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1.
J. W. Lloyd J. S. Rook W. E. Braselton M. E. Shea 《Preventive veterinary medicine》1993,17(3-4):175-181
A study was designed to characterize potential relationships between liver concentration of nine specific elements and age in preweaned Michigan lambs. All lambs that died before weaning in 1986 from 33 Michigan sheep producers were submitted to the Michigan State University Animal Health Diagnostic Laboratory for necropsy. Inductively coupled argon plasma emission spectroscopy was used to measure liver concentrations of Ca, Cu, Fe, K, Mg, Na, Na, P, and Zn in 888 lambs. Linear and non-linear regression techniques were employed to evaluate the relationship between liver element concentration and age. The potentially confounding variables farm of origin and cause of death were significant (P<0.01) in all models. No linear relationship was found between any liver element concentration and lamb age. Significant (P<0.05) non-linear relationships were found between liver concentrations of Cu, Fe, K, Na, Mg, and Zn and lamb age. Because of the large sample size of lambs selected from non-experimental populations, these results should provide diagnosticians with a useful guide for the interpretation of similar data when investigating perinatal lamb mortality. 相似文献
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J. W. Lloyd J. S. Rook W. E. Braselton M. E. Shea 《Preventive veterinary medicine》1993,17(3-4):183-189
Relationships were characterized between liver concentration of Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn and cause of death in pre-weaned Michigan lambs. In 1986, the 888 lambs that died before weaning from 33 Michigan sheep producers were submitted to the Michigan State University Animal Health Diagnostic Laboratory for necropsy. Inductively coupled argon plasma emission spectroscopy was used to measure liver element concentrations. The five major causes of death discovered by gross necropsy were dystocia-stillborn, starvation-hypothermia, pneumonia, abortion and trauma. Each of the five causes of death had significant (P<0.05) associations with various liver element concentrations when evaluated with logistic regression. These results suggest that liver element concentrations in perinatal lambs dying of common production diseases can be expected to vary with the cause of death. 相似文献
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Assessing the fit of a model is an important final step in any statistical analysis, but this is not straightforward when complex discrete response models are used. Cross validation and posterior predictions have been suggested as methods to aid model criticism. In this paper a comparison is made between four methods of model predictive assessment in the context of a three level logistic regression model for clinical mastitis in dairy cattle; cross validation, a prediction using the full posterior predictive distribution and two “mixed” predictive methods that incorporate higher level random effects simulated from the underlying model distribution. Cross validation is considered a gold standard method but is computationally intensive and thus a comparison is made between posterior predictive assessments and cross validation. The analyses revealed that mixed prediction methods produced results close to cross validation whilst the full posterior predictive assessment gave predictions that were over-optimistic (closer to the observed disease rates) compared with cross validation. A mixed prediction method that simulated random effects from both higher levels was best at identifying the outlying level two (farm-year) units of interest. It is concluded that this mixed prediction method, simulating random effects from both higher levels, is straightforward and may be of value in model criticism of multilevel logistic regression, a technique commonly used for animal health data with a hierarchical structure. 相似文献
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The GnRH antagonist antarelix (Teverelix™) was administered to mares (0.01 mg/kg, i.v., twice a day) during the periovulatory period. In Experiment 1, 20 mares were divided into a treated (A3d−) and a control (Control−) group. A3d− mares received antarelix for 3 days from the day when the dominant follicle (F1) reached 32 mm (D0). In Experiment 2, 10 mares were divided into a treated (A6d+) and a control (Control+) group. A6d+ mares received antarelix for 6 days from D0 and hCG was injected in all animals (1600 IU, i.v.) on D1. Pregnancies were determined 13 days after ovulation. In both experiments, antarelix interrupted or totally abolished the LH surge. In Experiment 1, 5/10 of the A3d− mares (with maximum LH concentrations of 11.6 ng/ml at the beginning of treatment) ovulated at the same time as the Control− mares; the other five mares (with LH concentrations under 5.4 ng/ml) ovulated 13.4±0.6 days later. In Experiment 2, all the A6d+ mares ovulated at the same time as the Control+ mares. In treated mares which ovulated during the treatment, progesterone concentrations and fertility did not differ from control mares. These results demonstrate that in mares: (1) a small elevation of endogenous LH can induce ovulation, (2) ovulation can be postponed approximately 13 days after a 3-day antarelix treatment if initiated just before the preovulatory LH surge, (3) ovulation can be induced by hCG on depressed levels of endogenous LH, (4) the inhibition of the post ovulatory LH surge has no effect either on the corpus luteum or on fertility. 相似文献
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Berentsen AR Dunbar MR Johnson SR Robbe-Austerman S Martinez L Jones RL 《Veterinary microbiology》2011,149(1-2):126-132
