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Jeff W Tyler

Publications and source records attributed to Jeff W Tyler.

At least 19 recordsLinked to original sources
PubMed2005

Evaluation of a cow-side immunoassay kit for assessing IgG concentration in colostrum.

OBJECTIVE: To determine sensitivity and specificity of a cow-side immunoassay kit for assessing IgG concentration in colostrum. DESIGN: Prospective study. ANIMALS: 76 dairy and 11 beef cows of various parities. PROCEDURE: Colostrum from first, second, and third milkings and milk samples were collected, and IgG concentration was determined by means of radial immunodiffusion. The immunoassay was performed according to the manufacturer's instructions, and sensitivity and specificity were calculated by comparing results of the immunoassay (positive vs negative) with results of immunodiffusion (< 50 g/L vs > or = 50 g/L). RESULTS: 135 colostrum or milk samples were collected. Mean +/- SD colostral IgG concentrations, determined by means of radial immunodiffusion for dairy and beef cows were 65.4 +/- 51.4 g/L and 114.8 +/- 42.7 g/L, respectively. Mean IgG concentrations for first-, second-, and third-milking colostrum samples and for milk samples were 92 +/- 49.0 g/L, 74.6 +/- 45.1 g/L, 47.5 +/- 32 g/L, and 6.8 +/- 3.8 g/L, respectively. Sensitivity of the immunoassay (ie, percentage of samples with IgG concentration < 50 g/L with a positive immunoassay result) was 93%, and specificity (ie, percentage of samples with IgG concentration > or = 50 g/L with a negative immunoassay result) was 76%. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the immunoassay kit was an acceptable cow-side test to identify colostrum samples with IgG concentrations < 50 g/L. The immunoassay kit should be useful in screening colostrum for adequate IgG concentration before feeding to calves or storage.

Animals↗
PubMed2005

Prevalence and risk factors associated with outcome of surgical removal of pedunculated lipomas in horses: 102 cases (1987-2002).

OBJECTIVE: To determine the prevalence of pedunculated lipomas and identify risk factors affecting postoperative complications and survival in horses at a veterinary teaching hospital undergoing surgery for colic caused by pedunculated lipomas. DESIGN: Retrospective study. ANIMALS: 102 horses with a diagnosis of pedunculated lipoma. PROCEDURE: Age, breed, weight, and sex of horses with pedunculated lipomas were compared with the total equine hospital population and the population of horses admitted for abdominal surgery during the same period. Follow-up information was obtained by reevaluation or contact with owners via telephone or written request. RESULTS: Prevalence of pedunculated lipomas as a reason for abdominal surgery in horses, compared with the population of horses with and without lipomas admitted for abdominal surgery, was 10%. Castrated male Saddlebred and Arabian horses > 14 years old were identified as being at risk for developing pedunculated lipomas. Postoperative complications were detected in 72% of horses with pedunculated lipomas. Variables associated with low survival rates included surgery before 1992, heart rate > 80 beats/min, abnormal color of abdominal fluid, pale mucous membranes, surgery requiring intestinal resection, and inability to attain a mean arterial pressure > or = 100 mm Hg. Horses undergoing surgery from 1992 to 1996, weighing < 409 kg (900 lb), or requiring jejunojejunal anastomosis had a high survival rate. CONCLUSIONS AND CLINICAL RELEVANCE: Although many of the variables reflected the health of the horse at the time of surgery, results may help veterinarians recognize risk factors associated with development of pedunculated lipomas and better predict the outcome of horses undergoing surgery for colic caused by pedunculated lipomas.

Age Factors↗
PubMed2005

Effect of delayed colostrum collection on colostral IgG concentration in dairy cows.

