Artificial Inseminations in dogs
The most common reason for breeders to choose artificial insemination (AI) is an inability of the male and female to breed. The most common cause for inability of the male to breed is beeause of inexperience or dominance of the bitch. We have seen many bitches dominate males, except when they have estrus, and the males will refuse to mate. However,sperm from males for breeding can be callected without mounting the female or off another female. In addition, failure to breed may be due to an orthopedic problem such as disc disease, stifle problem. or muscle weakness. Some cases of prostatic disease may also cause inability of the male to mount a bitch in estrus. Artificial insemination may also be chosen because of major size differences between the mates. The most common reason in the female is objection to the male or the presence of a vaginal structure which impedes intromission by the male and causes pain during breeding. AI can also be used in cases where bitches are suspected to ovulate before standing heat or have very short heats. Less commonly, medical reasons account for the use of AI. Some owners wish to avoid any veneral contact between male and. female. Inseminating semen into the vagina still provides intimate contact between bitch and stud and any agent could be transmitted from the stud to bitch. However, AI avoids transmission of any agent from the bitch to the stud so in bitches suspected to have brucelia, AI would be the method of choice. Semen may also be collected and shipped in the cooled state for distant destinations and inseminated into bitches.
Spermatogenesis an endocrinology
Under the regulatory influence of luteinizing hormone (LH), tostosterone sets on the task of inducing spermatogenesis in the terstitial cells (Leidig cells), and maintaining the functions of organs related to reproduction. The follicle stimulating hormone(FSH) is essential for the maintainence of spermatogenesis. FSH and LH are both under the control of gonadotropin (CnGH) that is released from the, hyothalamus. A non-steroidal substance called inhibin is responsible for mediating FSH. Sertoli cells promote and complement Sperm maturation under the influence of FSH. In a similar manner, LH release is under the influence of testosterone.
Collection of semen
When the bulbus glandis begins to enlarge, the sheath is slipped poeteriorly with the collection hand if the stud mounts and attempts to breed or by masturbation (with the use of the opposite hand) if the stud does not mount. The sheath must be pushed behind the bulbus glandis for ejeculation to occur. Failure to exteriorize the penis results in an incomplete erection and failure to ejaculate. Once the penis and bulbus glandis are extruded from the sheath, the thumb and index finger gently hold on to the base of the penis, proximal to the bulbus glandis, with downward pressure. In most studs this is followed by aggressive pelvic thrusting movements, however, we have collected several studs without any pelvic thrusting. The first fraction of semen is thought to be prostatic in origin. The sperm-rich second fraction of the ejaculate usually begins as the pelvic thrusting terminates. At the same time, many males will stop over the collector’s arm, as if dismounting the bitch. The collector should simply bring the penis between the rear legs of the stud for continued collection. Semen is collected for 5-6 min or until a clear third fraction of the ejaculate appears.
Insemination sperm concentration
Depending on the contents, canine semen is divided into 3 fractions the second fraction contains the spermatozoa with 1.4xl 00.000,000 sperms present in per ml at the time of ejaculation and volume of less than 2 ml. As such an any natural mating, 1.8xl 00,000 000 sperms are introduced in the vagina. However the actual amount needed for insemination is not more than 1%. Thus, in artificial inseminated into several bitches. For conception to be secured. 2.3xl 00,000,000 spermatozoae are required. We have insemination about 100,000.000 sperm per insemination in bitches on estrus day2, and our results are overwhelmingly better than those obatined with natural mating.
Semen is drawn into a sterile insemination straw attached to an insemination device. The bitch is hold between the logs of an assistant at a 60 degree angle with the hind quarters elevated. The insemination device is passed upward toward the sacrum until it passes over the brim of the pelvis and then until it meets resistance. Semen is deposited into the vagina vault slowly without any air to prevent semen being expelled from the vagina. Since the cervix is impossible to cannulate easily the semen needs only be placed in the anterior vagina. The bitch is held at this angle for 5-10 min to allow the semen to pool near the cervix even though some spermatozoac have been reported to arrive in the oviducts as early as 25 sec after insemination. The entire insemination procedure is rarely a problem for the bitch. There should not be any pain discomfort associated with this procedure and for this reason many breeders prefer the technique over natural mating in many Japanese and American breeding kennels.