Seroconversion after early vaccination at four weeks against canine parvovirus (CPV) using a high antigen titre vaccine was evaluated in 121 puppies from three breeds of dogs housed in kennels representative of the private practitioner's environment. The trial included 52 German shepherd pups, 25 Rottweiler pups and 44 Boerboel pups. From each group 11, 4, and 18 puppies acted as control dogs, respectively. Depending on the different groups, puppies were vaccinated at 4, 6, 9 and 12 weeks. The experimental group differed from the control group in that they received the high titre vaccine at 4 weeks of age, whereas the control group was not vaccinated at 4 weeks. Blood was collected from all pups prior to vaccination to measure maternally derived colostral antibody. The results indicated that vaccination at 4 weeks of age in pups with high maternally derived antibody levels, results in seroconversion rates that may lead to a reduction in the window of susceptibility with respect to CPV infection. The implications of the findings with respect to dogs in heavily contaminated environments are discussed. 相似文献
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Epidemiology of Mycobacterium bovis in free-ranging white-tailed deer,Michigan, USA, 1995-2000 总被引:3,自引:0,他引:3
O'Brien DJ Schmitt SM Fierke JS Hogle SA Winterstein SR Cooley TM Moritz WE Diegel KL Fitzgerald SD Berry DE Kaneene JB 《Preventive veterinary medicine》2002,54(1):47-63
An endemic area of bovine tuberculosis (TB) (Mycobacterium bovis) currently affecting wild white-tailed deer (Odocoileus virginianus) in northern lower Michigan, USA, constitutes the first self-sustaining outbreak of the infection in free-ranging North American cervids. Given this precedent, epidemiologic insights gained from the outbreak afford the opportunity to guide not only current surveillance and intervention but also control efforts for future outbreaks involving wildlife reservoirs. Our specific objectives were to evaluate retrospective data from field surveillance conducted from 1995 to 2000 to determine apparent prevalence, trends in apparent prevalence, and the effects of various factors on the odds of being M. bovis positive.Data were gathered from post-mortem examinations of 62,560 wild deer collected from all 83 Michigan counties. Records of survey method, sex, age, geographic area and infection status as determined by mycobacterial culture were subjected to trend analysis and multivariable logistic regression. Apparent prevalence for the period was 0.54% (336/62,560) statewide. Prevalence varied widely with geographic area, but significantly decreased since 1995 in the core area of the outbreak-which coincided with implementation of control strategies. Significant risk factors were geographic area, sex, age, and the sex-by-age interaction. The survey method by which deer were obtained for testing was not a predictor of infection.Our results to date suggest an outbreak characterized by broad areas of very low prevalence surrounding focal areas where prevalence is sometimes orders-of-magnitude higher (e.g., deer originating from the core area were up to 147 times more likely to be TB positive than deer from other areas). Our results also identify older male deer as most likely to be M. bovis positive (OR=11.3, 95% CI 3.2, 40.3 for bucks > or =5 years vs. does < or =1.5 years)-an observation consistent with the biology and behavior of the species. Synthesizing these results with those of other ongoing investigations, we hypothesize a two-stage model of disease transmission where TB is maintained at very low prevalence in matriarchal groups, with primary dissemination of the disease attributable to the dispersal and movements of bucks (as well as to the large aggregations of animals created by human activities). 相似文献
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Hess MB Parker NA Purswell BJ Dascanio JD 《Journal of the American Veterinary Medical Association》2002,221(2):266-7, 240
Lufenuron, a benzoylphenyl urea derivative, was evaluated as a treatment for endometrial fungal infections in 4 mares. Intrauterine lavage was performed with lufenuron suspended in sterile saline (0.9% NaCl) solution. Cytologic evaluation and fungal culture of the endometrium, as well as subsequent reproductive performance, were used to monitor efficacy of this treatment. Fungal endometritis in mares is associated with infertility. Treatment is often ineffective and costly, and recurrence following treatment is not uncommon. Intrauterine infusions of lufenuron were effective in eliminating fungal endometritis in the 4 mares of this report. 相似文献
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Gary J. Nie DVM PhD Diplomate ACT Diplomate ABVP Kristina E. Johnson DVM Timothy D. Braden PhD James G.W. Wenzel DVM PhD Diplomate ACT Diplomate ACVPM 《Journal of Equine Veterinary Science》2003,23(6):266-273
A 25- or 35-mm diameter glass ball was placed in the uterus of mares to observe the effect on interovulatory interval, luteal function, estrous behavior, the endometrium, and subsequent fertility. The 25-mm glass ball was spontaneously expelled from the uterus of 6 of 12 mares (50%), whereas none of the 35-mm glass balls was expelled. Teasing results were consistent with the concentration of circulating progesterone. Luteal function was extended in 7 of 18 mares (39%) maintaining a glass ball, whereas an extended luteal period occurred in 4 of 32 mares (13%) observed as controls. Extended luteal function occurred in 7 of 62 diestrus periods (11%) among mares following ball placement, whereas 4 of 50 diestrus periods (8%) were extended in control cycles. The mean luteal life span in mares with a glass ball and extended luteal function was 87 days (range, 76 to 109 days); there were no significant differences in length of luteal function in both groups of mares that received the 2 different ball sizes. Endometrial changes observed between preplacement and postremoval samples were minimal. When mares were bred in the season subsequent to glass ball removal, 17 of 23 (74%) conceived. Placing an intrauterine glass ball in a mare may be an alternative to exogenous hormone therapy to prevent cycling in some mares. Luteal function was extended to nearly 90 days in approximately 40% of mares. The 35-mm diameter glass ball appeared to have an advantage for retention over the 25-mm size. Results of our study could not completely rule out idiopathic persistence of the corpus luteum as an explanation for the extended luteal function observed in mares with a glass ball. Readers are cautioned that many questions still exist about the use of intra-uterine glass balls in mares. Further work is required to confirm the efficacy of the use of an intra-uterine glass ball for prolonged luteal function in mares and to identify its mechanism of action.
