Inhibitory Effects of Pergolide and Cabergoline Formulations on Daily Plasma Prolactin Concentrations in Geldings and on the Daily Prolactin Responses to a Small Dose of Sulpiride in Mares

Two experiments were conducted to assess the efficacy and duration of action of two dopaminergic compounds, pergolide and cabergoline, on daily prolactin secretion in geldings and on prolactin responses to a small dose of sulpiride over 10 days. In the first experiment, oral administration of 2 mg of pergolide was compared to a single injection of 2 mg of pergolide in a slow-release vehicle and a single injection of 5 mg of cabergoline in slow-release vehicle. Controls received vehicle only. All drug treatments reduced (P < .05) prolactin concentrations relative to that in controls but differed substantially in duration of action (oral pergolide approximately 6 hours or less, injected pergolide 6 to 24 hours, and injected cabergoline at least 6 days). In the second experiment, repeated small doses of sulpiride (2 μg/kg of body weight intravenously) were used to stimulate prolactin release in mares, and the ability of seven daily injections of pergolide (2 mg each) and a single injection of cabergoline (5 mg) in slow-release vehicle to suppress this release were compared. Control mares receiving vehicle injections had robust prolactin responses to the sulpiride injections on all days of injection (days 1, 0, 1, 2, 3, 4, 6, 8, and 10 relative to treatment). Prolactin responses were muted (P < .05) by pergolide and cabergoline treatments on the first day of injection (day 0, 30 min after treatment) and were basically absent on days 1 to 8. The single injection of cabergoline continued to be suppressive through day 10, whereas mares previously treated with pergolide (through day 6) had begun to recover a prolactin response by day 10. We conclude that either daily 2-mg pergolide injections in slow-release vehicle or a single injection of 5 mg of cabergoline in slow-release vehicle is an effective way to apply dopaminergic activity to horses for approximately 7 to 10 days and may have application in the treatment of pituitary pars intermedia dysfunction in affected horses.     

Dose-Response of Prolactin to Increasing Doses of the Dopamine Receptor Antagonist,Sulpiride, in Horses: Effect of Season in Mares and Stallions of Estradiol Pretreatment in Geldings

Two experiments were performed to determine whether dopaminergic input to the adenohypophysis (1) differs across seasons in mares and stallions proportionally with changes in prolactin secretion and (2) is altered by estradiol administration in geldings. In experiment 1, prolactin responses to increasing doses of l-sulpiride in eight mares and eight stallions in March, June, September, and December were used to estimate the theoretical dose equivalent to 50% of maximal response. Prolactin areas increased (P < .001) with increasing doses of sulpiride and were greatest (P < .05) in March for stallions, but in June for mares. Mean half-maximal dose, which was assumed to be proportional to the dopaminergic input to the pituitary, was lowest (P < .05) in June and greatest in September. Experiment 2 used the same approach to determine whether the stimulatory effect of estradiol pretreatment on prolactin secretion was associated with an alteration of the half-maximal response. Geldings (n = 6/group) were administered 100 mg of estradiol cypionate in oil, or oil alone, on day 0 (October 3) and increasing doses of l-sulpiride starting on day 6. Estradiol treatment increased (P < .08) the prolactin response to l-sulpiride at 0.41 μg/kg body weight and all higher doses (P < .05); mean half-maximal dose did not differ (P > .1) between groups. We conclude that dopaminergic input to the adenohypophysis of mares and stallions varies with season and that the stimulatory effect of estradiol on prolactin secretion is not associated with a decrease in dopaminergic input to the adenohypophysis.     

Responses of Adenohypophyseal Hormones to Substance P Administration in Geldings: Comparison to Responses After Brief Exercise and Sulpiride Administration

