# Cats/Dogs and menstruation (hopefully not too icky)
**URL:** https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075
**Category:** Factual Questions
**Created:** [August 25, 2001, 10:06am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075 "2001-08-25T10:06:01Z")
**Posts on this page:** 14
**Page:** 1
### Author:  [@PookahMacPhellimey](https://boards.straightdope.com/u/PookahMacPhellimey)
#### Post date: [August 25, 2001, 10:06am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/1 "2001-08-25T10:06:01Z")
Sorry if this sounds a little yuckie, but I have wondered this for a while actually. (hey, I have a boring job).
Following on from the thread about cat-years, I just wondered why you never see a cat or dog er…having her period. (sorry again)
I mean, a lot of them are sterilised and another lot are actually pregnant, but still, I think our cat is intact and not preggers and still, never any blood…
So, does it work differently for them than for humans? Can we human-women have it their way too? Please?
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### Author:  [@Gaspode](https://boards.straightdope.com/u/Gaspode)
#### Post date: [August 25, 2001, 10:32am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/2 "2001-08-25T10:32:17Z")
Nope, sorry you can’t.
Basically their are two types of placental mammals: eostral and menstrual. Menstrual mammals flush away the uterine lining after each cycle if implantation of an embryo doesn’t occur. Oestral animals simply resorb the lining with minimal fuss. Guess which category humans fall into?
Dogs, which are eostral, do bleed prior to ovulation but don’t menstruate as such. Cats don’t even do that so you won’t see your cat bleeding.
And if you want to know why humans (and other apes) menstruate when 99% of mammals don’t I suggest you do a search in GD where some speculation and WAGs were posted a short time ago. Basically the answer is unknown.
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### Author:  [@PookahMacPhellimey](https://boards.straightdope.com/u/PookahMacPhellimey)
#### Post date: [August 25, 2001, 10:39am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/3 "2001-08-25T10:39:26Z")
Ah, what a shame…☹
Thanks though, question answered.
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### Author:  [@DougC](https://boards.straightdope.com/u/DougC)
#### Post date: [August 25, 2001, 12:41pm UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/4 "2001-08-25T12:41:17Z")
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- Not to disagree with Gaspode’s answer, but cats only ever expel uterine lining after giving birth. If female cats are left unspayed and are never mated (that is, if they are kept from males), in a couples or so of years they will eventually get a uterine infection which if left untreated will kill them in short order. Treatment can be limited to removing the infected uterine lining (leaving their reproductive capabilities intact) but because it’s expensive and doesn’t really solve anything most people just have the vet remove the infected uterus while performing the rest of an ordinary spaying, solving two problems at once, permanently.
- I dunno if dogs are the same way or not. I had a friend who had a female dog that would bleed (ugh) but it was no show dog; I never heard any reason for it not being spayed, or if that would have mattered or not.
-We used to have a vet tech on the board… - MC
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### Author:  [@Gaspode](https://boards.straightdope.com/u/Gaspode)
#### Post date: [August 25, 2001, 11:53pm UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/5 "2001-08-25T23:53:54Z")
> [@](#):
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> cats only ever expel uterine lining after giving birth. If left unspayed they will get a uterine infection which will kill them.
Do you have a cite for this?
The vast majority of animals never expel the uterine lining except at birth, that’s a defining character of oestral animals, but the only animals I’ve ever heard of that die as a result of not mating are polecats, and that’s for slightly different reasons. I know a few people that have breeding queens and they aren’t coupled every year by any means, and often when they are coupled they don’t conceieve. They’ve never mentioned any ill effects from this aside from needing to administer hormones to prevent the animal from cycling continuously. My physiology text only notes that “If a queen is not mated, she will come back into heat every 10-30 days until… disrupted by illness or conception.” A quick ‘Google’ search turned up nothing.
Consider me sceptical.
> [@](#):
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> I dunno if dogs are the same way or not
No they’re not. My family has always had unspayed bitchs and the worst problem they suffer from is the occasional phantom pregnancy.
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> I never heard any reason for it not being spayed, or if that would have mattered or not
Spaying involves removal of the ovaries and would have certainly stopped the proestral bleeding simply because the animal wouldn’t cycle.
