Pedigrees get sick.
Village dogs
eat scraps
and do fine?
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Pricey purebreds keep landing at the vet, while village dogs eat scraps and stay fine? A purebred costs thousands, and still the skin trouble, bad joints and heart problems show up one by one. The yellow dog at the village gate never sees a needle, lives on leftovers, and looks livelier than anyone.
So are scraps better for dogs? Quite the opposite. Onion, garlic and salty dishes can hurt a dog. Leftovers are not the secret. Then are village dogs just born tough? That's only half right.
Start with the true half. Your front door has two keys. Lose one, and the other still lets you in. Every part of a dog's body also comes with two blueprints, one from dad, one from mom. If one is faulty, the other covers for it, and the dog stays healthy. Only when both are faulty does the illness appear.
That's exactly where purebreds get into trouble. To keep a breed looking the same, breeders only mate it with its own kind. Go back a few dozen generations, and there are only a handful of ancestors. Scientists have measured it: on average, a purebred dog is about as inbred as the child of a brother and sister.
When the parents are relatives, both blueprints are often copied from the same book. If one has a flaw, the other likely has it too. Village dogs are the reverse. A dog from one village has pups with a dog from the next, so the two blueprints come from all over, and rarely fail together. The real name for that blueprint is a gene. A disease that needs both copies broken is called a recessive genetic disease, and that's what a dog DNA test at the vet looks for.
Some breeds were also picked for looks. Flat faces struggle to breathe, and giant bodies wear out their joints. But what about the other half? Take a guess: among free-roaming dogs nobody looks after, out of five puppies, how many grow up?
A study that followed them for five years found: only about one. Cars, illness and parasites take many before they grow up, and nobody writes it down. So the dogs you see at the village gate are the toughest few. Every village dog you've met is a survivor.
When a purebred gets sick, it goes straight to the vet, and every visit is on record. When a village dog gets sick, it often just toughs it out. Even counting all that, mixed-breed dogs still live over a year longer on average. But that's an average, and not every purebred is sickly. Before buying, ask whether the parents were health-tested, and follow your vet's advice.
Village dogs are tough partly because their blueprints are mixed, and partly because the weak ones vanished long ago. How old did the dog back home live to be?
The scraps
are not the secret
Village dogs are not healthy because of the scraps.
Onion and garlic damage a dog's red blood cells, and very salty food is bad for them too. Leftovers often contain all three. We covered foods dogs must not eat in another episode.
So are village dogs just "born tough"? That is only half right.
Two keys
to the front door
Lose one key, and the other still gets you in.
Every part of a dog also has two blueprints: one from dad, one from mom. If one is faulty, the other covers for it and the dog stays healthy. Only when both are faulty does the disease show up.
The real name for the blueprint is a gene. A disease that appears only when both copies are bad is a recessive genetic disease. A dog DNA test at the vet checks whether either blueprint has that bad line.
A breed goes back
to just a few dogs
To keep a breed looking the same, breeders only mate it with its own breed. Go back a few dozen generations and there are only a handful of ancestors. Why dogs changed shape so fast is in this episode.
On average, a purebred dog is about as inbred as the puppy of a brother and sister.
When the parents are relatives, both blueprints are often copied from the same book. If one is faulty, the other likely is too. Some breeds were also picked for looks: flat faces struggle to breathe, and giant bodies strain the joints.
A village dog's blueprints
come from everywhere
That is the true half of "village dogs are tough".
You never see
the ones that didn't grow up
Among free-roaming dogs nobody looks after, only about one puppy in five grows up.
In a five-year street study, most puppies were gone before they grew up: cars, illness, parasites. Many causes involved people, and nobody wrote any of it down.
So the dogs you see at the village gate are the toughest few. Looking only at the survivors is called survivorship bias. A sick pedigree gets taken to the vet and every visit goes on record; a sick village dog usually just toughs it out.
Count everything, and
mixed breeds still live a year longer
In vet records of over 100,000 dogs in England, mixed breeds lived over a year longer than purebreds on average.
That is an average, though. Not every pedigree is sickly. Before buying, ask whether the parents were screened for genetic diseases; if your dog is ill, follow your vet's advice.
half mixed blueprints,
half the weak ones
you never saw.
Quick check
Why are purebred dogs more prone to genetic diseases?
Lose one house key and the other still opens the door; inbred dogs often get two keys from the same faulty mould.
