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Biomedical subjects

S P Snyder

Publications and source records attributed to S P Snyder.

At least 19 recordsLinked to original sources
PubMed1994

Photosensitization associated with exposure to Pithomyces chartarum in lambs.

An epidemic of photosensitization was observed in a group of lambs on irrigated autumn pasture in western Oregon. Signs included crusting, necrosis, and sloughing of the skin over the nostrils, lips, and ears, and of the mucous membranes of the buccal regions. Microscopic examination of plant material from the pasture disclosed spores of Pithomyces chartarum. This fungus has been documented as a causal factor in photosensitization in sheep and cattle (facial eczema) in other parts of the world. An infective agent or other plant material that could have induced the clinical signs in the lambs was not evident. Weather and humidity conditions were ideal for fungal growth during the grazing period, and the fungus was detected in large numbers before and during the epidemic. Even though facial eczema has not been reported previously in northwestern United States, we feel the circumstances surrounding this epidemic warrant such a diagnosis.

Animals↗
PubMed1994

Polycythemia in a llama.

The PCV of a llama increased from 50.8 to 74.0% during a 19-month period. The llama remained clinically normal unless stressed, when it would become dyspneic and tachypneic. Thoracic auscultation revealed sounds consistent with pneumonia, but were probably attributable to pulmonary congestion resulting from polycythemia. A diagnosis of secondary absolute polycythemia was made on the basis of high serum erythropoietin concentrations and no evidence of hypoxia. Necropsy revealed congestion of the lungs and liver. Cause of the polycythemia was not determined. Polycythemia should be considered as a differential diagnosis in a llama with exercise intolerance and harsh bronchovesicular sounds.

Animals↗
PubMed1994

Performance of single comb White Leghorn layers fed corn-soybean meal and barley-corn-soybean meal diets supplemented with a direct-fed microbial.

An experiment was conducted with Single Comb White Leghorn (SCWL) layers to determine the effect of feeding either corn-soybean meal (C-S) or barley-corn soybean meal (B-C-S) diets with or without condensed cane molasses solubles (CCMS) or with or without CCMS-1,100 mg Lactobacillus (Lacto)/kg (ppm) diet on performance, nutrient retentions, digesta passage rate, and histological changes of the gastrointestinal (GI) tracts. Six dietary treatments were fed for eight 28-d periods and consisted of C-S (control), C-S + CCMS, C-S + CCMS-1,100 ppm Lacto (4.4 x 107 cfu/mg Lacto), B-C-S (control), B-C-S + CCMS, and B-C-S + CCMS-1,100 ppm Lacto. The CCMS served as the carrier for the Lacto, and the CCMS-Lacto premix (55 g Lacto/kg) was incorporated at 2% of the diet. Lactobacillus supplementation in C-S diets improved (P < .05) egg weight, egg mass, egg size, and body weight gains, and in B-C-S diets improved body weight gains. There were no differences in feed consumption, feed conversion, internal egg quality, and egg specific gravity among the dietary treatments. Passage rates of digesta were increased (P < .05) when either C-S or B-C-S layer diets were supplemented with Lacto. Lactobacillus supplementations of the C-S and B-C-S diets increased (P < .05) fat and calcium, and fat, phosphorus, copper, and manganese retentions, respectively. Increased cellularity of Peyer's patches in the ileum indicated a stimulation of the mucosal immune system that responds to antigenic stimuli by secreting immunoglobulin (IgA).

Animal Feed↗
PubMed1992

Dietary pyrrolizidine (Senecio) alkaloids and tissue distribution of copper and vitamin A in broiler chickens.

The effect of feeding a diet containing 5% tansy ragwort (TR) (Senecio jacobaea), a poisonous plant containing pyrrolizidine alkaloids (PA), on the blood and liver levels of copper, zinc, iron and vitamin A in broiler chicks was examined. Serum and liver copper and liver iron concentrations were increased in chicks fed a diet with 5% TR, while serum and liver zinc and vitamin A decreased. When PA were removed from the diet, partial restoration of normal serum vitamin A level occurred, indicating that the ability to mobilize liver vitamin A is not irreversibly inhibited by PA. The decline in serum vitamin A occurred by 8 days of TR feeding with a concurrent decline in growth rate. When chicks were fed a diet high in vitamin A (25,000 IU/kg), followed by a basal diet containing TR, serum vitamin A levels were significantly (P < 0.01) decreased, while liver vitamin A level increased. This indicates that mobilization of previously stored vitamin A from the liver is impaired by PA. Prior feeding of a high vitamin A level resulted in protective effects against PA toxicity, as assessed by histopathology. This study shows that a dietary source of PA modifies metabolism and tissue distribution of minerals and vitamin A.

Administration, Oral↗
PubMed1991

Subchondral bone cysts with fractures of the extensor processes in a horse.

