Is a Healthier English Bulldog Possible?

16:51 minutes

Credit: Science Friday
Credit: Science Friday

The loveable, wrinkly, squishy-faced English bulldog is the fourth most popular purebred in the United States. The breed is also notorious for health problems, including breathing difficulties, overheating, and skin infections, to name a few. While the median age is about 8.4 years, many bulldogs live only 6 or fewer. What’s more, because of body structure problems, most bulldog mothers must deliver by c-section.

In 2009, stirred by controversy over these health problems, the United Kingdom’s Kennel Club made some revisions to the breed standards, in the name of heartier dogs. And organizations like the Bulldog Club of America say that careful breeding can help weed out genes that lead to ill health.

But do enough good genes exist in the pool, or has inbreeding wiped out the possibility of better breeding? New research suggests that crossbreeding with other breeds may be the only option for producing healthier bulldogs.

Veterinary researcher Niels Pedersen, a distinguished professor emeritus at the University of California-Davis, explains what he found in his explorations of the English bulldog gene pool, and how we might ensure a healthier future for the breed. He’s joined by Peter Photos, a science advisor for the Bulldog Club of America.

Segment Guests

Niels Pedersen

Niels Pedersen is professor emeritus of veterinary medicine at the University of California-Davis in Sacramento, California.

Peter Photos

Peter Photos is a science advisor for the Bulldog Club of America and a breeder of French bulldogs. He has a Ph.D. in biomolecular engineering.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. For the rest of the hour we’re going to the dogs– the English bulldog. They’re a lovable, wrinkly, squishy-faced breed, notorious for health problems. You have your breathing difficulties, to overheating, to skin infection in all these furry folds. While the median age is about 8.4 years, many live only six years or fewer.

Can better breeding give us a better English bulldog– a breed founded with just 68 dogs in the 1850s? Maybe one that doesn’t wheeze, or overheat, or have the highest rate of hip dysplasia in the dog world? Well, that depends on what genes such an inbred breed has to work with.

And here to discuss is my guest, a man who has explored what genetic variation has to offer the English bulldog– Dr. Niels Pedersen. He’s a distinguished professor emeritus of the veterinary school at the University of California-Davis, and author of new research published late last month.

Also with us is Dr. Peter Photos, science advisor for the Bulldog Club of America, a breeder of French bulldogs. He has a PhD in biomolecular engineering. Welcome to Science Friday, doctors.



IRA FLATOW: Hi, nice to have you both. Dr. Pedersen, how hard is it to be an English bulldog? What’s their health like?

NIELS PEDERSEN: Well, their health is not very good if you look overall. They have probably the largest number of health problems across a very broad spectrum, ranging from problems associated with their head structure to problems associated with their bone structure, problems associated with their skin, and problems associated with limited diversity within the genes that regulate the immune system, causing higher incidence of allergies, as well as autoimmune disorders.

IRA FLATOW: You looked at about 140 English bulldogs in your work. What did you conclude about their genetic variation there?

NIELS PEDERSEN: We concluded that they had very limited genetic diversity, and that any two bulldogs that we tested were very closely related to each other. And that the amount of diversity– not only did they lack diversity, but the diversity that they had was highly concentrated in certain regions of the genome that were similar between dogs– these large, what we call, runs of homozygosity that are associated with the very extreme physical traits or abnormal– I call them abnormalities, that readers would call them traits.

IRA FLATOW: And so why is this important in determining how healthy a breed can be?

NIELS PEDERSEN: Well, there’s been an argument for a long time, whether there is enough genetic diversity left in the breed to do what’s called reverse genetics, or to actually use the genetics that exist in the breed to improve the breed by selecting back to an earlier form that was healthier. You know, peer breeders really are against outcrossing. Any outcrossing would mongrelize their dogs, and the term “mongrel” is not a term they like.

So basically, what we looked at is the amount of diversity using a number of different parameters. And what we concluded was that they have bred themselves pretty well into a corner and probably did not have enough diversity to use reversed genetics to improve the breed.

IRA FLATOW: Peter Photos, you’re a breeder of French bulldogs. What’s your take on these findings?

PETER PHOTOS: I thought it was a great paper. I thought it was a very interesting paper. The interesting thing is, if you were to take every breed of dog from the Chihuahua to the Dane, about 200 breeds or so, and put them on a spectrum, and on the left you put the most inbred dog– or the least genetic diversity, and on the right you’d put the ones with the most genetic diversity, you’ll actually find, even with Dr. Pedersen’s work and his numbers, that the bulldog is not at an extreme. It’s actually just a little bit left of center.

