Today, many dog breeders and veterinarians have found artificialinsemination (AI) to be an invaluable tool. Many of them see it as away to increase the quality of a breed by overcoming limitations ofboth time and space. An exceptional male, chosen for his intelligence,personality, and conformation can continue to produce offspring longafter his death, or be mated with females from which he is separated bythousands of miles. Additionally, by saving his semen, he will be ableto breed with many more females than would be physically possiblethrough normal one-on-one mating. There are also cases where valuablemales have been injured and can no longer mount a female. Theirgenetics are of course unaltered and artificial insemination allowsthem to continue to contribute to their breed. A bitch that has thesame qualities as the above male and has the potential to build akennel from her progeny, may not yet be in heat, but a suitable matingcan be arranged, the semen taken and saved until she is ready to bebred.
Today, the actual technique and methods of artificialinsemination are relatively easy and done by many private individualsand most veterinary clinics. Although the field is relatively new incanine medicine, it has been successfully practiced in cattle and otherspecies for many decades. Although we rest on the shoulders of theresearch and experience developed in bovine practice, we have not yetduplicated their rate of success. This is not because of our technique,but rather the relative instability of canine sperm when frozen orchilled. Additionally, in cattle, the regularity and competency of thereproductive physiology of the female has been consistently selectedfor breeding, while this is not the case in dogs. Cattle that do nothave a predictable estrus cycle or high levels of fertility areeliminated from the herd. It is a very pragmatic business. In caninemedicine, breeders are often much more emotionally attached to theiranimals. They routinely keep and repeatedly attempt to breed problembitches and those with irregular cycles, thus allowing undesirabletraits to maintain themselves in the genetic pool.
Collecting semen
Collectingsemen from a stud dog is very simple. A female in heat is broughttogether with the male. When he tries to mount her, his penis isredirected into an artificial vagina and stimulated to cause anejaculation. The presence of the female is useful to excite the maleand makes collection easier. (During estrus, organic compounds known as'pheromones' are excreted from the female's vagina. These airbornechemicals are responsible for attracting males from long distances tothe female. They even indicate the stage of her heat.) However, suchfemales are not always available when a male is to be sampled. In thatcase, a common practice is to save and freeze cotton swabs that we havewiped through the vagina of a female when she was in peak estrus. Atthe time of semen collection, the swabs can be wiped around the tailarea of any dog (even a spayed one). The male will then respond to her just as if she were in heat.
Semen evaluation
Aftercollecting the semen, the sperm cells are checked to ensure that theyare sufficiently concentrated, adequately motile, and appearanatomically normal. This is done because we know that in many'sterile' males, the problem is not that they do not produce spermcells, but rather their quality or quantity is very low. Infertilemales may have abnormal sperm cells, which are unable to travel all theway to the oviducts of the female, or cannot penetrate the ovum forfertilization to occur. The microscopic semen evaluation is noguarantee that the sperm present are in fact capable of fertilization.There may be flaws all the way down to the molecular level of the DNAin the sperm that make a male dog sterile.
Insemination
Ifthe sperm cells seem to be adequate in number and appear normal, theymay be immediately infused into a female using a long plastic or glasstube. Attempts are made to at least reach the level of her cervix,which in large dogs may be several inches inside the animal.
Ifthe bitch is not going to be bred immediately, the semen may either bechilled or frozen. Chilled semen should be used within 24 hours and cantherefore be shipped 'Next Day Air' to anywhere in the country or evenoverseas, and a female can be bred with it the next day. This has mademales available to appropriate females all over the world withouteither one of them needing to travel.
Freezing semen
Semencan also be frozen in liquid nitrogen canisters and kept that way foryears. This allows females to be bred with males who are also milesaway or who have even died years before. When we consider the expenseof stud fees and or transporting one or both of the breeding animals,frozen and chilled semen is relatively inexpensive. Furthermore, itgreatly increases the number of potential mates to choose from.
The heat cycle in a bitch
In a typicalcanine heat cycle (we underline the work typical because in some breeds'typical' bitches are getting harder and harder to find), the dog'svagina swells and she bleeds for 7 to 9 days. This is the preparatoryProestrus stage. Next, the bleeding diminishes and she becomesreceptive to the male and allows him to mate. This is Estrus. Onlyduring the 3 to 7 days of Estrus will the bitch be in the proper stageto become pregnant.
After 3 to 7 days, she moves into the Metestrous stage, is no longer fertile, and will not accept a male's advances.
'Problem breeders'
Sometimesartificial insemination is used even though both dogs are present. Thiscommonly occurs when either the male or female dog is a problembreeder. In these cases, either the male will not mount or showinterest in the female or the female will not allow the male to mounther. Often, these are simply problems of inexperienced dogs. In wilddogs, breeding has a learned component where the younger males learnfrom interactive play behavior and by observing adults. By separatingpuppies from their family units at 7 to 8 weeks of age, we haveeliminated this portion of the learning process. When mating young orfirst time breeders, it is always best to have one of the pair beexperienced. Usually this individual, be it the male or female, will'take charge.'
In other instances, the two dogs may not seemequally interested in mating. This may result from the female not beingin the correct stage of her heat cycle. Therefore, she does not eithercorrectly stimulate the male or will not yet allow him to mount. Overthe years, we have been asked to examine and find out why breeding isnot occurring as expected, only to discover that the female was not inthe correct stage of her cycle. This can sometimes be determined bybehavior. However, it is easily and more accurately determined byeither a vaginal smear that is examined under a microscope or via ablood test that determines the level of the hormone progesterone.
Thereare however, instances of behavioral problems where dogs will notbreed. The female is in the correct stage of heat, but one or the otherof the dogs just lacks the natural desire to mate.
Concerns regarding artificial insemination
Oneof the problems with selective breeding is that every time we selectfor one thing, we are probably unknowingly selecting for or againstmany others. Today, in many breeds, numerous individuals are showingabnormal reproductive physiology and behavior. The Proestrus stage goeson for 3 to 5 weeks, males have abnormal sperm counts, the female nevergoes into true Estrus, litter numbers decrease drastically, mothersshun their offspring, etc. Sooner or later, good breeders look at theirlines and recognize these problems. They must try to eliminate thesetraits just as they would hip and eye disorders. By using artificialinsemination to get around these shortcomings of their dogs, they onlypotentiate the problem.
Another concern is the use of artificialinsemination when one of the two dogs is vicious and constantly attacksthe other one. We will not even help out in these cases, and it is notbecause we are afraid of getting bitten. Behavior is a trait that weshould select for just as we do intelligence and conformation. Anyonewho has ever tried to help a child overcome their fear of animals afterbeing bitten or has been involved in a lawsuit in one of these casesrealizes this.
Many breeders also live under the false sense ofsecurity that diseases cannot be transmitted between the mating pair,if artificial insemination is used. Admittedly, the male will not beable to get anything from the female, as he never comes in contact withher. However, the female can contract several conditions via the semen.
Additionally,it must be remembered that artificial insemination in canine medicinedoes not have the level of success seen in natural intercourse.Depending on the technique and ability of those performing it, breedersshould only expect a 65 to 85% success rate and usually somewhatsmaller litters would be noted. Part of this disparity is probably dueto a shortcoming in either the male or female, but our technique stillhas room for improvement. We have made giant strides in the last fewyears, and with continued research, we may approach the levels seen incattle.
Conclusion
Usedcorrectly, artificial insemination is a useful tool in improving theoverall quality of all canine breeds, allowing a wider range ofpotential breeding partners. If it is used to genetically eliminateundesirable characteristics (rather than bypass them), or to improve orpotentiate desirable ones, it will have a positive effect whenever used.
