Dog Breeding and Genetics - Research Proposal Example

Running Head: MAMMALIAN BREEDING Mammalian Breeding [Name Of Student] [Name Of Institution] MAMMALIAN BREEDING INTRODUCTION Dog breeders of centuries ago knew only that like begat like, and they measured heredity in terms of "blood." Now, savvy breeders speak of Coefficient of Inbreeding or Coefficient of Relatedness, instead of blood, when studying pedigrees. By the mid-20th century most breeders knew only about dominant and recessive genes. Now breeders know puppies don't act like Mendel's pea plants, and they speak of polygenic, epistatic and threshold effects. By the last decade breeders became aware that no breed was immune from hereditary health problems. Today's better breeders know their breed's health problems, as well as any genetic tests and registries available for those problems, and they support research to further canine health. Yesterday's breeders had to accept life's hard knocks when a bitch cycled abnormally or developed pyometra. Today's breeders consult with reproductive specialists (theriogenologists) to save her reproductive potential. Yesterday's skilled breeders could read a vaginal smear and perform an artificial insemination (Dunner, 2003). Today's informed breeders know when to request a progesterone or lutenizing hormone test and when to consider a surgical or endoscopic insemination. Yesterday's breeders studied road maps and airline schedules; today's study chilled and frozen semen shipping and importation procedures. Yesterday's breeders often had a stud dog who looked forward to company; today's breeders often have a stud dog who considers his veterinary theriogenologist an intimate friend. AIM Koharik Arman in the paper called: A new direction for Kennel club Regulations and breed standards wrote: "Many Kennel Clubs worldwide still prescribe conservative, centuries' old ideologies and traditions that are harmful to the canine species. These ongoing attempts to create the ultimate canine conformation, with continually elevated ideals, are precisely what result in detrimentally exaggerated physiques and diseased animals." In this paper I will discuss the various problems and issues related to breeding. DISCUSSION When we try to create a cultivated variety of animals through breeding they come to be known as Purebreds,and then that animal is known as pedigreed. The phrase purebred is repeatedly confused with the Thoroughbred, which actually points to a particular breed of horse. Many people have dog breeidng as their hobby and when taken seriously it has created a lot of problems for the animal itself. Breeding is a serious issue and needs to be dealt in the same manner. Without proper knowledge and skills, many people cross-breed different types and the resulting breeds have highly altered habbits and traits. Many organizations also allow inbreeding which as a consequence produces genetic disorders amongst the dogs such as eye diseases and hip dysplasia in canines. Usually there are 2 broad categories of purebred dog breeds ; classified as kennel club and independent breed clubs. A recent hot topic in the world of dog breeding has been the concept of genetic diversity and population genetics, i.e., the maintenance of a highly diverse gene pool, not restricted by successive generations of inbreeding or line-breeding. Please note that all purebred dogs are highly inbred relative to their feral ancestors, or they would not breed true to type. Some breeds, such as those starting from very small populations and those highly popular breeds that have huge numbers of genetic problems, are so inbred, however, they could be considered an endangered subset of their species (Dunner, 2003). Normal breeding of such animals only would result in a further increase in their "coefficient of inbreeding," which is the probability that a dog with two identical genes received both genes from a common ancestor on both sides of the family tree. This is used as a statistical indication of how inbred an animal is. The imperative is for fanciers to breed for healthy traits and to avoid unhealthy traits. The reality is that, until recently, most breeding practices have concentrated on conformation standards and really have not fully addressed the health concerns specific to our breeds (Sharp, 2003). (The last 20 years have seen a real change in the European breeding codes postulated by the Federation Cynologique Internationale. The U.S. registries have been much slower to institute changes in breeding practices.) We have witnessed a loss of genetic diversity occurring from the overuse of certain top-winning studs (this is called the Popular Sire Effect), made even more possible through cooled and frozen semen. When an organism has genetic diversity, it means each gene has multiple alleles (copies) at each gene locus (Dolf, 2001). On the other hand, a national distribution of genes vs. a regional distribution may have contributed to the overall genetic well-being of our purebred canine friends. Because of difficulties in transportation, etc., little regional pockets of dogdom in the past had tended to become inbred. Bringing in unrelated dogs from other regions helped introduce greater diversity. For many people breeding is just another money-minting exercise without