Birth defects are any structural or physiological abnormality that develops either before birth or during birth and is present at the time of birth.
Birth defects, also called congenital anomalies, are typically the result of faulty development, infection, environmental factors, heredity, or injury.
A genetic disease is one caused by a mutation of the genetic coding. It can be either acquired or inherited.
Often genetic issues are inherited in a Mendelian fashion, although some are the result of spontaneous mutation in the genetic code of an individual and are not inherited.
To identify and track genetic disease it is important to familiarize yourself with the issues and/or diseases themselves and the genetics involved.
Certain disease processes are directly tied to genetic inherited mutation, some are tied in with genetic predisposition or genetic factor, and others are not inherited at all.
By scientifically identifying the cause and nature of these issues with the help of your pathologist and/or veterinarian, you can get a better idea of whether or not the issues you are seeing are idiopathic, environmental, or hereditary.
A high incidence of tumors, disease, or birth defects in a line would give one incentive to discontinue or limit the line. The appearance of isolated incidents may, or may not, be reason to stop a line. Consulting veterinarians, testing, and researching are important factors in the decision-making process for the breeder.