Even when you take into account the effective number of alleles per locus, there’s still a relatively decent number of genes out there that are still workable. Especially when you can compare it to, say, the Akita. The Akita is a Japanese breed, a little bit more wolf-looking like. And if you look at its alleles per locus, it’s almost the same as the bulldog.

Yet the bulldog has achieved a remarkable difference in the way it looks, and the size, and the shape, and its behavior. So, in fact, I would say that the bulldog, given its morphology change from a wild village dog to the dog it is today, it’s done it in a very few number of steps, and as few steps as could be done.

The boxer, for example, is a much more tightly-bred dog and it doesn’t have as many health problems. And really, the health problems may be due, not necessarily to the issue of the genes within the bulldog, but the way it’s bred. There’s randomly-bred dogs and there’s appropriately-bred dogs. And dogs that are randomly bred tend to be not as well built, not as close to the standard as they should be, and therefore they tend to be less healthy.

And really, that’s a big difference between your average backyard breeder and a responsible good breeder who is breeding towards what the AKC calls the standard.

IRA FLATOW: Niels, would you agree with that?

NIELS PEDERSEN: No, I guess I wouldn’t agree with all of it. We have looked at genetic diversity in a number of breeds, and that’s available on our Vet Genetics Laboratory website. The Akita has more– it lacks diversity, but it has more diversity than the bulldog does.

In fact, we’ve only found one breed that has less genetic diversity than the bulldog, and that breed, which I can’t mention because the research is still ongoing, is actually a performance dog that has started from a much smaller founder population but is very healthy, largely because performance traits are less heritable and the dog is bred for performance. And also, the dog still looks very much like a dog.

You have to realize that the problem with dogs like the bulldog is that they’re bred to these extremes for these certain physical traits that would be considered very abnormal. In other words, brachycephaly is not a normal trait for dogs. Extremely wrinkled skin is not a normal trait. A very abnormal chondrodystrophic skeleton is not a normal trait. And it’s not normal to have very little diversity in your genes that control your immune system. So I guess I would have to gently disagree.

IRA FLATOW: Let me go to the phones. People are bulldog owners and they have something to say. Let’s go to Ian in Hereford, Pennsylvania. Hi, Ian, did I get that right?

IAN: It’s close enough.

IRA FLATOW: That’s like my name. That’s good.

IAN: Well, I have a question, and that is that I think it’s admirable to try and resolve these issues that you would have in a dog’s genetics. But I’m just wondering, at what point in the breeding process do you cross the line into cruel and unusual treatment of a dog, simply by bringing it into the world with such extremes?

I mean, some dogs have to be born through C-section and that’s like a form of forced surgery. And dogs that are born blind and have many, many defects based on the breeding, and I’m just wondering if at some point there’s got to be a line that’s crossed there.

IRA FLATOW: Any response?

PETER PHOTOS: So, as a breeder, I could tell you that one of the most important things– every breed, the Bulldog Club of America being no exception, has what’s called a standard of what a bulldog is and what are the components that make a bulldog a bulldog. And there are a lot of breeders out there that try to breed to the standard as carefully as possible.

If you do breed to that standard, the dog tends to be very healthy. And if you breed for color, for example, people who just try to breed a fancy-colored bulldog, or someone in their backyard that has a little female dog, and they want to have litters, they’ll breed to a random stud.

That’s when you get into trouble, because you don’t understand the genetics and you don’t understand what’s behind the dog. Any responsible breeder will know exactly if there is, for example, juvenile cataracts that could run in the lines, we’d genetically test for that. And any dogs that are carriers typically aren’t bred. So the line really should be, one, if you don’t know what you’re doing, you shouldn’t do it.

And people who do know what they’re doing are extremely careful. They keep extremely good records, they know their pedigrees, they know what inbreeding is acceptable, what levels of inbreeding, when to outcross. And they do try to outcross as far as possible, but still within the breed. These are done all the time by very responsible breeders.

IRA FLATOW: The UK Kennel Club made some changes to the breed standard following major controversy over the bulldog health in 2009. Is there anything about the breed standard that could be changed to make the bulldog healthier?

NIELS PEDERSEN: Ira, can I make some comments? As a veterinarian, my first concern is the health of the dogs. And what we want to see are dogs that are going to live a normal lifespan and die from the normal type of degenerative and old-age diseases that one would expect. And I would argue that the line is crossed when a breed can’t run freely, a breed can’t breathe freely, a breed can’t reproduce freely, and a breed can’t be free of things that affect its immune system.

And so, in all of those categories, bulldogs do not run freely, they do not breathe freely, they do not breed freely, and they have problems with their immune systems, and other things, as well. So, where you cross the line depends on how you look at it. And I’m sure that many veterinarians would say that that line has been crossed a long time ago.

