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There was an apocalypse. Humans left cities in swathes, leaving their canine companions behind in the ruined cities. My question is, which types of dogs survive?

Criteria -The dogs are going to be left up to their own devices for the next few generations. -The general ecosystem is the same as it was before the war

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    $\begingroup$ @kleer001's answer brings up a useful clarifying question - when you say "next few generations", are you referring to dog generations, or human generations? $\endgroup$ – jdunlop May 14 at 0:55
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    $\begingroup$ The little kickable mutt-dogs do not survive. I declare it to be so! $\endgroup$ – JBH May 14 at 17:14
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    $\begingroup$ @JBH - The ones that were bred as ratters will probably do just as well as the rats do. $\endgroup$ – T.E.D. May 14 at 19:48
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    $\begingroup$ While the dogs would slowly mix into mongrels, I would bet my money on Czechoslovakian Wolfdog and sighthounds (greyhounds, borzoi, irish wolfhound etc.). Wolfdog still has enough wolf genes to survive in the wild, while sighthounds have a mind independent on humans and a strong hunting instinct. Many hunting dogs would probably do fine, including poodles. $\endgroup$ – Sulthan May 14 at 21:49
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    $\begingroup$ The ones that can crossbreed with mutant cockroaches. Or the ones that addres kept as pets by said cockroaches, or as livestock.... $\endgroup$ – nijineko May 15 at 3:34
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Mongrels

There is no reason to think that left to themselves, dogs will remain in breeds. They will cross breed. In a few generations, there won't be any separate breeds. All dogs will be mongrels.

There may be some specialist types. For example, smaller dogs may specialize in hunting in tunnels (e.g. rabbit warrens). The largest dogs will likely become smaller, as large dogs are subject to back and joint problems. Long-haired dogs may appear most often towards the poles and short-haired may tend towards the equator.

Mongrels exhibit hybrid vigor and are healthier than purebred dogs. If dogs are left to themselves, mongrels will take over the world.

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    $\begingroup$ You might end up with something like en.wikipedia.org/wiki/Indian_pariah_dog $\endgroup$ – Borgh May 14 at 13:16
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    $\begingroup$ Certainly the survivors descendants will be mongrels, but some breeds and groups of breeds will get more of their genes into the mix than others. $\endgroup$ – arp May 14 at 17:14
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    $\begingroup$ It's also worth noting that the OP doesn't specify whether the time elapsed is human generations or dog generations. If the dogs are abandoned for a few human generations, then yes, you'd expect to see adaptation. Otherwise, you'll have mutts, but not specialized ones. $\endgroup$ – jdunlop May 14 at 17:53
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    $\begingroup$ Mongrels are not generally healthier than purebred dogs, it depends on the genetic mix. Purebred dogs are about predictability, mongrels are unpredictable, including their health. You are correct in everything else though. $\endgroup$ – Sulthan May 14 at 21:40
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    $\begingroup$ There is a problem with declining gene diversity in pure-breed dogs. The extent of the problem has more to do with the breed - Labradors for instance are fairly healthy, but King Charles Cavalier Spaniel owners pretty much expect their dogs to contract mitral valve disease. A report on a UC Davis study says 10 genetic disorders are significantly more likely to occur in purebreeds, and 1 genetic disorder is more likely in mixed-breeds. $\endgroup$ – mcalex May 15 at 4:36
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Dogs are dogs. Barring some of the more physically-incapacitated dogs, as long as they have a means of escaping their homes, there is unlikely to be any particularly advantageous breed.

That last one does offer some insight - the dogs that would do best in any given city would be the dogs who are best suited for the local climate. A husky or eskimo dog, used to air-conditioning in South Carolina, would probably fare poorly if suddenly left to the elements. A chihuahua or doberman, with velvety-thin fur, would probably do badly without humans to put their coats on in a Chicago winter.

But when it comes to being able to hunt for their food - dogs are dogs. They're generally pretty good at it.