AI has been comparable to natural service in terms of both pregnancy rate (81%) and litter size (5–9 pups) when more than 250×1,000,000 morphologically normal sperm have been. inseminated in bitches which are standing, and/or have greater than 8-0 90% superficial cells in their vaginal smear. We usually recommend 2-3, or more, services every other day as long as the bitch is considered receptive but have achieved good pregnancy rates when only one insemination was achieved with high numbers of normal spermatozose. This is possible since canine sperm can live in the uterus for 4-11 days after a single breeding. History is important as bitches are fairly consistent from previous estrous cycles as far a number of days in proestrus and estrus as well as inetrestrous inetrvals. We usually like to follow estrual smears through estrus to determine when the first day of diestrus (D1) is so that we can determine when ovulation occurred and vvhen parturition would occur.
Long-term preservation of semen utilizing deep freezing techniques have been available for several years and the American Kennel Club (AKC) approved the registration of litters resulting from insemination with frozen thawed semem in 1981. The advantages of using frozen semen include decreased shipment of bitches, wider distribution of desirable genetic strains, disease prevention, decreased numbers of breeding males in a research colony. and preservation of semen from dogs with diseases thare are models of human disorders. There are presently 17 approved canine semen freezing facilities in the U. S… Yet, despite obvious advantages, AKC. approval, and the relative access to necessary facilities, use of frozen semem has still not gained wide spread approval or use among breeders or veterinarians. This is due, in part, to the expense of shipping the male to the freezing faciiiy, the expense of freezing and storing semen and the perceived low conception rate. Rates of 0-60% have been reported following intravaginal insemination compared to 66-83%. If semen was deposited directly into the uterus following exterioration of the uterus via surgery, The reasons for poorer conception rates with intravaginal versus intrauterine insemination are not known but may be related to poor sperm transport through the cervix. For this reason several commercial semen preservation units are now working on methods to cannulate the bitch’s cervix. From 1981-1987, there have been 92 litters registered by AKC as the result of frozen thawed semen. Compare this with 44,800 litters registered by AKC in the month of July, 1987 alone. As this indicates, the large majority of dog breeding is still done either naturally or Al.
Freezing procedures and treatment of semen
Extracted semen is diluted with the primary diluent under about 37degC to produce sperm concentration of 1×10/ml. The diluted semen is then placad in a room of constant temperature of 5degC, and is then cooled at a rate of 1degC per min until the semen per sec attains 5degC. The secondary dilution is then performed at 5degC room temperature. The addition of the secondary diluent is divided into 4 times at 15-20 min intervals. On completion of the secondary dilution the diluted semen is auctioned and stored in straws at 5degC before the straws are sealed. The straws are left standing in the cryogenic chamber and is then equilibrated with glycerin for 2hr. After equilibriation the diluted semen is frozen with the use of computer-control programmed freezer and simple highspeed freezer. Freezing by simble high-speed freezer is procedured by placing the straws standing in an up-down agitated wire-mesh basket positioned horizontally in a freezing basin previously cooled by liquid nitrogen so as to lower the straws to the desired temperature. Cooling is performed from 5degC to subfreezing temperature (-2.5degC-5degC) at a rate of 10degC per 1 min interval. Cooling is maintained at subzero temperature for 1 rnin. Thereafter, the temperature is further lowered to-80’C at a rate of 20’C per 1 min interval, and stored by immersing the straws containing the frozen semen in liquid nitrogen. The above cooling curve of the cooling procedure performed by the programmed freezer is input in a computer so as to automatically monitor the procedures whenever necessary.
After confirming semen straws with the cotton-plugged and Immersed in lac 600 ml volume beaker containing warm water of 38’C are completely thawed, the straws are immediately removed.
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