Biomedical subjects

H G Townsend

Publications and source records attributed to H G Townsend.

47 records · Page 3Linked to original sources

PubMed1989

Clinical and pathological effects of flunixin meglumine administration to neonatal foals.

The effects of daily intravenous administration of flunixin meglumine at dosages of 0.55, 1.1, 2.2 and 6.6 mg/kg for five days were examined in neonatal foals. Six two day old foals were used to evaluate the effect of each dosage. Foals were examined every day and blood samples collected on days 1, 3 and 6. All foals were euthanized after six days, necropsied and examined for lesions. The major clinical abnormality was diarrhea, but the incidence was not related to the dosage of flunixin meglumine administered. The foals receiving 6.6 mg/kg of flunixin meglumine had significantly more gastrointestinal ulceration and greater cecal pathology and cecal petechiation scores than those foals treated with saline. The foals in the 6.6 mg/kg treatment group had a greater loss of total protein during the study, but the difference was not significant. There were no statistically significant blood cellular or biochemical alterations associated with the administration of flunixin meglumine. There were no significant clinicopathological differences between healthy foals treated with the recommended dosage of flunixin meglumine and those treated with physiological saline.

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PubMed1989

Diagnosis of copper deficiency and effects of supplementation in beef cows.

The effects of feeding supplementary dietary copper to a herd of 400 beef cows, were studied over a two year period. In the first year of the trial, the calves showed clinical signs of copper deficiency. There was improved growth following subcutaneous injection of copper ethylenediamine tetraacetate, and the treated calves had a 2.8% increase in adjusted weaning weights. In the second year of the trial pregnant cows were fed a basal ration of bromegrass silage, barley and minerals over the winter feeding period. The feed was supplemented with copper so that half received 5.5 mg/kg of copper on a dry matter basis and half 40 mg/kg. Calving occurred in the spring and half the calves were treated with injectable copper at birth and again at 12 weeks of age. There was no evidence of copper deficiency in the calves and there was no effect of high level copper supplementation on calf birth weight, or neutrophil candidacidal activity. Susceptibility to diarrhea varied in a complex fashion; morbidity was lowest in calves born to dams fed supplementary copper and highest in calves born to supplemented dams and injected with copper at birth. The cows and calves grazed the same copper deficient pasture over the summer. The average daily gain for calves born to supplemented cows was 0.999 +/- 0.010 kg/day (x +/- SEM) which was significantly greater than the 0.972 +/- 0.009 kg/day for calves from nonsupplemented dams (p = 0.044). The benefit of copper supplementation on 200 day weaning weight was estimated at 4.8 kg. Evidence of copper deficiency was seen when a herd test showed mean serum levels below 9 mumol/L and liver values below 0.09 mmol/kg wet matter.

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PubMed1989

Factors associated with average daily gain, fever and lameness in beef bulls at the Saskatchewan Central Feed Test Station.

Data obtained from the Saskatchewan Central Feed Test Station in Saskatoon, Saskatchewan, Canada were examined for evidence of factors related to average daily gain and the diseases occurring in 326 beef bulls during the 1983-84 test. Average daily gain was found to be significantly associated with breed, pen assignment and initial test weight but was not associated with disease or age upon arrival at the test station. Lameness was associated with breed and initial weight, while fever (suspected respiratory disease) was associated with age. The predicted odds of lameness was approximately seven times greater in the animal with the heaviest as compared to the lightest initial test weight and the predicted odds of fever was approximately five times greater in the youngest as compared to the oldest animal.

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PubMed1986

Relationship between spinal biomechanics and pathological changes in the equine thoracolumbar spine.

The relationship between spinal biomechanics and pathological changes occurring in functionally normal equine thoracolumbar spines was studied in 23 horses. Ventrolateral vertebral body osteophytes occurred in 36 per cent of the spines. The majority occurred between the 10th and 17th thoracic vertebrae with the largest being found between the 11th and 13th thoracic vertebrae, the region of the thoracic spine where the greatest amount of lateral bending and axial rotation occurs. Impingement of the dorsal spinous processes was detected in 86 per cent of the spines with most lesions occurring between the 13th and 18th thoracic vertebrae. The severity of occurrence of impingement did not appear to be related to regional spinal mobility. Degeneration of intervertebral discs was observed in three of four specimens that were sectioned sagittally. It occurred in the first thoracic and the lumbosacral intervertebral discs and appeared to be related to the increased dorsoventral mobility and the increased disc thickness of these joints. The characteristic distribution of fractures of the thoracolumbar spine is discussed with respect to the biomechanics of the spine.

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PubMed1985

Chronic eosinophilic dermatitis: a manifestation of a multisystemic, eosinophilic, epitheliotropic disease in five horses.

A generalized, chronic, progressive, exfoliative dermatitis in five horses is described. Histologically, the lesion is characterized by a superficial and deep perivascular dermatitis which is eosinophil-rich with a marked lymphocytic and plasmacytic component, accompanied by marked acanthosis and hyperkeratosis. More severe cases progress to a lichenoid pattern with the same cellular composition with focal eosinophilic spongiosis and eosinophilic subcorneal pustules. Clinically, the disease is associated with chronic, severe weight loss and is fulminating. The skin lesions are accompanied by lymphoplasmacytic and eosinophilic infiltrates and formation of eosinophilic granulomas in other epithelial organs, most noticeably the pancreas, in which a chronic, fibrosing pancreatitis develops. Other epithelial organs involved to various degrees are salivary glands, the gastrointestinal system, including the oral cavity and esophagus, biliary epithelium and bronchial epithelium. The etiology of this disease is unknown.