Edit: It's worth noting that most responsible dog owners will spay or neuter their pets, so after a decade or so, the number of dogs will be drastically reduced. This will presumably rebound after an interval, but most pets will die without reproducing, because they cannot.

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    $\begingroup$ I think it's also worth pointing out that certain breeds won't survive for other reasons - it's likely that many long-haired breeds like poodles would fare poorly regardless of local climate due to their fur getting matted without humans to take care of them, as are dog breeds with significant genetic/physical difficulties like pugs or American bulldogs - some of whom are incapable of breeding without humans to give them Caesarian sections. $\endgroup$ – nick012000 May 14 at 4:26
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    $\begingroup$ @JohnDvorak not with that attitude. $\endgroup$ – Malkev May 14 at 9:41
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    $\begingroup$ @JohnDvorak "they can't breed without a c-section" source? Some quick googling suggests while Chihuahuas do have higher pregnancy risks, its definitely not 100% of births that require a c-section. $\endgroup$ – mbrig May 14 at 15:14
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    $\begingroup$ There are a lot of irresponsible pet owners out there, and a lot of places where responsible pet owners can afford to drown litters of puppies but not to spay female dogs. I don't think neutered pets will have that much impact on the population curve, certainly not after a couple of years. $\endgroup$ – arp May 14 at 17:18
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    $\begingroup$ @Sulthan have you seen what happens to the fur of feral poodles? It can get so matted that their feet start rotting off - just Google image search something like “feral poodle fur matting” to see how bad it can get for yourself. $\endgroup$ – nick012000 May 14 at 22:02
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None.

Dog breeds are a human invention. Eventually they will breed out to look more and more like wolves as they bred with wolves (because they are a subspecies of wolves). In fact the more 'bred' a dog is the less survivable it becomes. Think of the contemporary pug with their squished faces, or this: http://blog.vetdepot.com/top-10-dog-breeds-with-the-most-health-issues

also for more discussion:

https://www.quora.com/How-many-generations-would-it-take-for-dogs-to-revert-to-wolves-if-a-wide-cross-section-of-modern-breeds-were-left-to-breed-freely

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  • $\begingroup$ Yep the wildest ones will probably do better and survive better and slowly breed better. $\endgroup$ – mathreadler May 14 at 8:40
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    $\begingroup$ I wouldn't be sure about that. There are way more dogs than wolves, and wolves only live today in very remote areas (or zoos). $\endgroup$ – T.E.D. May 14 at 19:20
  • $\begingroup$ True T.E.D. , but don't forget that Wolves are not just the species, but a nearly optimal combination of traits that fits very nicely into a niche. A niche that current domesticated dogs will fit very nicely into once the selection pressure of humans is removed. So, if an apocalypse removed all the humans and wolves and left dogs those dogs would eventually be indistinguishable (except by fine genetic investigation) from our contemporary wolves. $\endgroup$ – kleer001 May 14 at 23:28
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    $\begingroup$ I’m not sure why the descendants would look more like wolves than coyotes, foxes or jackals. The undomesticated canines best at surviving in citiies today are coyotes. $\endgroup$ – Davislor May 15 at 5:42
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    $\begingroup$ @kleer001 - A large part of their "looks" is just cosmetic though. For the stuff that isn't (eg: size), some of it may end up having advantages that being more wolf-like would lose. This is why there are (as Davislor points out) other caniforms still running around today, and doing much better than Wolves I might add. $\endgroup$ – T.E.D. May 15 at 15:48
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The only pure "breed" that might continue to exist in some isolated areas for more that a generation or two without human intervention would be the Anatolian Sheep Dog because and only because they've been bred for two things:

  • to be actively and aggressively territorial toward any predators, either canine or feline, entering their flock's range.

  • to live with their flocks without human input or oversight the vast majority of the time.

They exhibit extremely strong Assortive Mating behaviour, that borders on behaviour driven Symatric Speciation, they don't outcross with other canines, rather they eat them when they can catch them.

