# Why don't cats, small dogs and other small pets protect us like a canary in a mine? **URL:** \ **Category:** Factual Questions\ **Created:** [January 29, 2017, 1:44am UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469 "2017-01-29T01:44:25Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 29, 2017, 4:28pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/21 "2017-01-29T16:28:22Z")
Birds are more susceptible to poisoning by gases than most mammals - for example, pet birds are often killed by gases produced by heated teflon products, which have no noticeable effect on other pets or humans. ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [January 29, 2017, 4:32pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/22 "2017-01-29T16:32:06Z")
> [@snfaulkner](#): > > A biRd off it’s roost is very quickly identifiable as a problem. The Norwegian Blue prefers keepin’ on its back. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [January 29, 2017, 4:41pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/23 "2017-01-29T16:41:53Z")
> [@Thudlow\_Boink](#): > > The Norwegian Blue prefers keepin’ on its back. To nitpick, it’s _kippin’_, British slang for sleeping. ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [January 29, 2017, 5:14pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/24 "2017-01-29T17:14:42Z")
Thank you. ---
**Author:** ![crucible](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@crucible](https://boards.straightdope.com/u/crucible)\ **Post date:** [January 30, 2017, 4:35am UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/25 "2017-01-30T04:35:17Z")
> [@robardin](#): > > Wait… Your son goes through 40 lbs. of cat litter _a week_? > > Does he run a cat shelter, or does he have a tiger or something? I may have exaggerated a bit. They do like to change the material every day (three cats using the same box, oddly) and I suppose they use 2 or 3 pounds of pelletized old newspapers a day, though, so…15-20 pounds. To me, the litter box rarely offends the nose when we visit, unlike some places. ---
**Author:** ![clairobscur](https://avatars.discourse-cdn.com/v4/letter/c/839c29/32.png) [@clairobscur](https://boards.straightdope.com/u/clairobscur)\ **Post date:** [January 30, 2017, 11:42am UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/26 "2017-01-30T11:42:14Z")
I don’t know if it has ever been done deliberatly, But I’ve read or heard about a number of instances of people visiting a cave alerted to the presence of CO because their dog dropped dead. Doesn’t the CO tends to “sink” in the air and be present at higher concentration closer to the ground, also(which would make pets more likely to succumb to it than their owners)? ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 30, 2017, 12:46pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/27 "2017-01-30T12:46:37Z")
> [@clairobscur](#): > > Doesn’t the CO tends to “sink” in the air and be present at higher concentration closer to the ground, also(which would make pets more likely to succumb to it than their owners)? The molar mass of CO is 28. This is a close match for N2 (28), O2 (32), and atmospheric air (~29), so even if you introduced it in a layer near the ground, you wouldn’t expect a strong tendency to remain stratified. ---
**Author:** ![pool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pool/32/4152_2.png) [@pool](https://boards.straightdope.com/u/pool)\ **Post date:** [January 30, 2017, 1:02pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/28 "2017-01-30T13:02:11Z")
Hey, why did my pet canary, Gary just die? All I did was cook his favorite breakfast on my new Teflon pan. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [January 30, 2017, 1:05pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/29 "2017-01-30T13:05:46Z")
I was rather curious about this - so a tiny bit of searching around and thinking about things turned up a few thoughts. Birds are fundamentally different animals to mammals. We may well expect different attributes in their metabolism and the like. My first thought was that perhaps smaller animals had proportionality less blood volume, and thus the effects of CO could happen faster - but no - all mammals and birds seems to have a very consistent ratio of blood volume to mass. So, what about the blood itself? Well it seems birds have very different blood - as a result of evolving during a significantly different time and different oxygen concentration in air. Their red blood cells remain nucleated, and are about double the diameter of mammalian cells. Most importantly (I suspect) avian red blood has a relatively poor affinity for oxygen. It is getting on for half that of humans. This probably is the core issue. In the face of reduced oxygen levels (CO[sub]2[/sub] or methane) or a reduced capacity for carrying oxygen in their blood (CO), birds may well reach the point of no useful oxygen transport much earlier than humans, and thus go unconscious at lower concentrations of the various gasses. A generally faster rate of breathing and heat rate in a small body probably makes the onset much faster as well. And as noted, they fall of a perch.\* \*Unless they have been nailed there. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [January 30, 2017, 1:15pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/30 "2017-01-30T13:15:51Z")
