This cat looks like a normal Maine Coon to the unsuspecting victim. Except for one little detail:

Red claws that inject a neurotoxin into the victim onpon scratching it. What would be the most appropriate way a cat could evolve toxic claws?

I am looking for ways to explain why this cat evolved the toxic claws and how they work exactly. This includes the type of neurotoxin that could be used.

I would imagine that it would be a good weapon if the cat needs to incapacitate the victim with the first sneak-attack and then wait for the toxin to take full effect. This would only be necessary if the victim would be a potential danger to the cat if it could attack the cat.

You can choose an appropriate prey for the cat, so that this mechanism would evolve. The bigger the prey that can be killed by a single cat with the proposed technique the higher I rate the answer.

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    $\begingroup$ It's already a thing in a way en.wikipedia.org/wiki/Cat-scratch_disease Might go with something like this. Bacteria is bad for its victims but the cat would be immune. Much like how we thought Commodo Dragons worked. $\endgroup$ – Mormacil Mar 30 '17 at 18:28
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    $\begingroup$ In the severe cases it works within 24 hours. That's faster then the poison of a Comodo Dragon. I argee it's not a neurotoxin hence a comment and not an answer. But it would work if it's more potent. $\endgroup$ – Mormacil Mar 30 '17 at 18:33
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    $\begingroup$ Well for cats to evolve poison claws they need a good reason for it,Like hunting big prey like deer,Maybe your cats eat poisonous insects and get the toxins from the bugs. $\endgroup$ – Seraph Myrmidon Mar 30 '17 at 19:49
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    $\begingroup$ They already did, it's called a platypus. $\endgroup$ – Shufflepants Mar 31 '17 at 13:49
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    $\begingroup$ This is the kind of evolutionary trait that puts an animal at the top of the food chain, it enables it to kill prey much larger than it is, and if it did arise from a mutation, by now every cat on the planet would have them with various adaptations. If it was somehow the first cat to have that mutation, the toxin would be very weak and would evolve to become more efficient against its preferred prey. You pretty much need something like a cat that escaped from a biological warfare lab somehow if it's the only one. $\endgroup$ – Drunken Code Monkey Apr 1 '17 at 7:04

11 Answers 11


So far as I am aware all venom is created in glands and generally derive from enzymes that already exist for some practical function. A mutation of the code for one of these enzymes is usually the source of poison creation.

This article is exceptionally helpful in explaining the evolution of venom.

It includes vipers, jellyfish, spiders, scorpions, centipedes, bees, cone snails, newts, platypus, and even a primate. All these animals produce molecules that attack a victim in minutes or even seconds.

So for poison to evolve in a cat is not that improbable, after all it exists in the platypus and a loris.

Importantly not all of these animals create their poison in their mouth. The Loris has glands under its arms not unlike a lemur. Though from what the article says they then apply their toxin to their teeth to deliver.

Specifics to the cat:

I would think the most likely evolutionary path for a cat would be a mutation changing the chemicals produced in their scent marking glands. If you're familiar with cats you know they scent mark and it stinks. My reasoning is that would be similar to the lemur/loris set up. Lemurs have glands used for scent marking, the loris has evolved similar glands to also be toxic.

So there you go...its really not that far of a stretch biologically speaking.

If you insist on delivery via claws that is a bit more challenging. Odds are a cat is not going to evolve glands in its feet nor hollow claws for injection. First, feed aren't a great place to have poison glands. Feet experience a lot of stress, cats walk run and climb so glands in the feet, not ideal.

An important note is that cats already rely on their claws for mobility, grappling prey and fighting off predators. What I am trying to point out is that IF you had claws injecting toxins they would have to be hollow and hollow claws would not be strong enough for climbing thus reducing the viability of the species. They would also be less effective when grappling prey...again reducing viability.

As for a solution, you can take advantage of the fact that a cat licks its backside...so it would similar to the loris create the toxin and then have it on its bite. I suppose it could walk through its own spray and have it on its claws as well but that would probably be less effective since walking would end up removing most of the poison in short order.

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    $\begingroup$ They can put poison on their claws from the outside during grooming. $\endgroup$ – alamar Mar 31 '17 at 13:06
  • $\begingroup$ @alamar yeah I specifically mention that as an option. $\endgroup$ – James Mar 31 '17 at 13:12
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    $\begingroup$ The venom could be delivered in a way that it coats the claws instead of being passed through a hollow inside. $\endgroup$ – mirabilos Mar 31 '17 at 13:59
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    $\begingroup$ You could also make the claw anatomy partly composed of a toxin, like an alloy for metals. $\endgroup$ – Anoplexian Mar 31 '17 at 16:53
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    $\begingroup$ Maybe a mucus that fills the claw sheathe, so that a thin layer is reapplied every time they are retracted? $\endgroup$ – thegreatemu Mar 31 '17 at 18:25

Cat claws are already pretty toxic. Cat scratch fever is a real thing. That's because they have all manner of bacteria on their feed from the litter box and whatever else they walk in.

