-Adult Onset Neuropathy (AON)-

Adult Onset Neuropathy (AON) is an inherited neurological disorder that typically appears later in a dog’s life, usually between the ages of seven and nine. Affected dogs first show mild coordination problems, which gradually worsen over time.

The condition often begins subtly:

The gait becomes unsteady and uncoordinated

The hind legs appear weak, and the dog may adopt a wide stance
As the disease progresses, the front legs can also be affected
In advanced stages, difficulty swallowing may occur

The symptoms progress over the course of a few years and significantly reduce the dog’s quality of life. While there is currently no cure, responsible genetic testing can prevent the condition from being passed on.
How is AON inherited?
AON follows an autosomal recessive inheritance pattern, which means:

A dog will only be affected if it inherits two copies of the mutated gene — one from each parent
Carriers have one copy of the mutation. They do not show any signs of illness but can pass the gene to their offspring
If two carriers are bred, there is a 25 percent chance that a puppy will inherit both mutations and develop the disease

Solid-colored English Cocker Spaniels are particularly affected, as this mutation occurs more frequently in this variety. If you are considering a solid-colored Cocker, it’s important to keep this in mind.

Genotype	Meaning	Health Status	Breeding Eligibility
N/N (frei / clear)	The dog is clear (of the gene mutation	Genetically clear; not affected and not a carrier	Suitable for breeding without restriction
N/AON (Träger / carrier)	Heterozygous carrier; unaffected.	Carries a 50% risk of passing the gene to its progeny	Mate only with a partner free of the condition
AON/AON (betroffen / affected)	Is homozygous for the defective gene.	At a very high risk of late-onset disease	Not recommended for breeding

Why Genetic Testing Matters
A reliable genetic test for AON has been available since 2015. It accurately determines whether a dog is clear, a carrier, or affected. Through responsible breeding practices, this test allows us to prevent puppies from being born with this serious condition.
Conclusion:
With the help of modern genetics, we can ensure that no Cocker Spaniel ever has to suffer from AON — as long as dogs are carefully tested and thoughtfully paired.