Timothy A Snider

Oklahoma State University - Stillwater, Stillwater, Oklahoma, United States

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Publications (23)43.37 Total impact

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    ABSTRACT: Objectives: The effects of insertion speed in revolutions per minute (RPM) and pilot hole predrilling for placement of threaded external skeletal fixation pins on temperature and morphological damage in cortical bone were evaluated. The null hypothesis states that insertion speed and predrilling will have no significant effect on temperature and morphological damage. Methods: Fixation pins were inserted into cadaveric canine femurs at speeds of 700 RPM and 150 RPM, with and without pre-drilling. Temperature was measured at each cortex 0.5 mm and 3.0 mm from each insertion site. Samples were examined grossly and by scanning electron microscopy for evidence of morphological damage. Data were analysed for maximum temperature, temperature increase, sites above thermal necrosis thresholds, microcracks, thread quality and gross damage. Results: Predrilling had a significant effect on maximum temperature, temperature increase, sites exceeding necrosis thresholds, microcracks, thread quality and gross damage. Speed of insertion had no significant effect on any of the measured parameters following predrilling, but had a significant effect on thread quality without predrilling. Clinical significance: Our results fail to reject the null hypothesis concerning insertion speed, which had no significant effect on thermal damage, and minimal effect on morphological damage, which was negated by predrilling. Our results reject the null hypothesis concerning predrilling and support the practice of predrilling fixation pin insertion sites.
    Veterinary and comparative orthopaedics and traumatology : V.C.O.T. 07/2014; 27(4).
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    ABSTRACT: Non-typhoidal Salmonella serovars (NTS) are the leading cause of foodborne illnesses worldwide and the leading cause of hospitalization and death due to foodborne illnesses in the United States. While there has been some progress in vaccine development against Salmonella spp., there are no broadly protective vaccines. A compounding factor in the development of these vaccines is the lack of a natural model. Most vaccine research is performed utilizing a mouse typhoid model. Unlike mice, calves infected with Salmonella develop gastroenteritis similar to the disease in humans. The initial step in developing a model of infection in older calves is the determination of a bacterial dose that elicits substantial clinical disease without causing death. Ten-week-old calves were orally inoculated with increasing doses of either Salmonella enterica serovar Typhimurium or Newport. Clinical illness scores were assigned based on rectal temperature, fecal consistency, attitude and hydration. Gross and microscopic pathology findings were also evaluated. These older calves exhibited clinical and pathologic signs of severe gastroenteritis without death losses with effective dose of 1×108CFUs for S. Typhimurium and 1×107CFUs for S. Newport.
    Veterinary Microbiology 11/2013; · 3.13 Impact Factor
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    ABSTRACT: A 6-year-old spayed Labrador Retriever Mix dog was evaluated for a 2-week history of progressive generalized weakness and reluctance to stand. Physical examination revealed severe weakness with obtunded mentation, head tilt, bilateral nystagmus, and decreased vision. CBC findings included mild nonregenerative anemia, marked thrombocytopenia, and a few atypical mononuclear cells on the blood film. The cells were 15-30 μm in diameter and had round to oval to reniform centrally placed nuclei with stippled chromatin, prominent nucleoli, and abundant basophilic cytoplasm with numerous discrete vacuoles and, occasionally, small azurophilic granules. Similar cells were found in bone marrow. On histologic examination of tissues collected at necropsy, neoplastic cells were detected in bone marrow, hepatic sinusoids, cerebral and meningeal vessels, and in capillaries of the heart, renal interstitium, small intestinal submucosa, and muscularis, and alveolar septa. A small discrete mass in the right atrium consisted of similar neoplastic cells, and the spleen was diffusely infiltrated. Tissue distribution was suggestive of intravascular lymphoma. Neoplastic cells in tissue sections were immunoreactive for vimentin, CD18, CD45, and granzyme B and lacked immunoreactivity for cytokeratin. Neoplastic cells on bone marrow aspirate smears and blood films lacked immunoreactivity for CD3, CD79a, CD1c, CD11b, CD11c, CD11d, and E-cadherin. In the absence of immunophenotypic evidence for the neoplastic cells being derived from B-cell, T-cell, or histocytic/dendritic lineages and the lack of clonal antigen receptor gene rearrangement(s), along with positive immunoreactivity for granzyme B, a tumor of NK cells was considered likely. Based on current knowledge, this is the first report of canine intravascular lymphoma, of probable NK cell origin, with peripheral blood involvement.
