Kisspeptin‐10 stimulates the release of luteinizing hormone and testosterone in pre‐ and post‐pubertal male goats

The aims of the present study were to clarify the effect of kisspeptin‐10 (Kp10) on the secretion of luteinizing hormone (LH) and testosterone (T) in pre‐pubertal and post‐pubertal male ruminants. Four male goats (Shiba goats) were given an intravenous (i.v.) injection of Kp10 (5 µg/kg body weight (b.w.)), gonadotoropin‐releasing hormone (GnRH, 1 µg/kg b.w.), or 2 mL of saline as a control at the ages of 3 (pre‐pubertal) and 6 (post‐pubertal) months. A single i.v. injection of Kp10 significantly stimulated the release of LH and T in both groups. The area under the response curve (AUC) of LH for a 60‐min period after the i.v. injection of Kp10 was significantly greater in the pre‐pubertal goats (P < 0.05). The AUC of T for a 120 min period post‐injection did not differ between the two age groups. A single i.v. injection of GnRH also significantly stimulated the release of LH and T in both groups (P < 0.05). The secretory pattern of LH and T in response to GnRH resembled that in response to Kp10. These results show that the LH‐releasing response to Kp10 is greater in pre‐pubertal than post‐pubertal male goats. They also show that Kp10, as well as GnRH, is able to stimulate the release of T in male goats.     

Oral pharmacokinetics of acetaminophen to evaluate gastric emptying profiles of Shiba goats

The pharmacokinetics of acetaminophen was investigated following oral dosing to Shiba goats in order to evaluate the properties of gastric emptying. Acetaminophen was intravenously and orally administered at 30 mg/kg body weight to goats using a crossover design with a 3-week washout period. The stability of acetaminophen in rumen juice was also assessed. Acetaminophen concentrations were measured by HPLC. Since acetaminophen was stable in rumen juice for 24 hr, the extremely low bioavailability (16%) was attributed to its hepatic extensive first-pass effect. The mean absorption time and absorption half-life were unexpectedly short (4.93 and 3.35 hr, respectively), indicating its marked absorption from the forestomach, which may have been due to its smaller molecular weight. Therefore, acetaminophen was considered to be unsuitable for evaluating gastric emptying in Shiba goats.     

Supplementing organic-complexed or inorganic Co,Cu, Mn,and Zn to beef cows during gestation: physiological and productive response of cows and their offspring until weaning

One hundred and ninety non-lactating, pregnant beef cows (three-fourth Bos taurus and one-fourth Bos indicus; 138 multiparous and 52 primiparous) were assigned to this experiment at 117 ± 2.2 d of gestation (day 0). Cows were ranked by parity, pregnancy type (artificial insemination = 102 and natural service = 88), body weight (BW), and body condition score (BCS) and assigned to receive a supplement containing: 1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 95) or 2) an organic-complexed source of Cu, Mn, Co, and Zn (AAC; Availa 4; Zinpro Corporation, Eden Prairie, MN; n = 95). The INR and AAC provided the same daily amount of Cu, Co, Mn, and Zn, based on 7 g of the AAC source. From day 0 to calving, cows were maintained in a single pasture and were segregated three times weekly into 1 of the 24 individual feeding pens to receive treatments. Cow BW and BCS were recorded on days −30, 97, upon calving, and at weaning (day 367). Milk production was estimated at 42 ± 0.5 d postpartum via weigh–suckle–weigh (WSW) method. Liver biopsies were performed in 30 cows per treatment on days −30, 97, upon calving, and the day after WSW. Calf BW was recorded at birth and weaning. Liver and longissimus muscle (LM) biopsies were performed in 30 calves per treatment upon calving and 24 h later, the day after WSW, and at weaning. No treatment effects were detected (P ≥ 0.49) for cow BCS during gestation, despite AAC cows having greater (P = 0.04) BW on day 97. Liver Co concentrations were greater (P < 0.01) for AAC compared with INR cows, and liver concentrations of Cu were greater (P = 0.02) for INR compared with AAC cows on day 97. Upon calving, INR cows had greater (P ≤ 0.01) liver Cu and Zn concentrations compared with AAC cows. No other treatment differences were noted (P ≥ 0.17) for cow and calf liver trace mineral concentrations. Cows receiving AAC had greater (P = 0.04) hepatic mRNA expression of metallothionein 1A at calving, and their calves had greater (P = 0.04) hepatic mRNA expression of superoxide dismutase at weaning. Milk production did not differ between AAC and INR cows (P = 0.70). No treatment effects were detected (P ≥ 0.29) for mRNA expression of LM genes associated with adipogenic or muscle development activities in calves at birth and weaning. Calf birth and weaning BW also did not differ (P ≥ 0.19) between treatments. In summary, supplementing AAC or INR to beef cows during the last 5 mo of gestation yielded similar cow–calf productive responses until weaning.     