any concern for the the health and welfare of their dogs. This is also known as backyard breeders and these are the people who as a whole have caught irrepairable damage to the dogs in general. This does not imply that all breeders fall under the puppy-mill category at all. Snuppy which is the first cloned dog, shows that it is probabale to breed a dog that comes to be the genetic twin of any other dog, even though it is yet very tricky and expensive to do so. In the coming times, it may be possible as some dog lovers may choose to create a twin of their pet. Certainly, there is an opportunity for abuse and indiscriminate breeding. We more than suspect genetic arguments to arise from proponents of genetic diversity, and the most probable point of contention will be that cloning fosters the Popular Sire Effect. In breeds that have few founders (the number of dogs used to start a breed) or that have experienced a genetic bottleneck, an overused sire can have a devastating effect. The Mastiff, for example, suffered a genetic bottleneck after World War II because hardships in Europe made it impossible to keep many dogs, especially giant ones (Dunner, 2003). Their populations almost decimated, some breeds had to rely on a few survivors, which reduced the gene pool and created a limited foundation for the breed. Besides war, other bottlenecks occur when a breed becomes extremely unpopular and rare, or when dogs from one country or, worse, one kennel are used to found the breed in another part of the world. Yet, one of the most pervasive bottlenecks is brought on voluntarily by breeders--the rush to breed to only a few favored sires while the majority of potential breeding males are never bred (Sharp, 2003). This is another area in which the AKC could step in to guide each parent club in the proper use and regulation of clones within the various breeds by providing guidelines for registering clones. As previously mentioned, the AKC declined to answer the cloning question. Parent breed clubs are working with the AKC to identify the genetic problems by using DNA parentage certification and genetic testing. This information is becoming so readily available that it is easy to comprehend the actual genetic disease problem in dogdom. In my opinions, as fanciers we need to find the best dogs we have from a genetic standpoint, and we need to save those genes, wherever we might find them (Dunner, 2003). More purebred dogs are riddled with genetic problems than not. The expression of these genetic defects is increasing due in part to practices such as inbreeding (mating siblings, father to daughter, mother to son, or other close relatives) and line-breeding. "With inbreeding in general, there is no attempt to increase the relationship between the offspring and any particular ancestor. In a line-breeding program there is a deliberate attempt to maintain or increase the relationship between the offspring and a specific admired ancestor (or ancestors). This feature distinguishes line-breeding as a special form of inbreeding." (Dolf, 2001)Both these techniques concentrate the good genes, but they also double up on the deleterious genes associated with the inborn errors of metabolism or protein replication most often seen with genetic disease. Ironically, breeders use these types of breeding to retain within their bloodlines the genes of some special dog. With cloning, they would not need to use these practices because they now would have access to the genes of the original dog. With more than 400 genetically transmitted diseases identified among purebreds, the scope of the problem of poor genetic health is large indeed (Dolf, 2001). Despite the best efforts of responsible breeders, experience shows that whenever a breed becomes popular, puppy mills and individuals without knowledge of health and genetics begin breeding for profit. The result is a long list of serious health problems that show up more and more frequently (Dolf, 2001). Dogs that are bred from the northern wolves are inclined to be considerable canines, well-muscled and well-suited for chasing big game (Akita), herding reindeer (Samoyed), and dragging sledges (Alaskan Malamute and Siberian Husky). Dogs that urbanized from wolves in moderate or extra southern climates have a propensity to encompass shorter coats and be further rationalized than their northern cousins. Sighthounds (Afghan Hounds, Salukis, Basenjis, and Greyhounds), dingoes, and pariah dogs are a part of this category. Mastiff-type dogs almost certainly were produced as an outcome of gigantism initiating in populations of a certain type of mountain wolf in somewhere in northern India or Tibet. The majority of additional breeds are supposed to have developed from cross-breeding amid the northern, dingo-pariah, and mastiff groups, a number of by means of an admixture that comes from dwarfism genes. The classes of dog recurrently used to create the hybrid have a tendency to be overriding, fairly sovereign, and even unfriendly. They are complicated to educate for inexpert owners and can be forceful to other dogs and hazardous to cats and additional tiny mammals. This mixture of wolf nature and breed characters can be risky in raw hands. Even though the temptation to possess an unusual pet is well-built, families who