    Veterinary Clinical Pathology 03/2012; 41(1):84-91. · 1.29 Impact Factor
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    ABSTRACT: A 5-year-old female spayed Shetland Sheepdog Mix dog was evaluated for a history of recent seizure activity, progressive hind limb ataxia, polyuria, and polydipsia and no history of gastrointestinal signs. Physical examination findings included conscious proprioceptive deficits, ataxia, and anterior uveitis along with a hypermature cataract in the right eye. Results of a CBC, serum biochemical profile, urinalysis, and computed tomography scan of the brain were unremarkable. Cerebrospinal fluid (CSF) analysis revealed marked eosinophilic pleocytosis and rare organisms consistent with Prototheca spp within neutrophils and macrophages. On postmortem histologic examination, mononuclear inflammation and numerous intralesional algal organisms, similar to those seen on the cytologic preparation of CSF, were found in the brain, eyes, kidneys, and heart. Abnormalities were not detected on gross and histologic examination of the gastrointestinal tract. Cultures of CSF and subdural/olfactory bulb, but not intestinal tract, yielded growth of Prototheca spp, and PCR analysis and DNA sequencing confirmed the organism as Prototheca zopfii genotype 2. We have reported a rare case of disseminated protothecosis that was diagnosed by evaluation of CSF in a dog presented with neurologic signs and no overt enteric disease. Protothecosis should be considered as a rare cause of seizures, even in the absence of obvious enteric signs, and should be included in the differential diagnosis of eosinophilic pleocytosis.
    Veterinary Clinical Pathology 03/2012; 41(1):147-52. · 1.29 Impact Factor
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    ABSTRACT: The clinical findings, diagnostic tests, and treatment of clinical anemia in a mature Angus cow infected with the hemoplasma Mycoplasma wenyonii are described. Mycoplasma wenyonii has been previously reported to cause clinical anemia in young or splenectomized cattle; however, infection has not been associated with severe anemia in mature animals.
    The Canadian veterinary journal. La revue veterinaire canadienne 09/2011; 52(9):1018-21. · 0.77 Impact Factor
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    ABSTRACT: The serine protease coagulation factor thrombin functions primarily in hemostasis, but is also involved in atherosclerosis, thromboembolic disease, cancer and inflammatory disease. Direct measurement of coagulation proteins including thrombin in plasma samples poses a significant challenge because of lack of specific probes and low thrombin concentrations. In addition, high plasma protein concentrations in samples can result in high backgrounds. These challenges were overcome using a bi-cell surface plasmon resonance (SPR) spectrometer with an immobilized thrombin aptamer to measure thrombin in samples passed through a low volume flow cell. For thrombin in Tris-EDTA buffer, the limit of detection (LOD) was 25 nM. Coefficient of variation (CV) for detection of 50 nM was 12.2% and 12.4% for intra and inter-day measurements respectively. This detection was specific for both thrombin aptamer and for thrombin. Using serum samples spiked with thrombin, the LOD was 50 nM with a linear range of detection from 50 nM to 200 nM. However use of serum samples was associated with consistent, low-level background drift. The contributions of nonspecific protein absorption onto the sensor surface and sample flow speed were assessed, and strategies to reduce this background drift were explored. We conclude that the bi-cell SPR platform with an aptamer capture probe can be employed as a highly sensitive real-time, label-free biosensor for the detection of coagulation factors in plasma samples.