OBJECTIVE: To determine the effect of timing of first-milking colostrum collection on colostral IgG concentration. DESIGN: Prospective study. ANIMALS: 13 healthy Holstein cows. PROCEDURES: All calvings were observed. After parturition, calves were not allowed to suckle and were separated from the dam. Colostrum was collected from a single randomly selected quarter at 2, 6, 10, and 14 hours after parturition until all 4 quarters were sampled. Colostral IgG concentration was determined via radial immunodiffusion. RESULTS: Mean colostral IgG concentration was 113, 94, 82, and 76 g/L at 2, 6, 10, and 14 hours after calving, respectively. Colostrum collected 6, 10, and 14 hours after calving had significantly lower IgG concentrations than did colostrum collected 2 hours after calving. Mean colostral IgG concentration at 14 hours after calving was significantly lower than that at 6 hours after calving. Cows in their third or greater lactation had mean colostral IgG concentrations 2 hours after calving (132 g/L) that were greater than the first and second lactation cows (mean, 95 and 100 g/L, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that early or immediate colostrum collection from dairy cows will maximize colostral IgG concentration. Adjustment of routine dairy farm management procedures may be required to maximize colostrum quality and minimize prevalence of failure of passive transfer in dairy calves.

Animals↗
PubMed2004

Use of somatic cell counts and California mastitis test results from individual quarter milk samples to detect subclinical intramammary infection in dairy cattle from a herd with a high bulk tank somatic cell count.

OBJECTIVE: To determine whether somatic cell counts (SCCs) or California mastitis test (CMT) scores for individual quarter milk samples could be used to detect subclinical intramammary infection among dairy cattle in a herd with a high bulk tank SCC. DESIGN: Prospective clinical trial. ANIMALS: 278 Holstein-Friesian dairy cattle from a single herd. PROCEDURE: Individual quarter milk samples were collected and submitted for bacterial culture, California mastitis testing, and determination of SCC. Additional milk samples were collected 34 days later and submitted for bacterial culture. RESULTS: During the initial visit to the herd, milk samples were collected from all 278 cows. However, because of blind mammary quarters or missing data, results for 1,057 quarter milk samples were included. Bacterial culture did not yield any growth for 622 (58.8%) of these samples. Regardless of the cutoff that was used, sensitivity of the CMT score was < or = 0.50 and sensitivity of the SCC linear score (SCS) was < or = 0.60. For 497 mammary quarters, results of bacterial culture of samples collected 34 days apart were concordant; bacterial culture did not yield any growth for 342 (68.8%) of these quarters. Regardless of the cutoff that was used, sensitivity of the CMT score was < or = 0.61 and sensitivity of the SCS was < or = 0.76 for mammary quarters with concordant bacterial culture results. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that neither CMT score nor SCC is sensitive enough to be useful as a screening test for identifying infected mammary quarters among dairy cattle in a herd with high bulk tank SCC.

Animals↗
PubMed2004

Transmissible spongiform encephalopathies in ruminants.

Transmissible spongiform encephalopathies (TSEs) have been observed in North American sheep, cervidae, and cattle. The causative agent of TSEs seems to be proteins that induce a conformational change in normal host proteins. Common clinical signs ofTSEs include chronic weight loss and deteriorating neurologic function. Mechanisms of TSE transmission vary among host species. The diagnostic approach for TSEs of ruminants is presented,and the history and justification of regulatory programs to control and eradicate TSEs are outlined.

Animals↗
PubMed2004

Characterization of gelatinases in bronchoalveolar lavage fluid and gelatinases produced by alveolar macrophages isolated from healthy calves.

OBJECTIVE: To characterize gelatinases in bronchoalveolar lavage fluid (BALF) and gelatinases produced by alveolar macrophages of healthy calves. SAMPLE POPULATION: Samples of BALF and alveolar macrophages obtained from 20 healthy 2-month-old calves. PROCEDURE: BALF was examined by use of gelatin zymography and immunoblotting to detect gelatinases and tissue inhibitor of metalloproteinase (TIMP)-1 and -2. Cultured alveolar macrophages were stimulated with lipopolysaccharide (LPS), and conditioned medium was subjected to zymography. Alveolar macrophage RNA was used for reverse transcriptase-polymerase chain reaction assay of matrix metalloproteinases (MMPs), cyclooxygenase-2, and inducible nitric oxide synthase. RESULTS: Gelatinolytic activity in BALF was evident at 92 kd (14/20 calves; latent MMP-9) and 72 kd (18/20; latent MMP-2). Gelatinolytic activity was evident at 82 kd (10/20 calves; active MMP-9) and 62 kd (17/20; active MMP-2). Gelatinases were inhibited by metal chelators but not serine protease inhibitors. Immunoblotting of BALF protein and conditioned medium confirmed the MMP-2 and -9 proteins. Endogenous inhibitors (ie, TIMPs) were detected in BALF from all calves (TIMP-1) or BALF from only 4 calves (TIMP-2). Cultured alveolar macrophages expressed detectable amounts of MMP-9 mRNA but not MMP-2 mRNA. CONCLUSIONS AND CLINICAL RELEVANCE: Healthy calves have detectable amounts of the gelatinases MMP-2 and -9 in BALF Endogenous inhibitors of MMPs were detected in BALF (ie, TIMP-1, all calves; TIMP-2, 4 calves). Lipopolysaccharide-stimulated alveolar macrophages express MMP-9 but not MMP-2 mRNA. The role of proteases in the pathogenesis of lung injury associated with pneumonia has yet to be determined.

