Members of subsequent litters entered into cat shows for the first time in 1986, and the first championship for this breed was awarded in 1992. (meeowcat.com)
For example, some infections like canine herpes or brucellosis can't be cured, and they can't be prevented from killing in subsequent litters. (breedingbusiness.com)
While this is not an immediate problem (the puppies are just carriers for the recessive gene), when these puppies are mated with subsequent litters down the line, the defective gene will become more and more common, thus producing more individuals who carry two copies of the defective gene, and have the disease. (onegreenplanet.org)