    Biosensors & bioelectronics 06/2011; 26(12):4832-6. · 5.43 Impact Factor
  • Timothy A Snider, Adam W Stern
    Journal of the American Veterinary Medical Association 05/2011; 238(9):1119-21. · 1.72 Impact Factor
  • T A Snider, C Sepoy, G R Holyoak
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    ABSTRACT: The equine endometrial biopsy, an important tool in equine reproduction science, has experienced a rich period of increasing knowledge, development, and application over the past 40 y. Much of the foundational work in this field was conducted by Dr. Robert M. Kenney. In view of his recent passing, this review is dedicated to our alumnus, Dr. Robert M. Kenney (OSU, 1954). In this manuscript, we pay tribute to Kenney-eponymous for the equine endometrial biopsy grading system-by reviewing the procedure. We present this review in three parts: 1) how observational data are acquired; 2) how these data are interpreted; and 3) how these data are applied in equine reproduction science and medicine.
    Theriogenology 02/2011; 75(9):1567-81. · 2.08 Impact Factor
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    ABSTRACT: Amblyomma americanum was confirmed as a competent vector in the transmission of Cytauxzoon felis to domestic cats. Infection with C. felis was produced and replicated in four domestic felines by the bite of A. americanum adults that were acquisition fed as nymphs on a domestic cat that survived cytauxzoonosis. Numerous attempts to transmit C. felis with Dermacentor variabilis at the same time were not successful. All cats upon which infected A. americanum were transmission fed exhibited disease typical of cytauxzoonosis, and the eitiologic agent's presence was confirmed. Clinical signs including fever, inappetence, depression, and lethargy were observed beginning 13 d postinfestation. Pale mucus membranes, splenomegaly, icterus, and dyspnea were also observed during the course of the disease. Rectal temperatures of the C. felis-infected principal cats fluctuated from high to subnormal before returning to the normal range. Clinical signs of cytauxzoonsis improved by 24 d postinfestation in all but one cat, with survivors remaining parasitemic and subclinically infected with C. felis. Unengorged A. americanum and D. variabilis were collected from wild habitats to determine the minimum infection rate of C. felis in ticks from an enzootic area. Infection of C. felis was found only in wild-collected A. americanum. The minimum infection rate of C. felis in A. americanum was 0.5% (one of 178) in males, 0.8% (three of 393) in nymphs, and 1.5% (three of 197) in females. We found no wild-collected D. variabilis infected with C. felis. Our results confirm that A. americanum is a primary vector of C. felis.
    Journal of Medical Entomology 09/2010; 47(5):890-6. · 1.86 Impact Factor
  • Adam W Stern, Timothy Snider
    Journal of the American Veterinary Medical Association 06/2010; 236(12):1297-9. · 1.72 Impact Factor
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    T A Snider, A W Confer, M E Payton
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    ABSTRACT: Cytauxzoonosis, caused by Cytauxzoon felis, is a regionally common, often fatal tick-borne disease primarily affecting the domestic cat. Retrospective analysis of case records from January 1995 to June 2005 identified 148 domestic cats diagnosed with cytauxzoonosis, having suitable archived lung sections. Lung sections were examined and graded on relevant parameters, the chief purpose of which was to characterize the pulmonary lesion of fatal feline cytauxzoonosis. Parameters were scored 0 to 3 for no lesion, mild, moderate, and severe, respectively. Evaluated parameters included the presence of interstitial pneumonia, increases in number of alveolar macrophages, degree of intra-alveolar hemorrhage, neutrophils infiltrating peribronchial and septal interstitium, and degree of vascular occlusion. Overall, interstitial pneumonia was moderate (1.72 +/- 0.65); alveolar macrophage numbers were mild (1.20 +/- 0.60); and intra-alveolar hemorrhage was mild (0.78 +/- 0.75). Neutrophil infiltrates were moderate (1.89 +/- 0.76), and vascular occlusion was moderate to severe (2.26 +/- 0.61). Pulmonary edema was common; its scoring was incorporated into the assessment for interstitial pneumonia. Interestingly, a thrombus was detected in the lung of 1 cat. The current understanding of the pathogenesis of cytauxzoonosis focuses on vascular occlusion by macrophages distended by megaschizont parasite stages within liver, spleen, and lung. These findings corroborate the current understanding yet shed light on the possibility that macrophage activation and inflammatory mediators lead to an interstitial pneumonic process characterized by neutrophilic infiltrates and pulmonary edema. These characterized lesions are likely correlative with the respiratory distress seen in affected cats.
