April 15, 2004

 

 A puppy paternity test - April 15, 2004

 
A puppy paternity test
AKC turns to DNA testing to ensure registry accuracy

On television, DNA testing is high drama—leading detectives to the identities of killers and other criminals, and helping to sort out heart-wrenching disputes over the paternity of a child. In real life, DNA testing has found many less dramatic, but important roles, including helping to confirm the parentage of purebred dogs.

Though determining the paternity of a puppy is unlikely to make great primetime television, it can mean a lot to the health of a breed over a couple of generations—particularly, if the puppy goes on to sire many litters of his own. That's why the American Kennel Club has turned to DNA testing to ensure the accuracy of its purebred dog registry, giving breeders the tools they need to make sound decisions that will improve the health of purebred dogs, over time.

The AKC officially launched its DNA testing and certification program in 1998 and has since built a database of more than 238,000 DNA profiles from 178 breeds. The profiles do not contain information about the dogs' health or breeds, but rather the genetic equivalent of fingerprints.

While most of the DNA testing done by the AKC is voluntary, DNA testing is required by the AKC when:

  • a kennel is inspected as part of the AKC's Compliance Audit Program

  • a litter has multiple sires

  • frozen or fresh extended semen are used

  • a stud sires seven or more litters in a lifetime

  • there is a consumer-initiated compliant about a breeder

So far, breeders have responded positively to the program, said Glenn Lycan, director of case Management and DNA operations at the AKC. The phrase "AKC DNA-certified" has become a common new marketing tool for dog breeders hoping to offer consumers more certainty about the heritage of their dogs.

"This is actually a consumer-driven program," Lycan said.

A genetic fingerprint
Scientists at MMI Genomics, the company that tests DNA for the AKC, creates the genetic fingerprint for a dog by analyzing a sample of the dog's DNA and identifying 14 genetic markers. At each marker, a dog has two alleles or versions of the same marker—one version is inherited from the dog's sire and one from its dam. Each dog has a unique combination of these alleles that can be used to distinguish the animal from all others.

The staff members at MMI record each dog's alleles at these 14 sites and send them to the AKC, where staff members enter the information in a database. Once the dog's information and that of its dam and sire are entered in the database, they can be compared to determine whether the dog is indeed the result of this pairing.

For example, if a sire with alleles A and E at the first marker mates with a dam with alleles C and G at the first marker, they can produce offspring that have the following combinations of alleles; AC, CE, AG, or GE. If the puppy in question has one of those combinations, it's called an inclusion, and it means it's possible that the puppy is the offspring of that pair.

If the puppy does not have one of those combinations, it's called an exclusion, and it means the puppy cannot be the offspring of that pair, unless there has been a mutation in one of its alleles. If the puppy has no more than one exclusion—allowing for the possibility of a mutation—at each of the 14 sites, then its parentage has been confirmed.

"(With DNA testing) we can with 99.9 percent accuracy guarantee the integrity of the pedigree," Lycan said.

In addition to boosting the integrity of the AKC's registry and giving breeders more accurate information on which to base breeding decisions, the DNA registry provides a solid foundation for research on genetic diseases in purebred dogs, according to Dr. George A. Padgett. A retired Michigan State University professor, he has authored dozens of scientific articles on genetic diseases in various dog breeds.

"I think it's a positive step," Dr. Padgett said. "It will allow (researchers) to be certain of the identity of the dogs (they are studying)."

He said prior to DNA registration, researchers couldn't readily verify the pedigrees of a dog and had to rely on owner statements alone.

Dr. Padgett, a vocal advocate for more open dialogue about diseases in purebred dogs and open disease registries, said he hopes the AKC will continue to advance the use of DNA.

"(DNA registration) will lead the way to better control of disease because we will be able to positively identify animals who develop these diseases," Dr. Padgett said.

Lycan said the AKC plans to continue to refine its DNA handling techniques to improve the program. For more information on the AKC's DNA certification program visit www.akc.org.


–Bridget M. Kuehn