Animals↗
PubMed2003

Use of a polymerase chain reaction assay to detect bovine leukosis virus in dairy cattle.

OBJECTIVE: To evaluate the use of a polymerase chain reaction (PCR) assay in detecting bovine leukosis virus (BLV) in adult dairy cows. DESIGN: Prospective study. ANIMALS: 223 adult dairy cows. PROCEDURE: Cows were tested for BLV status by use of an ELISA and a PCR assay. Sensitivity, specificity, predictive values of positive and negative tests, and the percentage of cows correctly classified by PCR assay were calculated. Ninety-five percent confidence intervals were calculated for sensitivity and specificity. RESULTS: Sensitivity and specificity were 0.672 and 1.00, respectively. Prevalence of BLV in this herd was 0.807. Predictive value of a positive test was 1.00, and predictive value of a negative test was 0.421. The percentage of cows correctly classified by PCR assay was 73.5%. CONCLUSIONS AND CLINICAL RELEVANCE: A positive PCR assay result provided definitive evidence that a cow was infected with BLV. Sensitivity and negative predictive value for PCR assay were low. Consequently, PCR assay alone is unreliable for routine detection of BLV in herds with high prevalence of the disease.

Animals↗
PubMed2003

Evaluation of a bladder tumor antigen test as a screening test for transitional cell carcinoma of the lower urinary tract in dogs.

OBJECTIVE: To evaluate the veterinary version of the bladder tumor antigen (V-BTA) test as a screening test for transitional cell carcinoma (TCC) of the lower urinary tract of dogs. ANIMALS: 229 client-owned dogs. PROCEDURE: Urine samples from dogs were shipped overnight to a single laboratory to facilitate testing within 48 hours of collection by use of the V-BTA rapid latex agglutination urine dipstick test. Groups of dogs included the following: 1) dogs with TCC of the lower urinary tract, 2) healthy control dogs, 3) unhealthy control dogs with non-TCC urinary tract disease, and 4) unhealthy control dogs without urinary tract disease. Test sensitivity and specificity were calculated by use of standard methods. Logistic models were developed to assess the effect of disease status, test conditions, urine composition, and signalment on the performance of the V-BTA test. RESULTS: A total of 229 urine samples were analyzed, including 48 from dogs with suspected (n = 3) or confirmed (45) TCC. Test sensitivities were 88, 87, and 85% for all dogs with (suspected and confirmed) TCC, dogs with confirmed TCC at any site, and dogs with confirmed TCC of the urinary bladder, respectively. Test specificities were 84, 41, and 86% for healthy control dogs, unhealthy control dogs with non-TCC urinary tract disease, and unhealthy control dogs without urinary tract disease, respectively. The test performed slightly better on centrifuged urine samples than on uncentrifuged urine samples. CONCLUSIONS AND CLINICAL RELEVANCE: Our results indicate that the V-BTA test is useful in screening for urinary tract TCC in dogs.

Animals↗
PubMed2003

Clinical evaluation of mitoxantrone and piroxicam in a canine model of human invasive urinary bladder carcinoma.

