Artificial insemination (AI), now a common procedure in small animal reproduction, is as effective as natural breeding. It can be used for breeding with fresh semen if the bitch will not stand for the male because of behavioral or anatomic problems, if the male has physical problems that prevent mounting, or the male refuses to mount the female. Of course, in some instances, a male is inaccessible and AI using cooled or frozen semen is the only alternative. The clinician should ensure that the bitch is in estrus before proceeding. -8-Fr polypropylene urinary catheter
STEP BY STEP ARTIFICIAL INSEMINATION**Preparation**The first step is to ensure that the bitch is in estrus. Identifying estrus can be done using vaginal cytology for a fresh semen breeding, and combining hormone analysis (progesterone and/or luteinizing hormone) when using chilled or frozen semen to identify the most fertile days to breed.
A complete semen analysis including motility, volume, concentration, and morphology should be performed on fresh or chilled semen, and the motility of frozen semen should be assessed before insemination. A semen analysis before breeding will help answer questions later if the bitch fails to become pregnant.
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Frozen semen should be thawed according to the instructions provided by the freezing facility, and it should be used immediately upon thawing. (That is, it should be thawed only when the catheter is within the uterus.)
Vaginal ApproachOnce the bitch is confirmed as being in estrus or the most fertile days have been determined, and the semen sample is ready, AI can be performed. For large dogs, the bitch can be restrained gently on the floor (smaller dogs can be placed on a table), the tail moved aside, and the dorsal commissure of the vulva lifted by placing the fingers above the vulva and lifting.
A small animal insemination pipette is then placed in the dorsal commissure of the vulva (A) and directed dorsally and almost caudally to create a ‘dimple' between the dorsal commissure of the vulva and anus (B). The dorsal placement of the pipette helps prevent entry into the urethra (C). The pipette is then redirected cranially into the cranial vagina (D);however, for the transcervical approach (page 15) the cervix normally cannot be entered using this technique. If the pipette will not advance, it may be caught on one of the many vaginal folds and it should be withdrawn slightly and redirected past the fold. The syringe can be placed on the pipette either before elevating the hindquarters or after (E).
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Procedure PearlIf the pipette will not advance, it may be caught on one of the many vaginal folds and it should be withdrawn slightly and redirected past the fold.The bitch can then be lifted by the hocks and the semen pushed through the pipette with a small amount of air following it to ensure emptying. After insemination, the bitch can be lowered. There is no need to elevate the hindquarters after artificial insemination, as in a study conducted by the author, pregnancy rates and fecundity were not different if the bitch's hindquarters were elevated for 0, 1, or 10 minutes.
Transcervical ApproachIf frozen semen is used, or direct placement of the semen into the uterus is desired to increase the chance of pregnancy with fresh or chilled semen, then a transcervical approach can be used. Transcervical insemination is technically more challenging, and requires specialized equipment, but is routine in some reproductive practices using a rigid cystourethroscope.
However, once the transcervical scope is within the cranial vagina (A), the cervix is visualized (B) and a smaller polypropylene catheter is passed through the cervix into the uterus.
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Reference1. Artificial Insemination in the Dog. Eilts BE, Paccamonti DL, Pinto CRF. In Root-Kustritz MV (ed): Small Animal Theriogenology-St. Louis: Butterworth Heinemann, 2003, pp 61-95.
Suggested ReadingFertility in a canine breeding colony using vaginal artificial insemination or transcervical insemination of fresh semen. Eilts BE, Paccamonti DL, Pinto CRF, et al. 5th Biannual EVSSAR Congress Proc, 2006, p 302.All articles published by are made immediately available worldwide under an open access license. No special permission is required to reuse all or part of the article published by , including figures and tables. For articles published under an open access Creative Common CC BY license, any part of the article may be reused without permission provided that the original article is clearly cited. For more information, please refer to https:///openaccess.
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Among equids, the mule (jackass stallion × mare) is the most common hybrid, followed by the hinny (horse stallion × jenny). This study describes the outcome of inseminating mares and jennies with either fresh horse or donkey semen of proven fertility. Pregnancy rates in horse females were significantly higher than in donkey females, while horse and donkey males did not affect pregnancy rates. Overall, intraspecific pregnancy rates were significantly higher than interspecific ones.
Horses and donkeys differ phenotypically and karyotypically, although they can interbreed freely. Eight Standardbred mares and nine Amiata donkey jennies were included in the study. Semen was collected from two horses and two donkey stallions of proven fertility. A first pregnancy diagnosis was performed on day 10 after ovulation and repeated every day until embryo detection or until day 16. Irrespectively of the sire species, pregnancy rates in horse females (20/30, 66.7%) were significantly higher than in donkey females (19/70, 27.1%) (p < 0.05), while horse and donkey males did not affect pregnancy rates. Comparing overall intraspecific and interspecific AI, pregnancy rates were 25/37 (67.6%) and 14/63 (22.2%), respectively (p = 0.0001). The lowest pregnancy rate was obtained when inseminating jennies with horse stallion semen (8/49, 16.3%). No statistical differences were found when comparing embryo diameters, day at first pregnancy diagnosis, or in vitro embryo morphological quality among groups. In this study, much poorer results were obtained with jennies than with mares. Interspecific AI resulted in lower pregnancy rates than intraspecific Al, and AI to produce hinny hybrids resulted in the lowest pregnancy rate. Further studies are required to better understand the mechanism involved in such different outcomes in relation to intra- and interspecific breeding in domestic equids.
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In reproductive biology, a hybrid is an offspring produced from a cross between parents of different species or sub-species and is usually sterile. Hybridization between different mammalian species has been reported to occasionally occur in nature (e.g., sheep × goat, tiger × lion, dog × wolf, etc.); however, apart from the mule, it is far more commonly the result of intentional breeding programs [1].
The mule (jackass × mare, 2n = 63) and the hinny (horse stallion × jenny, 2n = 63) are the most common equine hybrids since their parents (E. Caballus, 2n = 64 and E. Asinus, 2n = 62) are the only equine species that have been truly domesticated. For centuries, mules have been bred for use in agriculture, the military, or for leisure activities, thanks to the mixture of physical and mental attributes of the two parental species. Mules have played an important role in military actions, for example, they were used in World Wars I and II to carry artillery, food supplies, and even wounded soldiers on the battlefield [2, 3, 4].
Due to mechanization, mules have lost their traditional role and are now used both for hippotherapy and leisure riding. However, the mule is still irreplaceable for deforestation work in inaccessible mountain areas and the management of big bovine herds, above all in South America [5]. In contrast, hinnies seem to be much less common and diffused [6, 7].
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There are many different equine hybrid combinations, such as breeding between Przewalski (Equus Prezwalskii, 2n = 66) and domestic horses (E. Caballus, 2n = 64) horses, wild (e.g., E. Hemionus; 2n = 54) and domestic (E. Asinus; 2n = 62) asses, as well as between various subspecies of zebras (E. Greuyii, 2n = 46; E. Burchelli, 2n = 44; E. Zebra, 2n = 32) [6]. When breeding has occurred between domestic horses and wild asses or zebra species, pregnancies and foals were obtained only when the female of the partnership was the horse [8]. However, conception does not occur in attempting reciprocal crosses by mating a male domestic horse with a wild female donkey or a zebra [8] and significantly lower conception rates were achieved when attempting to produce hinnies instead of mules [6].
This disparity in pregnancy rates between reciprocal hybrid mating in equids is also seen in other species. For example, high fertilization rates have been reported when inseminating female
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