What popularity costs a breed

There is a quiet pattern in the way breeds fall in and out of favour, and once you see it, it is hard to unsee. A breed catches the public mood — sometimes through a film, sometimes through an Instagram aesthetic, sometimes for reasons no one quite agrees on — and within a decade or so it becomes one of the most registered breeds in the country. By the time that has happened, the breed is, by almost any honest measure, in worse shape than it was before anyone wanted it.

This is not an accident. Popularity, in a breed, is a welfare problem with a long fuse. It does not look like one at the time. It looks like more puppies being born, more breeders entering the market, more enthusiasm. It is only ten or fifteen years later that the bill arrives, in the form of vets booking corrective surgery earlier, insurers raising premiums, and owners discovering — too late — that the thing they fell in love with came with a chronic condition attached.

It is worth being plain about how this happens, because the mechanisms are well understood, even when the consequences are not widely seen.

The gene pool gets narrower, not wider

You might imagine that a popular breed has more genetic material to work with than an unpopular one. More dogs, more variety. The opposite is true.

When a breed becomes fashionable, a small number of stud dogs end up siring an outsized share of the next generation. Geneticists call this the popular sire effect. A single dog with a winning conformation, or a famous owner, or just the right look, will be used hundreds of times — sometimes more than a thousand. Within two or three generations, his genes are everywhere in the breed, and so are the recessive faults he carried. Everyone is, genetically speaking, a closer relative of everyone else than they were the decade before.

The measure for this is something called effective population size — roughly, the number of unrelated breeding animals contributing to the next generation. Conservationists treat anything below 100 as a critical threshold. Many of the popular UK pedigree breeds sit well under that figure, and have done for years. A breed can have hundreds of thousands of registered dogs alive at any moment and still have the genetic diversity of a few dozen. The numbers are real; the variety is illusory.

The horse world has the same pattern in a less visible form. Successful sport-horse stallions sire thousands of foals over a career; the popular thoroughbred and warmblood stallions are bred from to the point where almost every competitive sport-horse pedigree has the same handful of names somewhere in it. The mechanics are different — the scale of one stallion's reach is larger, the species is more genetically robust — but the same compression is happening.

The breed itself starts to change

The other thing popularity does is reward whatever look got the breed popular in the first place. Buyers want what they have seen. Breeders are people who would like to sell their puppies. So, gently and unmistakably over the years, the breed drifts toward the version that sells.

In some breeds that drift is harmless. In others it is the welfare story.

The French Bulldog of 2026 does not look quite like the French Bulldog of forty years ago. The face is shorter. The body is heavier. The legs are a little more bowed. Almost none of those changes are good for the dog. They are, however, what buyers are taught to associate with the breed, and so they are what tends to be produced. The same drift has happened, more slowly, to the Pug, the English Bulldog, the Cavalier King Charles Spaniel, the German Shepherd whose back now slopes in a way that wrecks its hips. None of these changes are deliberate cruelty. They are the cumulative result of a market quietly preferring the version that breathes worse, walks worse, ages worse.

It is uncomfortable to put it that bluntly. The data is unambiguous. The French Bulldog as a population has a clinically severe airway disorder — Brachycephalic Obstructive Airway Syndrome — that is now more or less endemic; corrective surgery on the soft palate or nostrils is a routine vet conversation for the breed, not a rare intervention. The Cavalier King Charles Spaniel has documented rates of syringomyelia, a painful neurological condition caused by the skull not having room for the brain, that led a Norwegian court to rule in 2022 that breeding the breed in its current form violated the country's animal welfare law. (The ruling has been partially walked back on appeal since, but the underlying veterinary data has not.) None of this is fringe. None of it is contested in the literature. And in every case, the conditions track the breed's rise in popularity.

Demand creates the bad supply

If popularity only narrowed the gene pool, that would already be enough of a problem. It also creates the conditions for the worst end of the industry to expand.

