R. Wilborn - Academia.edu (original) (raw)

Papers by R. Wilborn

Research paper thumbnail of Presumptive Albendazole Toxicosis in 12 Alpacas

Journal of Veterinary Internal Medicine, 2009

Research paper thumbnail of Establishment, Validation, and Application of Multispectral Imaging Technology to Studies of Bovine Reproductive Tract Development

Biology of Reproduction, 2012

Research paper thumbnail of Bilateral Catastrophic Metacarpal Fractures in a Quarter Horse Gelding

Journal of Equine Veterinary Science, 2016

Abstract A 5 year-old, 450 kg, American Quarter Horse gelding was presented for postmortem examin... more Abstract A 5 year-old, 450 kg, American Quarter Horse gelding was presented for postmortem examination. The horse had sustained multiple fractures of the metacarpal bones of both fore limbs while being ridden at a canter. Based on the radiographic presence of parasagittal fractures in the condyles of the distal third metacarpus, we theorized that the fractures in this horse likely originated in the metacarpophalangeal joint and propagated into the diaphysis resulting in catastrophic failure. The unique finding in this case is that these injuries occurred in a horse that was not being trained for racing. Owners and trainers should be aware that horses trained for disciplines other than racing can develop condylar fractures similar to racing Thoroughbreds and Quarter Horses.

Research paper thumbnail of Infection of an equine placenta with a novel mycobacterial species leading to abortion

Journal of Veterinary Diagnostic Investigation, 2012

A 25-year-old pregnant American Quarter Horse mare presented with a 1-week history of progressive... more A 25-year-old pregnant American Quarter Horse mare presented with a 1-week history of progressively worsening vaginal discharge. Transrectal ultrasound revealed increased thickness of the combined uterus and placenta with evidence of chorioallantoic edema but no placental separation. A thickened amnion was visible on transabdominal ultrasound. Abortion occurred 2 days after presentation despite medical treatment. At necropsy, the chorioallantois had variable but diffuse thickening with focally extensive browning of the chorionic surface in the right horn and adjacent body. There were fluid-filled sacculations on the allantoic surface of the umbilical cord, allantoamnion, and chorioallantois associated with diffuse perivascular fluid microscopically. A nonbranching acid-fast bacterium identified as belonging to the genus Mycobacterium Runyon group IV was isolated from the chorioallantois and uterine fluid. Ziehl-Neelsen stain confirmed the presence of intracellular acid-fast bacilli in trophoblasts of the gravid horn and the cervical star area. The current case is unique in that the mycobacteria did not initiate a significant granulomatous inflammatory response in the chorion unless villar necrosis occurred. Sequence analysis of the 16S ribosomal RNA gene and the rpoβ gene, encoding the β subunit of RNA polymerase, indicated that the strain of mycobacteria isolated in this case belonged to a novel species of rapidly growing mycobacteria and not to an established species. Mycobacteria are an uncommon and sporadic cause of placentitis and abortion, but should be suspected in cases of chronic placentitis that are not restricted to the cervical star area.

Research paper thumbnail of Effect of Kisspeptin on Regulation of Growth Hormone and Luteinizing Hormone in Lactating Dairy Cows

Journal of Animal Science and Biotechnology, 2011

Kisspeptin ( KP ) , a neuroendocrine regulator of reproduction, is hypothesized to be an in鄄 tegr... more Kisspeptin ( KP ) , a neuroendocrine regulator of reproduction, is hypothesized to be an in鄄 tegrator of metabolism and hormones critical to the regulation of reproduction. Lactation is associated with enhanced growth hormone ( GH) responsiveness and reduced fertility. Our study was designed to de鄄 termine the effects of lactation on KP鄄stimulated GH and luteinizing hormone ( LH) secretion. Five non鄄 lactating and five lactating dairy cows were used in the study. Experiments were conducted with lactating cows at weeks 1, 5 and 11 after parturition. The experimental treatments ( saline and KP [ 100 and 400 pmol / kg body weight] ) were given intravenous鄄 ly and blood was collected and plasma was stored un鄄 til later assay to determine concentrations of GH, LH, progesterone and non鄄esterified fatty acids. We found that neither dose of KP stimulated an increase in GH secretion. The low dose of KP increased (P <0. 05) LH concentrations only in lactating cows. The higher dose of KP elicited an increase in circulating LH con鄄 centrations in both lactating and non鄄lactating cows. The lower dose of KP increased ( P < 0. 05) the area under the curve for LH only in cows during week 5 of lactation, and the area under the curve of LH follow鄄 ing the highest dose of KP was greater ( P < 0. 05) in cows during week 5 of lactation than that for the other groups of cows. In summary, lactation status and stage of lactation did not change the sensitivity of the GH system to KP. However, an effect of stage of lactation on KP鄄stimulated LH secretion was detected in the dairy cows. Study of the KP system during lac鄄 tation in dairy cows may provide critical insights into the mechanisms for lactation鄄associated changes in the reproductive axis.