Nine adult geldings were used in three experiments to study the possible role of substance P in the prolactin responses to nondopaminergic stimuli. Experiment 1 was performed as an incomplete Latin square design to determine the secretory responses of prolactin, growth hormone (GH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) to IV administration of substance P. Doses tested and compared to no peptide (0 dose, control) were 62, 125, 250, and 500 μg of substance P. The three highest doses of peptide caused an immediate rise in heart rate, sweating, salivation, rhinorrhea, stretching of hind legs, and defecation. The lowest dose (62 μg) caused minor sweating, some rhinorrhea, and a rise in heart rate. Recovery from these physical responses was complete in approximately 30 minutes. All doses of substance P caused an immediate rise (P < .01) in plasma prolactin concentrations, with the three highest doses producing similar responses, and the 62 μg dose producing a minimal response (P < .05). Concentrations of ACTH (P < .01) and GH (P = .05) also increased after substance P administration; concentrations of LH, FSH, and TSH were unaffected. Experiment 2 compared the effects of brief exercise on hormonal characteristics. Two minutes of trotting increased (P < .01) plasma concentrations of GH, ACTH, and prolactin, as well as LH (P = .055). Experiment 3 determined the relative responses of prolactin to a fixed dose of sulpiride (0.1 mg/kg of body weight). In general, the prolactin responses to substance P were similar to those after exercise, which were both generally less than after sulpiride. These data are consistent with a possible role of substance P in the prolactin response to stressful stimuli.     

Accumulation of Fluid in the Infundibulum During the Estrous Cycle in Mares

The funnel-shaped cranial portion (infundibulum) of the oviduct is contiguous with the ovulation fossa in mares. An accumulation of fluid in the infundibular area was discovered by transrectal ultrasonic imaging and was studied daily in both oviducts of 12 mares from day –10 to day 10 (day 0 = ovulation), and from day –6 to day 6 during 35 estrous cycles of young, intermediate, and old mares (n = 8 mares/group). The infundibulum was identified by processes (fimbriae) and folds in the pocket of fluid. The amount of fluid accumulation was scored from 0 to 3 (nil to maximum). Frequency of detection of fluid in the infundibular area increased between day –10 (46% of oviducts) and day –3 (88%), and decreased between day –3 and day 7 (8%; P < .002). The day-to-day profile for changes in the score for amount of fluid was significant (P < .0001) and similar to the profile for frequency of detection of the infundibulum. The profiles for the two infundibular end points and scores for endometrial echotexture (an indicator of edema) were similar to the reported profile for systemic estradiol concentrations. The frequency of infundibulum detection was greater (P < .0009) for the side ipsilateral to the preovulatory follicle and ovulation (51%) than for the opposite side (36%). No difference among ages was found for either oviductal end point. Results indicated that changes in the amount of fluid accumulation in the infundibular area and endometrial edema were estrous cycle dependent and similar to previously reported changes in systemic concentrations of estradiol.     

Prolactin and Gonadotropin Responses in Geldings to Injections of Estradiol Benzoate in Oil, Estradiol Benzoate in Biodegradable Microspheres, and Estradiol Cypionate

We previously reported success in inducing early ovulation in seasonally anovulatory mares with a combination of estradiol pretreatment followed by daily administration of a dopamine antagonist (sulpiride). Although every-other-day injections of estradiol benzoate (EB) were effective in that experiment, practical application of this technology would require simplification of the treatment regimen. The current experiment was designed to compare, in a gelding model, the biologic responses of two alternative, one-injection regimens for estradiol delivery to the established EB treatment used previously. Fifteen long-term geldings were sampled via jugular venipuncture from November 5 to 7, 2006, and were then administered intramuscular injections of vegetable oil (n = 4); EB, 11 mg in oil (n = 4; controls); EB in biodegradable microspheres (300 mg; n = 3); or estradiol cypionate, 100 mg in oil (n = 4). Injections of EB in oil were repeated every other day for a total of 10 injections, as was done in our previous experiment. Jugular blood samples were drawn from all geldings at 3, 6, 12, 24, 36, and 48 hours relative to injections, and then on the mornings of days 3, 4, 6, 8, 10 to 18, 22, 26, and 30. On days 10 through 13, all geldings received subcutaneous injections of 125 mg sulpiride, a dopamine receptor antagonist, to stimulate prolactin secretion. On day 12, each gelding received an intravenous injection of 30 μg gonadotropin-releasing hormone (GnRH) analog and 3 mg thyrotropin-releasing hormone (TRH); frequent blood samples were drawn to characterize the luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin responses. Relative to geldings receiving oil, all geldings receiving estradiol injections had a rise (P < .05) in estradiol concentrations lasting at least 12 days. Daily LH concentrations increased (P < 0.01) in all treated groups, but the response was delayed approximately 14 days in the geldings receiving EB in microspheres. Daily FSH concentrations decreased (P < .01) in all treated groups, with the greatest response in the geldings receiving EB in microspheres. Prolactin in daily samples increased (P < .01) similarly in all estradiol-treated groups after injection of sulpiride. The LH response to GnRH analog was greatest (P < .05) in geldings receiving EB in oil and estradiol cypionate; the FSH response was not altered by treatment. The prolactin response to TRH was greater (P < .01) in estradiol-treated geldings relative to controls, but did not differ among groups. Compared with the responses to every-other-day EB injections in oil, as we used previously, a single injection of 100 mg estradiol cypionate gave the most similar and consistent responses. Because of these similar responses in this gelding model, it is likely that a single injection of 100 mg estradiol cypionate can be used in lieu of every-other-day injections of EB in oil in the treatment regimen we reported previously for stimulating ovarian activity in seasonally anovulatory mares.     

