[Show abstract][Hide abstract] ABSTRACT: Eighteen Doberman pinscher dogs with clinical signs of cervical spondylomyelopathy (wobbler syndrome) underwent cervical myelography and magnetic resonance (MR) imaging. Cervical myelography was performed using iohexol, followed by lateral and ventrodorsal radiographs. Traction myelography was performed using a cervical harness exerting 9 kg of linear traction. MR imaging was performed in sagittal, transverse, and dorsal planes using a 1.5 T magnet with the spine in neutral and traction positions. Three reviewers independently evaluated the myelographic and MR images to determine the most extensive lesion and whether the lesion was static or dynamic. All reviewers agreed with the location of the most extensive lesion on MR images (100%), while the agreement using myelography was 83%. The myelogram and MR imaging findings agreed in the identification of the affected site in 13-16 dogs depending on the reviewer. MR imaging provided additional information on lesion location because it allowed direct examination of the spinal cord diameter and parenchyma. Spinal cord signal changes were seen in 10 dogs. Depending on the reviewer, two to four dogs had their lesions classified as dynamic on myelography but static on MR images. Myelography markedly underscored the severity of the spinal cord compression in two dogs, and failed to identify the cause of the signs in another. The results of this study indicated that, although myelography can identify the location of the lesion in most patients, MR imaging appears to be more accurate in predicting the site, severity, and nature of the spinal cord compression.
[Show abstract][Hide abstract] ABSTRACT: To compare morphologic and morphometric features of the cervical vertebral column and spinal cord of Doberman Pinschers with and without clinical signs of cervical spondylomyelopathy (CSM; wobbler syndrome) detected via magnetic resonance imaging (MRI).
16 clinically normal and 16 CSM-affected Doberman Pinschers.
For each dog, MRI of the cervical vertebral column (in neutral and traction positions) was performed. Morphologically, MRI abnormalities were classified according to a spinal cord compression scale. Foraminal stenosis and intervertebral disk degeneration and protrusion were also recorded. Morphometric measurements of the vertebral canal and spinal cord were obtained in sagittal and transverse MRI planes.
4 of 16 clinically normal and 15 of 16 CSM-affected dogs had spinal cord compression. Twelve clinically normal and all CSM-affected dogs had disk degeneration. Foraminal stenosis was detected in 11 clinically normal and 14 CSM-affected dogs. Vertebral canal and spinal cord areas were consistently smaller in CSM-affected dogs, compared with clinically normal dogs. In neutral and traction positions, the intervertebral disks of CSM-affected dogs were wider than those of clinically normal dogs but the amount of disk distraction was similar between groups.
The incidence of intervertebral disk degeneration and foraminal stenosis in clinically normal Doberman Pinschers was high; cervical spinal cord compression may be present without concurrent clinical signs. A combination of static factors (ie, a relatively stenotic vertebral canal and wider intervertebral disks) distinguished CSM-affected dogs from clinically normal dogs and appears to be a key feature in the pathogenesis of CSM.
American Journal of Veterinary Research 10/2006; 67(9):1601-12. · 1.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To establish the reference ranges for motor evoked potential (MEP) latency and amplitude in clinically normal Doberman Pinschers, compare the MEPs of Doberman Pinschers with and without clinical signs of cervical spondylomyelopathy (CSM; wobbler syndrome), and determine whether MEP data correlate with neurologic or magnetic resonance imaging (MRI) findings.
16 clinically normal and 16 CSM-affected Doberman Pinschers.
Dogs were classified according to their neurologic deficits. After sedation with acepromazine and hydromorphone, transcranial magnetic MEPs were assessed in each dog; latencies and amplitudes were recorded from the extensor carpi radialis and cranial tibial muscles. Magnetic resonance imaging was performed to evaluate the presence and severity of spinal cord compression.
Significant differences in cranial tibial muscle MEP latencies and amplitudes were detected between clinically normal and CSM-affected dogs. No differences in the extensor carpi radialis MEP were detected between groups. There was a significant correlation (r = 0.776) between the cranial tibial muscle MEP latencies and neurologic findings. Significant correlations were also found between MRI findings and the cranial tibial muscle MEP latencies (r = 0.757) and amplitudes (r = -0.453).