A popular breed is a profitable one. Profitable breeds attract every kind of breeder — including the kind who keep brood bitches in shedded conditions, breed them every season, and sell the resulting puppies on through a chain of middlemen, often with paperwork that has been improved along the way. The UK passed Lucy's Law in 2020 specifically to make this harder to do legally, by banning the third-party sale of puppies under six months. The law has helped at the margin. It has not made the trade go away. It has driven it slightly more underground.

The mechanism is direct. The more a breed is wanted, the higher the price a puppy can be sold for; the higher the price, the more attractive it is to produce them in volume; the more they are produced in volume, the worse the welfare conditions in which they are bred. By the time the buyer is looking at the advert, the supply chain has already done the harm. The puppy in the photograph is healthy-looking and well-lit. The mother, in a barn somewhere, may have been bred from on every season of her life and never set foot outside the building. None of that is visible from where the buyer is standing.

What this means for an owner who has fallen in love with a breed

There is no satisfying answer to this. It is not the owner's fault that the breed they love is in welfare trouble, and it is no good telling people to fall in love with something else. People who want a Frenchie want a Frenchie.

But there are choices an owner can make, even inside that, that change the picture.

The first is to look harder. The breeders worth buying a popular-breed puppy from in 2026 are, in our experience, the ones openly working against the trend. They breed less, not more. They use stud dogs from less-related lines, sometimes from outside the country. They reject the most exaggerated conformation. They will tell you what their last litter's hip scores were before you ask, and they will be slightly suspicious of you if you don't. They run waiting lists, sometimes long ones, because they refuse to scale to meet demand. They are not romantic about what they are doing, and they are very rarely the easiest breeder to buy from. That is rather the point.

The second is to consider the unfashionable cousin. Some of the breeds whose welfare has held up best are the ones who never quite had their moment in the sun. The Welsh Springer to the popular Cocker. The smooth-coated and bearded collies behind the Border Collie. The plainer working strains behind almost every show breed. These are not lesser dogs. They are, in many cases, the version of the breed that the showy version was bred away from. They are still findable, from breeders who never went chasing the market.

The third is to take the welfare implications of a popular brachycephalic breed seriously before bringing one home. That means budgeting for likely surgery — not as a worst case but as a likely case. It means having a vet conversation about insurance and exclusions before buying, not after. It means understanding that the dog you are choosing may have a shorter, more medically complicated life than a typical dog of similar size. Some owners will take that on knowingly and give the dog a wonderful life inside it. The dishonest version is the one where the breed is marketed as if those issues are not endemic.

Why this is a market problem, not a moralising one

A great deal of the writing on this subject treats the buyer as the problem. The buyer is not the problem. The buyer cannot, on the basis of an advert and an Instagram aesthetic, tell which puppy came from which kind of breeder, or which lines carry which faults, or what the effective population size of the breed they like has done over the last twenty years. That information is not available to them, and the people most willing to tell them are the people with the most to gain from selling them a puppy.

What is broken here is the information layer. The careful breeders who are working against the popularity trend, the studs being chosen for genetic diversity rather than fashion, the health-testing results that mean something, the breeders who turn buyers away — none of that is visible from outside the closed circles in which it happens. Until it is, the market will keep rewarding the version of breeding that produces a Frenchie in time for the buyer's holiday.

That is the layer we are trying to build. Not a directory of "good" and "bad" breeders, which is the wrong framing and would in any case be impossible to maintain honestly. The aim is more modest. To make the evidence — the testing, the lineage, the health record across years, the breeder behind the puppy, the owner's experience after one year and after five — visible enough that a buyer who is paying attention can use it. We do not think this fixes the problem on its own. We think it changes which breeder is easier to find than which other breeder, and over time, that changes what the market produces.

The short version

If you are about to buy a puppy from a fashionable breed, the most welfare-aligned thing you can do is to slow down. The popular breed in any given year is, almost by definition, the breed whose welfare has been most stressed by the previous ten years. That does not mean don't get one. It does mean: do the work before you do, and reward the breeders who are doing the harder, slower, less profitable thing. They are the people the breed needs you to find.

— Rene