How is NCL5 inherited and which breeds are affected?

NCL5 is autosomal recessive, caused by a CLN5 gene mutation. It primarily affects Border Collies and Australian Cattle Dogs. Affected dogs have two copies, carriers have one (clinically normal). DNA testing is definitive and widely available. The breeding rule: never mate two carriers. Carrier × Clear pairings are safe. Test all breeding stock and share results with breed health registries. Given the devastating nature of NCL5, DNA testing before any breeding is a non-negotiable responsibility. Our vets can help interpret results and advise on breeding programs.