Introduction
In recent years, there has been a debate among veterinary practitioners concerning the efficacy of various extra-label uses of progestin products (eg, cattle growth implants and human depo-progestin injectables) to modify behavior in mares. Clients who own horses are more frequently seeking means to suppress behavioral signs of estrus, expecting that with such suppression the mare will train or perform better. Requests for these progestin products by mare owners puts veterinary practitioners in the precarious situation of using pharmaceuticals, extra-label, without scientific evidence of efficacy, in mares.In reality, the only truly effective means of suppressing behavioral signs of estrus in most intact mares is to maintain sufficient concentrations of circulating progesterone or its equivalent. Today the only efficacious way to maintain a sufficient level of progesterone or its equivalent is for the mare to have a functional corpus luteum (CL), administer exogenous progesterone (eg, ≥50 mg in oil, intramuscularly, daily), or administer daily synthetic progestins (eg, altrenogest [Regumate], Hoechst Roussel Vet, Warren, NJ).1, 2 and 3Recently, placement of a glass ball of 30-mm diameter in the uterus has been suggested as a reversible means of preventing mares from cycling and displaying behavioral signs of estrus (message to Equine Clinicians Network, Dr Randy J. T. de Greef, March 19, 2000). If this technique is effective, it would be of value to mare owners because it would eliminate the need for daily treatments over extended periods.We have been unable to find literature that would support or refute this idea in horses. However, the effects on ovarian function, body weight gain, and pregnancy rate in nulliparous heifers of a copper-bearing intrauterine device were studied.4 The researchers reported that the heifers receiving the intrauterine device had lower progesterone concentrations than did control subjects. Nevertheless, nearly all of the treated heifers had better weight gain, were anestrus, and did not become pregnant during the study; however, multiple ovarian follicular cysts developed in many of them. The idea of using an intrauterine device to suppress estrus is said to have originated centuries ago in the Middle East as a common means of keeping camels from cycling and becoming pregnant (personal communication, Dr Ahmed Tibary, College of Veterinary Medicine, Washington State University, Pullman, Wash, May 2000).To our knowledge, the efficacy and long-term effects of glass ball treatment have not been critically evaluated. Our objectives in this study were to observe the effect of placement of an intra-uterine glass ball on interovulatory interval, luteal function, estrous behavior, the endometrium, and subsequent fertility of mares.Materials and methods
Animals
A total of 38 light-horse breed mares ranging in age from 3 to 20 years were used for this study. Mares were maintained in accordance with the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (1st revised edition, January 1999). All experimental procedures involving animals were approved by the Institutional Animal Care and Use Committee at Auburn University (IACUC Protocol No. 0308-R-2307).Intra-uterine device
Two glass ball (www.glassmarbles.com) sizes, 25- and 35-mm diameters, were evaluated in this study (Fig 1).Full-size image (49K) |
In preparation for placement, the glass balls were sterilized by autoclaving. Initial attempts at autoclaving resulted in several broken balls. However, use of a liquid cycle with a temperature of 250°F (121°C) and pressure of 16 psi, with no prevacuum or dry cycle and a slow cool-down phase, did not result in further breakage.Upon entering the study, mares were monitored daily via transrectal palpation and ultrasonography for their progression through the estrous cycle. A glass ball was placed in the body of the uterus at the first examination following ovulation. The perineum was cleaned with cotton, tap water, and antiseptic dish detergent. A sterilized sleeve was donned and a small amount of sterile lubricant was applied to the back of the hand. Grasping the glass ball, it was manually carried into the vagina. The ball was placed in the cervical lumen and moved forward with the index finger to the caudal uterine body. After removing the hand from the vagina, the ball was located on transrectal palpation and pushed forward to the horn-body junction if it had not already moved to that position. Once the ball was positioned in the uterus, the vulva was again cleaned as previously described. The uterus was infused with 1 g of ticarcillin disodium (Ticar, SmithKline Beecham Pharmaceuticals, Philadelphia, Pa) in a 35-mL volume and each mare received 250 μg cloprostenol (Estrumate, Bayer Corporation, Shawnee Mission, Kan) intramuscularly to prevent a persistent endometritis if contaminants were introduced with the glass ball.At the end of the glass ball phase of the experiment for a mare, the ball was removed from the uterus during the following estrus when the cervix was softest. Occasionally a mare would require sedation to allow better manipulation of the ball per rectum. Mares with pendulous horns presented the most difficulty. Removal was accomplished by manipulating the glass ball, per rectum, caudally toward the cervix, through the cervix, and then to the vulva for retrieval. If the cervix was not fully dilated, a gloved hand was taken per vagina to the caudal cervical os and the glass ball was retrieved from the lumen.
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Mares were also teased to a stallion, and blood was taken for determination of progesterone concentrations. Daily evaluation was continued until 2 ovulations had been detected; after this, daily blood sampling and teasing was continued until 2 more ovulations were detected. However, if at any time mares were found to maintain luteal tissue (continued ultrasonic evidence of a CL, palpable tone in the uterus and cervix, absence of estrus signs on ultrasonography, and absence of estrus behavior) for 35 days, daily evaluation was discontinued and the mares were moved to pasture and blood samples were taken weekly to monitor progesterone concentrations.In mares that did not experience prolonged luteal function (>35 days), the glass ball was removed from the uterus after 4 ovulations had been detected. In mares that experienced prolonged luteal function, the glass ball was removed after progesterone concentrations had fallen to <1 ng/mL followed by a subsequent rise to >4 ng/mL, indicating a subsequent ovulation. Mares that spontaneously expelled the glass ball were removed from the study upon discovery without further sampling.Immediately following removal of a glass ball, an endometrial biopsy was taken for comparison with the preplacement sample. Following removal of the glass balls, mares were bred during the next season under the protocol of another study. Standard breeding management for artificial insemination and several stallions were used. The results reported are for the season and reflect pregnancy outcome at 15 days after ovulation.Estrous cycles (n = 50) were observed in 32 of 38 study mares to establish an interovulatory interval and incidence of spontaneous persistence of the CL as a control for the effect of the treatment protocol. Observations were made during separate control cycles when a glass ball was not in the uterus of any mares that were also used in a treatment group during the study. At least one cycle was evaluated for each of the 32 mares, with some contributing a second cycle. The reproductive tract and circulating progesterone concentrations were evaluated in the same fashion and on the same daily schedule as the treatment groups. During the control cycles, the mares were simultaneously being observed to establish estrous cycle control data for another study. Therefore, when spontaneous persistence of a CL occurred and a luteal phase lasted 30 days, the mare was given prostaglandin to lyse the CL.