Research paper thumbnail of A review of the general pharmacology of ketamine and its clinical use for injectable anaesthesia in horses

Research paper thumbnail of Comparative Aspects of the Endotoxin- and Cytokine-Induced Endocrine Cascade Influencing Neuroendocrine Control of Growth and Reproduction in Farm Animals

Reproduction in Domestic Animals, 2008

Research paper thumbnail of Interaction of Kisspeptin and the Somatotropic Axis

Neuroendocrinology, 2010

Kisspeptin, a regulator of gonadotropin-releasing hormone, has been hypothesized as an integrator... more Kisspeptin, a regulator of gonadotropin-releasing hormone, has been hypothesized as an integrator of nutrition and hormones critical to metabolism and the regulation of reproduction. Growth hormone (GH) is necessary for optimal reproduction and recent evidence suggests that its secretion may be influenced by kisspeptin. The objectives of this study were to determine whether the effect of kisspeptin to stimulate GH release is due to an interaction with growth hormone-releasing hormone (GHRH) or somatostatin (SS), or an effect at the hypothalamus. Intravenous injection and infusion of kisspeptin [500 pmol/kg BW (650 ng/kg)/h × 5 h] to cows (n = 5) increased serum concentrations of luteinizing hormone (LH) but not GH. Pretreatment with kisspeptin injection and infusion in cows (n = 5) reduced the stimulatory effect of GHRH (0.05 μg/kg BW) on GH secretion. However, the magnitude of the GH response to GHRH (assessed by incremental AUC) was not affected by kisspeptin. In these same cows, administration of kisspeptin prevented the increase in GH induced by SS infusion (0.5 μg/kg BW/ h × 1.5 h) withdrawal. Peripheral administration of kisspeptin [200 and 1,000 pmol/kg BW (260 and 1,300 ng/kg)] increased serum concentrations of LH but not GH in ewes (n = 8). However, concentrations of GH were stimulated by central kisspeptin treatment [100 and 200 pmol/kg BW (130 and 260 ng/kg)] in ewes. In addition to activating the gonadotropic axis, kisspeptin can activate the somatotropic axis in ruminants. Present data support the concept of a central site of action for this effect.

Research paper thumbnail of Interaction of Estrogen and Progesterone on Kisspeptin-10-Stimulated Luteinizing Hormone and Growth Hormone in Ovariectomized Cows

Neuroendocrinology, 2008

Growth hormone (GH) is necessary for optimal reproductive efficiency and its secretion is influen... more Growth hormone (GH) is necessary for optimal reproductive efficiency and its secretion is influenced by sex steroids. This study was designed to determine whether kisspeptin-10 (Kp10) could stimulate GH and if gonadal steroids enhance the GH response to Kp10 in cows. Intravenous injection of Kp10 at 100 or 200 pmol/kg body weight with or without treatment with estradiol cypionate and/or progesterone increased luteinizing hormone (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) plasma concentrations. Plasma concentrations of GH were increased following Kp10 in cows treated with estradiol cypionate and/or progesterone (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) but not in cows treated with Kp10 without gonadal steroids. These data suggest that reproductive steroids enhance the sensitivity of the somatotropic axis to physiologically relevant doses of Kp10, and support the possibility that Kp10 is an integrator of luteinizing hormone and GH release.