Probable cause of fracture in a Paint gelding was a congenital bone defect involving the extensor process area of the right and left forelimb distal phalanges. Radiographically and histologically, subchondral bone cysts at the fracture lines were suspected. These cysts were thought to have developed in association with abnormal ossification centers at the extensor process areas of the third phalanx. Partial avulsion of weak extensor processes would then occur from natural forces exerted on these weakened bony prominences via the common digital extensor tendon. Support for osteochondrosis as a cause of this bone cyst formation was seen in histologic examination of fragments removed. Within the bony trabeculae, a dysplastic focus of cartilage with mineralized plaques and osseous tissues was observed. Findings supported a diagnosis of osteochondrosis, to the extent that the disease is presently understood in horses. Surgical correction by fragment removal was performed to circumvent progression of degenerative joint disease, which was evident as partial cartilage erosion of the distal dorsal articular surface of the second phalanx and fracture fragments. Recovery from surgery was rapid, and several months after surgery, the horse was sound for pleasure riding.

Animals↗
PubMed1991

Erythrocyte dyscrasia, anemia, and hypothyroidism in chronically underweight llamas.

A syndrome characterized by anemia, erythrocyte dyscrasia, low body weight, and hypothyroidism was observed in 8 llamas (Lama glama). At initial examination (1 to 23 months of age; median, 7.5 months), llamas (3 males, 5 females) were markedly underweight (29 to 55 kg; median, 36 kg) and anemic (PCV, 12.9 to 25.5% [median, 19%]). Five of the llamas became progressively more anemic over time; in 2 of them, PCV decreased to less than 10%. Erythrocyte changes included severe poikilocytosis, anisocytosis, asymmetric distribution of hemoglobin within the cytoplasm, and cytoplasmic extensions from one or both poles. Six llamas had moderate to severe valgus deformities of the carpus. All llamas had low baseline serum thyroxine concentration and diminished response to thyrotropin administration. Baseline and post-thyrotropin triiodothyronine concentrations did not have consistent patterns. Five llamas were hypophosphatemic and 7 had low serum iron concentration (iron concentration was not determined in 1 llama). Orally administered iron supplementation did not induce clinical improvement. Because 3 of the affected llamas were full sisters, a genetic basis for the problem has to be considered. It was not possible to evaluate the familial relationship of the other 5 affected llamas. Although the underlying cause of the problem was not established, the prognosis for affected llamas is guarded to poor.

Anemia↗
PubMed1990

Efficacy of a vaccine to prevent Chlamydia- or Campylobacter-induced abortions in ewes.

In a sheep flock, Chlamydia psittaci, Campylobacter fetus, Ca jejuni, and Salmonella dublin caused abortions. A vaccine that contained C psittaci type I from 2 sources: a cow with pneumonia and an aborted ovine fetus, Ca fetus, Ca jejuni, and 4 strains of K99 Escherichia coli was given to 240 ewes before they were bred. All fetuses, placentas, and lambs, that died within 36 hours of birth were examined for infectious agents. Of 55 abortions, 30 (55%) were caused by Chlamydia or Campylobacter spp; 25 of the 30 (83%) abortions took place in the nonvaccinated group (n = 240). Forty-five more lambs survived in the vaccinated group than in the nonvaccinated group. Abortion rates for Chlamydia and Campylobacter spp (2.1 vs 10.4% in vaccinated and nonvaccinated groups, respectively) were significantly different (P = 0.003). Abortion rates for S dublin were not significantly different between groups. The Salmonella epizootic was controlled quickly by sanitation and treatment procedures. The vaccine was at least 80% efficacious against Chlamydia and Campylobacter spp and appeared to be protective.

Abortion, Veterinary↗
PubMed1990

Serologic and histologic diagnosis of toxoplasmic abortions in sheep in Oregon.

Between 1983 and 1989, we examined 586 fetuses and dead lambs submitted to a diagnostic laboratory in Oregon. Toxoplasmosis was diagnosed in 74 (12.6%), campylobacteriosis in 89 (15.2%), chlamydiosis in 75 (12.8%), miscellaneous infections in 153 (26.1%), noninfectious causes in 37 (6.3%), and undetermined causes in 158 (27.0%). Detection of Toxoplasma gondii agglutinating antibodies (greater than or equal to 20) in body fluids or heart serum was considered specific for the diagnosis of toxoplasmosis in ovine fetuses or lambs. Toxoplasma gondii antibody titers (reciprocal) in 285 fluids from fetuses or dead lambs were less than 20 (64.5%), 20 (4.5%), 40 (1.7%), 80 (0.7%), 160 (2.1%), 320 (1.7%), 640 (4.9%), 1,280 (2.8%), 2,560 (4.5%), 5,120 (3.8%), 10,240 (2.1%), and greater than or equal to 20,480 (6.3%).