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### Author:  [@DougC](https://boards.straightdope.com/u/DougC)
#### Post date: [August 26, 2001, 1:00am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/6 "2001-08-26T01:00:36Z")
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- No cite, really, that’s just what the vet told my mom and we went to pick up her cat that was sick, we were told, for this very reason. They vet said that this was a common condition in unmated cats, and it always required surgery to remedy either way. -Also said that allowing a cat to breed every two or three years is usually enough to prevent it. (I might be screwing up the terminology here, at the time I wasn’t exactly hanging on the conversation, but this was the gist of it) Is there a vet in the house? - MC
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### Author:  [@Guinastasia](https://boards.straightdope.com/u/Guinastasia)
#### Post date: [August 26, 2001, 1:17am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/7 "2001-08-26T01:17:33Z")
Would that be the same as cats going into heat?
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### Author:  [@hardygrrl](https://boards.straightdope.com/u/hardygrrl)
#### Post date: [August 26, 2001, 1:41am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/8 "2001-08-26T01:41:21Z")
I’ve seen my friend’s dog menstruate. Not up close, mind you, but she would leave little blood spots where she sat.
Most pet stores sell little pads for female dogs.
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### Author:  [@Gaspode](https://boards.straightdope.com/u/Gaspode)
#### Post date: [August 26, 2001, 4:24am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/9 "2001-08-26T04:24:07Z")
MC,
Pyometra (uterine infection) is certainly far more common in unspayed, unmated animals than in mated or spayed animals and is frequently fatal. This is however a far cry from saying that all unspayed female cats will inevitably succumb to pyometra and die after a few years. The reason the disease is most common in unspayed animals is the cervical dilation that occurs during eostrus that allows bacteria to migrate into the uterus. It is not directly linked to an unshed uterine lining. Mating every couple of years will not in any way prevent the disease. If bacteria find their way into the uterus the fact that the cat gave birth last spring will provide no protection at all.
hardygrrl,
You can’t have seen your friend’s dog menstruate because dogs are eostral, not menstrual animals. They don’t menstruate. What you saw was blood and intracellular fluid shed from the reproductive tract (mostly the uterus) during proestrus. This bleeding occurs immediately prior to ovulation, not following ovulation as does menstruation. It’s not the uterine lining being shed but is rather a result of the thickening of the uterine lining in preparation for implantation. Almost the exact opposite of menstruation. The uterine lining in dogs is neatly resorbed if implantation doesn’t occur and the amount shed is so perishingly small you’d never see it.
Guinastasia,
Would what be the same as cats going into heat?
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### Author:  [@bibliophage](https://boards.straightdope.com/u/bibliophage)
#### Post date: [August 26, 2001, 11:31am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/10 "2001-08-26T11:31:30Z")
The spelling above in inconsistent, which I mention only because it may be hindering people’s searches. The word is spelled estral, oestral, or even œstral, but not eostral.
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### Author:  [@choosybeggar](https://boards.straightdope.com/u/choosybeggar)
#### Post date: [August 27, 2001, 6:53am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/11 "2001-08-27T06:53:12Z")
> [@](#):
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> **Originally posted by bibliophage \*\*
> \*The spelling above i**n\*\* inconsistent…\*\*
😛
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### Author:  [@Gaspode](https://boards.straightdope.com/u/Gaspode)
#### Post date: [August 27, 2001, 9:29am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/12 "2001-08-27T09:29:23Z")
Misspelled not once but 5 times. :o
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### Author:  [@irishgirl](https://boards.straightdope.com/u/irishgirl)
#### Post date: [August 27, 2001, 9:41am UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/13 "2001-08-27T09:41:08Z")
we had a Pyrannean Mountain dog… like a bigger, white newfoundland.
she couldn’t be spayed because of the risk of anaesthetic on a dog that size…likewise we weren’t keen on puppies. (ever try to sell pedigree dogs THAT big?)
she died of uterine cancer, but at the grand old age of 10 (8 is old for a dog that size) and we decided to get a smaller dog and spay her.
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### Author:  [@bibliophage](https://boards.straightdope.com/u/bibliophage)
#### Post date: [August 27, 2001, 12:25pm UTC](https://boards.straightdope.com/t/cats-dogs-and-menstruation-hopefully-not-too-icky/78075/14 "2001-08-27T12:25:23Z")
> [@](#):
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> \*Originally posted by choosybeggar \*
> \*\*
>
> > [@](#):
> >
> > **Originally posted by bibliophage \*\*
> > \*The spelling above i**n\*\* inconsistent…\*\*
>
> 😛 \*\*
\*Dang. I _hate_ when that happens.