PETER PHOTOS: Well, I will come back with, the bulldog was originally bred to be a sporting dog and to bull bait. And 200 years ago it was bred to run and attack bulls and be courageous and brave. The bulldog’s purpose has changed dramatically, then. And if you look at other companion breeds– French bulldogs, Pekingese– Pekingese can’t run. They’re not designed to run. And a bulldog is not designed to run.

Having said that, I’ve seen many bulldogs that are in agility, that can run and jump and do plenty of things, and these all tend to be well-bred bulldogs. Bulldogs that have been very well-bred to the correct lines, outcrossed when appropriate, inbred when appropriate, and that’s how they arrived at those. Not through just a random, you know, I want a lilac bulldog and therefore I’m going to try to find another lilac bulldog to get to that, regardless of the other traits of the dog.

IRA FLATOW: I’m Ira Flatow. This is Science Friday from PRI, Public Radio International. Niels, did you want to jump in there?

NIELS PEDERSEN: Yes. The problem is the standard. They keep going back to this standard. And it’s true that every breed creates a standard. When it’s first created, a group of dogs are brought in that meet that standard. And then the breed is closed for any further genetic introgressions, basically forever. And that’s where the term “purebred” comes from.

So you have to start with a large genetic base. And that genetic base has to be very healthy to start with. Now, the problem with the standard– and it’s already been mentioned that these were dogs that were created to be very athletic and bait bulls, which was eventually outlawed in the 19th century by the British Parliament– but this standard was made. And if you look at those dogs, and in our paper we did include websites that give images of the dogs since the earliest times, since it was a bull baiting to the earliest, to the present time.

And that standard, it may have been set in stone, but the dogs have changed dramatically. Because what happens is breeders breed to the extremes of the standard, so they keep pushing that standard. So a standard is much like the Constitution of the United States. If you have Supreme Court justices that hold the line and do not allow that standard to change very much of that Constitution is one thing.

But when you have show judges that are continuously changing the standard by declaring a new type of dog a champion, which then sets a signal for everybody else, that standard is a moving target. It is not a constitution in a constitutional sense.

IRA FLATOW: Let me go to the phones to David in St. Michaels, Maryland. Hi, David.

DAVID: Hi, Ira. Ira, 45 years ago, I set out to reproduce the healthy agile bulldog of 1820, who had longer legs than today’s English bulldog, less extreme shoulders, they had tails, and they had longer noses. And as has been said, they were an agile dog. I have dogs now that are competing at active sports, service dogs, search and rescue. I even have one doing bedbug detection in Switzerland.

All of my dogs have been health-screened before they’ve been given permission to breed. I’ve been at this for 45 years. I called the breed Olde English Bulldogge– D-O-G-G-E. And people infringed on my name. I bred a purebred dog, and so my line is now called Leavitt bulldogs.

IRA FLATOW: All right. Well, there it can be done, I guess, if you want to bring back the bulldog. I can’t get a commercial in here for his bulldogs. We’ve run out of time. I want to thank Dr. Niels Pedersen, distinguished professor emeritus, University of California-Davis School of Veterinary Medicine.

Dr. Peter Photos breeds French bulldogs, is science advisor for the Bulldog Club of America. Gentlemen thank you for taking time to be with us today.

One last thing before we go. Earlier this week we got word that Nobel Prize-winning chemist Ahmed Zewail, a professor of Caltech has passed away. He won the Nobel Prize in chemistry in 1999 for his work in femtoscience– that’s using a high-speed laser to catch glimpses of atoms in motion. I talked to him a few days after the prize announcement in 1999 about creativity in science.

AHMED ZEWAIL: There is really no master plan that when I start to write on a piece of paper that we’re going to discover this, and then we discover it. It just– this is not the way it’s done in science. The way we do it is to ask a fundamental question– and we did about 20 years ago– being curious and interested in understanding how, for example, energy moves in molecules. What makes molecules break bonds or form bonds?

And as you do this, and if you have the right scientific base, lasers are developing, other techniques are developing. And so by asking the right questions and having the right people, you can keep advancing your vision until we came to the point in 1987, when we actually saw for the first time how a molecule, what’s really how the atoms and the behavior of a chemical reaction change with time.

And so it’s a whole long process. But of course, when some of us can make a breakthrough like this, it becomes extremely enjoyable, and fundamentally important.

IRA FLATOW: Nobel-winning chemist Ahmed Zewail, professor of Caltech, passing away at the age of 70 years old.

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About Christie Taylor

Christie Taylor was a producer for Science Friday. Her days involved diligent research, too many phone calls for an introvert, and asking scientists if they have any audio of that narwhal heartbeat.