Progesterone assay
Circulating progesterone concentrations were used to reflect luteal function. Concentrations higher than 1 ng/mL were considered indicative of functional luteal tissue. Plasma was harvested from blood collected from each mare. Plasma samples were frozen and held at −50°C until assayed in batches of approximately 200. Circulating concentrations of progesterone were quantified using a commercial radioimmunoassay kit (COAT-A-COUNT progesterone radioimmunoassay kit, Diagnostic Products Corporation, Los Angeles, Calif).Statistical analysis
Two measures were derived from each interovulatory period: the interovulatory interval in days and the number of days during which progesterone was >1 ng/mL. The effects of glass ball size, monitoring method, mare and their interactions were tested using the GLM procedure of Statistical Analysis System (SAS Institute, Cary, NC). Ages of mare among groups were compared with use of an unpaired t test (GraphPad InStat version 3.00 for Windows 95, GraphPad Software, San Diego, Calif). The proportion of mares experiencing extended luteal function or spontaneous persistence of a CL during the treatment and control cycles was determined. In addition, the proportion of diestrus periods that resulted in extended luteal function or spontaneous persistence of a CL was determined. The proportion of mares and diestrus periods in which extended luteal function occurred during treatment and control cycles were compared using a Fisher Exact Test (GraphPad InStat version 3.00 for Windows 95, GraphPad Software, San Diego, Calif).Results
A very small amount of uterine fluid (<1 cm depth) was observed via ultrasonography in 3 mares for 2 days following placement of the glass ball. By day 3, however, the fluid was no longer visible in any of the mares, one of which did go on to maintain luteal function for an extended period. None of the mares that developed uterine fluid experienced spontaneous loss of the glass ball.A total of 24 mares had a glass ball of either 25 mm (n = 12) or 35 mm (n = 12) diameter placed in the uterus. The 25-mm glass ball was spontaneously expelled in 6 of 12 mares (50%). Five were expelled within 24 hours of placement and a sixth during a subsequent estrus period, 11 days following placement. None of the 35-mm glass balls was spontaneously expelled.The glass ball was observed to randomly alternate between the left and right uterine horn-body junctions. Movement was observed in every mare except two. In those 2 mares, the 35-mm glass ball was consistently observed at the same site during each examination. One of the mares experienced extended luteal function and the other did not.Overall, 7 of 18 mares (39%) that maintained the glass ball experienced extended (>35 day) luteal function. Extended luteal function was detected during the first diestrus after ball placement in 4 mares, during the second diestrus in one mare, and during the third diestrus in 2 mares. Mean (±SEM) progesterone concentrations during the extended luteal periods are reported in Figs 3, 4, and 5.Full-size image (13K) |
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There was no difference between the 25- and 35-mm balls in terms of proportion of mares having extended luteal function (2 of 6, 33%, and 5 of 12, 42%; P > .05). Extended luteal function occurred in 7 of 62 diestrus periods (11%) among mares following ball placement. Again, there was no difference between 25- and 35-mm balls in terms of proportion of diestrus periods resulting in extended luteal function (2 of 20, 10%, and 5 of 42, 12%, P > .05).An extended luteal period occurred in 4 of 32 mares (13%) observed for control data. Progesterone concentrations remained above 1 ng/mL for 30 days after ovulation in 4 of 50 control diestrus periods (8.0%) observed. Of the 4 mares that experienced extended luteal function during the control cycle, a glass ball was placed in the uterus of 3 of the mares during the treatment cycles. However, none of the 3 mares experienced extended luteal function while the glass ball was in the uterus. The proportion of mares that experienced extended luteal function (7 of 18, 39%) while a glass ball was in the uterus was greater than the proportion of mares that experienced an extended luteal period (4 of 32, 13%) during the control cycle (P = .04). The proportion of diestrus periods in which extended luteal function occurred was the same whether a glass ball was present in the uterus (7 of 62, 11%) or not (4 of 50, 8%; P = .75).The interovulatory interval was 23.0 (±0.43) days for the control cycles (n = 46) in which an extended luteal period did not occur. This was longer than the interovulatory interval (20.2 ± 0.41 days) for the cycles (n = 55) that occurred subsequent to glass ball placement without apparent extension of luteal function (P < .001). A functional CL was maintained (15.5 ± 0.35 days, range 11 to 23 days) longer in control cycles than in cycles with glass balls (13.2 ± 0.42 days, range 7 to 18 days) in which extended luteal function was not apparent (P < .001). Mean (± SEM) progesterone concentrations for the control cycles (n = 46) and treatment cycles in which an extended luteal period did not occur are presented in Fig 6.