PURPOSE: Cyclooxygenase inhibitors show promise in chemoprevention and therapy of certain carcinomas, an effect that may be additive to that of standard chemotherapy. The purpose of this study was to evaluate the efficacy of combined therapy using the cyclooxygenase inhibitor, piroxicam, and mitoxantrone against a relevant canine model of human invasive bladder cancer. EXPERIMENTAL DESIGN: Fifty-five dogs with transitional cell carcinoma of the urinary bladder were enrolled in this nonrandomized one-armed prospective multi-institutional clinical trial. Mitoxantrone was administered i.v. (5 mg/m(2)) every 21 days for four treatments, and piroxicam was administered p.o. (0.3 mg/kg/day) for the study duration. Tumor staging was performed at baseline, day 42 and every 3 months after protocol completion. Endpoints included time-to-treatment failure and survival time (ST). RESULTS: Response data were available for 48 dogs and included one complete response, 16 partial responses, 22 with disease stabilization, and 9 with progressive disease for an overall 35.4% measurable response rate. Subjective improvement occurred in 75% of treated dogs. Median time-to-treatment failure and ST were 194 and 350 days, respectively. Using censoring and end point definitions similar to those of previous reports of dogs treated with piroxicam alone, the median ST in this study was 291 days, compared with 181 days with piroxicam alone. Diarrhea and azotemia were the most common treatment complications. CONCLUSIONS: Mitoxantrone/piroxicam induced remission more frequently than previously reported for either drug as a single agent in this canine model of invasive human transitional cell carcinoma. Additional evaluation of these drugs in combination protocols should be explored.

Animals↗
PubMed2002

Comparison of refractometers and test endpoints in the measurement of serum protein concentration to assess passive transfer status in calves.

OBJECTIVE: To evaluate 3 refractometers for detection of failure of passive transfer (FPT) of immunity in calves, and assess the effect of refractometric test endpoints on sensitivity, specificity, and proportion of calves classified correctly with regard to passive transfer status. DESIGN: Prospective study. ANIMALS: 90 calves. PROCEDURE: Blood samples were obtained from calves that were < 10 days old. Serum IgG concentration was determined by use of a radial immunodiffusion assay. Accuracy of 3 refractometers in the prediction of serum IgG concentration was determined by use of standard epidemiologic methods and a linear regression model. RESULTS: At a serum protein concentration test endpoint of 5.2 g/dL, sensitivity of each refractometer was 0.89 or 0.93, and specificity ranged from 0.80 to 0.91. For all refractometers, serum protein concentration test endpoints of 5.0 or 5.2 g/dL resulted in sensitivity > 0.80, specificity > 0.80, and proportion of calves classified correctly > 0.85. Serum protein concentrations equivalent to 1,000 mg of IgG/dL of serum were 4.9, 4.8, and 5.1 g/dL for the 3 refractometers. CONCLUSIONS AND CLINICAL RELEVANCE: The refractometers, including a nontemperature-compensating instrument, performed similarly in detection of FPT. Serum protein concentration test endpoints of 5.0 and 5.2 g/dL yielded accurate results in the assessment of adequacy of passive transfer; lower or higher test endpoints misclassified larger numbers of calves.

Animals↗
PubMed2002

Association between the strength of serologic recognition of bovine leukosis virus and lymphocyte count in bovine leukosis virus-infected cows.

OBJECTIVE: To determine whether strength of serologic recognition of bovine leukosis virus (BLV) by use of ELISA is associated with blood lymphocyte counts. DESIGN: Prospective study. ANIMALS: 161 cows with positive results of ELISA for BLV. PROCEDURE: Sample-to-positive ratio (S:P), which is the ratio between the test sample and a positive control sample, was compared among lymphocytotic and nonlymphocytotic cows. A regression model was constructed to evaluate the association between blood lymphocyte concentration and S:P, age, and the interaction of these terms. RESULTS: Mean S:P differed significantly between lymphocytotic (2.58 +/- 0.36) and nonlymphocytotic (2.38 +/- 0.39) cows. Age and S:P were significantly associated with lymphocyte count. CONCLUSIONS AND CLINICAL RELEVANCE: Sample-to-positive ratio and lymphocyte count were related; however, cows with high S:P were not always lymphocytotic. Culling cows on the basis of S:P will reduce the herd load of infectious virus faster than random culling of ELISA-positive cows; however, culling on the basis of lymphocyte count will eliminate a greater proportion of the reservoir of infection.

