The genetic disorder, prcd-PRA , causes cells in the retina at the back of the eye to degenerate and die, even though the cells seem to develop normally early in life. The “rod” cells operate in low light levels and are the first to lose normal function. Most affected dogs will eventually be blind. Typically, the clinical disease is recognized first in early adolescence or early adulthood, and unfortunately, at this time there is no treatment or cure for PRA.
Familial nephropathy (FN) is a type of hereditary kidney disease that leads to renal failure in affected dogs, usually at a young age. It is relatively widely spread across the English cocker spaniel dog breed, with just over 10% of English cockers in the UK carrying the gene mutation that leads to the condition.
Generally, dogs affected with the condition will go into irreversible renal failure by the time that they reach the age of two, which cannot be cured and ultimately proves fatal
Both Prcd-PRA and FN are inherited as a recessive trait. This means a disease gene must be inherited from BOTH parent in order to cause disease in an offspring. Parents must both be either “carrier” or ''affected'' by the diseases in order for either to be passed on. A ''carrier'' is a dog which has one disease gene and one normal gene, meaning he himself is not affected by Prcd-PRA or FN, but he can pass it on to his offspring. A clear dog has no disease gene and is termed “homozygous normal” or ''Double Clear'' this means both copies of his gene are same and therefore no puppies produced by this dog can ever be affected by Prcd-PRA or by FN. A dog with two disease genes is termed “affected” – both copies of the gene are abnormal and he himself will suffer from the effects of Prcd-PRA and will almost certainly go blind, on by FN with would almost certainly leady to his untimely death at around 2 - 3 years of age.
Although prcd-PRA or FN are inherited, it can be avoided in future generations by testing dogs before breeding. Identification of dogs that do not carry diseased genes is the key. These "clear" dogs can be bred to any mate - even to a prcd-PRA or FN affected dog, which may be a desirable breeding prospect for other reasons. The chance of producing affected pups from such breeding depends on the certainty of each parents test results.