The Effect of Sulpiride Treatment During the Periovulatory Period on Prolactin Concentration and Ovulation in the Mare

Sixteen estrous cycles from 10 cyclic mares were randomly assigned to a control or sulpiride group (n = 8 each). All mares received 1,500 IU of human chorionic gonadotropin (hCG) (hour 0) during estrus with a follicular diameter ≥32 mm. Mares were scanned every 12 hours until ovulation. In the treatment group, beginning at hour 0, each mare received 1.5 mg/kg of sulpiride every 12 hours intra-muscularly until ovulation or formation of a luteinized unruptured follicle (LUF). Concentrations of luteinizing hormone (LH) and prolactin (PRL) were measured by radioimmunoassay. In each group, there were 10 preovulatory follicles for the eight cycles. The ovulation rate (9/10, 90%) was similar in the control and sulpiride groups. Two mares formed an LUF, which was first detected at hours 48 and 72 for the sulpiride and control mares, respectively. The interval from hCG to ovulation was 49.5 ± 11.1 and 43.5 ± 5.8 hours, for the control and sulpiride groups, respectively (P > .5). LH followed the typical preovulatory surge pattern, with no difference between groups (P > .5). Sulpiride administration increased PRL concentration in treated mares at 24 (P < .1), 36, and 48 hours (P < .05) after treatment. In conclusion, sulpiride administration every 12 hours increased PRL concentration in treated mares after 24 hours of the beginning of treatment. However, at this time window and concentration, PRL did not have any effect on ovulation. The control mare that developed an LUF had a PRL concentration similar to other ovulatory control mares (always ≤10 ng/mL).     

Estradiol interactions with dopamine antagonists in mares: Prolactin secretion and reproductive traits

Two experiments studied the effects of pretreatment with estradiol benzoate before treatment with a dopamine antagonist on prolactin secretion and reproductive traits in mares during (1) the seasonal anovulatory period and (2) the normal breeding season. Experiment 1 was performed in winter with 17 mares selected for low follicular activity. Nine mares received estradiol benzoate injections every other day for a total of 10 injections; 8 mares received similar injections of vehicle. Ten days after onset of injections, all mares were placed on daily injections of sulpiride (250 mg) for 35 days or until ovulation. Plasma prolactin concentrations were higher (P < .001) in mares receiving estradiol than in controls for all assessments from days 12 through 36. Plasma luteinizing hormone (LH) concentrations were also increased (P < .05) by estradiol treatment from days 14 to 23. Mean day of first ovulation was 73.6 for control mares and 29.0 for estradiol-treated mares (P = .016). Estradiol treatment greatly enhanced prolactin secretion in response to sulpiride and increased LH secretion in seasonally anovulatory mares, which together hastened the date of first ovulation by an average of 45 days. Experiment 2 was designed to assess the efficacy of a long-acting, single-injection microparticle preparation of another dopamine antagonist, domperidone, for increasing prolactin secretion in cyclic mares in the summer. The experimental design and procedures used in experiment 1 were repeated, except that a single 3-g domperidone-microparticle injection was administered on day 11 rather than 45 days of sulpiride injections. Day 0 was the first day of estrus for each mare. Prolactin concentrations were higher (P < .05) in mares receiving estradiol than in control mares from days 12 through 25 and after a thyrotropin-releasing hormone injection on d 21. Estrous cycle traits (time to ovulation and time of luteal regression) were not affected (P > .1) by treatment. Estradiol enhanced the prolactin response to a single injection of 3 g domperidone in cyclic mares in the summer in a manner similar to the estradiol enhancement of prolactin secretion in response to daily sulpiride injections in anovulatory mares in winter. Thus, the single injection of domperidone could possibly replace the daily sulpiride injections used in experiment 1 to induce ovulation in seasonally anovulatory mares; this needs to be tested in future experiments.     