Research paper thumbnail of Theriogenology Question of the Month

Journal of the American Veterinary Medical Association, 2012

... Equine fetal diseases. In: Morrow DA, ed. Current therapy in theriogenology. 2nd ed. Philadel... more ... Equine fetal diseases. In: Morrow DA, ed. Current therapy in theriogenology. 2nd ed. Philadelphia: WB Saunders Co, 1986;699–704. 2. Hong CB, Donahue JM, Giles RC, et al. Etiology and pathol-ogy of equine placentitis. J Vet Diagn Invest 1993:5:56–63. ...

Research paper thumbnail of Selected hormonal and neurotransmitter mechanisms regulating feed intake in sheep

animal, 2010

Appetite control is a major issue in normal growth and in suboptimal growth performance settings.... more Appetite control is a major issue in normal growth and in suboptimal growth performance settings. A number of hormones, in particular leptin, activate or inhibit orexigenic or anorexigenic neurotransmitters within the arcuate nucleus of the hypothalamus, where feed intake regulation is integrated. Examples of appetite regulatory neurotransmitters are the stimulatory neurotransmitters neuropeptide Y (NPY), agouti-related protein (AgRP), orexin and melanin-concentrating hormone and the inhibitory neurotransmitter, melanocyte-stimulating hormone (MSH). Examination of messenger RNA (using in situ hybridization and real-time PCR) and proteins (using immunohistochemistry) for these neurotransmitters in ruminants has indicated that physiological regulation occurs in response to fasting for several of these critical genes and proteins, especially AgRP and NPY. Moreover, intracerebroventricular injection of each of the four stimulatory neurotransmitters can increase feed intake in sheep and may also regulate either growth hormone, luteinizing hormone, cortisol or other hormones. In contrast, both leptin and MSH are inhibitory to feed intake in ruminants. Interestingly, the natural melanocortin-4 receptor (MC4R) antagonist, AgRP, as well as NPY can prevent the inhibition of feed intake after injection of endotoxin (to model disease suppression of appetite). Thus, knowledge of the mechanisms regulating feed intake in the hypothalamus may lead to mechanisms to increase feed intake in normal growing animals and prevent the wasting effects of severe disease in animals.

Research paper thumbnail of Presumptive Albendazole Toxicosis in 12 Alpacas

Journal of Veterinary Internal Medicine, 2009

Research paper thumbnail of Presumptive Albendazole Toxicosis in 12 Alpacas

Journal of Veterinary Internal Medicine, 2009

Research paper thumbnail of Establishment, Validation, and Application of Multispectral Imaging Technology to Studies of Bovine Reproductive Tract Development

Biology of Reproduction, 2012

Research paper thumbnail of Bilateral Catastrophic Metacarpal Fractures in a Quarter Horse Gelding

Journal of Equine Veterinary Science, 2016

Abstract A 5 year-old, 450 kg, American Quarter Horse gelding was presented for postmortem examin... more Abstract A 5 year-old, 450 kg, American Quarter Horse gelding was presented for postmortem examination. The horse had sustained multiple fractures of the metacarpal bones of both fore limbs while being ridden at a canter. Based on the radiographic presence of parasagittal fractures in the condyles of the distal third metacarpus, we theorized that the fractures in this horse likely originated in the metacarpophalangeal joint and propagated into the diaphysis resulting in catastrophic failure. The unique finding in this case is that these injuries occurred in a horse that was not being trained for racing. Owners and trainers should be aware that horses trained for disciplines other than racing can develop condylar fractures similar to racing Thoroughbreds and Quarter Horses.

Research paper thumbnail of Infection of an equine placenta with a novel mycobacterial species leading to abortion