    Veterinary Pathology 05/2010; 47(4):698-702. · 1.93 Impact Factor
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    Adam W Stern, Stephen Smith, Timothy A Snider
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    ABSTRACT: Hypertrophic cardiomyopathy (HCM) was diagnosed during postmortem examination of 2 captive adult Bennett's wallabies (Macropus rufogriseus rufogriseus). The wallabies were members of a mob (herd) of 3 wallabies, and 2 died spontaneously without clinical signs of heart failure being detected. Gross lesions in both cases included marked concentric hypertrophy of the left ventricle, pulmonary edema, and multifocal hemorrhage and subcutaneous edema of the hind limbs. Histologic lesions of the heart were limited to mild cardiac myofiber disarray and marked cardiac myofiber hypertrophy. A specific etiology for the HCM was not determined in either animal. The cardiac changes are similar to the left ventricular hypertrophy previously described in kangaroos.
    Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 11/2009; 21(6):889-92. · 1.18 Impact Factor
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    ABSTRACT: An ultrasound examination of a pregnant 12-year-old Palomino mare's abdomen revealed multiple, variably sized, round, polypoid, cystic structures within the allantois. These cystic areas had clear hypoechoic centres and were surrounded by thin, irregular hyperechoic regions. The foaling was unremarkable. Grossly, the allantois was multifocally expanded by variably sized, 1–15 cm diameter, balloon-like allantoic vesicles containing clear watery or gelatinous fluid. Histological examination demonstrated marked separation of the allantoic surface from the chorionic surface by oedema fluid or gelatinous stroma. No other lesions were observed in the placenta. Similar lesions were observed in 2 other mares. No clinical complications were observed with the foals, fillies and mares after parturition. This is the first report of such large allantoic vesicles in the equine placenta.
    Equine Veterinary Education. 02/2009; 21(3):143 - 144.
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    ABSTRACT: Cytauxzoon felis was transmitted to a domestic cat by Amblyomma americanum. The infection was produced by the bite of A. americanum adults that were acquisition fed as nymphs on a domestic cat that naturally survived infection of C. felis. Fever, inappetence, depression, and lethargy were first noted 11 days post-infestation (dpi). Pale mucus membranes, splenomegaly, icterus, and dyspnea were also observed during the course of the disease. The body temperature of the experimentally infected C. felis cat was subnormal from 16 dpi until 24 dpi when it returned to within normal limits. All clinical signs of cytauxzoonsis began to resolve by 23 dpi when the cat became subclinically infected with C. felis. The cat developed a marked, regenerative anemia beginning by 13 dpi and reached a nadir at 20 dpi before recovering. A moderate neutrophilia and marked lymphocytosis also developed between 18 and 26 dpi. Schizonts of C. felis were observed in spleen aspirates of the infected cat at 15 dpi. DNA of C. felis was amplified by real-time PCR starting 17 dpi and piroplasms of C. felis were first noted by light microscopy 18 dpi. Dermacentor variabilis, Ixodes scapularis, and Rhipicephalus sanguineus were also tested in a similar manner at the same time but did not transmit C. felis. Prior to the present study, only D. variabilis had been shown experimentally to transmit infection of C. felis. This is the first report of C. felis being transmitted by A. americanum. The transmission of C. felis infection from one domestic cat to another indicates that domestic cats subclinically infected with C. felis may be a reservoir of infection for naive domestic cats.