Long-term Treatment of Insulin-insensitive Mares with Cabergoline: Effects on Prolactin and Melanocyte Stimulating Hormone Responses to Sulpiride and on Indices of Insulin Sensitivity

The main experiment assessed whether the inhibitory effects of the dopamine agonist, cabergoline, on prolactin and α-melanocyte stimulating hormone (MSH) concentrations would persist throughout a longer-term administration (65 days). The possible effect of cabergoline on insulin sensitivity was also studied. Ten mares known to be insulin insensitive were allotted to two groups (treated vs. control). An insulin challenge, a glucose tolerance test, and a sulpiride challenge were administered before treatment. On day 0, treated mares (n = 5) received an injection of 5 mg cabergoline in slow-release vehicle; control mares (n = 5) received an equivalent vehicle injection. Injections were repeated every 10 days for a total of seven injections. Sulpiride challenges were done 1 day before each cabergoline treatment to assess possible refractoriness to the treatment. Behavior and hair coat density were also monitored. Plasma prolactin was suppressed (P < .01) to undetectable levels in mares receiving cabergoline; control mares had robust prolactin responses to each sulpiride injection. There was no indication of refractoriness to cabergoline over time. Plasma MSH concentrations after sulpiride were also suppressed (P < .05) by cabergoline. After treatment, neither the glucose response to insulin nor the insulin response to glucose differed (P > .1) between groups. No behavioral changes were noted because of treatment. Weight of hair samples indicated that cabergoline perturbed (P < .05) winter coat growth. It is concluded that 5 mg of cabergoline in slow-release vehicle administered every 10 days is an effective way of delivering dopaminergic activity to mares that results in no noticeable detrimental effects and no refractoriness to the drug.     

Pharmacokinetics of Sulpiride After Intravenous,Intramuscular, and Oral Single-Dose Administration in Nurse Mares

Sulpiride (SLP) is an antipsychotic drug used in humans. Although no pharmacokinetic data are available for horses, it is commonly used to encourage ovulation in noncycling mares and to stimulate lactation in adoptive mares. The aim of this study is to assess the pharmacokinetics profile of SLP after intravenous (IV), intramuscular (IM), and oral (PO) administrations in normal horses. Animals (n = 6) were treated with 1 mg/kg SLP, administered by IV, IM, and PO routes according to a randomized crossover design (3 × 3 Latin square). Blood samples (5 mL) were collected at a programmed time and analyzed using a validated with fluorescence detection method. SLP was present at a detectable concentration up to 24 hours postadministration for all routes, except for one animal in the PO group. IV and IM administrations gave similar curves, with an IM average bioavailability of 118.0%. These high values were mainly the result of the profile generated by two horses, in which a secondary concentration peak occurred in the terminal phase of the curve. After PO administration, AUC_0-∞, and consequently bioavailability (20.4%), was low. This finding could be owing to the physicochemical features of the drug. Indeed, considering that SLP is a weak base, existing in the ionized form at gastric and physiological pH, it is unsurprising that it is poorly absorbable, especially in horses with a particularly acidic gastric pH. In conclusion, injective routes are definitely preferable to PO dosing because of the low bioavailability using this route.     

Assessment of Uterine Vascular Perfusion During the Estrous Cycle of Mares in Connection to Circulating Leptin and Nitric Oxide Concentrations

The objective of this study was to find difference in vascular perfusion of uterine horns or uterine body throughout the estrous cycle and their relation to circulating nitric oxide and leptin concentrations. Five cyclic mares were subjected to transrectal Doppler ultrasonography and blood sampling for 18 days. Area of color and power Doppler modes was measured in pixels. Day (P = .0001) of the estrous cycle and ovulation (P = .0001) influenced uterine blood flow. Uterine body blood flow directed away from the transducer (blue, P = .0001) increased from day −5 until day 0 (day of ovulation), and its power (P = .0001) blood flow increased from day −6 until day 0; then, both decreased until days 12 and 10, respectively. Conversely to the contralateral uterine horn, ipsilateral uterine horn blood flow directed away from the transducer (blue, P = .0001) increased from day −5 until day −1, and its power (P = .0001) blood flow increased from day −6 until day 0; then, both decreased until day 10. Nitric oxide concentrations (P = .0001) attained two major peaks; the first on day −3 and the other persisted from day 2 until day 5. Leptin concentrations increased (P > .001) with a maximum value on day 0 and then decreased until a minimum value on day 9. In conclusion, during the estrous cycle, ipsilateral uterine horn and uterine body blood vessels had similar blood flow. Both leptin and nitric oxide played a role during follicle growth, ovulation, and corpus luteum development and modulated uterine blood flow before and after ovulation.     