Experimental infection of pregnant goats with bovine viral diarrhea virus (BVDV) 1 or 2

Infections with bovine viral diarrhea virus (BVDV) of the genus pestivirus, family Flaviviridae, are not limited to cattle but occur in various artiodactyls. Persistently infected (PI) cattle are the main source of BVDV. Persistent infections also occur in heterologous hosts such as sheep and deer. BVDV infections of goats commonly result in reproductive disease, but viable PI goats are rare. Using 2 BVDV isolates, previously demonstrated to cause PI cattle and white-tailed deer, this study evaluated the outcome of experimental infection of pregnant goats. Pregnant goats (5 goats/group) were intranasally inoculated with BVDV 1b AU526 (group 1) or BVDV 2 PA131 (group 2) at approximately 25–35 days of gestation. The outcome of infection varied considerably between groups. In group 1, only 3 does became viremic, and 1 doe gave birth to a stillborn fetus and a viable PI kid, which appeared healthy and shed BVDV continuously. In group 2, all does became viremic, 4/5 does aborted, and 1 doe gave birth to a non-viable PI kid. Immunohistochemistry demonstrated BVDV antigen in tissues of evaluated fetuses, with similar distribution but reduced intensity as compared to cattle. The genetic sequence of inoculated viruses was compared to those from PI kids and their dam. Most nucleotide changes in group 1 were present during the dam’s acute infection. In group 2, a similar number of mutations resulted from fetal infection as from maternal acute infection. Results demonstrated that BVDV may cause reproductive disease but may also be maintained in goats.     

Trace amounts of antibiotic exacerbated diarrhea and systemic inflammation of weaned pigs infected with a pathogenic Escherichia coli