Results provided a reference range for MEPs in clinically normal Doberman Pinschers and indicated that cranial tibial muscle MEP latencies correlated well with both MRI and neurologic findings. Because of the high correlation between cranial tibial muscle MEP data and neurologic and MRI findings, MEP assessment could be considered as a screening tool in the management of dogs with spinal cord disease.
American Journal of Veterinary Research 10/2006; 67(9):1613-20. · 1.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Evidence suggests that neurogenesis occurs in the adult hypothalamus, including centers containing oxytocin and vasopressin producing neurons. The present study was undertaken to look at one of these centers, the paraventricular nucleus (PVN), to describe its morphology, confirm the presence of neurogenesis and examine the effect of reproductive status on the incidence of neurogenesis. Serial sections of the paraffin-embedded hypothalamus were made from five puberty gilts, four adult gilts and four lactating sows. Specific sections were Nissl-stained for PVN morphology, while others were stained with an oxytocin (OT) primary antibody, which binds to the cytoplasm of oxytocin-containing neurons, and proliferating cell nuclear antigen (PCNA) primary antibody, which binds to PCNA, a protein expressed in the nucleus during cell division. Cells labeled with both OT and PCNA were considered to be oxytocin-containing neurons that had recently divided, signifying the recent synthesis of a mature neuron. The general morphology of the PVN was similar in all pigs, and three subnuclei were identified and named based on cytoarchitecture. Neurogenesis was consistently observed in OT-containing neurons of all pigs studied. However, a significantly greater number of double-labeled (OT + PCNA) cells occurred in the PVN of lactating sows and adult gilts, when compared to puberty gilts. These observations confirm the process of neurogenesis in the hypothalamus of the adult female pig and suggest that the up-regulation of OT-containing neurons is correlated to age and possibly driven by sexual maturation, but not necessarily lactation.
Brain Research 09/2006; 1102(1):44-51. · 2.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Schistosomus reflexus (SR) is a rare and fatal congenital disorder. Primarily observed in ruminants, its defining features include spinal inversion, exposure of the abdominal viscera because of a fissure of the ventral abdominal wall, limb ankylosis, positioning of the limbs adjacent to the skull and, lung and diaphragm hypoplasia. Variable components of SR include scoliosis, cleft sternum, exposure of thoracic viscera, and abnormalities of the digestive and urogenital systems. This report presents the findings from an anatomical analysis of a female Holstein SR calf with thoracoschisis, scoliosis and anomalies of the appendicular skeleton, cardiovascular, respiratory, digestive and urogenital systems. Many of these malformations have not been previously reported. The reproductive tract of this case is particularly unique, displaying Muellerian duct abnormalities. These abnormalities suggest SR occurs as early as the post-gastrulation embryo and involves the intermediate mesoderm. Preliminary analysis of associated cases suggests that SR has a genetic aetiology.
[Show abstract][Hide abstract] ABSTRACT: Atresia Ani (AA) is one of the most common malformations of the lower gastrointestinal tract. It occurs in 1 in 1500 to 1 in 5000 human births. These patients suffer physically and psychologically from this disorder, and thus there is a research interest in the condition. There are 3 subcategories of AA: high, intermediate, and low. Each of these forms is likely related to separate etiological processes.
An anatomical study was performed on a porcine case of AA with a urorectal fistula and malformed urethra.
This animal was found to have the intermediate form of AA.
A new mechanism is hypothesized, distinct from that described for the high and low forms of AA. This proposed mechanism involves the persistence of the cloacal membrane. Evidence to support this hypothesis includes: location of the urorectal fistula in the region of the embryonic cloacal duct, the lack of anomalies usually seen in conjunction with AA associated with mutations of the Sonic Hedgehog gene, and the presence of a malformed urethra, which is significantly correlated to intermediate AA. This form of AA could be related to a failure of the cloacal membrane to break down at the appropriate time during urorectal separation.
