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Biomedical subjects

R K Shideler

Publications and source records attributed to R K Shideler.

At least 19 recordsLinked to original sources
PubMed1992

Effects of linear cooling rate on motion characteristics of stallion spermatozoa.

Three experiments were designed to analyze the effects of cooling rate on survival of stallion spermatozoa in a milk-based extender, at 0 to 96 hours after reaching the desired temperature. The samples were warmed to 37 degrees C and were evaluated by computer-assisted analysis of sperm motility. In Experiment 1, rate of cooling between 37 and 20 degrees C was evaluated. Sperm motion was not affected by cooling at plunge, -0.42 or -0.28 degrees C/minute. However, storage of spermatozoa at 5 degrees C after slow cooling below 20 degrees C was superior to storage at 20 degrees C. In Experiment 2, 3 cooling rates from 37 degrees to 5 degrees C were evaluated. Cooling at either -0.05 or -0.7 degrees C/minute was superior (P<0.05) to plunging spermatozoa to 5 degrees C. Cooling at -0.05 degrees C/minute rather than -0.7 degrees C/minute maximized the percentage of motile spermatozoa and their curvilinear velocity. In Experiment 3, cooling rates from 20 to 5 degrees C were evaluated, with all samples cooled at -0.7 degrees C/minute from 37 to 20 degrees C. Sperm motion was similar (P>0.05) after cooling below 20 degrees C at -0.012, -0.05 or -0.10 degrees C/minute, and the 2 slower rates were superior (P<0.05) to cooling at -0.3 degrees C/minute. It was concluded that stallion spermatozoa can be cooled rapidly from 37 to 20 degrees C, but should be cooled at <or=-0.1 degrees C/minute and preferably at -0.05 degrees C/min from 20 to 5 degrees C to maintain maximum sperm survival at 5 degrees C.

Journal Article↗
PubMed1988

Hemorrhagic necrotizing enterocolitis associated with Clostridium difficile infection in four foals.

Severe hemorrhagic necrotizing enterocolitis was determined to be the cause of death for 4 foals. Toxigenic Clostridium difficile was isolated form the intestine of each foal, and large, gram-positive, rod-shaped bacteria lined the surface of necrotic villi. This finding of toxigenic C difficile associated with enteritis in foals adds another possible cause to the list of infectious agents that should be considered when evaluating foals with enteritis. Definitive diagnosis requires a thorough diagnostic evaluation, including procedures that will identify the organism and demonstrate its toxigenicity.

Animals↗
PubMed1988

Ultrasonographic studies on the reproductive tract of mares after parturition: effect of involution and uterine fluid on pregnancy rates in mares with normal and delayed first postpartum ovulatory cycles.

During breeding of mares, ultrasonographic detection of uterine fluid accumulations in the first postpartum ovulatory period was associated with significantly decreased pregnancy rates, when compared with rates in control mares (P less than 0.005). The previously gravid uterine horn was recognized as the larger horn, when assessed for size by ultrasonography, for a mean of 21 days (range, 15 to 25 days) after parturition. On the basis of similar measurements obtained during 3 ultrasonographic scans (5-day period), uterine involution was determined to be completed in a mean of 23 days (range, 13 to 29 days). Progestin treatment did not affect uterine size, fluid accumulation, or rate of involution after parturition. However, delaying the first postpartum ovulation with 8 days of progestin treatment significantly improved pregnancy rates (P less than 0.05). More (P less than 0.05) mares became pregnant (23 of 28, 82%) when ovulation occurred after day 15 in the first postpartum ovulatory period, compared with those mares that ovulated before day 15 (6 of 12, 50%). We concluded that ultrasonographic detection of uterine fluid and postpartum progestin treatment can be used to manipulate breeding strategies and to improve pregnancy rates in mares bred during the first postpartum ovulatory period.

Animals↗
PubMed1987

Isolation of Clostridium difficile and detection of cytotoxin in the feces of diarrheic foals in the absence of antimicrobial treatment.

Clostridium difficile was isolated from the feces of 27 of 43 diarrheic foals (63%), and cytotoxin was detected in feces from 28 diarrheic foals (65%). The foals had not received any antimicrobial treatment before the onset of diarrhea. C. difficile was not isolated from feces of 18 normal foals without diarrhea and 62 adult horses (P less than 0.005). This finding of C. difficile and its toxins in association with diarrhea in foals adds another possible cause to the list of infectious agents which may cause diarrhea in foals.

Animals↗
PubMed1985

Fertility of young mares after long-term anabolic steroid treatment.

