What Is the Coefficient of Inbreeding (CoI)?
The Coefficient of Inbreeding (CoI) is a percentage that tells you how closely related the parents of a litter are. A high CoI means there is more inbreeding in a dog's background, which can increase the risk of health problems.
- A CoI of 0% means the parents are completely unrelated
- A higher CoI means more shared ancestors, which raises the chance of inherited conditions appearing
Think of it as a measure of genetic diversity. The lower the CoI, the more genetically diverse the puppy - and that's usually a good thing.
Why Is CoI Important for Labradors?
Labrador Retrievers are one of the most popular dog breeds in the UK, and many bloodlines are widely used. Without careful breeding practices, this can lead to high levels of inbreeding.
High CoI values have been linked to:
- Increased risk of inherited diseases
- Reduced litter sizes
- Weaker immune systems
- Shorter lifespans
Breeders who pay attention to CoI help reduce these risks and improve the long-term health of the breed.
What Is a Good CoI for Labradors?
The Kennel Club publishes a breed average CoI based on all Labradors registered with them. As of the latest data, the average CoI for Labradors is around 6.6%.
Here's a basic guide to interpreting a Labrador's CoI:
| CoI % | What it Means |
|---|---|
| 0-5% | Very good - low risk of inbreeding |
| 5-10% | Acceptable, especially if parents are health tested |
| Over 10% | Caution - higher chance of genetic issues |
Ideally, breeders aim to keep the CoI below the breed average.
How Is CoI Calculated?
The CoI is usually calculated based on five generations of ancestry, using pedigree records. The Kennel Club provides a free CoI calculator for registered dogs.
If a dog's parents, grandparents, or great-grandparents appear more than once in their pedigree, the CoI score will increase.
How Can Buyers Use CoI?
When browsing Labrador litters:
- Ask the breeder for the CoI of the planned mating
- Look for CoI values below the breed average
- Combine CoI with other factors like DNA testing and health screening
On some platforms, the CoI is displayed automatically for KC-registered dogs - so it's easy to compare litters at a glance.
The Inbreeding Coefficient (CoI) is an important tool to help keep Labrador bloodlines healthy and diverse. A lower CoI doesn't guarantee perfect health, but it helps reduce risks. When combined with DNA tests and official health schemes, it gives a much clearer picture of a puppy's future health.
