ABSTRACT. Cooled canine semen solutions for storage were investigated with three stock solutions: egg yolk-citrate-glycine-glucose solution, egg yolk Tris-fructose citrate solution (EYT-FC), and egg yolk sodium citrate dihydrate solution (EYCD). For the control group, the second fraction of semen was examined. Nine male beagles and 37 female (47 experimental cases) beagles for artificial insem ination (AI) were used. The qualities of semen stored at 4°C deteriorated earlier in the control and EYCD groups. In the other two groups, sperm motility was 60% or higher after storage for 6 days and 20% or higher after storage for 12 days. On a comparison of these two groups, the sperm motility and viability were slightly higher in the EYT-FC group. A high conception rate was obtained by AI using semen stored at a low temperature for a maximum of two days in the control group and four days in the EYT-FC group. KEY WORDS: artificial insemination, canine, cooled semen.J. Vet. Med. Sci. 65(3): 307-312, 2003 For artificial insemination (AI) of dogs, fresh semen [3,12,18,20,21], cooled semen [6-9, 12, 15], and frozen semen [3,12,16,19] In studies of cooled canine semen, semen preparations with milk [6,8,9,13,15] and egg yolk [1,2,4,5,7,[11][12][13][14] as the extender have been investigated. In studies with egg yolk-citrate-glycine-glucose extender (EYC-GG) performed by Foote [4,5] and egg yolk Tris-glucose extender performed by Iguer-ouada and Verstegen [11], canine sperm could be stored at 4°C for a prolonged period, although these were in vitro studies.Some attempts at fertilization have succeeded when using cooled semen. Gill et al. [6] and reported a high conception rate for cooled semen within 24 hr. Successful fertilization with semen stored for a long period has been reported. Harrop [8] stored semen in sterilized milk for 4 days, and this is the first successful fertilization with cooled semen. Seager and Fletcher [15] also stored semen in sterilized milk for 1-4 days similarly to Harrop [8] and obtained a conception rate of 53.0% (8/15), but the semen volume and number of sperm used for AI and the frequency of collecting semen were not clarified.Therefore, although many in vitro experiments have been performed with cooled semen as mentioned above, semen preparation applicable to AI for several days has not been clarified.We therefore investigated extenders, storage methods, and AI methods with cooled semen in dogs. For the extender, EYC-GG with which Foote [4,5] succeeded in long-term storage of canine sperm, EYT-FC, which we used for frozen canine semen [19], and egg yolk sodium citrate dihydrate (EYCD), which has long been used for domestic animals, were investigated. MATERIALS AND METHODS Animals:Nine male dogs aged 2-5 years were repeatedly used. For AI, there were 29 female dogs aged 7 months-1.5 years at the initial estrus and two multiparous dogs. Because of repeated use, the number of cases was 47. Since many dogs were used for AI at the initial estrus, the conception results were obtained from 58 dogs...

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ABSTRACT. The number of spermatozoa required to obtain conception by intratubal insemination in dogs was examined. Three groups consisting of 5, 8 and 8 dogs received 0.5 × 10 6 , 2.0 × 10 6 and 4.0 × 10 6 spermatozoa, respectively, into each uterine tube. No conception occurred in the 5 animals inseminated with 0.5 × 10 6 spermatozoa, but conception occurred in 6/8 (75.0%) and 3/8 (37.5%) dogs inseminated with 2.0 × 10 6 and 4.0 × 10 6 spermatozoa, respectively. Among the pregnant animals, three aborted (33.3%) and the mean number of newborns was small, 2.5 ± 0.5 (SE). One acardiacus anceps was observed with normal fetus in one animal with a Caesarean delivery. KEY WORDS: acardiacus anceps, canine, intratubal insemination.J. Vet. Med. Sci. 65(5): 659-661, 2003 Although it has been reported that the number of spermatozoa required to obtain conception by intrauterine horn insemination is 1/10 of that required by intravaginal insemination in dogs [8,10,12,13], 1.0 × 10 7 spermatozoa are required for insemination into one uterine horn in dogs [9]. It is generally considered that only a small number of spermatozoa inseminated into the uterus reaches the uterine tubes and fertilizes the ova. Most spermatozoa inseminated into the vagina and uterus are not involved in fertilization. Therefore, the number of spermatozoa to be infused may be reduced by inseminating spermatoza at a site close to the fertilization site. It has been reported that conception could be obtained by intratubal insemination with 1.0 × 10 5 spermatozoa in rabbits [4] and 2.5 × 10 5 spermatoza in rats [6]. However, we previously reported that the conception rate was 42.9%, when 4.0 × 10 7 spermatoza were inseminated in cats [11]. Therefore, the number of spermatozoa required for intratubal insemination varies among animal species and this may be due to variation in conditions for capacitation of spermatoza among the species.Canine intrauterine insemination requires surgical techniques. For insemination performed by laparotomy, a method of insemination into the oviduct close to the fertilization site is considered. To efficiently use spermatozoa, we investigated whether conception can be obtained by intratubal insemination with fresh semen in dogs and examined the number of spermatozoa needed for intratubal insemination Animals: Nineteen female beagles aged 2-6 years used in the experiment. Since two dogs (Bitch Nos. 315 and 330) were used twice, the number of cases was 21. Semen was collected at appropriate times from 6 male beagles aged 5-10 years with proven fertilizing ability. Animals for the experiment were kept one per cage measuring 160 × 75 × 65 cm. Animals were given commercial dog food in the morning and water in the morning, afternoon, and evening. Food for pregnant dogs was given twice a day (morning and evening) from 35 days of gestation.Collection of semen and test of semen quality: Semen was manually collected in three fractions immediately before artificial insemination. The semen quality in the second fraction containing spermat...

Several studies have reported that the plasma testosterone (T) level and semen volume are compensated after hemicastration (HEC) in adult dogs, but that the sperm count is not. Nevertheless, the effects of HEC in prepubertal dogs have not been reported. In this study, HEC was performed at 16 weeks of age in 8 male beagles, and the function of the residual testis was investigated until 48 weeks of age. The testis volume was consistently higher in the HEC group than the control (CON) group. After 40 weeks of age, compensatory hypertrophy was observed, with a mean testis volume of 125% of that in the CON group (p<0.05). Furthermore, the semen volume and plasma testosterone (T) level were similar to those in the CON group, suggesting functional compensation, but the sperm count was not compensated. These results showed that the testis volume, semen volume, and plasma T level were compensated after HEC in prepubertal dogs, but the spermatogenic function was not.