Their mouths are also pretty bad in the same way, but worse. If you get bitten deeply by a house cat, you should go to the hospital, and may be encouraged to go on a round of antibiotics.

It could be bad dental hygiene, but it could also be an evolutionary advantage. Instead of mauling their prey, a cat could simply inflict a wound and wait for the prey to die from infection.

Komodo Dragons and many other reptiles take this further. Their mouth bacteria produce a lot of toxins and an untreated bite is almost certainly lethal. They have evolved to withstand their own funk.

I would go with something along those lines: some kind of bacteria that lives on the cat claws, maybe feeding off some oily excretions in their paws. The bacteria infects its victims and excretes your neurotoxin.

  • $\begingroup$ exactly what I would have said. My own father got infected with bacteria from a house cat, we needed to take him to a hospital and it still took 2 weeks for the swelling to go down. $\endgroup$ – Reed Mar 31 '17 at 13:03

One approach is coevolution.

For example, you could have some species of fungus or bacteria that developed behaviors that caused them to "activate" their toxin-producing behavior when in the environs of a cat's claw sheaths (damp, dark, has cat pheromones, or activated by cat saliva enzymes, or what have you). Outside of this environment, they may be relatively benign -- at least to the cats.

The cats in their natural habitat would pick up these fungi or bacteria from the environment, or even their parents (who would be covered in the non-active spores / microbes). In the claw sheaths, a trifecta of dark, damp, and some other activation condition (may even be non-cat-specific) causes them to produce your choice of toxin. Of course, the cats would have evolved to be resistant to this toxin; otherwise, we would not even be talking about them.

Note that this approach means that the cat's claws themselves are not toxic, but without scientific investigation (ex. isolating the cats from their native environment and fellows, disinfection), you can't tell if their claws are toxic in and of themselves or not -- you'd be more worried about not getting scratched in the first place, and thus "their claws are toxic".


The evolution could be behavioral, and not such a stretch.

Consider curare

It is a formidable and fast acting neurotoxin. Indigenous rain forest people prepare it from the curare vine. The amount carried on a blowdart is enough to paralyze prey.

Certainly the amount of this or a similar poison on a cats claws would be enough to do likewise. Cats already sharpen their claws on wood. The evolutionary change: these cats seek out curare vine (or your world's equivalent) and sharpen claws on it before hunting, accumulating toxin on their claws. That is not a very dramatic change.

It is perfect for cats because the cats sheathe their claws after sharpening, so plant alkaloids will still be there when claws come out to attack. That would not work for a dog or some animal which ran on its claws.

This angle for a small cat which hunts large prey would mean the cat would probably eat its paralyzed prey while it was still alive. The prey, I mean. The cat would need to be alive.


Evolutionary history shows us that venom has evolved in predatory species which are:

  • too slow for chasing and catching their prey (e.g. snakes)

  • too fragile as compared to their prey (e.g. jellyfish)

A predator which is already fast and robust would have no need for venom glands to develop. If you want your cat to have venomous claws, you would need to put it under great ecological stress throughout its evolutionary history. The prey items should be faster and sometimes just too much to handle in a straight fight.

As for how they work, venom is oftentimes delivered through hollow fangs or stingers. Your cat would also need to have hollow claws, in which the hole connects to the venom gland. The venom gland should be located at the upper edge of the foot, so as to avoid accidental release due to shock.

You can make the venom so potent that the victim gets dizzy within seconds and gets disabled within minutes. This works great with chemical venom. Or you can give your predator an assault-and-chase strategy, where it scratches its victim and then follows it for a long time (a couple days perhaps?) until the slow effects gradually take over and bring it down. This strategy works good with bacteria-infested bite, most popularly associated with komodo dragons.

Theoretically a bacteria infested scratch would be able to take down anything from a mouse to an American bison, although the time difference to bring down the prey would be huge. The bison would perhaps take weeks before it succumbs to the toxins and falls.


Venom glands in snakes evolved from modified saliva glands. The only glands present in the paw area are related to the emission of sweat or pheromones.

It would be better for the claws to evolve to have a non-smooth surface that is able to collect dirt and remains of other prey. This surface would act as a growing ground for toxic bacteria.