    Veterinary Parasitology 01/2009; 161(1-2):110-5. · 2.38 Impact Factor
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    ABSTRACT: E. coli O157:H7 colonizes the bovine intestine, can contaminate food through fecal shedding, and causes human diarrheal and systemic illnesses. Catabolism of particular carbohydrates by E. coli has been found to be important for intestinal colonization of mice. In this study, we assessed whether catabolism of two mucin-derived carbohydrates are important for E. coli O157:H7 colonization of adult cattle. This was accomplished by competitively co-colonizing streptomycin-treated adult cattle with a wild-type strain of E. coli O157:H7 and isogenic mutants in catabolic pathways for mucin-derived carbohydrates N-acetylgalactosamine or l-fucose. Both mutants colonized poorly compared to the wild-type during the initiation stage of colonization (days 0-6). During the maintenance stage of colonization (days 7-15), the mutant unable to use N-acetylgalactosamine did not show a colonization defect, whereas the strain unable to use fucose had a significant colonization defect. These results support the concept that growth and colonization of E. coli O157:H7 in the bovine rectum has a nutritional basis, with a nutrient preference for l-fucose over N-acetylgalactosamine.
    Veterinary Microbiology 12/2008; 136(1-2):150-4. · 3.13 Impact Factor
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    ABSTRACT: Four white-tailed deer were inoculated with either the Ap-V1 or NY-18 strain of Anaplasma phagocytophilum. Ixodes scapularis nymphs were then allowed to acquistion feed on the inoculated deer and molt to adults. Only an Ap-V1 infected deer was infected persistently and able to infect nymphal Ixodes scapularis. Molted adult ticks maintained Ap-V1 infection as demonstrated by PCR and microscopy. We report, for the first time, a morphologic description of A. phagocytophilum in I. scapularis.
    Vector borne and zoonotic diseases (Larchmont, N.Y.) 11/2008; 9(5):565-8. · 2.61 Impact Factor
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    ABSTRACT: Infection of Trichinella spp. is common among animals in the Canadian Arctic. We determined the prevalence of Trichinella spp. infection in wolverines (Gulo gulo) from Nunavut, Canada. Diaphragms from 41 wolverines were examined by artificial digestion. Trichinella spp. larvae were detected in 36 (87.8%) examined animals. Trichinella T6 was detected in 33 (91.7%), Trichinella nativa in only one (2.8%), and a mixed Trichinella T6 and T. nativa infections were detected in two (5.6%) wolverines. This is the first report of Trichinella spp. infection in wolverines from Nunavut and the first report of sympatric Trichinella T6 and T. nativa in any host. The high prevalence of Trichinella spp. infection in combination with the natural history of wolverines suggests that the mustelid may be a key species in the natural cycle of these parasites in Arctic and Subarctic areas.
    Parasitology Research 09/2008; 103(3):657-61. · 2.85 Impact Factor
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    Timothy A Snider, Mason V Reichard
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    ABSTRACT: A 73-d-old white-tailed deer (Odocoileus virginianus) fawn was diagnosed at necropsy with a ventral abdominal cellulitis secondary to urine after preputial swelling, urethral obstruction and hemorrhage, and focal urethral rupture. During the acute antemortem disease phase, the urinary obstruction tentatively was attributed to potential urethral uroliths, but after euthanasia, extensive gross and microscopic examinations of the urogenital tract revealed no uroliths. This fawn had been copenned with another male fawn, both of which exhibited nonnutritive suckling of the penmate's genitalia before and after periodic milk replacer feedings. We attribute this uncommon presentation of urine-induced cellulitis to urethritis and urethral rupture secondary to repeated, nursing-induced, physical trauma to the prepuce. We examine the husbandry implications of this disease with regard to management of deer fawns in a laboratory setting.
