Familial nephropathy (cocker spaniel type) is an inherited disorder of the kidneys affecting dogs. Dogs with this disease usually start showing symptoms of chronic kidney disease between 6 months and 2 years of age. Normally protein is not present in the urine, but in affected dogs there is a defect that allows protein from the blood to be filtered by the kidneys and lost in the urine. Abnormal amounts of protein can be detected in the urine as early as five months of age. Symptoms of chronic kidney disease include excessive thirst and urination, vomiting, inappetence, weight loss, weakness and fatigue. If drinking excessively, some dogs may also inappropriately urinate in the house or in a crate. Affected dogs eventually die of chronic kidney failure within a year.
Genetic testing of the COL4A4 gene will reliably determine whether a dog is a genetic Carrier of familial nephropathy (cocker spaniel type). Familial nephropathy (cocker spaniel type) is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the COL4A4 gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Dogs that are not carriers of the mutation have no increased risk of having affected pups.
There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.
Davidson AG, Bell RJ, Lees GE, Kashtan CE, Davidson GS, Murphy KE. Genetic cause of autosomal recessive hereditary nephropathy in the English Cocker Spaniel. J Vet Intern Med. 2007 May-Jun; 21(3):394-401.
Donner J, Kaukonen M, Anderson H, Moller F, Kyostila K, Sankari S, Hytonen M, Giger U, Lohi H. Genetic Panel Screening of Nearly 100 Mutations Reveals New Insights into the Breed Distribution of Risk Variants for Canine
Hereditary Disorders. PLoS One. 2016 Aug 15;11(8):e0161005.
Lees GE, Helman RG, Kashtan CE, Michael AF, Homco LD, Millichamp NJ, Ninomiya Y, Sado Y, Naito I, Kim Y. A model of autosomal recessive Alport syndrome in English cocker spaniel dogs. Kidney Int. 1998 Sep;54(3):706-19.