The effect of prior treatment with anabolic steroids was studied in 46 three-year-old mares. In the preceding year, these mares had been assigned to 1 of 4 treatment groups and had received the manufacturer's recommended dosage of 1.1 mg of boldenone undecylenate (BU)/kg of body weight, 4.4 mg of boldenone undecylenate (4 BU)/kg, 1.1 mg of nandrolone decanoate (ND)/kg, or 0.04 ml of sesame oil/kg (control, C). Mares had received an injection every 3 weeks for 54 weeks for a total of 19 injections, with the final injection in December. In the following breeding season, fewer (P less than 0.05) mares in all groups previously administered anabolic steroids displayed estrous behavior than did mares in the control group. Duration of estrus was shortened (P less than 0.05) in mares that had received steroids. Abnormal sexual behavior that was observed during steroid treatment continued (P less than 0.05) for up to 6 months after treatment ceased. However, observations of abnormal behavior declined with time (P less than 0.05). All mares in each treatment group ovulated by the end of the trial, and the interval to first ovulation was similar (P greater than 0.05). Ovarian size, follicular development, and conditions of the tubular genitalia was adversely (P less than 0.05) affected in mares in all steroid-treatment groups until approximately the middle of March. After that time, no difference was noted among groups. First-cycle pregnancy rates were 83%, 67%, 50%, and 42% for mares in the untreated, BU, 4 BU, and ND groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Identification of carriers of Streptococcus equi in a naturally infected herd.

During an outbreak of strangles in a population of research horses, 4 mares were identified as carriers of Streptococcus equi. Three of the mares had typical signs of strangles (severe regional lymphadenitis with or without rupture of abscessed lymph nodes). The 4th mare experienced episodes of serous to mucopurulent nasal discharge, but never had more than a mild degree of lymph node enlargement. Streptococcus equi was isolated from the abscessed lymph nodes and from nasopharyngeal swab specimens from the first 3 mares from 6 to 19 weeks after rupture of involved nodes. Streptococcus equi was isolated from the nasopharynx of the 4th mare on introduction into the herd and intermittently over the ensuing 6 months. During the 7th month, mare 4 was placed in isolation, where she continued to shed S equi for 4 more months. A complete physical examination during the 10th month, including radiography of the head and thorax, did not reveal any relevant abnormalities, but a pharyngeal swab specimen was culture-positive for S equi. This isolate was used to inoculate 2 yearling colts, which developed strangles and from which S equi was reisolated. Shedding of S equi by mare 4 ceased in the 11th month, and at necropsy 2 months later, S equi was not recovered from any organ or tissue. Corticosteroid administration 3 weeks prior to necropsy had induced neither shedding of the organism nor clinical signs of strangles. The study provided clinical, epidemiologic, and bacteriologic evidence to support the existence of a carrier state following natural infection with S equi.

Abscess↗
PubMed1983

The effect of altrenogest, an oral progestin, on hematologic and biochemical parameters in mares.

Twenty mares were assigned to 1 of 4 groups: no altrenogest; altrenogest at 0.044 mg/kg BW; altrenogest at 0.132 mg/kg BW; or altrenogest at 0.220 mg/kg BW. Treatment was administered daily for 86 days. No signs of illness attributable to feeding altrenogest were observed during the trial. Treatment had no effect (P greater than .05) on the following parameters: WBC, differential WBC, platelet number, creatinine, LDH, CPK, total bilirubin, cholesterol, globulin, BSP, and erythrocyte sedimentation rate. When comparing values over time with pretreatment means or among treatment groups, there were differences (P less than .05) in RBC, PCV, Hb, ALT, PT, PTT, P, Na, TP, BUN, Cl and glucose. However, these changes remained within established normal ranges and also occurred in mares in the control group. There was no treatment by time interaction for any of these parameters. Treatment differences (P less than .05) were observed for K, Ca, alkaline phosphatase and AST during the course of the trial. However, only occasional values of these parameters were outside the established ranges. They were only slightly elevated and tended to be either sporadic or also occurred in control mares. Few of the observed changes could be attributed to the feeding of altrenogest.

Animals↗
PubMed1982

Effect of number and frequency of inseminations on fertility of mares.