Stimulation of Ovulation in Seasonally Anovulatory and Vernal Transitional Mares with Estradiol and Domperidone: Dose and Combination Studies

Three experiments were conducted to test the efficacy of different doses of estradiol cypionate (ECP) and domperidone for inducing ovulation in seasonally anovulatory (January; Experiments 1 and 2) and transitional period (March; Experiment 3) mares. In the first two experiments, mares in Kentucky and Louisiana were administered domperidone (3 g in biodegradable particles) alone or after pretreatment with 100 or 150 mg of ECP; another group received ECP, domperidone, and progesterone, and a fifth group received ECP and progesterone only (the latter two in Kentucky). Control mares in both states received no treatment. The proportion of mares ovulating within 35 days (for mares treated in January) was greater (P = .0002) for those receiving any combination of ECP plus domperidone relative to mares not receiving the combined treatment. Addition of progesterone to ECP plus domperidone did not enhance (P = .7) the response relative to the combination alone; domperidone by itself, or ECP plus progesterone, did not alter the response relative to controls (P > .24). Experiment 3 was conducted in Louisiana as a 2 × 3 factorial, with two doses of domperidone (1.5 or 3 g) and three doses of ECP (0, 75, or 150 mg). There was no main effect of domperidone or ECP dose; a greater proportion (P = .055) of mares receiving any combination of ECP plus domperidone ovulated in 21 days compared with those receiving no ECP. In conclusion, pretreatment with ECP before injection of domperidone 10 days later can be used to increase the proportion of mares ovulating early in the year; within the limits of the present experiments, there appears to be no difference in doses of ECP of 75, 100, or 150 mg, and no difference in doses of domperidone of 1.5 or 3 g.     

蒙古利亚矮种母马垂体促性腺激素的血清含量与妊娠状态和年龄的相关性

选用 10匹 4～ 16岁怀孕和 2 2匹 0 5～ 17岁非怀孕的蒙古利亚矮种母马 ,采用放射免疫法分别测定了其血清中FSH和LH的浓度。其结果显示 ,妊娠母马的血清FSH和LH含量分别为 0 3 0 83mIU /ml± 0 1611mIU/ml和 0 65 67mIU /ml± 0 40 61mIU/ml,显著低于非妊娠母马的 2 40 5 9mIU/ml± 0 64 46mIU /ml和 2 3 85 5mIU /ml± 0 3 5 2 9mIU/ml(P <0 0 5 ) ;此外 ,3～ 8岁组、10～ 14岁组和 15岁以上组非妊娠母马血清FSH和LH含量分别为 2 44 0 0mIU /ml±0 780 0mIU /ml、2 40 0 0mIU/ml± 1 3 0 78mIU /ml、5 3 75 0mIU/ml± 0 885 0mIU /ml和 1 840 0mIU/ml± 0 80 0 0mIU /ml、2 5 92 9mIU/ml± 0 5 93 0mIU/ml、3 975 0mIU /ml± 0 485 0mIU/ml。以上结果表明 ,在妊娠阶段 ,母马血清中的FSH和LH显著降低 ,而繁殖季节的非妊娠母马血清FSH和LH的浓度却随着母马的老年化而呈现增加的趋势。     

The Level of Prolactin,Serum Amyloid A,and Selected Biochemical Markers in Mares Before and After Parturition and Foal Heat

The aim of the study was to determine the level of prolactin (PRL), serum amyloid A (SAA), and selected biochemical markers (T-Chol, AST, TP, Mg²⁺, P⁺, and Ca²⁺) in the blood of mares during the perinatal period. The study involved 14 mares of the Polish Coldblood Horse breed, which were in the third trimester of pregnancy. Blood was collected for testing 2 weeks before parturition and then 24 hours after delivery and in the foal heat (9 days) and 9 days after ovulation and breeding. The research revealed significant differences in the level of PRL and SAA before and after delivery. The highest PRL level was found 24 hours after delivery, lowest in foal heat and 9 days after ovulation. Serum amyloid A concentration was within the accepted norms; however, on day 9 after foaling, a significant increase of this protein was observed. All biochemical markers were within physiological limits. However, significant increases in T-Chol, AST, and TP levels was observed 24 hours after the delivery, whereas in foal heat and after ovulation levels of T-Chol and TP significantly decreased and the AST level remained at a similar level. There were no significant changes in electrolyte levels such as Mg²⁺, P⁺, and Ca²⁺. The pregnancy rate in the foal heat was at 43%. Collectively, the results of this study in conjunction with clinical observations demonstrated that when the perinatal period was normal, no disturbances in health related to pregnancy, parturition, lactation, and reproductive status during the postpartum period were found.     