> [@Francis\_Vaughan](#): > > Well it seems birds have very different blood - as a result of evolving during a significantly different time and different oxygen concentration in air. This sentence makes no sense. No living thing today “evolved in a different time”. We have ancestors that were around and evolving in that era, just as much as birds. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [January 30, 2017, 1:25pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/31 "2017-01-30T13:25:43Z")
> [@naita](#): > > This sentence makes no sense. No living thing today “evolved in a different time”. We have ancestors that were around and evolving in that era, just as much as birds. Birds as a clearly separate class evolved at a different time to mammals. Evolution isn’t a simple linear thing that continues to evolve _everything_. Mammals are animals with quite clear characteristics that are different to birds, and we can look back in the archaeological record to see the time when these characteristics appeared. Birds appeared in the Jurassic, and mammals in the Triassic. Individual species may have come and gone, but the core nature of each class remains. Prior to the Triassic there were no mammals. Prior to the Jurassic there were no birds. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 30, 2017, 2:28pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/32 "2017-01-30T14:28:08Z")
> [@Francis\_Vaughan](#): > > So, what about the blood itself? > Well it seems birds have very different blood - as a result of evolving during a significantly different time and different oxygen concentration in air. Their red blood cells remain nucleated, and are about double the diameter of mammalian cells. Most importantly (I suspect) avian red blood has a relatively poor affinity for oxygen. It is getting on for half that of humans. This probably is the core issue. In the face of reduced oxygen levels (CO[sub]2[/sub] or methane) or a reduced capacity for carrying oxygen in their blood (CO), birds may well reach the point of no useful oxygen transport much earlier than humans, and thus go unconscious at lower concentrations of the various gasses. A generally faster rate of breathing and heat rate in a small body probably makes the onset much faster as well. This. Birds in general are much more sensitive to poisonous atmospheres than humans. This is particularly important where CO is concerned. Even if CO poisoning doesn’t kill you, it can make you seriously ill for an extended period; by the time you notice your own symptoms and get yourself to safety, you may find that have set yourself up to become too sick to work for the next week or so. This is a bad deal for the mine and for the miner. The canary gives a clear indication of trouble early enough, and at low enough concentrations, so that miners can evacuate to safety before they themselves are poisoned badly enough to require time off of work. Advantages of canaries over cats and dogs: [ul][li]They’re very small, which makes them very portable in a mine - much more so than a cat or dog. [/li][li]They require less care than a cat or dog; small cups of food and water, and a sheet of paper on the bottom of the cage for management of relatively non-odiferous waste. Cats and dogs need substantially more food and water, and produce large quantities of really stinky waste.[/li][li]They’re much more sensitive to CO than cats and dogs; they respond more quickly and to lower levels, giving humans adequate chance to evacuate before getting so exposed that they become committed to an extended period of recovery.[/li][li]Their indication is much more obvious; cats and dogs lie down all time for naps, but birds don’t lie down on the floor of the cage unless they’re sick.[/ul] In the case of the article cited by the OP, the ill-fated couple would have to have directly observed their cats (not a sure thing, since cats could be anywhere in the house. Note too that miners were trained to pay attention to their canaries and to understand the significance of a stupefied/incapacitated bird. The doomed homeowners would similarly have needed to make the mental connection between lethargic/incapacitated cats and the presence of an otherwise-undetectable atmospheric toxin, despite not having been trained to do so. Also, even if cats do have a slightly faster metabolism owing to their size, it’s not nearly on par with a canary; by the time the cats were showing obvious symptoms, the owners may have already been too stupefied themselves to understand what was happening and evacuate. Example, I recall a story years ago of a guy who knew he was suffering from CO poisoning and had to get out of the house, but it took him several minutes to remember how to use the doorknob.