Abortion, Veterinary↗
PubMed1989

Measurement of IgG concentration in ovine fetal fluids: a useful diagnostic test.

The Veterinary Diagnostic Laboratory at Oregon State University received 172 aborted ovine fetuses during the 1985-1987 lambing seasons; from 120 of these, body fluids were evaluated for IgG levels. Fifty-two (43%) of the fetal fluids had immunoglobulin G (IgG) levels greater than 15 mg/dl. Forty-five (87%) of the fluids with elevated IgG levels were confirmed or presumed toxoplasma or chlamydia abortions. A mean fetal fluid IgG concentration of 111.5 +/- 78 mg/dl was found for the 26 toxoplasma abortions; for the 19 chlamydia abortions, a mean IgG concentration of 109 +/- 91 mg/dl was found. Antibody titers equal to or greater than 1:40 against Toxoplasma gondii were detected in 23 fetal fluids. Fetal fluid IgG concentration less than 15 mg/dl was found to be associated with bacterial organisms (i.e., Campylobacter sp.) as the confirmed or presumed cause of abortion. These results suggest that measurement of fetal fluid IgG concentration is a useful, supportive diagnostic test in determining the cause of ovine abortion, and should be included as a routine laboratory procedure for ovine abortion diagnosis.

Abortion, Veterinary↗
PubMed1988

Sequential study of visceral lesions caused by isolates of an avian osteopetrosis virus (myeloblastosis-associated virus).

Ten-day-old chicken embryos were inoculated with isolates of myeloblastosis-associated virus that induced osteopetrosis of slow or rapid onset. Bursa of Fabricius, thymus, spleen, bone marrow, kidney, liver, and lung were examined at 15, 17, and 19 days in ovo and at 7 and 25 days after hatching by histologic and immunoperoxidase techniques. Tissues from 19-day-old in ovo embryos also were examined by electron microscopy. The lymphoid organs of embryos inoculated with all isolates manifested changes suggesting inhibited development. Virus was most often associated with macrophages, heterophils, and nonlymphoid stromal cells in these organs. Viral particles and antigen were abundant in tissues from embryos inoculated with slow-onset isolates, but cell necrosis was infrequent. The kidney and bursa had especially abundant viral particles and antigen. Conversely, viral particles and antigen were minimal in tissues from embryos inoculated with the rapid-onset isolate, yet intravascular cellular thrombi, substantial cell necrosis, and increased heterophils and hemocytoblasts were found.

Animals↗
PubMed1987

Nodular granulomatous episclerokeratitis in dogs: 19 cases (1973-1985).

We examined the age and breed prevalence and the response to treatment of 19 dogs with nodular granulomatous episclerokeratitis. Biopsy specimens were evaluated to determine the histologic characteristics of the lesions. In these dogs, this disorder was an idiopathic, bilateral disease characterized histologically by the presence of chronic granulomatous inflammation and reticulin fiber formation. The onset of clinical signs developed predominantly in young to middle-aged Collies, with a slow progression and benign clinical course. With treatment, the condition rarely threatened vision and was controlled easily with azathioprine (2 mg/kg) and/or corticosteroid. The dose of immunosuppressive drug was tapered to allow for minimal systemic effects and continued remission of clinical signs. The response to treatment was highly variable.

Adrenal Cortex Hormones↗
PubMed1987

A sequential study of bone lesions caused by isolates of an avian osteopetrosis virus, MAV-2(0).

The pathogenesis of avian osteopetrosis caused by rapid and slow-onset isolates of myeloblastosis associated virus, MAV-2(0), was studied by inoculation of 10-day-old chick embryos with virus. Femur and calvarium were examined at 15, 17 and 19 days in ovo and 7 and 25 days after hatching by histologic and immunoperoxidase techniques. Femur and calvarium were also examined by electron microscopy at 17 and 19 days in ovo and at 7 days after hatching. Avian osteopetrotic bone lesions were characterized by exuberant periosteal proliferation; the time of onset varied with different virus isolates. In the femur virus was first associated with osteoprogenitor cells, then with osteoblasts and finally with osteocytes as the cells progressed through normal sequences of differentiation. The amount of virus produced by these cells did not correlate with onset of periosteal proliferation. Slow onset isolates provoked early virus production, but proliferative lesions did not develop until later. Conversely, the rapid onset isolate induced little early virus production, although lesions were present. Periosteal proliferation was associated with and preceded by perivascular edema and perivascular cell necrosis within the bone cortex following infection by all isolates. However, the rapid onset isolate caused more severe lesions than other isolates. These lesions included vascular thrombosis, capillary necrosis and focal bone necrosis. The relationship between early vascular lesions and late periosteal proliferation seen with the slow onset isolates is not as clear as with the rapid onset isolate. Calvarial bone, a representative flat bone, was found to have virus present, but at a level less than the femur. Vascular lesions were rarely seen in the calvarium and bone proliferation did not occur at this site.