Changes in plasma melanocyte-stimulating hormone,ACTH, prolactin,GH, LH,FSH, and thyroid-stimulating hormone in response to injection of sulpiride,thyrotropin-releasing hormone,or vehicle in insulin-sensitive and -insensitive mares

Six insulin-sensitive and 6 insulin-insensitive mares were used in a replicated 3 by 3 Latin square design to determine the pituitary hormonal responses (compared with vehicle) to sulpiride and thyrotropin-releasing hormone (TRH), 2 compounds commonly used to diagnose pituitary pars intermedia dysfunction (PPID) in horses. Mares were classified as insulin sensitive or insensitive by their previous glucose responses to direct injection of human recombinant insulin. Treatment days were February 25, 2012, and March 10 and 24, 2012. Treatments were sulpiride (racemic mixture, 0.01 mg/kg BW), TRH (0.002 mg/kg BW), and vehicle (saline, 0.01 mL/kg BW) administered intravenously. Blood samples were collected via jugular catheters at −10, 0, 5, 10, 20, 30, 45, 60, 90, and 120 min relative to treatment injection. Plasma ACTH concentrations were variable and were not affected by treatment or insulin sensitivity category. Plasma melanocyte-stimulating hormone (MSH) concentrations responded (P < 0.01) to both sulpiride and TRH injection and were greater (P < 0.05) in insulin-insensitive mares than in sensitive mares. Plasma prolactin concentrations responded (P < 0.01) to both sulpiride and TRH injection, and the response was greater (P < 0.05) for sulpiride; no effect of insulin sensitivity was observed. Plasma thyroid-stimulating hormone (TSH) concentrations responded (P < 0.01) to TRH injection only and were higher (P < 0.05) in insulin-sensitive mares in almost all time periods. Plasma LH and FSH concentrations varied with time (P < 0.05), particularly in the first week of the experiment, but were not affected by treatment or insulin sensitivity category. Plasma GH concentrations were affected (P < 0.05) only by day of treatment. The greater MSH responses to sulpiride and TRH in insulin-insensitive mares were similar to, but not as exaggerated as, those observed by others for PPID horses. In addition, the reduced TSH concentrations in insulin-insensitive mares are consistent with our previous observation of elevated plasma triiodothyronine concentrations in hyperleptinemic horses (later shown to be insulin insensitive as well).     

Effect of Repeated Cabergoline Treatment on the Vernal Transition and Hair Shedding of Mares (Year 1) and a Subsequent Comparison of the Effect of Starting Date on Prolactin Suppression (Year 2)

Two studies were conducted to determine efficacy of cabergoline for suppressing prolactin (PRL) and the possible effects on vernal transition in mares. In experiment 1, six mares each received either vehicle or cabergoline (5 mg, intramuscularly) every 10 days for 12 treatments beginning February 4, 2013. Blood samples were drawn regularly, and mares were challenged with sulpiride periodically to assess PRL suppression. Weekly hair samples were obtained to determine shedding. Prolactin was suppressed (P < .05) by cabergoline, but suppression waned in spring. There was no effect (P > .05) of treatment on day of first ovulation, luteinizing hormone, or follicle stimulating hormone. Hair shedding was generally suppressed (P = .05). In 2014 (experiment 2), eight of the same 12 mares were used in a similar experiment to determine if the rise in PRL observed in experiment 1 was due to refractoriness to cabergoline or perhaps another factor. Treatment began on April 6, 2014, corresponding to the increase in PRL in treated mares in experiment 1. Mares were treated with cabergoline or vehicle until June 5. Prolactin was suppressed (P < .05) by cabergoline, and the pattern of apparent escape from suppression was similar to year 1. We conclude that (1) cabergoline at this dose alters hair shedding but does not alter the time of first ovulation in mares and (2) relative to our previous reports of cabergoline treatment in the fall, there is a seasonal effect on the ability of this dose of cabergoline to suppress unstimulated PRL secretion.     

