Description:

Also called Protein Losing Nephropathy (PLN), is a heritable disease of the kidneys that results in loss of plasma protein (normally retained in the blood) via the kidneys and into the urine.  The average age of diagnosis is between 4.3 and 8.3 years (mean 6.3 years).

When protein enters the urine several secondary changes happen.  The first is within the kidneys themselves.  Protein in the urine has a toxic effect on certain cells in the kidneys called the tubular cells, which are cells which line the microscopic tubules that the urine passes through.  Eventually these cells die and the tubule is replaced by scar tissue, meaning that tubule can no longer pass urine through it - hence there is progressive death of kidney tissue that will eventually lead to kidney failure.

The second effect is that the main plasma protein in the blood, called albumin, drops to lower than normal levels.  Albumin has a number of important roles in the body, one of which is to help maintain blood pressure and stop water in the blood from leaking out of the vessels into the tissue.  Thus PLN can lead to the development of fluid build up in tissue (called oedema), in the lungs (called pulmonary oedema) and in body cavities - for example into the abdominal cavity or into the chest cavity, between the lungs and the chest wall.  This can prevent the lungs from being able to expand properly, leading to compromised breathing.   Some dogs also suffer thromboembolism (blood clots) although the reason for this predisposition with PLN is not known.

There is no cure for PLN, but if it is detected early the progression of the disease should be able to be slowed and the secondary effects managed for a time.  For this reason it is important to screen breeding animals for this condition prior to breeding, and if the parental status is not known DNA testing would be recommended.  However the prognosis remains poor.