Omneity® Pellets
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Topic:Abdominal
Research in the abdominal health and conditions category examines digestive physiology, gastrointestinal disorders, and treatment protocols in horses. This page compiles peer-reviewed studies and journal articles on the pathophysiology of common digestive issues, diagnostic techniques for conditions like colic and gastric ulcers, and evaluations of various treatment strategies.
Use of push-pull perfusion techniques in studies of gonadotrophin-releasing hormone secretion in mares. Push-pull perfusion was used to study GnRH secretory ability of the hypothalamus in anoestrous, transitional, dioestrous and oestrous Pony mares. The technique involved placement of a concentric (tube within a tube) cannula into the area of the medial basal hypothalamus and perfusing a carrier medium (artificial cerebrospinal fluid) through the inner tube whilst aspirating from the outer tube so that the flow rate within the hypothalamic tissue was essentially constant. The perfusion rate was 0.5 ml/10 min and samples were collected at 10-min intervals for 10-15 h. The carrier medium, which co...
Circadian, circhoral and seasonal variation in patterns of gonadotrophin secretion in geldings. Blood samples were obtained from 5 mixed-breed, long-term castrated geldings during five 24-h periods between May 1984 and April 1985. Blood samples were collected, beginning at 09:00 h, at 15-min intervals for 8 h and hourly for the remaining 16 h. Plasma concentrations of LH and FSH were determined by RIA. Seasonal changes in hormone concentrations and frequency and amplitude of secretory pulses were evaluated. No diurnal variation in either LH or FSH secretion was observed: however, marked circhoral fluctuations in LH and FSH secretion were noted. Mean LH and FSH concentrations in these lon...
Alternative solutions to hCG induction of ovulation in the mare. Injection of hCG (2000-2500 i.u., i.v.) to mares when a follicle reaches 35 mm induces ovulation between 24 and 48 h. However, repeated injections induce antibodies against hCG. We report attempts to induce ovulation without this inconvenience. We called 'response' an ovulation between 24 and 48 h after treatment. The typical response to hCG was obtained in 73% (N = 145) of treated mares. After immunization against hCG, the response (0%, N = 10) was less than in nonimmunized controls (100%, N = 9). Simultaneous injection of dexamethasone and hCG resulted in induction of ovulation (71%, N = 14)...
Inhibition of ovulation in the mare by active immunization against LHRH. To investigate the hypothesis that the onset of the breeding season in the mare may be due to a daylength-induced seasonal increase in LHRH pulse frequency, 5 mares were immunized against LHRH. Beginning 1 December, 5 immunized and 5 untreated control mares were exposed to an abrupt, artificial increase in daylength (16L:8D) to advance the onset of the breeding season. In control mares ovulation occurred 49.6 +/- 3.5 (s.e.m.) days later (18 January), whereas in 3/5 immunized mares ovulation had not occurred by 1 April. In the remaining 2 mares, although ovulation occurred once (Mare 79) or twi...
Infusion of gonadotrophin-releasing hormone (GnRH) induces ovulation and fertile oestrus in mares during seasonal anoestrus. In Exp. 1, 30 Standardbred mares in deep seasonal anoestrus were divided into 3 equal groups and treated with 0, 50 (G50) or 100 (G100) ng GnRH kg-1h-1 for 28 days via osmotic minipumps. Ovulation occurred in 0/10, 3/10 and 7/10 mares respectively (P less than 0.05). Plasma GnRH profiles (Days -6, 0, 2, 6, 12, 20, 28 and 34 relative to pump insertion) were dose-dependent (P less than 0.01) and peaked on Day 12 of infusion. Mean daily plasma LH concentrations were biphasic in treated mares that ovulated, with LH peaks occurring around Day 6 and Days 16-20. By contrast, in treated mares that did...
Secretion of luteinizing hormone and follicle stimulating hormone in intact and ovariectomized mares in summer and winter. Sequential samples of blood were drawn via jugular catheters every 15 min for 24 h from four mares in each of five reproductive states: intact anestrous mares in winter, intact diestrous mares in summer, intact estrous mares in summer, ovariectomized mares in winter and ovariectomized mares in summer. Estrous mares were sampled on d 4 or 5 of estrus and diestrous mares on d 10 or 11 of diestrus. Each sample of plasma was assessed for concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) in two independent radioimmunoassays. A computer program was developed that dete...