Birth Defects Research Part A Clinical and Molecular Teratology 07/2005; 73(6):434-9. · 2.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Until recently, evidence supporting postnatal neurogenesis was controversial. Much of the debate has centered on the identification of the dividing cells as neurons versus glia. Because neurogenesis has become a well-documented phenomenon, there is a need for reliable protocols to identify recently divided neurons in a wide range of situations. To facilitate the investigation of postnatal neurogenesis of magnocellular neurons in the pig hypothalamus, a sequential immunohistochemical staining technique was developed for use on serial sections of paraffin-embedded tissue. Proliferating neurons were labeled using mouse-derived monoclonal antibodies to detect proliferating cell nuclear antigen (PCNA) and vasopressin (VP). PCNA, a nuclear protein essential for cell division, identifies recently divided cells in the brains of healthy animals. VP is a unique functional marker for a mature neuron. The presence of a cell with VP positive cytoplasm and a PCNA positive nucleus demonstrates the presence of a VP-producing neuron that has recently divided. This protocol allowed us to safely and accurately label recently proliferated neurons in the mature pig hypothalamus and can be used on archived tissue. This data can be used for further morphometric analysis, as serial sectioning allows for three-dimensional reconstruction of hypothalamic nuclei.
Brain Research Protocols 07/2004; 13(2):69-75. · 1.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The vasopressin and oxytocin-containing nucleus (VON) of the pig hypothalamus demonstrates dramatic postnatal growth in nucleus size, both volume and neuron number, during puberty, and continues to increase in size in the adult sexually mature female pig throughout its reproductive prime. This study was designed to show that postnatal neurogenesis is responsible for the VON growth that occurs between adolescence and maturity. Recently divided neurosecretory cells of the hypothalamus were identified in adolescent and mature non-lactating female pigs using a sequential immunohistochemistry double-labeling technique with monoclonal mouse antibodies to detect vasopressin and proliferating cell nuclear antigen (PCNA), a protein associated with the S phase of the cell cycle. A computer-assisted image-analysis system was used to assess nucleus volume and neuron counts. The VON of the mature dry sows was significantly larger in volume and number of vasopressin neurons than the VON of the adolescent pigs. Double-labeled cells were noted in the VON of both adolescent and mature dry sows, but the number and proportion of double-labeled cells was significantly higher in adolescent pigs. Our results indicate the presence of neurons containing PCNA in the VON of the pig hypothalamus. This suggests that mitosis of neurogenic precursors plays a role in the growth of the nucleus.
Brain Research 06/2003; 971(2):189-96. · 2.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A purebred Ayrshire calf was born with multiple congenital cardiac defects. The major defects included absence of an interventricular septum (i.e., single ventricle), transposition of the aorta and pulmonary trunk, interatrial septal defect, patent ductus arteriosus, and aortic arch anomalies. Despite the severity of the anomalies, the calf survived to 5 days of age, when it was found dead. This particular combination of cardiac defects has not been previously described in domestic animals.
[Show abstract][Hide abstract] ABSTRACT: To evaluate use of transcranial magnetic motor evoked potentials for assessment of the functional integrity of the cervical spinal cord in large-breed dogs with cervical spinal cord disease.
Randomized, controlled, masked study.
10 healthy large-breed control dogs and 25 large-breed dogs with cervical spinal cord diseases.
Affected dogs were allocated to 3 groups on the basis of neurologic status: signs of neck pain alone, ambulatory with ataxia in all limbs, or nonambulatory. Transcranial magnetic stimulation was performed on each dog with the same standard technique. Motor evoked potentials (MEP) were recorded from electrodes inserted in the tibialis cranialis muscle. Following the procedure, each dog was anesthetized and cervical radiography, CSF analysis, and cervical myelography were performed. The MEP latencies and amplitudes were correlated with neurologic status of the dogs after correction for neuronal path length.