Journal of Veterinary Diagnostic Investigation, 2012

A 25-year-old pregnant American Quarter Horse mare presented with a 1-week history of progressive... more A 25-year-old pregnant American Quarter Horse mare presented with a 1-week history of progressively worsening vaginal discharge. Transrectal ultrasound revealed increased thickness of the combined uterus and placenta with evidence of chorioallantoic edema but no placental separation. A thickened amnion was visible on transabdominal ultrasound. Abortion occurred 2 days after presentation despite medical treatment. At necropsy, the chorioallantois had variable but diffuse thickening with focally extensive browning of the chorionic surface in the right horn and adjacent body. There were fluid-filled sacculations on the allantoic surface of the umbilical cord, allantoamnion, and chorioallantois associated with diffuse perivascular fluid microscopically. A nonbranching acid-fast bacterium identified as belonging to the genus Mycobacterium Runyon group IV was isolated from the chorioallantois and uterine fluid. Ziehl-Neelsen stain confirmed the presence of intracellular acid-fast bacilli in trophoblasts of the gravid horn and the cervical star area. The current case is unique in that the mycobacteria did not initiate a significant granulomatous inflammatory response in the chorion unless villar necrosis occurred. Sequence analysis of the 16S ribosomal RNA gene and the rpoβ gene, encoding the β subunit of RNA polymerase, indicated that the strain of mycobacteria isolated in this case belonged to a novel species of rapidly growing mycobacteria and not to an established species. Mycobacteria are an uncommon and sporadic cause of placentitis and abortion, but should be suspected in cases of chronic placentitis that are not restricted to the cervical star area.

Research paper thumbnail of Effect of Kisspeptin on Regulation of Growth Hormone and Luteinizing Hormone in Lactating Dairy Cows

Journal of Animal Science and Biotechnology, 2011

Kisspeptin ( KP ) , a neuroendocrine regulator of reproduction, is hypothesized to be an in鄄 tegr... more Kisspeptin ( KP ) , a neuroendocrine regulator of reproduction, is hypothesized to be an in鄄 tegrator of metabolism and hormones critical to the regulation of reproduction. Lactation is associated with enhanced growth hormone ( GH) responsiveness and reduced fertility. Our study was designed to de鄄 termine the effects of lactation on KP鄄stimulated GH and luteinizing hormone ( LH) secretion. Five non鄄 lactating and five lactating dairy cows were used in the study. Experiments were conducted with lactating cows at weeks 1, 5 and 11 after parturition. The experimental treatments ( saline and KP [ 100 and 400 pmol / kg body weight] ) were given intravenous鄄 ly and blood was collected and plasma was stored un鄄 til later assay to determine concentrations of GH, LH, progesterone and non鄄esterified fatty acids. We found that neither dose of KP stimulated an increase in GH secretion. The low dose of KP increased (P <0. 05) LH concentrations only in lactating cows. The higher dose of KP elicited an increase in circulating LH con鄄 centrations in both lactating and non鄄lactating cows. The lower dose of KP increased ( P < 0. 05) the area under the curve for LH only in cows during week 5 of lactation, and the area under the curve of LH follow鄄 ing the highest dose of KP was greater ( P < 0. 05) in cows during week 5 of lactation than that for the other groups of cows. In summary, lactation status and stage of lactation did not change the sensitivity of the GH system to KP. However, an effect of stage of lactation on KP鄄stimulated LH secretion was detected in the dairy cows. Study of the KP system during lac鄄 tation in dairy cows may provide critical insights into the mechanisms for lactation鄄associated changes in the reproductive axis.

Research paper thumbnail of A review of the general pharmacology of ketamine and its clinical use for injectable anaesthesia in horses

Research paper thumbnail of Comparative Aspects of the Endotoxin- and Cytokine-Induced Endocrine Cascade Influencing Neuroendocrine Control of Growth and Reproduction in Farm Animals

Reproduction in Domestic Animals, 2008

Research paper thumbnail of Interaction of Kisspeptin and the Somatotropic Axis

Neuroendocrinology, 2010

Kisspeptin, a regulator of gonadotropin-releasing hormone, has been hypothesized as an integrator... more Kisspeptin, a regulator of gonadotropin-releasing hormone, has been hypothesized as an integrator of nutrition and hormones critical to metabolism and the regulation of reproduction. Growth hormone (GH) is necessary for optimal reproduction and recent evidence suggests that its secretion may be influenced by kisspeptin. The objectives of this study were to determine whether the effect of kisspeptin to stimulate GH release is due to an interaction with growth hormone-releasing hormone (GHRH) or somatostatin (SS), or an effect at the hypothalamus. Intravenous injection and infusion of kisspeptin [500 pmol/kg BW (650 ng/kg)/h × 5 h] to cows (n = 5) increased serum concentrations of luteinizing hormone (LH) but not GH. Pretreatment with kisspeptin injection and infusion in cows (n = 5) reduced the stimulatory effect of GHRH (0.05 μg/kg BW) on GH secretion. However, the magnitude of the GH response to GHRH (assessed by incremental AUC) was not affected by kisspeptin. In these same cows, administration of kisspeptin prevented the increase in GH induced by SS infusion (0.5 μg/kg BW/ h × 1.5 h) withdrawal. Peripheral administration of kisspeptin [200 and 1,000 pmol/kg BW (260 and 1,300 ng/kg)] increased serum concentrations of LH but not GH in ewes (n = 8). However, concentrations of GH were stimulated by central kisspeptin treatment [100 and 200 pmol/kg BW (130 and 260 ng/kg)] in ewes. In addition to activating the gonadotropic axis, kisspeptin can activate the somatotropic axis in ruminants. Present data support the concept of a central site of action for this effect.

