““A Little “Dog Nerd” Conversation About Genetics, COI, and Hybrid Vigor ””

Alright friends… buckle up. 😂

This blog is probably not for the people who are just here for the fluffy puppy pictures, tiny pink bows, and “awwwww” videos.

This one is for my fellow dog nerds.
The ones who love learning about pedigrees, genetics, bloodlines, and all the behind-the-scenes things that actually shape the future health of dogs.

So if you’ve ever wanted a tiny peek into the brain of a breeder who has spent years obsessing over dogs, structure, temperament, genetics, and bloodlines… welcome. 😂

Yesterday during our 🐶 Doodle Drop 🐶 session, I briefly mentioned something called the Coefficient of Inbreeding — often shortened to COI.

And afterward I thought:
“Sherri… you just dropped a full-on science term into a doodle conversation and then kept moving.” 😂

So this morning I wanted to slow down and explain it a little better because honestly, I think it’s an important conversation if we truly care about the long-term health and wellbeing of dogs.

And yes… this is one of those blogs where your husband walks by and says:
“What exactly are you reading right now?” 😂

First… Let Me Say This Clearly

I love purebred dogs.

Before Teddy Bear Goldendoodles, Teddy Bear Schnoodles, and Teddy Bear Twoodles ever became part of my world, I was deeply involved in breeding imported Golden Retrievers.

And this is actually kind of funny because years ago, when I began importing lighter European bloodlines, I started referring to them as “English Golden Retrievers.” Truthfully, they are still simply Golden Retrievers 😂 — but somehow that phrase completely took over the internet.

What mattered most to me, though, was not the label. It was the genetics behind the dogs.

I intentionally sought out bloodlines from different countries around the world because I personally believed broader international diversity could strengthen the breed versus repeatedly concentrating the same genetics generation after generation.

And back then, before modern DNA testing became available, breeders had to figure a lot of this out the hard way.

We would literally sit and pour over pedigrees for hours and hours — tracing bloodlines back generation after generation looking for common dogs repeatedly appearing within the lineage.

And trust me… that was no small task. 😂

That’s one of the reasons authentic deep pedigrees were so valuable. They weren’t just fancy papers to frame on the wall. They were one of the only tools breeders had to evaluate genetic concentration and make thoughtful breeding decisions before advanced genetic testing existed.

I truly loved — and still love — the breed.

But over time, even with carefully selected imported lines, I started noticing recurring health concerns within some bloodlines.

Not every dog.
Not every line.
But enough that it made me stop and really think deeply.

I saw cancers.
Skin and allergy issues.
Autoimmune concerns.
Orthopedic weaknesses.
Certain temperament sensitivities.

And honestly, one thing I personally began noticing over the years was this:

I simply did not see the same level of recurring genetic weaknesses in many of the thoughtfully developed hybrid dogs that I had sometimes observed within tightly concentrated purebred lines.

That doesn’t mean hybrid dogs are magically perfect.
And it certainly doesn’t mean purebred dogs are “bad.”

But from my own personal experience, I did begin seeing stronger overall genetic health and diversity in many hybrid programs because we were no longer repeatedly backcrossing into some of the same concentrated genetic weaknesses generation after generation.

And that’s what led me deeper into learning about something called the Coefficient of Inbreeding.

So… What Is the Coefficient of Inbreeding?

Okay smarty pants section incoming. 😂

The Coefficient of Inbreeding (COI) is basically a scientific measurement used to estimate how genetically related two breeding dogs are.

In simple terms:
– A higher COI means there’s more repeated genetics within the bloodline.
– A lower COI generally means there’s more genetic diversity.

Think of it like making a photocopy of a photocopy of a photocopy over generations. Eventually, weaknesses can become more concentrated.

Now before anybody panics and sends me angry emails 😂…
This does NOT mean every purebred dog is unhealthy.
And it does NOT mean every hybrid dog is automatically healthy.

Genetics are far more complicated than that.

But over time, many breeders and researchers have recognized that tightly concentrated gene pools can sometimes allow recessive weaknesses to surface more frequently.

That can include things like:
– cancers,
– allergies,
– autoimmune disorders,
– orthopedic problems,
– fertility struggles,
– immune weakness,
– and sometimes temperament instability.

How Do They Test for This?

Years ago, breeders mainly estimated COI through pedigrees by studying how often the same dogs repeatedly appeared within a lineage.

Today, DNA testing has become much more advanced.

Companies can now evaluate thousands of genetic markers across a dog’s genome to estimate actual genetic diversity and inbreeding percentages much more accurately than pedigree charts alone.

Honestly, I find this fascinating because it allows breeders to make more informed decisions for future generations rather than simply breeding based on appearance or titles.

What Personally Shifted My Thinking

As the years went on, I became increasingly interested in thoughtfully planned outcrossing and hybrid programs.

Not careless breeding.
Not random mixing.
But intentional genetic diversification with purpose.

And honestly, this is where something called hybrid vigor started making more and more sense to me.

What Is Hybrid Vigor?

Hybrid vigor is the idea that carefully combining healthy, genetically diverse lines can sometimes reduce the concentration of inherited recessive weaknesses that become more common in tightly concentrated gene pools.

Again — this does NOT mean hybrids are magically perfect unicorn dogs. 😂

But personally, I truly felt like we began overcoming some of the genetic concentration concerns I had observed over the years through thoughtfully developed hybrid programs.

That became part of the heart behind our:
– Teddy Bear Goldendoodles,
– Teddy Bear Schnoodles,
– and Teddy Bear Twoodles.

For me, this was never about simply creating trendy “designer dogs.”

It was about striving toward:
– healthier dogs,
– emotionally intuitive dogs,
– stronger temperaments,
– trainability,
– family companionship,
– and long-term wellbeing.

And Just a Tiny Honest Side Note… 😂

While I deeply respect ethical purebred breeders and preservation breeding, I’ll also gently say this…

I’m not always sure that respect has fully gone both ways over the years when it comes to hybrid breeders. 😂

But that’s probably a story for another blog and another day.

Because honestly, at the end of the day, I think most truly ethical breeders — whether purebred or hybrid — actually want the same thing:
healthier, happier dogs living long beautiful lives with the families who love them.

## At The End of the Day…

This conversation should never become:
“Purebred versus Doodle.”

That’s honestly not my heart at all.

Without purebred dogs, there would be no Goldendoodles, Schnoodles, or Twoodles.

But I also believe we should continue asking important questions about genetics, diversity, stewardship, and the future health of dogs.

Because as breeders, we are not simply producing puppies.

We are shaping future generations.

And I believe these dogs deserve breeders who are willing to keep learning, growing, studying, and making thoughtful decisions rooted in both science and love.

— Sherri Smeraglia
Smeraglia Kennel | Teddy Bear Goldendoodles