Histology of the normal and retained equine testis. Abdominal, inguinal and scrotal testes of horses were examined grossly and by light microscopy. An average of 1.5, 2.3 and 4.6 layers of spermatogenic cells, and mean seminiferous tubule diameters of approximately 66.2, 83.6 and 146.6 micron in the abdominal, inguinal and scrotal testes, respectively, were recorded. The interstitial spaces and the number of interstitial cells (of Leydig) seemed to be increased while spermatogenesis appeared to be arrested in the retained testes. Early spermatocytes were the most mature stages of the spermatogenic cells in the retained testes. An extensive vacu...
Changes in thecal and granulosa cell LH and FSH receptor content associated with follicular fluid and peripheral plasma gonadotrophin and steroid hormone concentrations in preovulatory follicles of mares. Individual antral follicles from 11 horse mares were studied at three stages of the oestrous cycle to determine the characteristics of the presumptive ovulatory follicle. Mares were ovariectomized (ovex) during the late luteal phase on Day 14 after ovulation (Group 1) and on the 1st (Group 2) or 4th (Group 3) day of oestrus. Every follicle greater than 5 mm in diameter was dissected from each ovary; follicles greater than or equal to 15 mm in diameter were analysed separately while others were pooled by size for subsequent analyses. The presumptive ovulatory follicle possessed the following ch...
Relationship of age and season and consumption of Senecio vulgaris to LH/hCG receptors in the stallion testis. Testes were obtained from 70 colts and stallions and were pooled according to age (4 months to 23 years) to determine the relationship of age to LH/hCG receptor kinetics. The receptor concentration (Rt) increased from 0.069 x 10(-11) M/mg crude membrane fraction (CMF) for the 4-14-month pools to 0.464 x 10(-11) M for the 2-3-year-old pools. A 10-fold increase in testicular size also occurred, and so the total number of receptors per testis was significantly increased. A further increase to 1.237 x 10(-11) M/mg CMF was observed for stallions older than 5 years. No differences in binding affinit...
Genetic and temporal variation in serum concentrations and biological activity of horse chorionic gonadotrophin. The variation in the quantity of circulating chorionic gonadotrophin (CG) and its follicle-stimulating hormone (FSH) and luteinizing hormone (LH) activity in rodent bioassay systems was investigated. A portion of the variability in total CG could be attributed to the stallion that sired the pregnancy and it was possible to select sires and mares to increase CG production. It was further demonstrated that FSH activity per unit of CG was greater at Days 71 and 104 of gestation than at Day 39. LH activity per unit of CG varied with the sire, but no effect of day of gestation could be shown. It wa...
Release of LH, FSH and GnRH into pituitary venous blood in mares treated with a PGF analogue, luprostiol, during the transition period. Nine mares received cannulae to collect blood from the pituitary venous outflow in the intercavernous sinus (ICS) and the jugular vein; in 4 mares, only jugular cannulae were used. Those 4 mares and 3 of the mares with cannulae in both positions received 7.5 mg luprostiol i.m. and 1 mare with both cannulae was treated with 3.75 mg uprostiol i.v. Blood samples were kept before and after treatment at 2-, 5- or 10-min intervals and concentrations of LH, FSH and GnRH were determined by RIA. Treatments resulted in an immediate sharp rise of LH and FSH in ICS and jugular blood samples within 2-10 mi...
Effect of pulsatile gonadotrophin release on mean serum LH and FSH in peri-parturient mares. Changes in the pattern of LH and FSH in serum were studied in 6 mares foaling during the summer. Samples were collected frequently (every 15 min) for 24 h twice before foaling, -33 +/- 2 and -12 +/- 2 days, and for 12 h after foaling, on Day 0 and Day 4. Simultaneous pulses of FSH and LH were observed before foaling (r2 = 0.99). Before foaling, gonadotrophin pulses were infrequent (6 in 264 h of observation). On the day of foaling, LH and FSH pulse frequency increased (P less than 0.005) with 2-4 pulses per mare. The amplitudes of pulses of LH and FSH were higher before parturition than for th...
Transitory changes of hormones in the plasma of parturient pony mares. Frequent blood samples were collected from 8 pony mares before, during and after labour, parturition and placental expulsion and assayed for progesterone, oestradiol, androstenedione and LH concentrations by radioimmunoassay. A significant (P less than 0.05) decrease in progesterone, oestradiol and in the progesterone:oestradiol ratio was not detected until 0.5 h after foaling. Androstenedione concentrations rose before and peaked at parturition and then declined. A significant (P less than 0.05) rise in LH was detected 0.5 h after parturition. This LH peak was not detected in one mare and she...