The experiment was conducted to investigate the effects of trace amounts of antibiotic on growth performance, diarrhea, systemic immunity, and intestinal health of weaned pigs experimentally infected with an enterotoxigenic Escherichia coli. Weaned pigs (n = 34, 6.88 ± 1.03 kg body weight [BW]) were individually housed in disease containment rooms and randomly allotted to one of the three dietary treatments: nursery basal diet (CON) and two additional diets supplemented with 0.5 or 50 mg/kg carbadox to the nursery basal diet (TRA or REC), respectively. The experiment lasted 18 d with 7 d before and 11 d after the first E. coli inoculation. The E. coli F18 inoculum was orally provided to all pigs with a dose of 10¹⁰ colony-forming unit (CFU)/3 mL for three consecutive days. Fecal and blood samples were collected on day 0 before inoculation and days 2, 5, 8, and 11 postinoculation (PI) to test the percentage of β-hemolytic coliforms in total coliforms and complete blood cell count, respectively. Sixteen pigs were euthanized on day 5 PI, whereas the remaining pigs were euthanized at the end of the experiment to collect the jejunal and ileal mucosa and mesenteric lymph node for gene expression and bacterial translocation, respectively. Pigs in REC had greater (P < 0.05) final BW and lower (P < 0.05) overall frequency of diarrhea compared with pigs in the CON and TRA groups. Pigs in TRA had the lowest (P < 0.05) average daily gain and feed efficiency from day 0 to 5 PI, highest (P < 0.05) percentage of β-hemolytic coliforms in fecal samples on days 2 and 5 PI, and greatest (P < 0.05) bacterial colonies in mesenteric lymph nodes on day 11 PI compared with pigs in the CON and REC groups. Pigs in TRA had the greatest (P < 0.05) neutrophils on day 5 PI and higher (P < 0.05) white blood cell counts and lymphocytes than other groups on day 11 PI. Pigs in TRA had the greatest (P < 0.05) serum C-reactive protein on days 2 and 5 PI and serum tumor necrosis factor-α on day 5 PI, compared with pigs in the CON and REC groups. Pigs fed REC had increased (P < 0.05) mRNA expression of zona occludens-1 (ZO-1) and occludin (OCDN) and reduced (P < 0.05) interleukin-1 beta (IL1B), interleukin-6 (IL6), and tumor necrosis factor-alpha (TNFA) in ileal mucosa on day 5 PI, compared with the CON, whereas TRA upregulated (P < 0.05) mRNA expression of IL1B, IL6, and cyclooxygenase-2 (COX2) in the ileal mucosa on day 11 PI, compared with the REC. In conclusion, trace amounts of antibiotic may exacerbate the detrimental effects of E. coli infection on pig performance by increasing diarrhea and systemic inflammation of weanling pigs.     

Colour Doppler ultrasound imaging of blood flows variations in neoplastic and non‐neoplastic testicular lesions in dogs

Testicular tumours are the most common neoplasms in male dogs accounting for approximately 90% of all tumours affecting the genitourinary tract. Gray‐scale ultrasonography in combination with colour and power Doppler imaging has been well accepted as an accurate technique for assessing scrotal lesions and vascularization of the testis. Colour Doppler sensitivity for low blood flows appears promising in the study of testicular disorders. The aim of this study was to assess if colour and power Doppler ultrasound is a good tool for the investigation of testicular lesions in dogs, to report the sonographic features of lesions and to measure colour and power Doppler parameters such as resistive index (RI), pulsatility index (PI), hypovascularization and hypervascularization (VI) determining if they can be used to distinguish testicular neoplasms from the wide spectrum of non‐neoplastic pathological findings. In this study, 50 male dogs of various breeds, aged between 7 and 14 years, presented with testicular disorders were selected. RI and PI were calculated. Mean RI values for neoplastic, inflammatory and degenerative lesions were 0.54, 0.45 and 0.58, respectively. Mean PI values were 0.62, 0.55 and 0.63, respectively. Hypovascularization and hypervascularization of the lesion were evaluated throughout the vascularity index (VI). Vascular signals in neoplasms were significantly intensified around and inside the mass if compared with those measured during inflammatory and degenerative lesions. VI markedly increased in solid tumours. Pathological testes were removed; macroscopical, histological and immunoistochemical evaluations were carried out. Colour Doppler showed increased intralesional and peripheral flows in all neoplastic lesions analysed. No flows were detected around cysts.     

Oral pharmacokinetics of the acidic drugs,diclofenac and sulfamonomethoxine in male Shiba goats

In the present study, we examined the oral pharmacokinetics of the acidic drugs, diclofenac (DF) and sulfamonomethoxine (SMM), which have different physicochemical properties, in Shiba goats. DF and SMM were intravenously and orally administered to 5 male goats using a crossover design. The T_max of DF and SMM were reached 1.5 and 5.6 hr after they have been orally administered, respectively, and this was followed by their slow elimination. The elimination of both drugs was markedly faster after being intravenously rather than orally administered, which indicated flip-flop phenomena after the oral administration. The mean absorption times (MATs) of DF and SMM were 6 and 15 hr, respectively. This slow absorption may have been due to slow gastric emptying in goats. The large difference observed in MATs between DF and SMM may have been because DF, which is more lipophilic than SMM, was partly absorbed from the forestomach. Therefore, these results suggest that the absorption of highly lipophilic drugs from the forestomach may be markedly high in Shiba goats. In case of drugs whose elimination is quite fast, their efficacies may appear from the early stage after oral administration even in ruminants, because elimination rate is the determinant factor of T_max in flip-flop phenomena. Such drugs may be used orally even in ruminants.     