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The mean age of all mares in the study was 9.6 years (range, 3 to 20 years). Mares that experienced extended luteal function were younger, at 8.3 years (±0.87), than mares that did not experience extended luteal function, at 12.6 years (±1.05, P = .012). Mares that spontaneously expelled the glass ball were younger, at 6.3 years (±2.0), than mares that did not expel the glass ball, at 10.9 years (±0.87, P = .024).The interassay and intra-assay coefficient of variation for the progesterone assay was 7% and 3%, respectively. The sensitivity of the assay was 0.02 ng/mL. Estrous behavior observed during the study accurately reflected circulating progesterone concentrations. All mares with a glass ball invariably displayed behavioral estrus scores of 1 or 2 when progesterone concentrations were <1 ng/mL, while scores of 0 were observed when concentrations were >1 ng/mL. Those that experienced extended luteal function also displayed scores of 0 throughout the period while progesterone concentrations were >1 ng/mL and estrus behavior was monitored. A single CL was observed at the primary ovulation site throughout the observation period. No additional CLs were observed in any mare with a glass ball following the primary ovulation.No change in endometrial category was observed between the preplacement and postremoval endometrial samples in any of the mares in the 25-mm glass ball group. In the 35-mm group, the score declined by a category in one mare, improved by a category in 2 mares, and was unchanged in the other 9 mares. The difference in category assigned in those 3 mares was attributed to mild changes, up or down, in the amount of lymphocytic inflammation observed. The mare that declined by one category did not experience extended luteal function, whereas 1 of 2 mares with improvement in endometrial category experienced an extended luteal period.During the season following glass ball removal, 23 of 24 mares were bred, including all of the mares that had experienced extended luteal function. During the season, 17 of 23 (74%) of the mares bred subsequently conceived, including 5 of 7 (71%) of those that had experienced extended luteal function.
Discussion
Placement of the glass ball through the cervix was relatively easy in most of the mares. Occasionally the cervix of a mare would require some degree of manual dilation to push a 35-mm diameter ball through its lumen; however, the 25-mm balls generally passed with ease. During preliminary work, we had found that the glass ball was more likely to be expelled from the uterus if it was placed a day or two before ovulation. Based on the anecdotal information from the Netherlands (message to Equine Clinicians Network, Dr Randy J. T. de Greef, March 19, 2000) and our preliminary experience, we decided to place the glass ball in the uterus at the examination following ovulation. Our assumption when placing the glass ball following ovulation was that the cervix would have started to close under the influence of rising progesterone, which might help prevent it from being expelled. We found that younger mares were more likely to expel the glass ball, perhaps because younger mares have more effective uterine clearance (in estrus and the periovulatory period) and a less dependent uterine position than do older mares. The smaller diameter and lighter weight of the 25-mm glass ball also may have contributed to the spontaneous expulsion from 6 mares, although it is also possible the cloprostenol contributed to the loss in some mares. However, losses observed during preliminary work were not associated with cloprostenol administration, and neither was the loss in this study from the mare that expelled the ball during the subsequent estrus at 11 days following placement.Idiopathic persistence of the primary CL, also known as spontaneous persistence of the CL,7 cannot be completely ruled out as an explanation for the extended luteal function observed in this study. The incidence of idiopathic persistence is reported to vary widely.8 and 9 Ginther and Pierson8 did not observe idiopathic persistence in any of 69 interovulatory intervals, while Stabenfeldt and Hughes9 suggest it can occur in as many as 25% of estrous cycles. However, acceptance of inadequate evidence for the condition may have led to an overestimation of the incidence in some reports.7The proportions of diestrus periods that resulted in an extended luteal period were not different between the control (4 of 50) and glass ball (7 of 62) cycles. However, the proportion of cycles in mares with glass balls inserted is heavily biased by the 4 cycles from each mare that did not experience extended luteal function. A greater proportion of mares (7 of 18) experienced extended luteal function when a glass ball was in the uterus than without a ball (4 of 32) during the control cycles. Four of the mares that experienced extended luteal function with a glass ball in the uterus did so during the first diestrus following placement and did not experience subsequent ovulations. These mares are consequently underrepresented in the proportion of diestrus periods among the mares that had a glass ball inserted, especially if all or some of the mares had experienced additional periods of extended luteal function following subsequent ovulations. This would seem to make the proportion of mares a more valuable indicator of glass ball efficacy. However, in all fairness, we should point out that 2 of 7 mares that experienced extended luteal function did so after the third ovulation following glass ball placement (Fig 5). The control data were collected from 32 mares in 50 estrous cycles; only 18 of the mares were observed in more than one cycle. This may have biased our results for fewer occurrences of idiopathic persistence of the CL, although we believe it is unlikely.Five of the 7 mares in this study that experienced extended luteal function when a glass ball was in the uterus had never previously been observed to have prolonged interovulatory intervals over multiple seasons. Historic data were not available for the other 2 mares. The average length of the luteal period reported to be associated with idiopathic persistence of the CL is approximately 2 months.7 The average length of luteal function observed in this study was 3 months. These several points would seem to support the idea that the extended luteal function observed in this study was indeed affected by the glass ball protocol rather than idiopathic persistence. Therefore, although it is not possible to positively distinguish idiopathic persistence of the primary CL from extended luteal function influenced by the glass ball protocol, we believe that our observations in this study suggest a genuine effect. An explanation is not readily apparent for our observation that mares experiencing extended luteal function were younger than those that did not experience extended luteal function.Two possible explanations for an effect of the glass ball have been discussed (Equine Clinicians Network archives). First, the glass ball simulates a conceptus and through movement and physical contact prevents