As such Anatolians will probably continue guarding their flocks until either the predators get too numerous and kill them off or the sheep experience a large scale dieback for some reason, like the fact that they're not being shorn or the fact that the flocks aren't being culled yearly.

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  • $\begingroup$ In support of others (@Brythan, @kleer01), genetic variability guards against many problems (e.g. disease) for a population of interbreeding organisms, and makes them better able to adapt to new circumstances (and these are definitely very new circumstances). Dog breeds have been produced and protected (e.g. with the help of vets) by humans with no regard to this issue, and it's likely that many breeds are fragile. If some breed X had a special advantage in the new circumstances, it's likely that X+mutt hybrids would do even better in the end, but assortative inbreeding makes that difficult. $\endgroup$ – Mars May 14 at 15:35
  • $\begingroup$ @Mars I picked this breed from a number of breeds with similar habits because humans disappearing is not really new territory for them, these dogs spend the vast majority of their lives with very little if any human contact in the modern situation. $\endgroup$ – Ash May 14 at 15:39
  • $\begingroup$ Ash, yes, I think it was a very interesting point (and I upvoted). I still would worry that what we're talking about will in the end be a very different world, even for dogs who are used to doing without humans, and stuff will happen, eventually, that will make it difficult to survive. All it takes is the right virus or a new predator, and if the population doesn't have some members with genes that help it respond, the whole population can go extinct, or become so small that it has even less genetic variability. At that point it might go exitinct just by a series of unfortunate chance events. $\endgroup$ – Mars May 14 at 15:45
  • $\begingroup$ If there's a breed that has similar ability to persist without humans but that is more likely to mate with other dogs--and if there are other dogs available for mating--that could produce a population that would do very well without humans over a long period of time. To whatever extent the special abilities of the breed helped dogs survive, those abilities would be likely to be selected for, even among the hybrid descendants. $\endgroup$ – Mars May 14 at 15:48
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    $\begingroup$ @Mars Just the lack of human predator suppression will probably do them in eventually, too many wolves, bears and/or introduced species like tigers are going to overwhelm even the most vigilant shepherds. Out-breeding, by definition, removes a "breed" as a distinct thing, dogs as a species will survive just fine without people but the distinct breeds won't unless they have a strong tendency not to out-cross with other breeds. $\endgroup$ – Ash May 14 at 15:52
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I suspect working dogs, especially breeds which have existed for a long time (and so have few health problems), and which exist in favorable climates, would contribute much more to a wild gene pool of surviving dogs under this scenario. For example: the common husky would do very well in moderate to cold climates. It's used in trapping/hunting and is prized for its endurance. I'm also not certain as another poster suggested that all dogs would necessarily revert to wolves given enough time. The African dog and the Australian dingo come to mind, the latter of which has existed for a few thousand years.

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    $\begingroup$ +1 for dingos. Basically a dog that has already adapted to a harsh environment. They were bred with sheep dogs to produce a working breed hardy enough to survive the Australian Outback. $\endgroup$ – Wolfgang May 16 at 1:07
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The ones that can.

Your viable dog population is going to be a fraction of the total.

If the humans leave their dogs behind in the cities, they are (mostly) not going to leave them locked up indoors or in yards. They'll probably cut open their food bags and fill some water bowls. Which gives the dogs a week or two to figure out other food/water sources and social structures.

Dogs who can reproduce will be a small portion of all dogs. So they will compete for food and other resources with the dogs who can't reproduce.

Most pets are fixed (sterilized). Many ferals are fixed (while captured feral dogs are often fixed then put up for adoption, feral cats are more likely to be fixed then released to keep the population stable...some feral dogs will actually be strays, not true ferals, and others will be released ferals. This varies a lot country to country and, even within my country, the United States, it varies by community.

Large portions of dogs who are not sterilized will be: too young, too old, or in puppy mills (which render mothers incapable of surviving on their own). Some of the puppies may survive if protected by other dogs.