would like a wolf-like mammal that is fine with offspring should choose for a well-tempered German Shepherd, or a Keeshond or a Samoyed. further skilled dog owners may think about a Siberian Husky, Alaskan Malamute, Chow, or Akita. In my opinion, the moral issue is not whether to preserve or to clone. The moral issue is whether we are saving the best we have in order to avoid genetic problems in the future. For argument's sake, if preserving endangered flora and fauna species is good, is it a big leap of faith to suggest that maybe some of our great dogs, ones that stand out above all others, are worthy of reproducing or cloning? (Dunner, 2003) With frozen semen, a direct descendent is available. With frozen DNA, the future promises a nearly identical twin (mitochondrial differences notwithstanding) will be possible. (A mitochondria, which could be described as a cell within a cell, is responsible for energy production and cellular respiration, and it contains DNA found nowhere else. Mitochondrial inheritance does not obey the classic rules of genetics. Because a surrogate's egg is used, the surrogate provides the DNA from her mitochondria, not the DNA donor animal's (Dolf, 2001). Therefore, the clone is not exactly the same animal but a mixture of the DNA donor and the surrogate for traits that only have to do with how the cells produces energy.) Another point to consider is that in the future we conceivably will be able to "correct" genetic defects. Manipulation of the canine genome may be possible some day using recombinant DNA techniques presently in development. What if you have a great dog that you find to be a carrier of a late-onset genetic disease? (Sharp, 2003)With this new technology you could clone that dog's genetic material and breed a dog without the disease. For now, however, we must deal in conjecture and speculation. Although cloning can guarantee an animal with identical appearance, it cannot guarantee a copy of temperament because environment plays a role in behavior. As well, some health conditions are not linked to genetics, or they are linked but also have an environmental component. Environmental differences may Cause a clone to contract a condition the source animal did not have. Even the clone of a perfectly healthy animal still would require proper socialization, training, nutrition and veterinary care (Dolf, 2001). Other points to consider include: When cloning becomes possible and economically viable, it may be feasible to slow the rate of decrease in diversity, which is inevitable with the normal mating of a dog to a bitch, within those highly inbred breeds. Breeders would feel less pressure to breed a dog before it is proven by age. This might reduce the number of dogs bred before they are listed with the Orthopedic Foundation for Animals, etc., or before a late-onset, genetic disease presents, such as might be the case with cataracts. National and even international, rather than regional, availability of studs and dams would be possible. Countries with quarantines would be able to import genes to which they otherwise would not have access. (Sharp, 2003) THE FUTURE OF BREEDING New technology moves by leaps and bounds. When asked about the major strides within the last century, most canine reproductive specialists would point to artificial insemination with frozen and fresh-chilled semen and the retention of the reproductive capability of bitches with pyometra through prostaglandin therapy and antibiotics (Dunner, 2003). Because this technology is market-driven, cloning and artificial insemination now are in use in cows, pigs, turkeys, chickens, goats and fish--animals whose husbandry is a major industry with a significant economic impact. Therefore, research into the canine reproductive cycle has lagged behind those of more economically viable species. Most breeders doing natural breeding still rely on behavioral cues such as flagging (when the bitch lifts her tail to one side) and receptiveness to the male and physical signs such as color of discharge and swelling of the vulva (Dolf, 2001). The onset of the use of frozen and fresh-chilled semen encouraged scientists to develop certain laboratory tests. These include vaginal smears that at best give a retrospective view of the bitch's cycle and are not useful by themselves in timing insemination. Serial testing of serum levels of progesterone is the "gold standard" used in a reproduction specialist's practice, but these tests also have technical problems associated with their application. These technical problems include a less than full understanding of the canine reproductive physiology and reproductive endocrinology. We hope for more accurate, pertinent and predictive tests in the future. (Dunner, 2003) Some of the problems and challenges with cloning dogs are due to the singular nature of canine reproduction. Not only do bitches cycle irregularly but the canine also is unique in that the bitch ovulates immature eggs (called oocytes), which normally take several days to mature. Researchers must replicate the internal environment of the bitch's oviduct so the eggs will continue to mature. Visualizing the in vitro maturation of the oocytes also is difficult and is compounded by the fact that the stages of maturation are hard to view due to