prostaglandin release from the endometrium, in turn maintaining the CL (an endogenous progesterone source) indefinitely. A second theory suggested that the glass ball would stimulate mild inflammation, in turn causing release of small amounts of prostaglandin that would be inadequate to achieve luteolysis. As long as the glass ball was present, the endometrium would remain in a prostaglandin-depleted state and the CL would be maintained.In the event that the first theory discussed was correct, two glass ball sizes were evaluated in this study to account for a range in vesicle diameter that would be expected to occur naturally during the early stages of pregnancy. However, this theory seems to assume that the physical presence of a spherical structure, in this case a glass ball, in the uterine lumen will prevent prostaglandin release. This is contrary to conventional logic that would assume, as has been demonstrated in other species, that a chemical messenger is produced by the equine conceptus to allow maternal recognition of pregnancy and avoid prostaglandin release.10The second theory is as equally confusing, considering that there are countless reasons why a mare may have low-grade endometrial inflammation, yet clinically we do not recognize scores of mares that maintain their luteal tissue indefinitely. Both theories suggest that the glass ball is mobile enough to contact the majority of the endometrium or cause low-grade endometrial inflammation throughout the uterus. Our findings did not support the idea that the glass ball was particularly mobile in the uterus. Although the ball did move between the uterine horn-body junctions in most mares, the distance moved was only a few centimeters. In 2 mares, the glass ball did not move at all. One of the mares experienced extended luteal function in spite of the lack of ball movement. It probably also would be more logical to assume that an irritant to the endometrium would cause low-grade inflammation, which in turn would likely trigger sufficient release of endogenous prostaglandin F2α to cause luteolysis.11 and 12 Uterine biopsy results did not reflect an increase in endometrial inflammation. Further, the interovulatory interval and functional life of the CL was >2 days longer during control cycles than in cycles when a glass ball was in the uterus. This would suggest that the ball was more likely to cause early regression of the CL.Placing the glass ball following ovulation could predispose a mare to endometritis, considering the procedure involved passing a foreign object, although sterilized, through the cervical lumen after a mare has entered diestrus. A mare susceptible to endometritis may not have time to clear her uterus of contaminants before closing the cervical lumen completely. Based on this rationale and experience during our preliminary work, we decided to provide treatments simultaneous to glass ball placement that were intended to help prevent a persistent postplacement endometritis. Hence, each mare in this study was infused with ticarcillin disodium (Ticar) and treated with cloprostenol (Estrumate) following glass ball placement. Uterine fluid was only observed in a few mares in the first few days following glass ball placement, and it resolved quickly. Nevertheless, it is advisable to re-examine a mare with ultrasonography following placement of a glass ball to ensure a detectable endometritis has not developed.Discussions on the Equine Clinicians Network suggested that the glass ball had no long-term detrimental effects on the uterus. The relatively minor ultrasonic changes detected in the uterus following glass ball placement, the endometrial biopsy results, and a conception in 74% of the mares following glass ball removal would seem to support this claim.It is interesting that the mares experiencing extended luteal function were able to maintain progesterone concentrations above 1 ng/mL for an average of nearly 3 months. This is the period in which we would expect the fetoplacental unit to begin assuming maintenance of pregnancy through the production of pregnanes in an ever-increasing number of pregnant mares. The progesterone profiles in these mares were very similar to those reported for mares hysterectomized 3 days following ovulation.13 The primary CL was present 70 days following ovulation in hysterectomized mares, but disappeared by 140 days.13 We found this was also true of mares that experienced extended luteal function with a glass ball in the uterus.The efficacy of an intrauterine glass ball for maintaining luteal function and thus preventing cycling and behavioral estrus in mares appears to be moderate. Our results were not quite as good as those reported from the Netherlands (Dr Randy J. T. de Greef, message to Equine Clinicians Network, March 19, 2000). The Dutch veterinarian indicated that the technique works in at least 75% of cases; in contrast, we found the technique to be effective in only approximately 40% of mares. Perhaps a placebo effect for mare owners, as is suspected with the use of progestin implants, would explain the additional success reported from the Netherlands.The glass ball protocol takes advantage of endogenous progesterone production to suppress behavioral estrus. Some variation in estrus behavior will be observed in any group of mares teased to a stallion throughout the cycle. However, mares are typically expected to reject a stallion when a functional CL is present and to change from indifferent to receptive as estrogens rise in the absence of a functional CL. Teasing results in this study were consistent with the behavior expected for the concentration of circulating progesterone detected. We did not monitor the mares that experienced extended luteal function beyond their subsequent ovulation, although we speculate that if the glass ball had been left in the uterus, some of the mares may have experienced another extended luteal period. Another researcher related information to us about 2 mares in which he had placed a glass ball (personal communication, Dr Peter Daels, National Institute of Agricultural Research, Nousilly, France, April 2000). The mares experienced extended luteal function, then, following administration of prostaglandin, both mares returned to estrus, retained the glass ball, ovulated, and again experienced extended luteal function.This technique offers the advantage of suppressing behavioral estrus because of endogenous progesterone production over an extended period following a single administration of a glass ball. The disadvantage is that it does not work in every mare nor does it appear to have an immediate effect in every mare following intra-uterine placement of the glass ball. However, when it is effective it may serve as an alternative method for suppressing estrous cycle and/or behavior and thus avoiding the need for administration of exogenous progestin products. Readers are cautioned that many questions still exist about the use of intra-uterine glass balls in mares. Further work is required to confirm the efficacy of the use of an intra-uterine glass ball for prolonged luteal function in mares and to identify its mechanism of action. 相似文献12.