Differential Effects of Continuous Exposure to the Investigational Metastin/Kisspeptin Analog TAK-683 on Pulsatile and Surge Mode Secretion of Luteinizing Hormone in Ovariectomized Goats

The aim of the present study was to determine if the estradiol-induced luteinizing hormone (LH) surge is influenced by the constant exposure to TAK-683, an investigational metastin/kisspeptin analog, that had been established to depress the pulsatile gonadotropin-releasing hormone (GnRH) and LH secretion in goats. Ovariectomized goats subcutaneously received TAK-683 (TAK-683 group, n=6) or vehicle (control group, n=6) constantly via subcutaneous implantation of an osmotic pump. Five days after the start of the treatment, estradiol was infused intravenously in both groups to evaluate the effects on the LH surge. Blood samples were collected at 6-min intervals for 4 h prior to the initiation of either the TAK-683 treatment or the estradiol infusion, to determine the profiles of pulsatile LH secretion. They were also collected at 2-h intervals from –4 h to 32 h after the start of estradiol infusion for analysis of LH surges. The frequency and mean concentrations of LH pulses in the TAK-683 group were remarkably suppressed 5 days after the start of TAK-683 treatment compared with those of the control group (P<0.05). On the other hand, a clear LH surge was observed in all animals of both groups. There were no significant differences in the LH concentrations for surge peak and the peak time of the LH surge between the TAK-683 and control groups. These findings suggest that the effects of continuous exposure to kisspeptin or its analog on the mechanism(s) that regulates the pulsatile and surge mode secretion of GnRH/LH are different in goats.     

Follicular Development and Ovulation in Sows: Effect of hCG and GnRH Treatment

Follicular growth, chronology of ovulation and embryo morphology were compared in sows ovulating spontaneously and sows, in which the ovulation was attempted induced by hCG or GnRH.Indwelling catheters were placed on day 1 (weaning = day 0) in the ear veins of 18 sows, which were then randomly divided into 3 groups: a control group (N = 6), a group (N = 6) given 750 iu hCG (Physex®) im 76h after weaning (hCG group) and a group (N = 6) given 500 µg GnRH (Fertagyl®) im 76h (N = 3) or 100h after weaning (N = 3) (GnRH group). Follicular diameter and time of ovulation were monitored by ultrasonography every 4h from day 3 until ovulation or development of cysts by means of a sector scanner fitted with a 5.0/7.5 MHz multiangle probe. Heat detection was performed every 8h from day 3 until ovulation. On day 13, the sows were slaughtered, the number of corpora luteae (CL) was counted, and embryos were flushed from the uteri. The control group showed clear heat symptoms, and on day 3, the follicles were typically 3–7 mm and grew up to 7–10 mm over 2 days, where they remained for approximately 24h until ovulation took place 41h ± 9h after first sign of standing heat. The hCG group exhibited no signs of heat, and the follicles only reached 5–8 mm in diameter at time of ovulation, which occurred 40h ± lh after hCG-injection. The GnRH group exhibited inconsistent signs of heat, and the follicles reached a maximum size of 7–12 mm in diameter where they remained for more than 24h. Only 2 sows in this group ovulated within 84–92h after the GnRH injection, and development of bursa cysts and cystic follicles was a common finding. The average number of CL was 18.2 ±5.7 per sow (N = 16, range: 3–27) with no significant difference between the groups. Total embryo recovery was 79 ± 13 % with no significant difference between groups. The embryo diversity calculated as standard deviation of the maximum diameter was higher in the hCG group as compared with the control group.It is concluded that (1) transrectal ultrasonography can be used in sows for accurate assessment of follicular growth and ovulation; (2) the use of hCG results in lack of heat symptoms and reduced follicle size at the time of ovulation when injected 76h after weaning; (3) administration of a single injection of GnRH, if given before the first signs of heat, results in inconsistent heat symptoms and no or late ovulations.     