the high lipid content of the cells (Sharp, 2003). Once the proper stage of maturation has been achieved, the nucleus containing the genetic material is removed from a recipient egg. An adult fibroblast from the skin of the animal one wishes to clone is placed next to the enucleated recipient egg in a petri dish so that their membranes touch. With the cell membranes touching, an applied electrical field is used to fuse the two membranes. After a couple of hours, the adult cell has been "reprogrammed" so that certain genes have been turned off and others have been turned on (Dolf, 2001). The adult donor fibroblast cell is equivalent to the one-cell stage and contains only the genetic material of the animal to be cloned. How this occurs has yet to be discovered. In the laboratory, the process of fertilization is mimicked by a series of calcium spikes--often induced by an electric current. The cell continues to replicate to about the eight-cell stage and then it "runs out of gas." (Dolf, 2001)This is where dog cloning runs into another stumbling block. As yet no one has developed a growth medium that will provide the proper growth factors specific to the canine. One way of getting around this problem would be early insertion of the eight-cell stage into the surrogate dam. Timing of the insertion of the embryo(s) into the surrogate must be synchronized carefully to match exactly the hormonal levels and environmental factors needed by the conceptus. Basic research in this particular field also would pave the way for extending the reproductive capability of outstanding bitches (Schumtz, 2002). One barrier to this process, embryo transfer to surrogates, will depend on precisely matching the heat cycles of both bitches. With this in mind, note that at the December 1999 AKC board meeting, it announced the approval of the onetime only use of a surrogate dam to produce a litter using the fertilized eggs of a 9-year-old Labrador Retriever bitch under "certain established criteria." What those criteria are has not become available yet, but we hope that further guidelines will be published soon. If these problems can be overcome then the cloning of dogs may become a commonplace reality. The technology is here--we can preserve the genes of our best dogs; we just cannot yet create dogs from DNA samples (Dolf, 2001). Cloning, however, only would be a temporary measure. What is needed is assortative mating--breeding like phenotype dogs to like phenotype dogs with different pedigrees. Unfortunately, some lines are so inbred that there are no true outcrosses left. (Schumtz, 2002) Purebreds can benefit from the introduction of cloning into a breeding program if the program is properly managed. Cloning can be used as a way of reaching back to the past before diversity was lost. CONCLUSION Yesterday's breeders were faced with many ethical dilemmas. Today's breeders are, as well. We still can't make every puppy healthy. We still can't guarantee a long life. And we now have to ponder whether our grand efforts to get some dogs to reproduce could ultimately create dogs who can't breed naturally. Tomorrow's breeders will be faced with even more advances and ethical dilemmas. Will we freeze ovaries and eggs from valuable bitches, just as we now freeze semen? Will we transplant embryos from one bitch to another? (Switonski, 2003) Will we genetically engineer better dogs, inserting good genes in place of bad ones? Or even create new breeds better suited to modern jobs and life? Will we clone favorite dogs--perhaps minus a gene that caused an early death? These aren't just fantasies; they're all ideas being investigated in companion animals right now. Ultimately, the question will not be "can we," but "should we?" Perhaps the answer to creating better, healthier dogs will not be found in modern technology but in old-fashioned know-how. Might problems arising from generations of closed breeding be more simply conquered by incorporating into our pedigrees unregistered dogs from some breeds' countries of origin--or, lacking that, even mixing in other breeds? (Schumtz, 2002)The breeders who created our breeds often resorted to these practices; how do we ensure we do not become so enchanted by the utopia of breed purity that we are blinded to its downside? We can only see farther than yesterday's breeders if we embrace new technologies and knowledge without losing sight of old know-how and experience. We have to be not only part artist and part scientist, but also part nurse, lawyer, economist, communicator, humanitarian, historian and futurist. REFERENCES Dolf (2001) Journal of Animal Breeding and Genetics, Volume 118 Issue 1 Page 3-19, February 2001 Dolf. (2001) DCT and EDNRB map to DogMap linkage group L07. Animal Genetics 32:5, 321–321 Dunner. (2003) Contribution of a new set of canine microsatellites to the knowledge of the canine genetic map. Animal Genetics 34:1, Schmutz. (2002) Linkage mapping of TYR to dog chromosome 21. Animal Genetics 33:6, 476–477 Sharp. (2003) KITLG maps to canine chromosome 15 and is excluded as a candidate gene for merle in dogs. Animal Genetics 34:1, 75–76 Switonski. (2003) Microsatellite polymorphism and genetic distances between the dog, red fox and arctic fox. Journal of Animal Breeding and Genetics 120:2, 88–94 Read More