    Journal of the American Association for Laboratory Animal Science: JAALAS 08/2008; 47(4):61-3. · 1.15 Impact Factor
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    ABSTRACT: Cytauxzoon felis is a tick-transmitted protozoan parasite of domestic and wild felids in the south-central and southeastern United States. Infection of domestic cats (Felis domesticus) with C. felis is typically acute and characterized by fever, anorexia, listlessness, anemia, icterus and usually death within 19-21 days. To determine the temporal occurrence and environmental risk factors associated with infection of C. felis in domestic cats from Oklahoma, information in the electronic medical records from the Oklahoma Animal Disease Diagnostic Laboratory (OADDL) and Boren Veterinary Medical Teaching Hospital (BVMTH) was retrospectively searched. A total of 232 cytauxzoonosis cases from 1995 to 2006 from OADDL (n=180) and 1998 to 2006 from BVMTH (n=52) were combined and analyzed. The number of cytauxzoonosis cases remained relatively consistent from year to year. Diagnosis of C. felis infection in domestic cats followed a bimodal pattern with a peak in the number of cases in April, May, and June followed by a second smaller peak in August and September. The majority (n=72; 31.0%) of cytauxzoonosis cases were diagnosed in May. No cases of C. felis infection were diagnosed in December and only a few (n=10; 4.3%) cases were observed from November through March during the 12-year period. In cases for which the client's address was available, geographic coordinates were assigned and landscape characteristics were quantified within a 100-m radius of each cytauxzoonosis case location. Of cytauxzoonosis cases (n=41) with a known client address, a majority (n=28; 68.3%) occurred in low density residential areas and more cases (n=8; 19.5%) were found in urban edge habitat than expected at random. Locations of diagnosed cytauxzoonosis cases were significantly associated with more wooded (31.8+/-4.03%) cover and closer (55.5+/-18.45m) proximity to natural or unmanaged areas than randomly selected control sites. Practicing and diagnostic veterinarians can expect to see a distinct temporal pattern in cases of cytauxzoonosis and more cases can be expected in domestic cats living in close proximity to environments that support tick vectors and bobcats.
    Veterinary Parasitology 05/2008; 152(3-4):314-20. · 2.38 Impact Factor
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    ABSTRACT: A 2-year-old captive-bred sexually intact female African pygmy hedgehog (Atelerix albiventris) was evaluated because of vague signs of illness including inappetence, weakness, lethargy, and weight loss over a 20-day period. Abnormalities detected via initial clinicopathologic analyses included anemia, thrombocytopenia, leukopenia, hypoproteinemia, and hypoglycemia. Results of a fecal flotation test were negative. Three weeks after the initial evaluation, splenomegaly was detected via palpation and ultrasonography. The hedgehog was treated with broad-spectrum antibacterial agents, resulting in an initially favorable response. Fenbendazole was also administered against possible occult parasitic infestation. After 3 weeks of illness, the hedgehog's condition had worsened and supportive care and administration of additional antibacterial agents were instituted. The hedgehog died, and pathologic examinations revealed severe splenomegaly; granulomatous infiltrates were evident in multiple organs, and Histoplasma capsulatum yeasts were detected intralesionally. Histoplasmosis can develop in a wide range of mammalian species. African pygmy hedgehogs are becoming increasingly popular as exotic pets, and vague signs of illness and splenomegaly are often attributed to hemolymphatic malignancies, which are somewhat common in this species. Practitioners should be aware that similar clinical signs may be associated with histoplasmosis in these animals. Although the hedgehog of this report was confined indoors, it originated from an area where histoplasmosis was endemic; this indicates that the disease should be included as a differential diagnosis for hedgehogs that develop vague signs of illness and are known to originate from such geographic regions.
    Journal of the American Veterinary Medical Association 02/2008; 232(1):74-6. · 1.72 Impact Factor