From the September Issue of ShowSight. Click to subscribe.
In the world of purpose-bred dogs, history shows that there have been many healthy forms of breed improvement. Many were based on a series of little experiments. Some failed, but others succeeded and were copied. Success varied widely from breed to breed and most were based, in part, on the creativity and imagination of the breeders. Now with the advances in research, a growing number of breeders have become more engaged in genetic “experiments” which occur each time they plan and carry out a mating. Some will use outcross mating which brings together two animals less related than the average for the breed. Breeding unrelated dogs tends to promote more heterozygosity and usually more variation in the traits seen in their litters. A reason to outcross would be to bring in new genes or traits that are not present but needed. Outcrossing can also mask the expression of recessive genes and allow their propagation in the carrier state. Others will choose to line-breed which is an attempt to concentrate the genes of one or more specific ancestors through their appearance in the pedigree. Those who line-breed should use quality ancestors on both the sire and dam’s side of the pedigree and through careful selection choose offspring that meet the quality expected. Line breeding helps breeders make systematic improvements with each breeding.
Research has continued to be an important part of breed development and the combined funding by the AKC Canine Health Foundation and Morris Animal Foundation ($95 million), Nestle Purina Pet Care ($14 million) and Zoetis ($1.9 million), when taken together, have helped breeders produce many notable accomplishments and a large number of healthy offspring.
In 2003 the human genome project was completed with baffling results that found it was not just the number of genes that mattered but something else. For example, rice was found to contain 12 pairs of chromosomes, humans 23 and canines 39. Inside the chromosomes are the genes that produce the traits that make each individual unique. What was also discovered was that it was not just the number of genes that were important, but also their efficiency, gene expression and the diversity of their proteins. For example, a single strand of tightly wound DNA is three microns long and fits into a space of only two-three cubic microns of a cell’s nucleus (roughly one millionth of a yard). With these discoveries, the question for breeders is not whether to use DNA tests or other protocols, but what to do with the results. In the past, many breeds suffered because quality dogs were thrown away, along with years of good breeding, because breeders did not know how to interpret and use test results. Today we know that when breed health initiatives are used they can become a demanding process that offers rewards for improved health for a breed or the misuse by uninformed breeders and their clubs. These events often lead to unintended consequences. Perhaps the better question is: can the undesired trait be inherited? Does it occur with increased frequency in your breed? What is the mode of inheritance? What is the reliability of the health test?
If a health test or other protocol produces false-positive or false-negative results, breeders need to be careful because all of the descendants that inherit this portion of the chromosome will also have false test results (Bell). This has been documented with families of Bedlington Terriers tested for the autosomal recessive copper toxicities gene (Bell). It is obvious that direct gene tests are better than linkage-based tests and a test with 90% or 95% level of confidence is better than no test at all (Bell). However, as genomic research progresses, researchers will continue to identify the defective genes responsible for the disorders and they will also develop direct gene tests to replace linkage-based tests. For example, the defective gene for copper toxicities in the Bedlington Terrier has now been identified and a direct gene test is now possible. But just having a test is not the solution. Unless breeders learn how to interpret and use the test results, progress will be slow and at a great cost.
Because the majority of genetic disorders are caused by recessives, it is important to identify the affected, the carriers and the normal in order to find the solutions needed for making a breed improvement. To do this, breed clubs need to promote breeder education programs and provide mentors for new puppy buyers. Making a breed improvement and controlling unwanted disorders involves those who have learned how to manage the carriers. Good breeding also involves knowing how to use “Formula Breeding” and the principles of “Breeding Up” (Battaglia). No one approach is recommended for every breed and every unwanted disorder.
Pedigree analysis must be considered when using DNA tests, X-rays and other health protocols. For example, in a three generation pedigree there are 14 ancestors. Knowing only about a few ancestors can mislead breeders into believing what is not true. What also becomes a factor is that breeders and owners who use health tests usually have some level of emotional reaction when a pup is produced with a genetic disorder. According to Dr. Bell, the reaction tends to follow what he calls a grief cycle:
- Denial: This isn’t genetic. It was caused by something else.
- Anger: This isn’t right! Why is this happening?
- Bargaining: My dog sired more than 100 other dogs that are healthy. So this one doesn’t really count, right?
- Depression: My breeding program or kennel is ruined. No one will breed to my animals.
- And, finally, acceptance: My dog was dealt a bad genetic hand and there are ways to manage genetic disor ders, breed away from this, and work toward a healthier breed.
