PERMISSION TO CROSSPOST
Here is the article from Dr Meyer-Wallen, Cornell University, USA:

   In the laboratories at the Baker Institute for Animal Health, Cornell University, Dr. Vicki Meyers-Wallen focuses upon inherited disorders that  affect canine reproduction. Our goal is to identify genes that have a negative impact upon reproduction, with the final goal of producing practical tests to identify those carrying harmful mutations. The long term goals are to reduce, and eventually remove, such deleterious genes from purebred dog populations, thus improving the reproductive soundness of purebred dogs.   We are asking for breeders and owners to participate in our study by allowing us to collect blood samples from their dogs and related dogs.   Those interested can e-mail Dr. Meyers-Wallen a mailto:vnm1@cornell.edu. We are studying the DNA to find the gene mutations that cause cryptorchidism (undescended testicles). Since this is the most prevalent inherited disorder of the canine reproductive system, it would be very helpful to have a test to detect carriers of these genes. Then breeders could plan matings in which  no cryptorchid offspring would be produced, while allowing the offspring to receive other desirable genes that such carriers may have.  To this end, we have recently initiated studies of canine cryptorchidism,  which is the failure of one or both testes to descend into the scrotum.   Unilaterally cryptorchid dogs have only one testis in the scrotum.  Bilaterally cryptorchid dogs have no testes in the scrotum. The undescended testes may lie within the inguinal area or within the abdomen. This is an inherited disorder, and is inherited as a recessive trait. In the dog, both testes normally descend into the scrotum by 2 weeks after birth (even though one can not really feel them there at the time), but should be detectable in the scrotum by 6 weeks of age.

Based on the few pedigree studies in dogs and experimental studies in other animals, testis descent in the dog is thought to be controlled by at least 3  genes, the identity of which are unknown. Recessive mutations in such genes result in cryptorchidism. Delayed descent of the testes may be a similarly  inherited trait, as there is evidence in mice that mutations in 1 or 2 of  the genes controlling testis descent in that species can result in delayed testis descent. It has been shown in other animals, such as pigs and goats,  that the prevalence of cryptorchidism in herds can be reduced over time by selecting against this trait. That is, cryptorchid animals and male and female parents of cryptorchid animals were not used as breeding stock.  This  approach has not been used extensively in purebred dogs. However, if both  male and female carriers could be identified by a practical test, then  matings of carriers could be more easily avoided.   The recently published canine genome sequence allows us to study dog genes more effectively. Using this information, we and our collaborators studying human and mouse cryptorchidism, have performed pilot studies in dogs.  We have not yet found mutations causing cryptorchidism, but we need to examine many more dogs, their related family members, and dogs of several breeds.   In  further studies, we plan to include dogs from family lines that have this problem, as well as a few lines that do not. All participants are purebred dogs, but their identity and that of their owners is held in confidence.  That is, the identity of dogs and owners will be not be revealed by the researchers at any time. Using DNA markers and linkage analysis techniques, as we have in other projects, we plan to examine DNA for markers that allow  us to identify the chromosome location of genes responsible for cryptorchidism. Once the locations are identified, the DNA sequence of those  regions is examined more closely to find specific genes and their mutations.