What it is
Each kidney holds a vast number of tiny filters that sift waste out of the blood into the urine while keeping useful proteins in. In familial nephropathy, a genetic fault leaves these filters weak or badly formed, so protein leaks through them and their ability to clean the blood slowly fades. As more and more filters fail, the kidneys can no longer keep up, and waste builds up in the body.
The disease is inherited and shows itself in young dogs, sometimes before they are fully grown. Because the kidneys can lose much of their capacity before anything shows, a dog can look well for some time.
Weakening kidneys make a dog drink more, so fresh water should always be within reach, and more toilet breaks will be needed. Tiredness, a poorer appetite and feeling off colour can come and go, and your dog may simply want more rest.
Signs you may notice
A young dog may start drinking and urinating more, eat less, lose weight, vomit or become sluggish. These signs can appear gradually, so they are easy to mistake for a passing upset.
When to see a vet
Book a vet visit if a young dog starts drinking or urinating more, eats less or loses weight. Go the same day if your dog keeps vomiting, stops eating altogether or becomes very weak.
This is general information, not veterinary advice. For your own dog's health, tests and treatment, see a vet.