I'm taking you at your word that the "general ecosystem" hasn't changed (though for some reason all the humans leave?) so dogs can form packs and hunt small to medium animals, drink fresh water, and not die from radiation or bio-weapons, etc. Some dogs will have access to houses (with doggie doors or other openings) which protect from the elements and help protect from predators.

Which breeds will do the best?

Small to medium-sized dogs who are suited for the climates they live in.

Very tiny dogs, teacup dogs, say under 6 lbs or so, may find niches if they can eat mice and so forth, but mostly will not do well. They won't be able to fight off larger dogs for access to food. They are even smaller than most cats but with less fighting power and the inability to leap or climb like cats can.

  • Papillon
  • Pomeranian
  • Toy terriers
  • Toy poodles
  • Maltese

Small dogs, in the 6-15 lbs range, are more cat-sized and can eat gophers, mice, maybe rats (most cats avoid rats), birds, and insects. If they can avoid predators, they should do okay.

  • Chihuahuas (the larger ones)
  • Smaller Terriers (various breeds; they're good ratters)
  • Pekingese
  • Miniature Schnauzers

Medium dogs, say about 15-40 lbs, can eat rats, gophers, badgers, squirrels, birds, etc. They have a decent chance of finding food.

  • Larger terriers
  • Dachshund (some hunts animals like badgers)
  • Miniature American Shepherds
  • Miniature Bull Terriers
  • Pugs
  • Spaniels
  • Whippets

Individual varieties within each breed will have different weight ranges and of course any individual dog may weigh more or less. So don't take these listings as definitive.

Also, you didn't specific location, you just said "cities." Dog breeds that tend to do well in Cairo will die in Anchorage. And vice versa. Even if you limit it to climates without super harsh winters or summers, in areas with natural water and urban wildlife, there's still going to be differences in which breeds do better.

What about larger dogs?

Larger dogs, say 40 lbs and up, will probably do better in the short term. There will be a lot of competition for food and access to water and shelter. Bigger dogs will generally win over smaller dogs.

Dogs in the 40-80 lb range might end up okay, but much larger dogs will not. Why? Because they require too much food. Unless the urban areas are small and next to wildlife areas, the large dogs will run out of food within a generation or two, if not sooner. They won't be able to breed and sustain their young. Some larger dogs will leave the urban areas, but that wasn't part of your premise, so we'll ignore them.

The actual breed won't matter so much.

Most of the dogs adapted to the climate who are able to breed will be strays and ferals and mutts used to living outdoors. While many purebreds are left unsterilized, they may be inbred, not bred for local conditions, or indoor dogs. Of course you'll have some working dogs who are purebred or close, but not as many in cities as in the country (or even the suburbs). City dogs are generally pets and usually chosen to do well in smaller homes.

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Most of the dogs are dead anyway

Dogs in cities and suburban areas that are not pestiferous ferals are dead. A large, desperate-for-food dog might break a window to get out (that's the problem with domestication), but the reality is most will starve in a week,1 whether kept inside the house or in a fenced yard.

Dogs in deserts or the arctic wastes are mostly dead

The rural dogs who live in desert or arctic conditions have two problems: water and temperature. The hardier breeds will survive, but most are dead. In the arctic areas you're talking Huskies, Saint Bernards, etc. Dogs bred for cold. In the deserts, beats me, maybe Dobermans, definitely Coyotes.

But what about the heartland?

In rural areas with nice climates and available water, I don't believe any breed has a particular advantage over another. I completely agree with Brythan (and you should upvote his answer) that eventually all you'll have are mongrels, but dogs are pack animals, and the domesticated breeds tend to be much less discriminating than wild breeds when it comes to who's a member of the pack. Breeds less suited to a particular area would find the situation much simpler due to the benefits of the pack.

Conclusion

Of the few dogs that survive the apocalypse, specialized breeds will survive at the environmental extremes, but everywhere else there won't be one breed more successful than another.


1Longer, if there's more than one dog.

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  • $\begingroup$ The Canaan dog would probably do well in the desert, if there are any around. $\endgroup$ – a CVn May 14 at 19:41

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