[/li] For your entertainment: some [pictures of miners with their canaries](https://www.google.com/search?q=canary+coal+mine&biw=987&bih=771&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjyup-ThOrRAhVG6iYKHV66B2kQ_AUICCgD#imgrc=_) For your edification: [Canaries were used in British coal mines until 1986,](http://news.bbc.co.uk/onthisday/hi/dates/stories/december/30/newsid_2547000/2547587.stm) when they were finally replaced with electronic CO monitors. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [January 30, 2017, 2:48pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/33 "2017-01-30T14:48:36Z")
> [@Francis\_Vaughan](#): > > Birds as a clearly separate class evolved at a different time to mammals. Evolution isn’t a simple linear thing that continues to evolve _everything_. Mammals are animals with quite clear characteristics that are different to birds, and we can look back in the archaeological record to see the time when these characteristics appeared. Birds appeared in the Jurassic, and mammals in the Triassic. Individual species may have come and gone, but the core nature of each class remains. > > Prior to the Triassic there were no mammals. Prior to the Jurassic there were no birds. True, but “class” is bad terminology to use when discussing evolution and prior to the Jurassic birds’ ancestors were members of other groupings, clades with distinct characteristics. Those ancestors were there in the Triassic, evolving their hearts out, but for whatever reason managed fine without what we can guess was an adaptation to slightly lower oxygen levels in our mammalian ancestors. All other members of neotheropoda happened to die out, but if they hadn’t, and the “lower oxygen” hypothesis explains mammal blood cells, I expect they would share circulatory system features adapting to low oxygen in some other way. Or to put it another way. We don’t know much about what parts of the avian circulatory system originated in their Triassic ancestors since organs, blood cells and blood chemistry don’t fossilise well, but if the lower oxygen level was a significant evolutionary pressure it’s likely bird circulatory systems have adaptions too, even if they don’t include the precise ones of mammals, which makes “birds evolved in the Jurassic when there oxygen levels were higher” true, but not an explanation of anything. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [January 30, 2017, 3:51pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/34 "2017-01-30T15:51:51Z")
> [@naita](#): > > …but if the lower oxygen level was a significant evolutionary pressure it’s likely bird circulatory systems have adaptions too, even if they don’t include the precise ones of mammals, which makes “birds evolved in the Jurassic when there oxygen levels were higher” true, but not an explanation of anything. Agreed. I’m no expert, this was my source: [http://file.scirp.org/pdf/ABB\_2013080815254829.pdf](http://file.scirp.org/pdf/ABB_2013080815254829.pdf) (2.9 in particular.) The thesis seems to be that the parallel development of homoiothermy was the driver. Birds evolved from predecessors that had a more efficient cardiovascular system - as you say a different adaptation to the earlier lower oxygen levels. Thus leaving them with the poorer oxygen affinity relative to mammals, but at time when the higher oxygen levels removed the pressure to improve efficiency as they emerged. The outcome is two different variations that address modern metabolic needs, one that has erythrocytes with a significantly poorer affinity for oxygen, but better cardiovascular efficiency. In a mine full of CO the affinity for oxygen matters. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [January 30, 2017, 7:16pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/35 "2017-01-30T19:16:52Z")
I’ve been reading the links. It’s cleared up a few of my misconceptions. Thank you. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [January 30, 2017, 7:24pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/36 "2017-01-30T19:24:18Z")
Ignorance fought. Tweetie, our canary when I was a little boy, died after my older brother futzed with the fireplace flue and closed it, and I still remember being perplexed because so little smoke spread around before my father fixed it. ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [January 30, 2017, 10:01pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/37 "2017-01-30T22:01:44Z")
