Understanding inbreeding: Risks, myths and realities

In captive populations of hedgehogs and tenrecs, managing genetics is one of the biggest challenges. With limited bloodlines available, breeders sometimes face the question of whether related animals can or should be bred together. This is where inbreeding comes into play, a topic surrounded by strong opinions, myths, and misunderstandings.

To make responsible choices, it’s important to understand what inbreeding is, what risks it carries, and where the line lies between myth and reality.

What Is Inbreeding?

Inbreeding occurs when two animals that are closely related are bred together. This increases the chance that their offspring will inherit identical copies of certain genes, both good and bad.

• Linebreeding is a mild form of inbreeding where distant relatives (e.g., cousins, half-siblings) are paired to preserve desirable traits.
• Close inbreeding (e.g., parent to offspring, siblings) drastically raises the risk of genetic problems.

The Risks of Inbreeding

1. Inbreeding depression

• Reduced fertility
• Smaller litter sizes
• Lower survival rates in juveniles
• Weaker immune systems

2. Expression of recessive diseases

Many genetic conditions are recessive, harmless when carried by one parent but harmful if inherited from both. In hedgehogs, one major concern is Wobbly Hedgehog Syndrome (WHS). Inbreeding increases the likelihood of two carriers producing affected offspring.

3. Reduced adaptability

Populations with low genetic diversity struggle to adapt to new environments, diseases, or stress. This is especially dangerous in tenrecs, where captive populations are already small.

Myths About Inbreeding

“Inbreeding always causes defects.”
Not necessarily. A single generation of mild inbreeding may not show obvious problems, especially if both parents are healthy. The danger comes from repeated inbreeding without introducing new diversity.

“Inbreeding only affects looks, not health.”
False. Some effects may not be visible immediately but show up as reduced fertility, weak immune systems, or higher mortality.

“Pedigreed animals are always safe from inbreeding.”
Not true. Pedigrees can hide inbreeding if the same ancestor appears multiple times. Careful reading and monitoring are needed.

Realities Breeders Must Face

• In small populations, some inbreeding is often unavoidable. The key is to manage it responsibly.
• Most registries recommend keeping the inbreeding coefficient (COI) below 4%. A COI above this threshold significantly increases the risk of health issues in future generations.
• Outcrossing should be used regularly to reintroduce genetic diversity and prevent accumulation of weaknesses.
• Keeping detailed records and pedigrees is essential for tracking relatedness and avoiding close pairings.
• In conservation contexts, limited inbreeding may be tolerated to preserve a population, but it always comes with long-term risks.

In Summary

Inbreeding is not simply “good” or “bad”, it is a genetic reality with measurable consequences. For hedgehogs and tenrecs, the biggest dangers are hidden recessive conditions and declining vitality over generations. The majority of registries advise keeping the COI under 4% to avoid major health concerns. Some inbreeding can occur in controlled contexts, but without careful monitoring it becomes a serious threat to population health. The guiding principle should always be: maximise diversity, minimise risk.