The fate and tissue disposition of deoxynivalenol in broiler chickens

To evaluate the fate of deoxynivalenol (DON) in broilers, DON was administered either intravenously or orally to broilers at a dose of 1 mg/kg BW. Concentrations of DON in plasma were measurable up to 4 hr and 2 hr after intravenous and oral administration, respectively. Following intravenous administration, the values for the elimination half-life, the volume of distribution and the clearance were 1.25 ± 0.25 hr, 7.55 ± 2.03 l/kg and 4.16 ± 0.42 l/hr/kg, respectively. The oral bioavailability was 15.46 ± 4.02%. DON was detectable in all tissues examined after oral administration. These results suggest that DON is able to penetrate into the various tissues in broilers, though poorly absorbed from their gastrointestinal tract.     

Testicular blood flow and plasma concentrations of testosterone and total estrogen in the stallion after the administration of human chorionic gonadotropin

The goal of this study was to investigate for the first time a possible association between plasma concentrations of testosterone and total estrogen and testicular blood flow in the stallion. Correlations between these variables were calculated before and after administration of human chorionic gonadotropin (hCG). Eight mature warmblood stallions received 5,000 IU hCG intravenously, and four stallions received solvent only. Testicular blood flow in the left and right testicular arteries was assessed using colour Doppler sonography by measuring blood flow volume (BFV) and pulsatility index (PI) immediately before (time 0) and 1, 3, 6, 12, 24, 72, 120 and 168 h after hCG administration. EDTA blood samples were collected after each examination from a jugular vein to measure plasma testosterone and total estrogen concentrations. After treatment, the BFV increased and was elevated at 1 h and between 12 and 24 h. The profile of the PI was contrary to that of the BFV throughout the study period. Following hCG, there was a biphasic increase in testosterone concentration with maxima between 1 and 3 h and between 24 and 72 h, and there was a monophasic increase in the total estrogen concentration with a maximum between 6 and 24 h. At time 0, the total estrogen concentration correlated significantly with BFV (r=0.90; P<0.05) but the testosterone concentration did not (P>0.05). The testosterone and total estrogen concentrations did not correlate with PI (P>0.05). The total estrogen concentration, but not testosterone, correlated well with BFV after injection of hCG (P<0.05). The results of this study indicated that the testicular blood flow volume of the stallion may be regulated by estrogens, but additional studies are necessary to investigate whether there is a causal relationship.     

Can testicular artery Doppler velocimetry values change according to the measured region in dogs?

Testicular tissue maintenance is performed by the testicular artery, and the hemodynamics of this artery can be evaluated using Doppler ultrasonography. The aim of this study was to characterize the peak systolic velocity (PSV), end diastolic velocity (EDV), pulsatility index (PI) and resistivity index (RI) of five regions of the testicular artery in dogs, including two proposed regions and three that have been previously described. Twenty‐two dogs were used, and the PSV, EDV, PI and RI of the testicular artery were measured in five regions: proximal, medial and distal supratesticular; marginal; and intratesticular. The median values for PSV (cm/s), EDV (cm/s), PI and RI in the five regions were as follows: proximal supratesticular (23.1, 3.7, 2.1 and 0.8); medial supratesticular (17.2, 4.5, 1.5, and 0.7); distal supratesticular (12.2, 5.7, 0.8, and 0.5); marginal (11.3, 6.5, 0.5, and 0.4); and intratesticular (5.7, 3.5, 0.5, and 0.4). There was a difference between the PSV of the medial and distal supratesticular regions. There were differences in the PSV, EDV, PI and RI among the distal supratesticular, marginal and intratesticular regions. Measurements of PSV, EDV, PI and RI of the testicular artery in dogs at the proposed regions showed different results due to the hemodynamic and morphological differences of the artery during its course in the spermatic cord and to the testicles. It is necessary to identify the region in testicular artery Doppler velocimetric evaluations of dogs, given that there is a difference according to the region measured.     