Ovarian granulosa theca cell tumours were removed surgically in 10 mares. Stapling instruments were used to facilitate haemostasis of the ovarian pedicle in five out of 10 cases and as a sole method of haemostasis in the remaining five cases. Postoperative haemorrhage from the ovarian pedicle was suspected in only one case. All cases survived long term follow-up from six months to four years. Results from this series of cases indicate that stapling instruments provide a rapid, easy and efficient means of ligating ovarian pedicles when performing ovariectomy in the mare. 相似文献
13.
Johnson-Ifearulundu YJ Kaneene JB Sprecher DJ Gardiner JC Lloyd JW 《Preventive veterinary medicine》2000,46(3):171-181
A prospective cohort study design was used to evaluate the impact of subclinical Mycobacterium paratuberculosis infection on days open in a sample of Michigan dairy herds with a history of cows positive for M. paratuberculosis diagnosed by fecal culture. Participating herds were tested and productivity and reproduction records were monitored for 18 months. All cows > or = 24 months old were tested for M. paratuberculosis infection using the ELISA and radiometric fecal-culture (RFC) techniques. Test-negative cows were re-tested at the conclusion of the monitoring period. Multivariable regression models were used. Using both tests in parallel, the overall sample apparent prevalence for M. paratuberculosis infection was 41.8% (223/533 animals tested). Adjusting for diagnostic sensitivity and specificity, this resulted in a calculated sample true prevalence of 59.9%. ELISA-positive cows (on average) had a 28-day increase in days open when compared to ELISA-negative cows (p=0.02). The diagnostic method used to define a case altered the apparent association between paratuberculosis test status and days open. Fecal culture was a less-effective diagnostic tool for use in herds with a high prevalence of infected animals. The increase in days open in the ELISA-positive cows was an indication that perhaps reduced estrus expression or an increased post-partum anestrous period occurred in the subclinically infected ELISA-positive animals. This might have been due to a negative energy balance associated with M. paratuberculosis infection. 相似文献
14.
Tissue and serum concentrations of amikacin after intramuscular and intrauterine administration to mares in estrus.
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J A Orsini M I Park P A Spencer 《The Canadian veterinary journal. La revue veterinaire canadienne》1996,37(3):157-160
Concentrations of amikacin in endometrial tissue and plasma were studied in mares in estrus after intrauterine infusion of 1.0 or 2.0 g once a day for 3 consecutive d, and after 9.7 or 14.5 mg/kg body weight (BW) had been injected intramuscularly once a day for 3 consecutive d to determine concentrations of amikacin sulfate in plasma and endometrial tissues, and whether parenteral administration provides any advantages over intramuscular infusion. No amikacin was detected in serum at the 1.0 g dose. At the infusion dose of 2.0 g once a day, very low levels of serum amikacin were detected at 1 and 4 h postinfusion on the 1st treatment day. Amikacin was found to penetrate the endometrium after intramuscular injection; however, the levels attained were not as high as those achieved following intrauterine infusion. Based on the tissue and serum concentrations of amikacin, an intrauterine infusion at a dose of 4.4 mg/kg BW/d would appear to be an appropriate therapeutic regimen for the treatment of gram-negative endometritis. 相似文献
15.
Carnevale EM Squires EL Maclellan LJ Alvarenga MA Scott TJ 《Journal of the American Veterinary Medical Association》2001,218(1):87-91, 37
In some mares with lesions of the reproductive tract, embryo collection and survival rates are low, or collection of embryos is not feasible. For these mares, oocyte transfer has been proposed as a method to induce pregnancies. In this report, a method for oocyte transfer in mares and results of oocyte transfer performed over 2 breeding seasons, using mares with long histories of subfertility and various reproductive lesions, are described. Human chorionic gonadotropin or an implant containing a gonadotropin-releasing hormone analog was used to initiate follicular and oocyte maturation. Oocytes were collected by means of transvaginal ultrasound-guided follicular aspiration. Following follicular aspiration, cumulus oocyte complexes were evaluated for cumulus expansion and signs of atresia; immature oocytes were cultured in vitro to allow maturation. The recipient's ovary and uterine tube (oviduct) were exposed through a flank laparotomy with the horse standing, and the oocyte was slowly deposited within the oviduct. Oocyte transfer was attempted in 38 mares between 9 and 30 years old during 2 successive breeding seasons. All mares had a history of reproductive failure while in breeding and embryo transfer programs. Twenty pregnancies were induced. Fourteen of the pregnant mares delivered live foals. Results suggest that oocyte transfer can be a successful method for inducing pregnancy in subfertile mares in a commercial setting. 相似文献
16.