Bell reported that unless a breed can grow and expand, over time, it will have problems maintaining genetic diversity, which has serious health implications. He also suggested that breeds establish a priority of health initiatives coupled with a statistically valid breed health survey every five-ten years in order to document the number and frequency of conditions that are occurring. Scientific surveys work best because they are designed to eliminate sampling errors and bias that can invalidate
Inherent in a good breeding program is support from the breed club and a willingness to reduce the stigma of disease which involves raising the level of conversation from gossip to constructive communication. Taking on the issue of genetic disorders needs to become a community effort. It begins with a club’s leadership, its breeders and owners. For each disorder there is a different level of risk and involvement. While breeds do not get to choose their problems, they must find a way to be supportive of others who are making a conscientious effort to continue breeding their animals while decreasing the risk of passing on defective genes. This requires tolerance and education, which should be given a priority. Knowing the dreaded diseases comes first. They are the disorders that can: kill, cripple, cause early death
A word of caution
The Animals Rights as a Group has for years successfully used the idea of linking the use of tests to undefined labels as a means for affecting and influencing breeders. Their latest undefined term is the “Responsible Breeder”, which by design has many vague meanings and interpretations. Most importantly, this term as they use it offers everyone who “does the right thing” the opportunity to label themselves a “Responsible Breeder”. Underneath its exterior is the special emphasis it brings to the quality of the pups being produced. It assumes that if a pup is of poor quality, unhealthy or has something wrong, it should not be bred. Most breeders agree with this notion and respond by withholding AKC registration papers or placing it on a limited registration or a spay/neuter contract. The underlying assumption is that they are being “Responsible Breeders”. The notion however is that the unsound and unhealthy should not be sold for breeding. This is fundamental to the label and with that logic it becomes the best indicator of whether a breeder is being responsible. Thus, it follows that testing is a way to measure the “Responsible Breeders” by what they produce and how they register it. This method identifies some breeders as better than other breeders and salutes those who breed to produce better quality. In the background however, there are some important and fundamental questions. For example, for most of the dreaded diseases there are no DNA tests which means there are different levels of risk and involvement when breeders choose to breed and avoid the dreaded disorders. The Animal Rights Groups hope that clubs will not take the time to train their breeders, develop mentors, or use DNA tests when they are available nor will they encourage using techniques that will manage the carriers. They know this could diminish their strategy. On the other hand, breed clubs and their breeders can determine whether their breeders are making progress via scientific surveys, training and educational programs, thus being “Responsible Breeders”. Said another way, quality pups are the goal, and how breeders sell their pups can be used as one method of progress. In retrospect, there is a lesson to be learned from the simple logic of pairing the idea of testing to undefined labels like the “Responsible Breeder” and the idea of “raising the bar”. Clubs are the stake holders and they need to drive the conversation with tolerance, education and a set of priorities. Included in their strategy should be a focus on how to use of test results when they become available and how to develop health initiatives that combine health survey data that document the number and frequency of conditions that
- Battaglia, Carmen. 2009. “A Gathering Storm”, Canine Chronicle, Ocala Florida, March Issue, pg. 162-166.
- Battaglia, Carmen. 2009. “Managing the Carriers”, Canine Chronicle, Ocala Florida, April Issue pg. 162-166.
- Bell Jerold, 2005. “Anatomy of a Breed Health Initiative”, Tufts’ Canine & Feline Breeding and Genetics Conference, September 29-October 1, 2005.
- Bell, Jerold S Bell, 2003. “Removing the stigma of genetic disease”, Tufts Cummings School of Veterinary Medicine, N. Grafton, MA. (Adapted from an article that originally appeared in the “Healthy Dog” section of the October, 2003 AKC Gazette and Tufts’ Canine & Feline Breeding and Genetics Conference, September 29-October 1, 2005.
- Bell Jerold, 2005. “The ins and Outs of Pedigree Analysis, Genetic Diversity, and Genetic Disease Control”, Tufts Cummings School of Veterinary Medicine, N. Grafton, MA.
About the Author
Carmen L. Battaglia holds a Ph.D. and Master’s Degree from Florida State University. As an AKC judge, researcher and writer, he has been a leader in promoting the better ways to breed dogs. An author of many articles and several books, he is also a popular guest on TV and radio talk shows including several appearances on Animal Planet. His seminars on breeding dogs, selecting sires and choosing puppies have been well received by breed clubs all over the country.
Those interested in learning more about his articles and seminars should visit the website https://www.breedingbetterdogs.com.