Examination of jackass (Equus asinus) accessory sex glands by B-mode ultrasound and of testicular artery blood flow by colour pulsed-wave Doppler ultrasound: Correlations with semen production

The accessory sex glands play a major role in the production of seminal plasma, and testicular artery blood flow seems to strongly influence testicular function. However, very little ultrasound imaging of these organs has been undertaken in donkeys. The present work reports the results of such examinations in five jackasses along the year. The accessory glands were inspected by B-mode ultrasound while the testicular artery blood flow was assessed by colour pulsed-wave Doppler ultrasound. The testicular artery was examined at pampiniform plexus (PPT), supratesticular area (ST) and capsular artery (CA). Values were recorded for the total arterial blood flow (TABF), peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), pulsatility index (PI) and time average maximum velocity (TAMV). Semen was obtained and assessed for sperm concentration, viability, abnormalities and motility using a CASA system. The bulbourethral glands, prostate and ductus deferens ampullae were relatively larger than in the stallion. Bulbourethral glands and ampullae sizes were inversely correlated with sperm motility. An reduction in blood flow between the level the PPP and the CA was observed, helping to reduce testis temperature and oxygen pressure. Blood flow at the CA showed the strongest correlation with semen production. PI and RI were positively correlated with the CASA motility variable STR (p = .02, p = .06) and sperm viability (p = .01), while sperm concentration (p = .05) correlated inversely with PSV, EDV, TAMV and TABF. EDV also correlated negatively with the CASA variables VSL, LIN, STR and VAP (p ≤ .05). PI and RI were also negatively correlated with testis length (p = .0093, p = −.0438).     

Effect of additional human chorionic gonadotrophin (hCG) on follicular growth and ovulation in gonadotrophin-treated gilts

The objective of this study was to determine the effect of additional human chorionic gonadotrophin (hCG) on the ovarian response of gilts previously treated with 200 IU hCG combined with 400 IU equine chorionic gonadotrophin (eCG) (eCG/hCG). Seventy-one prepuberal gilts (105 ± 7.5 kg) were assigned to groups: i) eCG/hCG (hCG-0; n = 25); ii) eCG/hCG followed by 100 IU of hCG at 24 h (hCG-100; n = 24); iii) eCG/hCG followed by 200 IU hCG at 24 h (hCG-200; n = 10); and iv) controls (CON; n = 12). Ovulation response was assessed by ovarian dissection or real-time ultrasonography. Additional hCG did not significantly improve numbers of gilts ovulating. Numbers of corpora lutea increased with hCG, and was higher in hCG-200 (P < 0.01). Compared to hCG-0, the frequency of cysts in gilts was higher in hCG-100 (P < 0.05) and further increased in hCG-200 (P < 0.01). The number of cysts per gilt was dose-dependently increased by additional hCG. We conclude that supplemental hCG will increase the number of corpora lutea but will be associated with follicular cyst development in a dose dependent manner.     

Dietary zinc concentration and lipopolysaccharide injection affect circulating trace minerals,acute phase protein response,and behavior as evaluated by an ear-tag–based accelerometer in beef steers