Data from 257 normally cyclic mares used in trials over a 10-year period were examined to establish the relationship between the number of inseminations per cycle, duration of oestrus and pregnancy rate. Mares that became pregnant were inseminated more (P less than 0.05) frequently per cycle than mares that did not become pregnant (3.4 versus 2.8). First-cycle pregnancy rates of 22.2, 34.0, 38.6, 52.5, 58.3 and 52.2% were attained when mares were inseminated 1, 2, 3, 4, 5 or 6 or more times per cycle, respectively. The duration of oestrus in mares that became pregnancy was longer (P less than 0.01) than in those that did not conceive (7.9 versus 6.4 days). Studies of 64 mares in the transitional season showed that first-cycle pregnancy rates for mares in which oestrus lasted less than 10, greater than or equal to 10, greater than or equal to 20, greater than or equal to 30 and greater than 40 days were 56.2, 76.2, 76.5, 77.3 and 88.9%, respectively. Overall pregnancy rates (after 3 cycles) were lower (P less than 0.05) for mares that had an initial oestrus of less than 10 days. Mares were inseminated every other day of oestrus with 100 X 10(6) progressively motile spermatozoa. First-cycle pregnancy rates were 64.3, 75.0 and 75.0% for mares inseminated 1-4, 5-10 and greater than or equal to 12 times per cycle, respectively. Fewer (P less than 0.05) mares became pregnant after 3 cycles when inseminated 1-4 times per cycle than did mares inseminated greater than or equal to 12 times per cycle (51.3 versus 75.0%). Numerous inseminations per cycle of mares with extended oestrus were not detrimental to fertility.

Animals↗
PubMed1981

Collection and transfer of equine embryos.

Embryos were recovered in 39 of 47 attempts (83%) during 1979 and in 75 of 104 attempts (72%) during 1980. The mean diameters of day 8 and 9 blastocysts were 1.00 and 2.13 mm, respectively. The injection of prostaglandin F2 alpha or prostalene on day 8 or 9 after ovulation resulted in a mean interval between embryo recovery attempts of 17.7 +/- 0.3 days. Number of embryos recovered within mares did not vary significantly with repeated attempts. Following surgical transfer, 8 of 15 recipients (53%) were pregnant at 50 days after ovulation, whereas only 4 of 15 recipients (27%) were pregnant at 50 days following nonsurgical embryo transfer.

Animals↗
PubMed1979

Disappearance of spermatozoa from the ejaculates of geldings.

Twenty-three geldings were used to determine changes in seminal characteristics following castration and the effect of frequency of ejaculation on these seminal characteristics. In Exp. 1, semen was collected from 8 geldings every other day after castration until the number of spermatozoa per ejaculate was below 1% of the precastration value. An average of 3 ejaculates was required to reduce the number of spermatozoa below this level. In Exp. 2, 15 stallions were castrated and each stallion was assigned to 1 of 3 groups for seminal collection at 7, 14 or 21 days post-castration. The ejaculates collected on these days contained an average of 23, 14 and 2 X 10(6) spermatozoa/ejaculate, respectively. In both experiments, all spermatozoa in ejaculates collected 7 or 8 days after castration were non-motile. Frequency of ejaculation did not appear to hasten the disappearance of spermatozoa from the ejaculates. It is considered that after castration several months may be required before the ampulla and vas deferens become devoid of spermatozoa and the ejaculates azoospermic, and that pregnancy is unlikely to result from mating or insemination 1 week after castration.

Animals↗
PubMed1979

Effects of synchronization and frequency in insemination on fertility.

Fifty-four normally cycling, non-lactating mares were given 2 injections (i.m.) of PGF-2 alpha (10 mg) 14 days apart without regard to stage of the oestrous cycle. At 19 days after the first PGF-2 alpha treatment, a single i.m. injection of either hCG (3300 i.u.) or a GnRH-analogue (500 micrograms) was administered. Each mare was inseminated with 100 X 10(6) motile spermatozoa at one of the following frequencies: once only on Day 20; every other day during oestrus or at least on Days 19 and 21; or daily during oestrus or at least on Days 19, 20, 21 and 22. Eighteen control mares received saline injections on Days 0 and 14, and were inseminated either on the 4th day of oestrus or every other day or daily beginning on the 2nd day of oestrus. More (P greater than 0.05) PGF-2 alpha treated mares displayed their 1st day of oestrus on Days 14 to 20 than control mares (80.6 versus 27.8%). During cycle 1, fewer (P greater than 0.05) treated mares became pregnant compared to controls; 38.9, 25.0 and 66.7% for PGF-2 alpha + hCG, PGF-2 alpha + GnRH-A and control mares, respectively. After three cycles, the pregnancy rates for mares inseminated every other day or daily were higher (P less than 0.05) than mares inseminated only once during oestrus (88.9 and 88.2 versus 64.7%).

Animals↗