Mean MEP latencies and amplitudes were significantly different between control dogs and dogs in each of the 3 neurologic categories, but were not significantly different among dogs in the 3 neurologic categories. A linear association was evident between MEP latencies and amplitudes and severity of neurologic deficits; the more severe the neurologic deficits, the more prolonged the latencies and the more decreased the amplitudes.
Transcranial magnetic MEP are useful to assess severity of cervical spinal cord disease in large-breed dogs. Impairment of the functional integrity of the cervical spinal cord was found even in dogs with neck pain alone.
Journal of the American Veterinary Medical Association 08/2002; 221(1):60-4. · 1.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Situs inversus is a rare congenital anomaly wherein the normal, left-right organ location is inverted. The anatomical inversion (heterotaxy) is usually detected in routine radiography or other medical interventions. A 5-month-old Holstein heifer calf was identified as a suspected situs inversus totalis during abdominal surgery. Following surgery the calf did not gain weight. On admission to the Ontario Veterinary Hospital, it was given a routine clinical examination and a detailed cardiovascular, Doppler ultrasound examination, which appeared normal. Because of declining health and chronic bloating in the heifer, euthanasia was performed. A detailed post-mortem dissection was carried out. No heart or lung anomalies were detected. Other thoracic organs were normal, except for a helical coil of the esophagus as it traversed the diaphragm. The rumen was located entirely on the right side of the abdomen and had a large area of adhesion to the parietal peritoneal wall. The left kidney was abnormally placed: retroperitoneal and cranial to the right. There were two spleens. The caudal vena cava was distended and twisted to the left. Thus the calf was situs inversus abdominalis. This suggests that the development of laterality in the early embryo may include both timing and positional regulation.
The Anatomical Record 06/2002; 267(1):47-51. · 1.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study provides an accurate, anatomical description of the rabbit's lumbosacral spinal cord. Following humane euthanasia, 64 rabbits were radiographed and dissected. The number of thoracic (T) and lumbar (L) vertebrae was 12T/7L in 43.8%, 13T/6L in 32.8%, and 13T/7L in 23.4% in the 64 rabbits studied. The 13th ribs were rudimentary, asymmetric, or both in 15 animals. The spinal cord terminated within the second sacral vertebra (S2) in 79.3%, within the first sacral vertebra (S1) in 19.0%, and within the third sacral vertebra (S3) in 1.7% of the sample. Spinal nerve contributions to the femoral, obturator, sciatic, and pudendal nerves were determined. Formulas to predict the termination of the cord relative to the vertebral column were established. Age, weight, sex, and method of preparation did not show a significant correlation with the length of the spinal cord.
Journal of the American Animal Hospital Association 01/2001; 37(1):27-34. · 0.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Conjoined twins with a doubling of all cranial structures, having two vertebral columns along their entire body length yet with a single pelvis, have not been described in the literature. The cause of conjoined twinning is incompletely understood; however, two main theories (fission and fusion) have been proposed and disputed.
A dicephalus, tetrabrachius (parapagus) conjoined twin Holstein heifer calf was studied.
Two normal heads were present on two necks. The twins were fused in the thoracic region. There were four forelimbs and an abnormal orientation of ribs. Two separate vertebral columns along the length of the animal ended with two tails. There was a single pelvis, and only two hindlimbs were present. The musculature of the medial forelimbs was complete but abnormally positioned. Some medial structures, caudal to the thorax, failed to develop in these twins. There were two hearts, each one supplying one half of the body. The cranial vasculature was doubled and normal. Caudally there were two aortas, each supplying the respective half of the twin. The right caudal vena cava drained all caudal parts of the body while the left caudal vena cava drained only the liver. There were two sets of lungs. Each twin had a separate esophagus that entered a separate stomach. The right abomasum (fourth stomach chamber) was herniated through the diaphragm into the thoracic cavity. The two duodenums from each stomach fused distal to the pyloric sphincters. Caudal to this point of fusion, all structures of the digestive and urogenital systems were single. The calf had a single anus and vulva.
The anatomical findings in this twin suggest a fission event followed by fusion of parallel embryonic axes.