西藏高原环境条件下内江母猪性周期中生殖激素含量的测定

测定了西藏高原环境条件下内江母猪性周期FSH、LH、E2、P4的含量,探讨了高原环境对母猪生殖内分泌的影响.内江母猪LH峰出现在周期1d,在3d可见LH的上升,达到另一小峰;FSH的分泌无明显规律,在周期15d出现FSH峰,在2d出现另一小峰;E2在LH峰前1d达到最大值(20.509±6.636)pg/mL;P4变化具有明显的规律性,P4峰产生于13d, P4基础浓度及峰值均显著高于平原其它猪种近2～3倍.     

Some Remarks on Repeatability and Heritability of the Bascule Technique in Jumping Horses

The genetic characteristics of jumping enable a correct selection program. Linear parameters of the jump were measured by video image analysis with and without the rider. Repeatability and heritability were calculated based on the statistical model using DMUAI, including effects of the year, month of training, obstacle height, horse conformation, and rider (if necessary). The highest repeatabilities were noted for the position of head and reached 0.45–0.56 for head position in comparison to withers and 0.48–0.55 in comparison to croup. Results varied between parameters with and without riders. Repeatability under rider was slightly higher, the opposite trend was observed in heritability. It seems that the relation of head to the rest of the body has higher heritability than the height of the head above the obstacle itself.     

Use of a Mycobacterial Cell Wall Extract (MCWE) in Susceptible Mares to Clear Experimentally Induced Endometritis With Streptococcus zooepidemicus

The ability of an immunomodulator, mycobacterial cell wall extract (MCWE), to clear uterine infection in susceptible mares after an experimental challenge withStreptococcus zooepidemicus was evaluated. Thirty mares susceptible to endometritis, based on the presence of uterine fluid during both diestrus and estrus, were selected from a herd of 896 and inoculated with a live culture of 5 × 10⁶ CFU of S. zooepidemicus on day 1 of estrus. Twenty-four hours later, mares were evaluated by ultrasonography, bacteriology, exfoliative cytology, and uterine biopsy to confirm infection. Forty-eight hours after inoculation, and on confirmation of uterine infection, mares were randomly assigned to one of four unbalanced experimental treatments to receive 1500 μg MCWE IU (n = 10) or IV (n = 10), or placebo IU (n = 5) or IV (n = 5). Mares were examined at ovulation and 7 days post-ovulation for uterine fluid via transrectal ultrasonography and for bacteriology, exfoliative cytology, and uterine biopsy. Efficacy was based on the ability of the mare to clear endometritis as determined by negative bacteriology and reduced numbers of polymorphonuclear cells (PMNs) on uterine biopsy. Because no statistical difference was detected between routes of administration on day 7 post-ovulation, the data sets were combined and re-analyzed to evaluate overall efficacy. Endometritis was observed in all placebo-treated mares 7 days post-ovulation, whereas treatment with MCWE resulted in the elimination of endometritis in 35% of the mares by the time of ovulation, and 70% of the mares by 7 days post-ovulation. Treatment with MCWE, compared with the placebo group, resulted in a significant decrease in the number of mares positive for endometritis at ovulation based on exfoliative cytology and bacteriology (P < .01) and at 7 days post-ovulation based on biopsy, exfoliative cytology, and bacteriology (P < .001). Results indicate that MCWE was an effective treatment for the elimination of endometritis caused by S. zooepidemicus in mares.     

Repeatability of a telephone questionnaire on cat-ownership patterns and pet-owner demographics evaluation in a community in Texas, USA

The repeatability of a telephone questionnaire on cat-ownership patterns, demographics and attitudes towards homeless cats in a community was evaluated. Randomly selected households (n = 100) within Caldwell, Texas, were included in the study. The response percentage was 84% (100/119) among those contacted and 75% (100/134) among all eligible respondents. Repeatability was measured by administering the same survey twice to the first 100 responding subjects, with an average (range) of 48 (25–64) days between interviews. The survey was initially administered from 6 June to 28 June 2005 and the follow-up survey was administered from 19 July to 11 August 2005. Repeatability for most cat-ownership characteristics was fair to good between the two interviews (kappa 0.47–0.82). Knowledge of companion animals and subject attachment to pet questions had good correlations between the two interviews (r_sp 0.52 and 0.60, respectively). Subject-demographic questions had excellent repeatability (kappa 0.66–1.00).