To assess plasma trace mineral (TM) concentrations, the acute phase protein response, and behavior in response to a lipopolysaccharide (LPS) challenge, 96 Angus cross steers (average initial body weight [BW]: 285 ± 14.4 kg) were sorted into two groups by BW (heavy and light; n = 48/group), fitted with an ear-tag–based accelerometer (CowManager SensOor; Agis, Harmelen, Netherlands), and stagger started 14 d apart. Consecutive day BW was recorded to start the 24-d trial (days −1 and 0). Dietary treatments began on day 0: common diet with either 30 (Zn30) or 100 (Zn100) mg supplemental Zn/kg DM (ZnSO₄). On day 17, steers received one of the following injection treatments intravenously to complete the 2 × 3 factorial: 1) SALINE (~2–3 mL of physiological saline), 2) LOWLPS: 0.25 µg LPS/kg BW, or 3) HIGHLPS: 0.375 µg LPS/kg BW. Blood, rectal temperature (RT), and BW were recorded on day 16 (−24 h relative to injection), and BW was used to assign injection treatment. Approximately 6, 24 (day 18), and 48 (day 19) h after treatment, BW, RT, and blood were collected, and final BW recorded on day 24. Data were analyzed in Proc Mixed of SAS with fixed effects of diet, injection, diet × injection; for BW, RT, dry matter intake (DMI), plasma TM, and haptoglobin-repeated measures analysis were used to evaluate effects over time. Area under the curve analysis determined by GraphPad Prism was used for analysis of accelerometer data. Body weight was unaffected by diet or injection (P ≥ 0.16), but there was an injection × time effect for DMI and RT (P < 0.05), where DMI decreased in both LPS treatments on day 16, but recovered by day 17, and RT was increased in LPS treatments 6 h post-injection. Steers receiving LPS spent less time highly active and eating than SALINE (P < 0.01). Steers in HIGHLPS spent lesser time ruminating, followed by LOWLPS and then SALINE (P < 0.001). An injection × time effect (P < 0.001) for plasma Zn showed decreased concentrations within 6 h of injection and remained decreased through 24 h before recovering by 48 h. A tendency for a diet × time effect (P = 0.06) on plasma Zn suggests plasma Zn repletion occurred at a greater rate in Zn100 compared to Zn30. These results suggest that increased supplemental Zn may alter the rate of recovery of Zn status from an acute inflammatory event. Additionally, ear-tag–based accelerometers used in this study were effective at detecting sickness behavior in feedlot steers, and rumination may be more sensitive than other variables.     

Effects of Intermittent Positive Pressure Ventilation on Cardiopulmonary Function in Horses Anesthetized with Total Intravenous Anesthesia Using Combination of Medetomidine,Lidocaine, Butorphanol and Propofol (MLBP-TIVA)

Effects of intermittent positive pressure ventilation (IPPV) on cardiopulmonary function were evaluated in horses anesthetized with total intravenous anesthesia using constant rate infusions of medetomidine (3.5 µg/kg/hr), lidocaine (3 mg/kg/hr), butorphanol (24 µg/kg/hr) and propofol (0.1 mg/kg/min) (MLBP-TIVA). Five horses were anesthetized twice using MLBP-TIVA with or without IPPV at 4-week interval (crossover study). In each occasion, the horses breathed 100% oxygen with spontaneous ventilation (SB-group, n=5) or with IPPV (CV-group, n=5), and changes in cardiopulmonary parameters were observed for 120 min. In the SB-group, cardiovascular parameters were maintained within acceptable ranges (heart rate: 33–35 beats/min, cardiac output: 27–30 l/min, mean arterial blood pressure [MABP]: 114–123 mmHg, mean pulmonary arterial pressure [MPAP]: 28–29 mmHg and mean right atrial pressure [MRAP]: 19–21 mmHg), but severe hypercapnea and insufficient oxygenation were observed (arterial CO₂ pressure [PaCO₂]: 84–103 mmHg and arterial O₂ pressure [PaO₂]: 155–172 mmHg). In the CV-group, normocapnea (PaCO₂: 42–50 mmHg) and good oxygenation (PaO₂: 395–419 mmHg) were achieved by the IPPV without apparent cardiovascular depression (heart rate: 29–31 beats/min, cardiac output: 17–21 l /min, MABP: 111–123 mmHg, MPAP: 27–30 mmHg and MRAP: 15–16 mmHg). MLBP-TIVA preserved cardiovascular function even in horses artificially ventilated.     