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PubMed1984

Relationship between intervertebral joint morphology and mobility in the equine thoracolumbar spine.

The anatomical features of 21 equine thoracolumbar spines, obtained from horses with clinically normal backs, were examined and the results compared with recent data on the mobility of the joint complexes of the horse's spine. The thoracolumbar spine can be divided into four regions based upon the morphology of the joint complexes: the first thoracic intervertebral joint (T1-2), the cranial and mid thoracic region (T2-T16), the caudal thoracic and lumbar region (T16-L6) and the lumbosacral joint. The mobility of the intervertebral joints in each of these regions can be related to their morphology, particularly the shape, size and orientation of the articular facets and the presence and frequent fusion of the lateral joints of the lumbar spine. The shape and thickness of the intervertebral discs also appear to be of importance.

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PubMed1983

Induction of parturition in mares: effect on passive transfer of immunity to foals.

Parturition was induced in 11 mares, using a synthetic prostaglandin. Eight mares, not treated, were used as controls. There was no significant difference between the serum immunoglobulin G (IgG) concentrations of the treated and control mares. The concentration of IgG in the colostrum of treated mares compared favorably with that reported for naturally foaling mares. Four foals from treated mares died or were euthanatized because of weakness during the 1st 24 hours after birth. The mean IgG concentration in the surviving foals from treated mares at 24 to 36 hours of age was 1,561 mg/100 ml, which was significantly (P less than 0.01) lower than the mean concentration of 2,731 mg/100 ml in foals from control mares. The mean serum IgG concentration in foals from control mares was significantly (P less than 0.01) greater than that of their dams, whereas the mean serum IgG concentration of the foals from treated mares was significantly (P less than 0.01) lower than that of their dams.

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PubMed1983

Kinematics of the equine thoracolumbar spine.

At least three types of movement take place in the joint complexes of the equine thoracolumbar spine: dorsoventral flexion and extension, axial rotation and lateral bending. Using the standard right-handed Cartesian coordinate system, these movements may be defined as rotation about the x, y and z axes respectively. Except in cases of intervertebral fusion, all three types of movement occur in each joint complex of the equine back. The greatest amount of dorsoventral movement takes place at the lumbosacral and the first thoracic intervertebral joints. The greatest amount of axial rotation and lateral bending was measured in the mid-thoracolumbar spine at the level of the 11th or 12th thoracic intervertebral joints. The caudal thoracic and the lumbar spine is the least mobile region of the equine back. In the mid-thoracic spine, lateral bending was always accompanied by a "coupled" axial rotation. The presence of the rib cage stabilised the cranial thoracic vertebrae against axial rotation.

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PubMed1981

Equine protozoal myeloencephalitis: a report of two cases from Western Canada.

Two cases of nonsuppurative myeloencephalitis are reported which clinically and pathologically resemble equine protozoal myeloencephalitis. Lesions in both horses were associated with Toxoplasma-like organisms visible in microscopic sections. Clinical signs and lesions in one case primarily involved the brain and in the other case principally involved the spinal cord and associated meninges. Positive identification of the organisms was not achieved; however, the etiological agent is unlikely to be a species of Toxoplasma. Recently published studies suggest a species of Sarcocystis is involved.

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PubMedDate not supplied

Repair and function of synovium after arthroscopic synovectomy of the dorsal compartment of the equine antebrachiocarpal joint.

The reparative ability of equine synovium was determined by gross, histological, and ultrastructural examination. The functional potential of the synovium was estimated by examination of synovial cell organelles with transmission electron microscopy. Results from rested and exercised horses were compared to determine the effect of exercise on synovial healing. The response of synovectomized joint to exercise was evaluated with a standardized lameness examination and by gross, histological, and histochemical observations of the articular cartilage. A 7-mm diameter motorized synovial resector was used to perform a subtotal synovectomy in 1 antebrachiocarpal joint of each of 8 horses; the contralateral joint served as a control. After 2 months rest, four randomly selected horses were rigorously exercised for the remainder of the study; the other four horses continued paddock rest. Lameness examinations and synovial fluid analyses were conducted at 0, 2, 30, 60, and 120 days. Synovium and articular cartilage from all horses were examined at necropsy at 120 days. None of the horses were lame during the study, and transient synovitis occurred in the synovectomized joints. The hyaluronan concentration of treated joints decreased at 2 days but returned to normal by 60 days. Synovial fluid composition, including hyaluronan concentration, was unchanged by exercise. Significant cartilage damage was not observed in any of the joints. At 120 days, the healing synovium was devoid of villi and its subintima was fibrotic, however transmission electron microscopy confirmed that an intimal layer was present within the repair tissue. The cells within the repair tissue appeared actively engaged in both synthesis and phagocytosis. Exercise did not modify any of these findings. The results of this study suggest that 120 days after subtotal synovectomy, the joint environment was maintained and and the resected synovium had evidence of restoration and increased metabolic potential. Synovectomized joints withstood exercise but synovial repair was not accelerated by exercise.

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PubMedDate not supplied

Equine vaccination.

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