Effects of rice bran oil on plasma lipid concentrations, lipoprotein composition, and glucose dynamics in mares 总被引:1,自引:0,他引:1
Plasma lipid concentrations, lipoprotein composition, and glucose dynamics were measured and compared between mares fed diets containing added water, corn oil (CO), refined rice bran oil (RR), or crude rice bran oil (CR) to test the hypothesis that rice bran oil lowers plasma lipid concentrations, alters lipoprotein composition, and improves insulin sensitivity in mares. Eight healthy adult mares received a basal diet fed at 1.5 times the DE requirement for maintenance and each of the four treatments according to a repeated 4 x 4 Latin square design consisting of four 5-wk feeding periods. Blood samples were collected for lipid analysis after mares were deprived of feed overnight at 0 and 5 wk. Glucose dynamics were assessed at 0 and 4 wk in fed mares by combined intravenous glucose-insulin tolerance tests. Plasma glucose and insulin concentrations were measured, and estimated values of insulin sensitivity (SI), glucose effectiveness, and net insulin response were obtained using the minimal model. Mean BW increased (P = 0.014) by 29 kg (range = 10 to 50 kg) over 5 wk. Mean plasma concentrations of NEFA, triglyceride (TG), and very low-density lipoprotein (VLDL) decreased (P < 0.001) by 55, 30, and 39%, respectively, and plasma high-density lipoprotein and total cholesterol (TC) concentrations increased (P < 0.001) by 15 and 12%, respectively, over 5 wk. Changes in plasma NEFA (r = 0.58; P < 0.001) and TC (r = 0.44; P = 0.013) concentrations were positively correlated with weight gain over 5 wk. Lipid components of VLDL decreased (P < 0.001) in abundance over 5 wk, whereas the relative protein content of VLDL increased by 39% (P < 0.001). Addition of oil to the basal diet instead of water lowered plasma NEFA and TG concentrations further (P = 0.002 and 0.020, respectively) and increased plasma TC concentrations by a greater magnitude (P = 0.072). However, only plasma TG concentrations and VLDL free cholesterol content were affected (P = 0.024 and 0.009, respectively) by the type of oil added to the diet. Mean plasma TG concentration decreased by 14.2 mg/dL over 5 wk in the CR group, which was a larger (P < 0.05) decrease than the one (-5.3 mg/dL) detected in mares that received water. Consumption of experimental diets lowered S(I), but glucose dynamics were not affected by oil supplementation. Addition of oil to the diet altered blood lipid concentrations, and supplementation with CR instead of water specifically affected plasma TG concentrations and VLDL free cholesterol content. 相似文献
17.
18.
O'Brien DJ Kaneene JB Getis A Lloyd JW Swanson GM Leader RW 《Preventive veterinary medicine》2000,47(3):187-204
Our aim was to investigate the geographic and time distributions of some biologically similar neoplasms in dogs and humans living in Michigan, USA, between 1964 and 1994. Our objective was to describe and compare the patterns of cancer in the two species while assessing the strength and dependence of those patterns. In this retrospective, registry-based study, histologically confirmed incident human and canine cancer cases were mapped, and second-order (K function) spatial analysis and one-dimensional nearest neighbor temporal analysis were performed on residence addresses and dates of hospital discharge/diagnosis. Included in the study were all 528 incident cases of canine lymphosarcoma, mammary adenocarcinoma, melanoma and spindle-cell sarcomas diagnosed at a veterinary teaching hospital between 1964 and 1994 having residence addresses in Ingham, Oakland, and Wayne Counties; and a stratified random sample of 913 incident human cases of comparable cancers diagnosed during the same time period from the same counties. Results suggest that processes determining spatial aggregation of cases in dogs and humans were not independent of each other, did not act uniformly over different geographic areas, operated at spatial scales <2000 m regardless of species, and tend to act upon dogs more strongly at shorter distances than on humans. Little evidence of interspecies concurrence of temporal clustering was found. 相似文献
19.
Gordoncillo MJ Abdujamilova N Perri M Donabedian S Zervos M Bartlett P 《Zoonoses and public health》2012,59(3):212-216
Methicillin-resistant Staphylococcus aureus (MRSA) have been reported in commercially raised pigs and their human handlers, raising concerns of zoonotic transmission. To determine whether MRSA in backyard-raised pigs is commonly transmitted to their human owners, a matched study of this type of pigs and their owners was conducted in selected counties in Michigan. Nasal swabs from matched owner-pig pairs (n = 50 pairs) with a few unmatched pig (n = 3) and human (n = 4) samples were collected and processed using standard isolation and identification protocols. No matched owner-pig pair was found; however, MRSA was isolated from 1/54 (1.9%) human samples and 2/53(3.8%) of the pigs. The single human isolate was not strain type USA100-1100 by pulsed-field gel electrophoresis (PFGE), was sequence type (ST) 8 by multilocus sequence typing (MLST), possessed SCCmec type IVb and agr I and was negative for the Panton-Valentine leukocidin (PVL) toxin gene. The two pig isolates were indistinguishable by PFGE (not USA100-1100), and both isolates were ST5 by MLST, possessed SCCmec type III and agr II and were negative for the PVL gene. Persons raising backyard swine from the selected Michigan counties had MRSA carriage rates similar to that of the general US population, suggesting that their avocational pig exposure did not increase their risk of MRSA. 相似文献
20.
将围产期健康乳牛30头随机分为3组,分别于产前第28d开始饲喂标准日粮(能量摄入i00%组)、标准日粮增加20%的日粮(能量摄入120%组)和标准日粮减少20%的日粮(能量摄入80%组),产后备组乳牛均饲喂标准泌乳日粮,至产后第56d结束,观察干奶期不同能量摄入水平对围产期健康乳牛血液葡萄糖、胰高血糖素和胰岛素浓度的影响。结果表明,产前低能饲喂可以增加围产期乳牛血浆葡萄糖浓度,干奶期不同能量摄入水平对围产期健康乳牛血液葡萄糖、胰高血糖素和胰岛素浓度起重要调节作用。 相似文献