly suffer nosebleeds.

But most of the time animals die without any facial bleeding at all, especially if the death is quick.

Where the blood came from is easy enough- that’d be from the capillaries/ venous collections basically. After death, the Heart pretty has stopped beating, so blood is no longer circulating in the body, and is in a state of statis. This is going to cause the pooling effects and various clotting effects (such as the one beo mentions) 3 days is certainly a great amount of time for the blood to pool towards the lowest points- because all the blood that WAS pushing pushed through the body no longer is. And if enough blood fills up the vessels, each will take the stress in various ways- the larger vessels are the least likely to break as they’re quite elastic and have thick musculature. The weakest ones however are the capillaries, these vessels are small enough sometimes to only allow a single cell through. So now with all the stasis of blood that’s not going anywhere you’re going to have a back flow- arteries don’t have valves, so the blood will pool and collect, following gravity, veins will fare better as they do have valves but even then many can give out, especially since there is no longer any pressure driving the blood forwards and through the valves.

But the key then would be the capillaries, these are most likely to burst first and cause the trickling of blood that you’re seeing caused by the pooling of blood. The nose certainly does have plenty of capilaries, and that’s an easy explaination for that sort of thing.

I was curious as I was thinking you meant instanteously there’s blood coming out of someone at the moment of death, as in movies and such. So I’d say it’s more likely just the capillaries bursting due to increased amounts of pooled blood due to the heart no longer pumping blood.

How long does it take for capillaries to burst after death?

I’d assume they gradually weaken causing this effect of bleeding after several hours which does seem to correspond with the effects seen.

This effect is probably exacerbated by freezing.

Blake: This is irrelevant. It doesn’t matter how that particular turtle died, I’m speaking of general taphonomical trends in post mortem changes.

You make alot of assumptions to support your points, but Im not really interested in that. Offering speculation isnt useful.

It’s highly relevant. When you claim that the bleeding is observed after non-traumatic deaths it’s hardly irrelevant to point out that such bleeding has never observed it after a non-traumatic death.

But you have absolutely no evidence that this is a general taphonomical trend.

I have made no assumptions at all. I have asked you for details and worked with the details you have provided.

Since there is no evidence that what you describe actually happens when there is no lung/head trauma it’s impossible to do anything but speculate isn’t it?

I’ve killed thousands of mice (by Co2 inhalation or lethal injection) and hundreds of rats (same ways), and I’ve never seen this with those kinds of deaths. Maybe we didn’t leave them sitting around long enough (probably a few hours before freezing is all I’ve seen), but I can’t say we wouldn’t if we left them hanging upside down in the lab for a few days. It’s definitely not something that invariably happens right after they die, though.

It’s from lung trauma, not head trauma. This could be from a traumatic injury, but there are several ways to die that involved the lungs filling with blood. Pulmonary embolism, untreated lung cancer, etc.

I’ve seen this before a few times… animals that have been hit by cars. It also happens when you’re still alive. When my dog, who is now 13, was a 4-month-old puppy, our neighbor’s dog attacked - shook her like a rat, and threw her. She bled from her nose and mouth almost immediately because two of her ribs had broken and punctured her lung. She pulled through after surgery, but it was a close call.