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Coefficient of inbreeding and genetics

Understanding recessive genes and inbreeding helps you breed healthier, longer-lived dogs.

Dominant and recessive

Many inherited conditions are recessive, meaning a dog needs two copies of the gene to be affected but can carry one copy silently. DNA tests let you identify carriers so you never pair two carriers of the same condition and produce affected puppies.

The coefficient of inbreeding

The coefficient of inbreeding (COI) estimates how related the parents are and how much of the genome is likely identical. A higher COI raises the chance that hidden recessive problems pair up and can reduce fertility, litter size and lifespan.

Breeding for diversity

Aim to keep the COI reasonable for your breed and avoid repeated close matings, even to a popular winning dog. A healthy gene pool, balanced against health tests and type, protects the breed's future far more than any single litter.

Test yourself: Genetics and inbreeding

What is a recessive genetic condition?
  1. One that needs two copies of the gene to affect the dog
  2. One that always shows in every generation
  3. One that only affects males

Correct answer: One that needs two copies of the gene to affect the dog

A recessive disorder appears only with two copies; a dog with one copy is an unaffected carrier.

What does a high coefficient of inbreeding (COI) increase the risk of?
  1. Brighter coat colors
  2. Hidden recessive problems pairing up, and reduced vitality
  3. Larger, healthier litters every time

Correct answer: Hidden recessive problems pairing up, and reduced vitality

A high COI raises the chance recessive faults meet and can lower fertility, litter size and lifespan.

Why use DNA tests before choosing a mating?
  1. To guarantee show wins
  2. To identify carriers and avoid pairing two of them
  3. To pick the puppies' names

Correct answer: To identify carriers and avoid pairing two of them

DNA testing reveals silent carriers so you never mate two carriers of the same condition.

How does a healthy gene pool benefit a breed?
  1. It protects long-term health, fertility and robustness
  2. It matters less than winning one big show
  3. It has no effect on the puppies

Correct answer: It protects long-term health, fertility and robustness

Maintaining diversity, balanced with health testing and type, safeguards the breed far more than any single litter.

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