Effects of low-dose G-CSF formulation on hematology in healthy horses after long-distance transportation

The present study evaluated the effects of single-dose filgrastim on hematology in 16 healthy horses after long-distance transportation. Horses were assigned to receive filgrastim (0.23 µg/kg, SC, once; G-CSF group; n=8) or saline (0.9% NaCl) solution (0.3 ml, SC, once; control group; n=8) ≤ 1 hr before transportation. Horses were transported 2,530 km using commercial vans over the course of approximately 44 hr. Clinical examinations and hematologic analyses were performed on all horses before and after transportation. Because the post-transportation white blood cell counts and bacillary neutrophil to segmented neutrophil ratio were significantly higher in the G-CSF group, filgrastim may have promoted the mobilization of neutrophils from marrow. Filgrastim deserves a further study for efficacy in preventing horse shipping fever.     

Effects of a gonadotropin-releasing hormone antagonist and altrenogest on luteinizing hormone concentration and ovulation in the mare

The objective of Experiment 1 was to determine a dose and frequency of gonadotropin-releasing hormone (GnRH) antagonist administration to effectively suppress serum luteinizing hormone (LH) concentration and to delay ovulation when administered to mares. The objectives of Experiment 2 were 1) to determine the effects of subcutaneous or intravenous administration of a GnRH antagonist or oral altrenogest on serum LH concentration in the estrual mare; and 2) to determine the effectiveness of human chorionic gonadotropin (hCG) in inducing ovulation in mares with suppressed LH concentrations. In Experiment 1, mares (N = 20) were randomly assigned and treated with either 5% mannitol (control, single subcutaneous injection, 1 mL, at time 0; n = 5); low-dose GnRH antagonist (single subcutaneous injection, 0.01 mg/kg, at time 0; n = 5); frequent low-dose GnRH antagonist (subcutaneous injections, 0.01 mg/kg, at 0, 6, 18, and 24 hours; n = 5); or high-dose GnRH antagonist (single subcutaneous injection, 0.04 mg/kg, at time 0; n = 5). Both the frequent low-dose and high-dose GnRH antagonist treatments resulted in significantly lower LH concentrations compared with controls at 90, 102, and 114 hours after treatment (P < .05). In Experiment 2, mares (N = 38) were randomly assigned and treated with subcutaneous sterile saline (control), altrenogest (oral), subcutaneous GnRH antagonist, or intravenous GnRH antagonist. LH concentration for the altrenogest group was lower than the control group at 3, 4, 18, and 30 hours after treatment (P < .05). LH concentration for both the subcutaneous and intravenous GnRH antagonist groups were lower compared with the control group at several time points (P < .05). Based on these data, dose but not frequency of administration of a GnRH antagonist lowered LH concentration in the estrous mare but did not delay ovulation. In addition, serum LH concentrations can be lowered and ovulation effectively postponed in mares treated with altrenogest followed by administration of hCG. This indicates that serum LH concentrations can be lowered and ovulation effectively postponed in mares treated with altrenogest followed by administration of hCG.     

Comparison of HCG, buserelin and luprostiol for induction of ovulation in cycling mares

Sixty nonlactating light-horse mares were used to compare the efficacy of hCG, buserelin (a GnRH analog) and luprostiol (a PGF₂α analog) for induction of ovulation in cycling mares. Mares were assigned to 1 of 4 treatments: 1) controls; 2) 40 μg buserelin IM at 12 hr intervals during estrus until ovulation; 3) 7.5 mg IM luprostiol; and 4) 3,300 IU hCG. Treatments were given once a mare obtained a ≥35mm follicle and had been in estrus ≥2 days. Both buserelin and hCG shortened (p<0.05) the interval from treatment to ovulation compared to controls; whereas, luprostiol failed to hasten ovulation. Number of follicles ovulated was similar among all 4 groups. Although buserelin and hCG were equal in their ability to induce ovulation, an average of 3.8 injections of buserelin was required for hastening of ovulation.