Tag archives: should I test my dog

Predicting Genetic Disease in Your Dog

Predicting Genetic Disease in Your Dog

Continuing the series on "when genes don't make sense," let’s talk about probabilities. Many people will hear that if a condition is recessive that one in four puppies will be affected or, if it is dominant, that 50% of the puppies will exhibit the trait or be affected with a condition. They will subsequently declare that because the outcome in their litter is different than these exact percentages, it therefore must not be… recessive, dominant or genetic at all.

On the other hand, many people in dogs will say things like "they need to breed a male in order to determine if he produces males or females."

These are different errors in reasoning relating to the same type of probability.

In the first case, people are expecting the actual results to be exactly what is predicted based on possible results or probabilities. In the second case, people are assigning meaning to the random variation that is usually observed (and actually expected) compared to what is predicted based on probability.

To start with the second scenario, millions of sperm are swimming as hard as they can to fertilize the eggs. Roughly 50% of these sperm carry an X chromosome ...