The Anatomical Record 06/1998; 251(1):60-5. · 1.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: XX/XY chimeric pigs are uncommon and their reproductive anatomy is variable and unpredictable.
A piglet was identified by its enlarged vulva as a possible intersex. Venous blood was collected at 1.5 and 9 months for karyotyping and determination of testosterone and estrone sulphate concentrations. At 1 year euthanasia was performed. The reproductive tract was carefully dissected and examined histologically.
As the animal matured the vulva did not develop relative to the size of the animal. Lymphocyte cultures indicated a 70% XX/30% XY chimera. The reproductive tract consisted of a strand of tissue enveloped by fascia. Histological study revealed presumptive Wolffian derivatives, coiled bilateral ducts along the tract, and a Müllerian derivative, a medially located duct in the caudal third of the tract. No gonads were found. Plasma levels of estrone sulfate and testosterone were negligible.
In utero exposure to exogenous androgens from a male co-twin or weak endogenous adrenal androgens may account for the enlarged vulva at birth and retention of the androgen dependent Wolffian duct primordia. An atesticular state is supported by retention of the Müllerian duct primordia and the negligible peripheral sex steroids.
The Anatomical Record 07/1995; 242(2):195-9. · 1.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Twins with doubling of the cranial and caudal poles, yet having a single thorax, are rare.
One set of diprosopus, dipygus porcine conjoined twins was studied.
In addition to the conjoining anomaly, these twins also exhibited ambiguous internal reproductive features. The twins had two snouts, three eyes, a single thorax, and were duplicated from the umbilicus caudally. Radiography indicated a single vertebral column in the cervical region. The vertebral columns were separate caudally from this point. There was a total of six limbs--one pair of forelimbs and two pairs of hindlimbs. Many medial structures failed to develop in these twins. Medial cranial nerves V-XII were absent or displaced although apparently normal laterally. The medial palates were present but shortened, whereas the medial mandibular rami had folded back on themselves rostrally to form a midline mass between the two chins. Each twin had only one lateral kidney and one lateral testis. Medial scrotal sacs were present but devoid of a testis. There was a midline, "uterine"-like structure which crossed between the twins. However, histological analysis of this structure revealed it to be dysplastic testicular tissue.
The relationship between the abnormal reproductive features in these twins and the conjoining is unclear. The anatomy of these twins, in addition to the literature reviewed, illustrates the internal anatomical heterogeneity of grossly similar conjoined twins. A review of the literature also suggests that conjoined twinning may be more common in swine than was previously suspected.
The Anatomical Record 07/1994; 239(2):224-9. · 1.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Preweaning mortality in piglets constitutes a major loss to the swine industry. Congenital defects account for a small but significant proportion of these losses. To implement appropriate strategies to reduce such losses, it is necessary to identify the specific causes and their relative importance. Consequently, a mail survey of swine production in Ontario was carried out to determine the prevalence and types of birth defects. Statistical comparisons of the prevalence of overall defects were made between accurate and estimate records, breeds (cross vs. purebred), size of operation (number of sows) and geographic location. The mean litter size of 11 pigs born per sow was not significantly different for those with accurate versus estimate records, but the difference in the prevalence of defective pigs (live and dead) was significant (accurate 3.1% vs. estimate 4.1%). Splayleg (spraddleleg) was the most common defect. The next four defects for both groups were belly rupture, other rupture, ridglings and other, but not in the same ranking. Purebred and small farm operations (< 25 sows) had a significantly higher prevalence of birth defects for estimated data only. Geographic location had no effect. Further work is required to determine whether recording prevalence of birth defects in Ontario swine will provide a useful monitor of environmental stress. The study provides a baseline for the prevalence and type of defects in Ontario swine.
Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire 05/1993; 57(2):67-73. · 0.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The study was conducted to determine whether consumer acceptability of fresh and cured pork differed among gilt, intersex, cryptorchid, and intact male market pigs. Samples of chops and bacon from 12 animals of each sex were tested using 9-point hedonic scales for sensory characteristics. Androst-16-ene steroid levels, blood levels of testosterone and estrogen were determined, as was ‘taint’ by a fry test of fat. A significant sex effect for tenderness (P < 0·0092) and juiciness (P < 0·0095) resulted from chops of intact males being liked least. Low consumer ratings were usually texture related. Cryptorchid pigs varied most in eating characteristics being the only sex to exhibit significant differences for liking of aroma and flavour of chops. The few significant differences obtained for bacon were not related to those obtained for chops. Fry test and steroid levels were not related to liking with the exception of testosterone which reduced mean liking.
[Show abstract][Hide abstract] ABSTRACT: Magnetically elicited transcranial motor evoked potentials (MEPs) were studied in 37 dogs with type 1 intervertebral disc (IVD) disease. The waveforms were recorded from both cranial tibial muscles before and after surgery. The latencies and amplitudes obtained were compared to those of a control population (n = 14). MEPs were recordable in all dogs with mild or no neurologic deficits, but they were recordable in only 50% of ambulatory dogs that were severely ataxic. MEPs could not be elicited from nonambulatory dogs. There was a significant attenuation of the amplitudes in all clinical cases, even if the dogs demonstrated back pain alone. Significantly prolonged latencies were associated with neurologic deficits. MEPs were not good predictors of neurologic recovery. The responses obtained from the side where the disc material was found were not different from those recorded from the opposite side. MEPs were very sensitive to lesions of the spinal cord, as indicated by the significant changes in the waves in patients with mild or no neurologic deficits and in the loss of response in dogs that still demonstrated purposeful movement. Neurologic exams provided more accurate diagnoses and prognoses than did MEPs in dogs with IVD disease.
Veterinary Surgery 12/1992; 22(1):5 - 10. · 0.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The ultrastructure of the ventral lateral geniculate nucleus (LGNv) associated with the superior colliculus was investigated. In addition to normal synaptic morphology tectal input was examined following unilateral ablation of the superior colliculus at survival times of 2 to 12 days. Eight cats were used (six experimental, two control). Examination of the ventromedial LGNv revealed a prevalence of Flat-Symmetric (FS) synapses (58.2 +/- 1.9%), relative to the usually more abundant, Round-Asymmetric (RA) contacts (41.8 +/- 1.8%). The functional morphology of terminating tectal fibres (although infrequent) was suggestive of the FS type. Since FS connections usually serve an inhibitory purpose, it is suggested that the tectal LGNv connection has a negative modulation function in the fixation and tracking process.
[Show abstract][Hide abstract] ABSTRACT: A group of 17 intact male pigs and 3 gilts ranging in weight from 96 to 260 kg was selected for sensory evaluation of boar taint in loin chops. Samples were evaluated by 10 trained judges using a 10-cm graphic scale for rating off-aroma, off-flavor, pork flavor, softness, tenderness, juiciness, and residual tissue. In addition, a fry test for taint was conducted by four experienced testers on fat samples from all animals. Androst-16-ene steroid levels were measured in salivary gland and fat. Two versions of a colorimetric assay for the androst-16-ene steroids were used, a complete version, in which cholesterol was removed from the tissue extracts using a digitonin-Sepharose affinity column, and a simplified version, which does not include this step. The off-aroma and off-flavor sensory scores showed a good correlation with the androst-16-ene levels in fat and salivary glands and high correlations were obtained between the androst-16-ene steroid levels in fat and salivary glands. The levels of the androst-16-ene steroids in the salivary gland were highly correlated with the levels of estrogen in the blood and to a lesser extent with the levels of testosterone in the blood. Similar correlation coefficients were obtained between salivary gland androst-16-ene steroid levels measured using either the complete or simplified versions of the colorimetric assay and the off-aroma and off-flavor sensory scores. The results of the fry test were variable and no statistically significant correlations were obtained between the fry test results and the off-aroma and off-flavor sensory scores from the trained sensory panel.(ABSTRACT TRUNCATED AT 250 WORDS)
Journal of Animal Science 04/1991; 69(3):1092-100. · 1.92 Impact Factor