German Shepherd

Historically severe in the breed. Both joints develop loosely, so they grind rather than glide. The result is arthritis, and in bad cases replacement surgery. Ask to see hip and elbow scores for both parents - they are the single most useful thing a breeder can show you.

A progressive and untreatable spinal cord disease. A progressive disease of the spinal cord, usually beginning after eight, causing gradual hind-limb weakness and eventually paralysis. It is not painful, but it is untreatable. A DNA test identifies at-risk dogs.

A genuine emergency in deep-chested dogs. The stomach fills with gas and twists, cutting off its own blood supply. Without surgery within hours it is fatal. Deep-chested dogs are most at risk, and feeding one large meal a day or exercising straight after eating makes it likelier.

The pancreas stops making digestive enzymes, so the dog eats well but loses weight and passes pale, greasy stools. It is managed for life by adding enzyme powder to every meal.

Joint cartilage wears down and the joint becomes stiff and painful. It is managed rather than cured, and keeping the dog lean is the single most effective thing you can do about it.

An aggressive cancer of the blood-vessel lining, most often in the spleen or heart. It frequently causes no symptoms at all until an internal bleed, which is why it is so often found late.

Drop ears and hairy canals trap warmth and moisture, which is exactly what yeast and bacteria want. Weekly checks and drying the ears after swimming prevent most of it. Left alone it becomes a lifelong cycle that is far harder to break.