In this way, if the injured prey manages to escape, it will die from sepsis soon. Or, at least, will make it weak enough for the cat to catch it.


Clearly, they didn't naturally evolve glands on or near their claws, because of practical issues that naturally select against evolving fragile and dangerous glands on areas of their bodies that they use for running, climbing, and poking holes in innocent furniture.

Your cats with toxic claws are, therefore, the result of bio-experimentation gone wrong. Some mad scientist clearly decided he wanted an army of venomous cats, for some reason (maybe he got tired of his guard dogs chewing his shoes, maybe he just really liked cats, whatever). Evidently, he succeeded in engineering and breeding a decent number of these cats by figuring how out to splice DNA from some other venomous animal into cat DNA and code them to develop poison glands at the base of their claws. Then, predictably, things went bad. He was celebrating his genius, petting one of his new toxic cats when it returned his affection and started kneading its claws on his lap.

After his death, his army of toxic cats went out into the wild, and thanks to their poisonous claws, they thrived and multiplied. Other species of cats and even dogs were quickly killed off or displaced, and thanks to their poisonous claws, these cats were able to take down big game like deer. With no effective competition and an abundance of food, this species underwent explosive population growth. Now, mere years or decades later, we have yet another cautionary tale about the dangers of covert biological weapons research and the inherent perils of raising felines.


Allow your cats to change their behaviour and prey.

Let them eat snakes, ripping out their venom glands with their claws before eating the rest of the snake.

Their claws will then become envenomed, ready to inject into any other prey animals.


I assume you're either working on homework, or writing (presumably) YA.

If it's the former, I can't come up with a good reason, and I'm a college bio major so best o' luck to ye. Spiders, the paradigm comparison, still need to rely on either a web to catch the victim or strength to overpower it, because the thing doesn't die quickly enough. With that in mind, think of this from a hypothetical cat's perspective: you're already a very efficient hunter of small prey - if you catch it, it's as good as dead, venom or no - but a big animal like a deer or hippo can still quite easily kill you even if the venom acts in 15s, and in reality it would probably take days in that small a dose. Not much help in either case.

As for writing, I already explained why venom makes no sense for offense.

As a defensive mechanism though, something that takes a little longer would make sense, especially if other large and aggressive predators existed. However, venom is still quite a stretch, because I would think that the venom-producing glands would have to evolve first, then the delivery method, and the former happening in a cat's legs sounds like a disadvantage for the cat - read: a self-eliminating trait in natural selection.

Rather than venom, change it to bacterial endospore that resides on the cat's claws. These bacteria would have a mutually beneficial symbiotic relationship with the cat: they gain a carrier that transmits them to other hosts, while the cat gains a potent weapon. The endospores are triggered by exposure to other animals but not the cat's own system. That makes quick death (<24hr) a bit farfetched - bacterial infection from spores usually takes longer to hit full swing - but by the virtually unlimited viability period of endospores would explain why the bacteria live on all of this species of cat, all the time for their entire lives, without dying off from lack of a host.

Whatever you decide to use, before you go ahead, ask yourself the following two questions:

Why would this come to exist? (you already are so good there)

Why would the cat not kill itself when it licks its claws or scratches off a scab?


Consider that Cats like to lick their paws. If their claws were toxic they would poison themselves. I don't think it's possible.

On the other hand eating venomous animals/objects does not necessarily make an animal's claws toxic. Consider koalas. I don't think their claws are toxic even though they eat eucalyptus.

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    $\begingroup$ This looks more like a comment than an answer that could stand on it's own. When you gain more reputation you will be able to comment on other people's answers. $\endgroup$ – sphennings Mar 31 '17 at 19:47
  • $\begingroup$ ? how so, I'm answering that I do not think it's possible--If they did, they'd kill themselves from the habit of licking their claws. $\endgroup$ – AsheKetchum Mar 31 '17 at 19:56
  • $\begingroup$ Is a cat not a real animal? o.0 $\endgroup$ – AsheKetchum Apr 3 '17 at 14:34

To evolve so much in a short span, they could co-evolve with another species, perhaps something that attacks and eats kittens. One evolves poison glands near it's claws, and the rest is history.

Or it could have a mutually beneficial relationship with a highly toxic bacteria that thrives on it's claws.

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    $\begingroup$ en.wikipedia.org/wiki/Evolutionary_pressure This is how a number of highly toxic species become highly toxic, such as frogs. They evolve, and then their predator evolves as well in a sort of evolutionary arms race, or perhaps a red queen race. Additionally, they could have prey that's difficult to kill, like an armadillo or something, but poison is effective against it. $\endgroup$ – JFA Mar 31 '17 at 20:42

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