> [@clairobscur](#): > > Doesn’t the CO tends to “sink” in the air and be present at higher concentration closer to the ground, also(which would make pets more likely to succumb to it than their owners)? > [@Machine\_Elf](#): > > The molar mass of CO is 28. This is a close match for N2 (28), O2 (32), and atmospheric air (~29), so even if you introduced it in a layer near the ground, you wouldn’t expect a strong tendency to remain stratified. Carbon dioxide (CO2), on the other hand, has a molar mass of 44. So a layer of it in a hole or basement will tend to stay there. Now, carbon dioxide isn’t quite as dangerous as carbon monoxide, but if the atmosphere in the hole is too enriched with CO2, there won’t be enough oxygen left and some poor soul wandering in can easily pass out. Often in this case, a passer-by or coworker will rush into the pit to help and pass out, too. Both of them will suffocate to death soon unless a more aware coworker can help. So it’s good to be aware of this possibility if you see someone in a confined pit or basement below you pass out, especially if there’s a furnace, engine, or other possible carbon dioxide source around. ---
**Author:** ![iamthewalrus\_3](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)\ **Post date:** [January 30, 2017, 11:32pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/38 "2017-01-30T23:32:59Z")
> [@Quercus](#): > > Carbon dioxide (CO2), on the other hand, has a molar mass of 44. So a layer of it in a hole or basement will tend to stay there. Now, carbon dioxide isn’t quite as dangerous as carbon monoxide, but if the atmosphere in the hole is too enriched with CO2, there won’t be enough oxygen left and some poor soul wandering in can easily pass out. Often in this case, a passer-by or coworker will rush into the pit to help and pass out, too. Both of them will suffocate to death soon unless a more aware coworker can help. > > So it’s good to be aware of this possibility if you see someone in a confined pit or basement below you pass out, especially if there’s a furnace, engine, or other possible carbon dioxide source around. Cite that this happens? The [hypercapnia response](https://en.wikipedia.org/wiki/Hypercapnia), which is what feels like suffocating, is triggered by excessive carbon dioxide in the bloodstream. There are lots of gases that you can suffocate on without noticing if you start breathing them and not oxygen because you don’t actually notice hypoxia. CO2 isn’t one of them. Someone going into a high CO2 atmosphere should immediately feel like they can’t breath and try to get the fuck out. ---
**Author:** ![slaphead](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slaphead](https://boards.straightdope.com/u/slaphead)\ **Post date:** [January 31, 2017, 5:31pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/39 "2017-01-31T17:31:30Z")
> [@iamthewalrus\_3](#): > > Someone going into a high CO2 atmosphere should immediately feel like they can’t breath and try to get the fuck out. But if they are breathing a low-oxygen atmosphere they may almost immediately pass out, especially if they start gasping for ‘breath’ and actively flushing out what oxygen remains in their lungs and bloodstream. Extra dangerous if they exert themselves by e.g. trying to drag someone else out. Breathing anything with very low oxygen levels is extremely dangerous whether you can detect it or not. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 31, 2017, 6:05pm UTC](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469/40 "2017-01-31T18:05:20Z")
> [@iamthewalrus\_3](#): > > Cite that this happens? The [hypercapnia response](https://en.wikipedia.org/wiki/Hypercapnia), which is what feels like suffocating, is triggered by excessive carbon dioxide in the bloodstream. > > There are lots of gases that you can suffocate on without noticing if you start breathing them and not oxygen because you don’t actually notice hypoxia. CO2 isn’t one of them. Someone going into a high CO2 atmosphere should immediately feel like they can’t breath and try to get the fuck out. I am directly aware of one incident in which an individual entered a room in which a CO2 fire suppression system had just been activated. He was quickly rendered unconscious. His coworker, aware of what had happened, entered the room to try to drag the victim to safety. the coworker was _nearly_ rendered unconscious, and had to retreat to fresh air before going back to finish dragging the unconscious victim to safety. It’s not that you don’t know you’ve inhaled a lungful of pure CO2 - it’s that once you do, your brain can be rendered hypoxic so quickly that you can’t reach safety before lapsing into inebriation and then unconsciousness. The problem in these cases isn’t particularly CO2 poisoning/hypercapnia, [which takes some time.](https://en.wikipedia.org/wiki/Hypercapnia#Tolerance) Instead, hypoxia is the killer. [Previous page](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469.md?page=1) [Next page](https://boards.straightdope.com/t/why-dont-cats-small-dogs-and-other-small-pets-protect-us-like-a-canary-in-a-mine/778469.md?page=3)