
I had a conversation with someone* a few months ago about dog joints, structure, movement and breeding spaniels, and during the conversation we had a hypothesis about why there are more joint problems today.
Hypothesis 1:
In the past hunting spaniels like cockers and springers (in the UK) would have been removed from the gene pool if they were not fit enough to complete a full season of hunting. This would have meant that individuals with e.g. a strong disposition for juvenile hip dysplasia would not have been bred – only dogs who performed well were selected for breeding**.

At some point in the past 10-15 years working spaniels have become popular pets, and the gene pool was flooded with pet dogs who have never been “tested” in the original job – creating a need for testing especially if the dogs are used for breeding when they are still young.
Hypothesis 2:

As I watched Grace swim this morning, I also wondered how much of the problems that are increasingly seen among the UK population of working cockers are due to dogs not getting the right exercise.
Working spaniels are not average dogs: their bodies are designed for optimal performance in the original job. Form and function are connected in dogs, so if the original job of a spaniel requires them to swim and run freely in varied terrain, that is what they also need to develop correctly and without problems.
Spaniel owners regularly laughed at pictures of their dogs having very flexible spines or their wiggly bodies, so we can perhaps assume that many of them have above average flexibility. Those flexible joints need strong muscles to keep them stable, and the original job of a spaniel would have developed them.

In short, my second hypothesis is that our spaniels need activities like swimming and running free specifically in a forest (like the original purpose) from very early on in their lives in order to develop the correct muscles to support their bodies.
Walking in a leash and running in a straight line for long periods of time like jogging with a human are not natural for a spaniel – huskies yes, but spaniels are designed for zigzag running.
The closer we stay to activities that include movement from their original job, the better it is for them.
*This person is researcher with a PhD in animal genetics, specialising in anthrozoology, canine nutrition and movement (agility). She also competes in canicross with her 5 working line cocker spaniels and occasionally breeds them.
** Of course, this created other problems such as inbreeding – let’s ignore this for now.