“Draw a three-generation Border Collie pedigree for Collie Eye Anomaly, an autosomal recessive condition, with two carrier parents, an affected female proband, and an affected puppy from the proband mated to a carrier male.”
Read the decisions behind it.
The two generation-I parents are carriers, allowing an affected daughter.
The female proband is affected and therefore has two disease alleles.
Her carrier mate provides the second disease allele needed for the affected puppy.
The unaffected generation-II sibling remains genetically unclassified.
Use this case to explain a recessive dog-breeding pedigree alongside DNA testing and veterinary ophthalmic assessment. It is not a substitute for clinical or breeding advice.
Other examples in this family.
Common questions
Is Collie Eye Anomaly recessive?
Yes. Collie Eye Anomaly is commonly inherited as an autosomal recessive condition.
Why can the affected proband have an affected puppy?
The affected proband contributes a disease allele to every offspring, and the carrier mate can contribute the second allele.
Does an unaffected dog have clear status?
No. An unaffected dog may be genetically clear or a carrier; DNA testing can distinguish those outcomes.