Plasma prolactin concentrations in non-pregnant mares at different times of the year and in relation to events in the cycle. Plasma prolactin concentrations were measured in mares using an homologous radioimmunoassay. An annual rhythm in plasma prolactin was found, with concentrations higher during the summer than during the winter. In addition to this seasonal pattern, occasional high concentrations of prolactin were seen when concentrations were otherwise basal. Blood samples taken from mares during an oestrous cycle in October-November showed that prolactin values were basal for most of the cycle, with a marked rise in prolactin shortly before the onset of oestrus. This prolactin peak was associated with an incre...
Reproductive patterns in cyclic and pregnant thyroidectomized mares. Three Quarter-horse mares were thyroidectomized at about 1.5 years of age. Three similar intact mares served as controls. The study continued through two breeding seasons. The thyroidectomized mares were lethargic, rear limbs were oedematous and hair coats were coarse. They displayed a tranquil oestrous behaviour when exposed to a stallion and were only mildly antagonistic when not in oestrus. Length of oestrous cycles varied but most often they were 19-24 days long. Duration of oestrus (mean +/- s.e.m.) for the control and thyroidectomized mares was 12.9 +/- 2.9 and 11.7 +/- 2.2 days respecti...
Reproductive characteristics of spontaneous single and double ovulating mares and superovulated mares. For embryos collected from mares 7 days after ovulation, embryo recovery for single-ovulating mares was 53% compared to 106% for double-ovulating mares. Pregnancy rates 50 days after surgical transfer were 68 and 129%, respectively. Concentrations of LH were similar during the periovulatory period for cycles which included single or double ovulations. Horse pituitary extract given for 5.5 days resulted in greater than or equal to 2 ovulations (mean 3.8) in 26 of 28 mares and 2.0 embryos were recovered per donor compared to 0.65 for controls. Non-surgical pregnancy rates for embryos collected f...
Pulsatile administration of gonadotropin-releasing hormone advances ovulation in cycling mares. Cycling standardbred mares were infused with saline or 20 micrograms gonadotropin-releasing hormone (GnRH) in a pulsatile pattern (one 5-sec pulse/h, 2 h or 4 h) beginning on Day 16 of the estrous cycle. Although serum concentrations of luteinizing hormone (LH) increased significantly earlier in all three GnRH-treated groups (within one day of the initiation of infusion) compared to saline-infused controls, there were no differences in peak periovulatory LH concentrations among treatments (overall mean +/- SEM, 8.98 +/- 0.55 ng/ml). The number of days from the start of treatment to ovulation w...
Changes in the hypothalamic-hypophyseal axis of mares associated with seasonal reproductive recrudescence. Four groups of mares, representing anestrus (AN; n = 8), early transition (ET; n = 7), late transition (LT; n = 8) and estrus (EST; n = 12) were used to examine changes in the hypothalamus and anterior pituitary during the period of transition from winter anestrus into the breeding season. Mares were of mixed breeding, between the ages of 3 and 20 years, and had shown normal patterns of estrous behavior and ovulation during the breeding season previous to this experiment. Hypothalamic content of gonadotropin-releasing hormone (GnRH) and anterior pituitary content of luteinizing hormone (LH) an...
Comparison of equine pituitary extract and follicle stimulating hormone for superovulating mares. Sixty light-horse, nonlactating mares were used to compare the efficacy of equine pituitary extract versus follicle stimulating hormone (FSH-P) for inducing multiple ovulations. On Day 12 of diestrus, mares were assigned to receive 1) no treatment, controls; 2) subcutaneous injections of 750 Fevold rat units of equine pituitary extract once daily; or 3) intramuscular injection of 150 mg of FSH-P twice daily. Ultrasound was used twice daily to visualize follicular changes and ovulation. For mares in Groups 2 and 3, treatment was initiated when two or more follicles > 20 mm were detected, and...
Herniation of the abdominal wall in pregnant mares. Abdominal wall hernia was detected in 4 pregnant mares. Antemortem diagnosis of the specific abdominal wall lesion was difficult. Ventral deviation of the abdomen, associated abdominal wall edema, and pain indicated rupture of the prepubic tendon. Three mares examined at necropsy did not have a rupture of the prepubic tendon but did have herniation of the abdominal wall. Abdominal pain was severe and was compounded by incarceration or entrapment of viscus.
