By: Norma Bennett Woolf Date: 10/31/1997 Category: | Canine Issues |
It's the stuff of which science fiction is made. First, a drop of bird's blood, then a horse's hair, now a few cells from inside the cheek of a Best in Show dog - the progression has been steady, leading DNA experts at several up-and-coming testing laboratories to the ultimate canine identification program: the DNA pawprint.
The claims seem outrageous - permanent identification, unequivocal determination of parentage, even discovery of genetic diseases - but they are becoming more commonplace with each passing day. The potential is enormous: not only will dog breeders be able to identify the sire of a litter or an individual dog if there's ever any doubt, but canine registries will have the tools to uncover fraud.
The system is based on bits of DNA, deoxyribonucleic acid, arranged on chromosomes, the tiny twisted strands of life in the nucleus of body cells. Each animal has its own DNA code, and scientists are cracking the code wide open. In a process known as DNA profiling, researchers have developed standard tests for sexing birds; identifying horses, cattle, and dogs; determining parentage of litters and individual dogs; discovering the genetic diversity in a population of rare breeds; and diagnosing inherited diseases.
In the field
DNA testing is out of the laboratory and into the field. Although the pool of users is small, it is growing. In April 1996, the United Kennel Club instituted its DNA profiling program with PE Zoogen, the recognized industry leader for the expansiveness of their program offerings. This article is an overview of DNA testing; we'll focus on specifics in future issues.
UKC promoted its the partnership with Zoogen as a tool for determining parentage of particular puppies if a bitch had been bred by different studs. The American Kennel Club has successfully used DNA tests to determine the sire and dam of litters to verify recordkeeping and prevent fraud, and individual breeders are using the tests to identify their dogs and build a genetic profile of their breeding programs.
PE Zoogen markets its test kits on all fronts. Born as Zoogen in 1989 as a commercial spin-off of research at the University of California, Davis, the company was purchased by PE Applied Biosystems, a division of Perkin-Elmer Corporation, in April 1996.
"The primary use of our genotyping services is for identification and parentage verification of dogs as part of registration," said Zoogen's Michael Miile. "Providing a unique DNA fingerprint for every dog registered and verifying parentage during the registration process dramatically increases an organization's ability to verify and document the accuracy of their records. This same accuracy and documentation is equally useful to the individual breeder."
Miile said that the technology is also useful in forensic cases involving dogs.
"The second major service that PE Zoogen will be providing using our DNA technology is disease and trait testing," Miile said. "The number of specific tests that are currently available is extremely limited at the current time, but researchers around the world are working at an exciting pace to discover DNA-based tests fro everything from hip dysplasia to coat color or hunting ability."
DNA testing is easy to use. Using a test kit, breeders can take a swab of cells from the inside of the dog's cheek, place the swab in an envelope, fill out the application form, and mail. Reports include a profile of the individual dog and a litter profile to determine which of two or more potential sires actually fathered each puppy.
Zoogen profiles check 22 genetic markers to draw that unique picture of each dog and puppy. With this test, they can distinguish closely linebred or inbred dogs and determine whether father or son sired a particular puppy.
Zoogen developed its markers through testing on 5000 dogs and proofed its system with tests on 1600 more dogs before offering the test to the public. The company touts its system as accurate enough to identify one dog out of 100 million dogs.
A member of the International Society for Animal Genetics and the DOGMAP Alliance, Zoogen is working on the canine genome project and on international standardization of genetic tests.
"Allowing the use of several different marker systems could have disastrous consequences for studbook registries: parentage testing will not be possible if the dam or sire is profiled using different markers, company literature asserts. "Repeatedly-bred dogs would require repeated testing, resulting in incredible waste, frustration, and excessive cost to the dog breeder. A standardized marker system leaves the registry free to use several independent labs yet gain important genetic data that will remain fully cross-comparable."
To this end, Zoogen has placed its technology in the public domain, making the markers available to any interested commercial or academic entities.
Benefits for Breeders
Patti and Rod Strand, Dalmatian breeders for more than 25 years, have embraced DNA testing for their breeding program.
"Our 10 year old Best in Show dog, Merry Go Round XKE has sired 25 American Champions including Group, Specialty and Best in Show winners and therefore is an important dog in many Dalmatians' pedigrees," Patti Strand said. " When AKC offers its constituency the option of using DNA for positive identification, I am certain it will rapidly become the identification of choice for serious breeders, recorded on registrations and in certified pedigrees. XKE is a very healthy 10-year-old, but because no one can predict the future we were eager to certify his parentage now for owners and future owners of his descendants. As serious breeders, another extremely attractive feature is that his DNA is archived and can be retrieved and studied at a later date when new genetic discoveries are made. Being able to ascertain whether an influential dog carried a specific virtue or problem retrospectively will enable breeders to make breeding choices more wisely."
Benefits for Registries
The integrity of AKC's stud book has come under considerable criticism. Since its inception, AKC has had to rely on the integrity of the breeder who files the litter registration because there has been no sure-fire system of identifying the offspring of certain dogs. DNA testing will revolutionize the registration process if AKC requires testing as a condition of registration.
UKC is the first registry to offer DNA testing to breeders. Owners of dogs whose parentage has been verified receive a pedigree with the DNA-VIP seal that documents the test. Dogs that have been profiled but have not had their parentage verified get the DNA-P designation seal.
Zoogen and UKC both guarantee the confidentiality of information gathered as a result of the tests. However, they do provide the group data to researchers and breeders involved in improving canine genetic health.
Genetic markers have been discovered for von Willebrand's disease in Scottish Terriers, Doberman Pinschers, and Shetland Sheepdogs; progressive retinal atrophy in Irish Setters; kinase deficiency in Basenjis; copper toxicosis in Bedlington Terriers; and phosphofructokinase deficiency in Springer Spaniels and Cocker Spaniels. Researchers are closing in on the markers for cardiomyopathy in Dobermans, dwarfism in Alaskan Malamutes, and PRA or other rod-cone diseases in several breeds.
Discovery of genetic markers for diseases will help identify carriers so they may be weeded out of a breeding program. Since many of these diseases become active when the dog is an adult, they can be passed to puppies before breeders suspect there is a problem.
"As these tests become available to the canine community, they will provide valuable information to the dog breeder who is trying to raise healthier dogs and the dog buyer who wants to own a healthy, happy dog. This testing, coupled with the identification and parentage verification testing discussed above, will give the dog fancy the opportunity to reduce or eliminate a number of important genetic diseases and enhance a number of positive traits if desired," Zoogen's Miile said.
About The Author
All Authors Of This Article: | Norma Bennett Woolf |