Research paper thumbnail of Interaction of Estrogen and Progesterone on Kisspeptin-10-Stimulated Luteinizing Hormone and Growth Hormone in Ovariectomized Cows

Neuroendocrinology, 2008

Growth hormone (GH) is necessary for optimal reproductive efficiency and its secretion is influen... more Growth hormone (GH) is necessary for optimal reproductive efficiency and its secretion is influenced by sex steroids. This study was designed to determine whether kisspeptin-10 (Kp10) could stimulate GH and if gonadal steroids enhance the GH response to Kp10 in cows. Intravenous injection of Kp10 at 100 or 200 pmol/kg body weight with or without treatment with estradiol cypionate and/or progesterone increased luteinizing hormone (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) plasma concentrations. Plasma concentrations of GH were increased following Kp10 in cows treated with estradiol cypionate and/or progesterone (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) but not in cows treated with Kp10 without gonadal steroids. These data suggest that reproductive steroids enhance the sensitivity of the somatotropic axis to physiologically relevant doses of Kp10, and support the possibility that Kp10 is an integrator of luteinizing hormone and GH release.

Research paper thumbnail of Theriogenology Question of the Month

Journal of the American Veterinary Medical Association, 2012

... Equine fetal diseases. In: Morrow DA, ed. Current therapy in theriogenology. 2nd ed. Philadel... more ... Equine fetal diseases. In: Morrow DA, ed. Current therapy in theriogenology. 2nd ed. Philadelphia: WB Saunders Co, 1986;699–704. 2. Hong CB, Donahue JM, Giles RC, et al. Etiology and pathol-ogy of equine placentitis. J Vet Diagn Invest 1993:5:56–63. ...

Research paper thumbnail of Selected hormonal and neurotransmitter mechanisms regulating feed intake in sheep

animal, 2010

Appetite control is a major issue in normal growth and in suboptimal growth performance settings.... more Appetite control is a major issue in normal growth and in suboptimal growth performance settings. A number of hormones, in particular leptin, activate or inhibit orexigenic or anorexigenic neurotransmitters within the arcuate nucleus of the hypothalamus, where feed intake regulation is integrated. Examples of appetite regulatory neurotransmitters are the stimulatory neurotransmitters neuropeptide Y (NPY), agouti-related protein (AgRP), orexin and melanin-concentrating hormone and the inhibitory neurotransmitter, melanocyte-stimulating hormone (MSH). Examination of messenger RNA (using in situ hybridization and real-time PCR) and proteins (using immunohistochemistry) for these neurotransmitters in ruminants has indicated that physiological regulation occurs in response to fasting for several of these critical genes and proteins, especially AgRP and NPY. Moreover, intracerebroventricular injection of each of the four stimulatory neurotransmitters can increase feed intake in sheep and may also regulate either growth hormone, luteinizing hormone, cortisol or other hormones. In contrast, both leptin and MSH are inhibitory to feed intake in ruminants. Interestingly, the natural melanocortin-4 receptor (MC4R) antagonist, AgRP, as well as NPY can prevent the inhibition of feed intake after injection of endotoxin (to model disease suppression of appetite). Thus, knowledge of the mechanisms regulating feed intake in the hypothalamus may lead to mechanisms to increase feed intake in normal growing animals and prevent the wasting effects of severe disease in animals.

Research paper thumbnail of Presumptive Albendazole Toxicosis in 12 Alpacas

Journal of Veterinary Internal Medicine, 2009