Clinical course of renal adenocarcinoma associated with hypercupraemia in a horse. A four-year-old shire mare with haematuria, colic, terminal weight loss and an abdominal mass had a large unilateral renal adenocarcinoma. Clinical signs were monitored for 11 months. Increased serum copper concentrations were measured on two occasions. Hypercupraemia is discussed as a possible paraneoplastic change.
Concentrations of prolactin, luteinizing hormone and follicle stimulating hormone in pituitary and serum of horses: effect of sex, season and reproductive state. Pituitary and serum from 86 male or female horses of various reproductive states were collected in the normal breeding season (summer) and in the nonbreeding season (winter) at a commercial slaughterhouse. Concentrations of prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay. Concentrations of pregnant mare serum gonadotropin and reproductive steroids in serum and gross appearance of the reproductive tract and gonads were used to catagorize reproductive state. Concentrations of PRL were higher (P less than .01) in summer than in wi...
Active immunization of intact mares against gonadotropin-releasing hormone: differential effects on secretion of luteinizing hormone and follicle-stimulating hormone. Five lighthorse mares were actively immunized against gonadotropin releasing hormone (GnRH) to determine the relative importance of this hypothalamic hormone in the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Five mares immunized against the conjugation protein served as controls. Mares were initially immunized in November and received secondary immunizations 4 wk later, and then at 6-wk intervals until ovariectomy in June. All mares immunized against GnRH exhibited an increase (p less than 0.01) in the binding of tritiated GnRH by plasma, an indication that a...
Diagnostic laparoscopy in the horse. Laparoscopy was performed in 5 clinically normal horses. Abdominal fluid protein content and WBC count increased markedly in all horses. Necropsy findings were confined to an increased amount of slightly turbid abdominal fluid. Five examples of applications of laparoscopy in horses with abdominal problems indicated that laparoscopy can be a valuable diagnostic procedure in the horse.
Surgical management of intussusception in the horse. During a 14 year period, 27 of 310 horses undergoing laparotomy because of abdominal pain were found to have an intussusception involving the small intestine (16 cases) or caecum (11 cases). The clinical signs, operative findings and techniques adopted to overcome the obstruction are described. An evaluation of possible predisposing factors provided further evidence of the important role of the tapeworm Anoplocephala perfoliata in initiating intussusception involving the ileum and caecum.
Effect of graded doses of gonadotrophin-releasing hormone on serum LH concentrations in mares in various reproductive states: comparison with endogenously generated LH pulses. Luteinizing hormone release induced by a range of small (3.3-33 micrograms) and large (300-500 micrograms) i.v. doses of gonadotrophin-releasing hormone (GnRH) was measured in acyclic (n = 4), luteal phase (n = 3) and follicular phase (n = 5) mares and compared with endogenously generated LH pulses in the same reproductive states. Extrapolation from log-linear dose-response curves showed that an LH pulse comparable to an endogenous one would be simulated by i.v. injection of 7.0 (n = 4) and 4.1 (n = 6) micrograms GnRH in luteal and follicular phase mares respectively; a much smaller dose than ...
Androgen and estradiol effects on gonadotropin secretion and response to GnRH in ovariectomized pony mares. In Exp. 1, 16 long-term ovariectomized pony mares were used to determine the effects of treatment with estradiol benzoate (EB) and dihydrotestosterone (DHT) benzoate alone, and in combination, on secretion of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in daily blood samples and after three consecutive injections of gonadotropin releasing hormone (GnRH). Administration of EB alone, or in combination with DHT, every other day for 11 d reduced (P less than .05) concentrations of FSH and increased (P less than .05) concentrations of LH in daily blood samples, and increased (P ...
Induction of ovulation in anestrous mares with pulsatile administration of gonadotropin-releasing hormone. Four seasonally anestrous mares (Standardbred), housed under a nonstimulatory photoperiod of 8 hours light:16 hours dark, were administered gonadotropin-releasing hormone (GnRH) in a pulsatile pattern (50 or 250 micrograms of GnRH/hour) for 8 to 18 days during February and March 1985. Treatment with GnRH, irrespective of dose or month, induced an increase in serum luteinizing hormone from a mean pretreatment value typical of anestrus (0.58 +/- 0.02 ng/ml +/- SE) to 10.84 +/- 1.27 ng/ml on day 8 of GnRH treatment. Ovulation in the 4 mares occurred 8.8 +/- 0.7 days after the initiation of pulsat...
