In a A SIMPLE GUIDE TO GENETICS WHEN APPLIED TO HEREDITARY DISEASES OF THE COCKER SPANIEL,BEAGLE and DEERHOUND.
The hereditary diseases which affect the Cocker Spaniel ,and which can be monitored by DNA tests, are:
Progressive Retinal Atrophy (PRA )
Familial Nephropathy (FN)
The hereditary diseases which affect the Beagle ,and which can be monitored by DNA tests, are:
Musladin Leuke Syndrome (MLS)
Neonatal Cerebellar Cortical Degeneration (NCCD)
The hereditary diseases which affect the Deerhound, which can be monitored by DNA tests ,are:
All the above diseases are governed by what is called a 'simple recessive' mode of inheritance.This means that in order for the disease to be passed on to any progeny BOTH parents have to be at least carriers.
I hope the following explanation helps you to understand how this works :
A dog which is clear of a disease carries NO genes for that condition.(no carrier gene from either parent.)
A dog which is a carrier of a disease carries ONE COPY of the gene for that condition.(from one parent.)
A dog which is affected by a disease carries TWO COPIES of the gene for that condition.(one from each parent.)
Only dogs which have TWO copies of the gene will actually express that disease,a so-called 'affected' animal,and also has the potential to pass it on, and only if a carrier is a mated to a carrier (or affected dog)will it have the potential to produce that disease.
Therefore, IMPORTANTLY, neither a DNA tested CLEAR or CARRIER dog will ever develop that disease.
Only a dog who has inherited a carrier gene from BOTH parents will actually develop the disease in question.
This is called a SIMPLE RECESSIVE Mode of Inheritance.
If you intend to keep your dog purely as a pet you can rest soundly in the knowledge that if your dog is clear or a carrier he/she will never develop that disease.
If you intend to breed from your dog/bitch then it is important to only consider mating clear to clear or carrier to clear,in order to prevent the perpetuation of the disease in question.This is why DNA testing is so important and so useful.
I hope this simple explanation helps you.
Sandy Platt . March 2013
Breed Health Coordinator for the Cocker Spaniel in the UK.