Animals↗
PubMed1987

Pathology of Campylobacter jejuni abortion in sheep.

Campylobacter jejuni was inoculated intravenously into pregnant ewes on gestation days 114 and 123 to reproduce ovine abortion. All ewes aborted 7-12 days post-inoculation. High numbers of C. jejuni were isolated from ewe tissues (caruncle, bile, cecal feces), fetal tissues, and placenta. C. jejuni colonies were identified in caruncles and placenta by light microscopy and immunoperoxidase techniques. Histologically, inoculated ewes had a severe purulent endometritis with vasculitis. Placentas from inoculated ewes and field cases showed necrosis and purulent inflammation; however, placentas from inoculated ewes had large numbers of bacterial colonies compared to few bacteria found in field cases. Histologically, only one fetus from the inoculated ewes showed lesions (purulent bronchopneumonia), whereas all fetuses from field cases had a distinct bronchopneumonia, and one fetus showed multifocal hepatic necrosis. These results suggest that C. jejuni (serotypes Penner 1 and Lior 2) is an important abortifacient organism for sheep.

Abortion, Veterinary↗
PubMed1985

Lymphocyte blastogenesis, complement fixation, and fecal culture as diagnostic tests for paratuberculosis in North American wild ruminants and domestic sheep.

The efficacy of the lymphocyte blastogenesis and complement-fixation tests and fecal culture for detection of Mycobacterium paratuberculosis infection was assessed in bighorn sheep (Ovis canadensis), elk (Cervus elaphus nelsoni), mule deer (Odocoileus hemionus), white-tailed deer (O virginianus), bighorn X mouflon (O musimon) hybrid sheep, and domestic sheep. Spontaneously infected bighorns were tested at the time of capture; experimentally infected animals were tested monthly for 12 months or periodically for 36 months. Lymphocyte blastogenesis tests were conducted with peripheral blood mononuclear cells and protein antigens of M avium, M bovis, and M paratuberculosis. Best diagnostic results were obtained when M avium purified-protein derivative was used as antigen and 20% bovine fetal serum was incorporated in the culture medium; a positive test was defined as a stimulation index greater than or equal to 3.5. Test sensitivity and specificity, respectively, were 82% and 94% in hybrid sheep and were 72% and 100% in domestic sheep. Sensitivity and specificity, respectively, were 39% and 94% in elk and 53% and 92% in deer. When infection was determined in spontaneously infected bighorns by culture of M paratuberculosis and/or the presence of acid-fast bacilli in characteristic microscopic lesions, sensitivity was 75% and specificity was 87%. Fecal cultures and the complement-fixation tests seldom correctly identified infected animals.

Animals↗
PubMed1984

Cutaneous lymphosarcoma and leukemia in a dog resembling Sézary syndrome in man.

A dog with a lymphoproliferative disease resembling the Sézary syndrome variant of mycosis fungoides in man had large numbers of circulating morphologically abnormal lymphoid cells, multicentric cutaneous nodules and plaques, and extracutaneous involvement of lymph nodes and viscera. The presence of Pautrier's microabscesses, intracutaneous hyperchromatic cells, and leukemic cells with convoluted nuclei distinguished the disease from other types of cutaneous lymphoma.

Animals↗
PubMed1983

Identification of carriers of Streptococcus equi in a naturally infected herd.

During an outbreak of strangles in a population of research horses, 4 mares were identified as carriers of Streptococcus equi. Three of the mares had typical signs of strangles (severe regional lymphadenitis with or without rupture of abscessed lymph nodes). The 4th mare experienced episodes of serous to mucopurulent nasal discharge, but never had more than a mild degree of lymph node enlargement. Streptococcus equi was isolated from the abscessed lymph nodes and from nasopharyngeal swab specimens from the first 3 mares from 6 to 19 weeks after rupture of involved nodes. Streptococcus equi was isolated from the nasopharynx of the 4th mare on introduction into the herd and intermittently over the ensuing 6 months. During the 7th month, mare 4 was placed in isolation, where she continued to shed S equi for 4 more months. A complete physical examination during the 10th month, including radiography of the head and thorax, did not reveal any relevant abnormalities, but a pharyngeal swab specimen was culture-positive for S equi. This isolate was used to inoculate 2 yearling colts, which developed strangles and from which S equi was reisolated. Shedding of S equi by mare 4 ceased in the 11th month, and at necropsy 2 months later, S equi was not recovered from any organ or tissue. Corticosteroid administration 3 weeks prior to necropsy had induced neither shedding of the organism nor clinical signs of strangles. The study provided clinical, epidemiologic, and bacteriologic evidence to support the existence of a carrier state following natural infection with S equi.

Abscess↗