Animals↗
PubMed2002

Evaluation of a commercially available immunoassay for assessing adequacy of passive transfer in calves.

OBJECTIVE: To evaluate diagnostic utility of a commercially available immunoassay for assessing adequacy of passive transfer of immunity in neonatal calves. DESIGN: Prospective study. ANIMALS: 123 calves. PROCEDURE: Blood and serum samples were obtained from the calves prior to 2 weeks of age. The immunoassay was performed, along with refractometry and an 18% sodium sulfite turbidity test. Serum IgG concentration was determined with a radial immunodiffusion assay. Sensitivity and specificity of the immunoassay, refractometry, and the sodium sulfite test were calculated by comparing results with results of the radial immunodiffusion assay. RESULTS: Sensitivity and specificity of the blood IgG immunoassay were 0.93 and 0.88, respectively, compared with 1.00 and 0.53 for the sodium sulfite test. For refractometry, sensitivity and specificity were 0.71 and 0.83, respectively, when a serum total solids concentration of 5.2 g/dl was used as the cutoff between positive and negative test results. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the immunoassay performs well in detecting calves with inadequate passive transfer of immunity.

Animals↗
PubMed2002

Comparison of hematologic and biochemical values for blood samples obtained via jugular venipuncture and via vascular access ports in cats.

OBJECTIVE: To determine whether hematologic and serum biochemical values for blood samples obtained from cats via vascular access ports (VAP) are comparable to those for samples obtained by direct venipuncture. DESIGN: Prospective study. ANIMALS: 14 healthy cats. PROCEDURE: A VAP was surgically implanted in a jugular vein in each cat. Blood samples were obtained from the VAP and by direct venipuncture of the contralateral jugular vein 10 weeks after VAP placement. Results of hematologic and serum biochemical analyses were compared by use of a paired t-test. The Pvalue to reject the null hypothesis was adjusted to account for multiple comparisons by using the Bonferroni procedure in which the nominal P-to-reject value is divided by the number of comparisons (0.05/24 = 0.002). RESULTS: Paired samples (VAP and venipuncture) obtained 10 weeks after VAP placement were evaluated for each cat. Of the 24 measured analytes, only potassium, total protein, and albumin concentrations differed significantly (P< 0.001 for all 3) between VAP and venipuncture samples. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that samples obtained from VAP are suitable for routine hematologic monitoring of feline cancer patients. Sample hemolysis may account for a slight increase in potassium, total protein, and albumin concentrations obtained from VAP samples. However, the values of variables most critical for monitoring of patients receiving chemotherapy (ie, mature neutrophil and platelet counts) are comparable. If proper techniques are used, VAP may be used for administration of chemotherapy as well as for blood collection in cats undergoing cancer treatment.

Animals↗
PubMed2002

Serum lactoferrin concentrations in colostrum-fed calves.

OBJECTIVE: To determine serum lactoferrin concentrations (SLFC) in neonatal calves before and after ingestion of colostrum and to develop models that predict SLFC as a function of colostral lactoferrin concentrations (CLFC) in calves. ANIMALS: 13 Holstein calves. PROCEDURE: Calves were fed 4 L of colostrum via oroesophageal feeder within 3 hours after birth. Serum samples were collected before ingestion of colostrum (day 0) and 2, 4, 6, and 7 days after birth. Colostrum and serum IgG concentrations were measured by use of radial immunodiffusion. The CLFC and SLFC were determined by use of an ELISA. RESULTS: Mean +/- SD SLFC on days 0, 2, 4, 6, and 7 were 2.5+/-1.6 (range 0.47 to 71), 6.0+/-3.0 (range 2.0 to 16.6), 12.0+/-12.4 (range 0.0 to 43.5), 171+/-13.6 (range 2.2 to 39.4), and 13.6+/-16.4 (range 0.0 to 43.8) mg/ml, respectively. The SLFC on days 6 and 7 differed significantly from SLFC on day 0. The model that best estimated SLFC on day 6 predicted that (SLFC)2 was a function of the logarithm of relative efficiency of passive transfer (REPT) and ([CLFC]2 x [REPT]2), where R2 = 0.4. The model for SLFC on day 7 predicted that (SLFC)2 was a function of log(REPT), where R2 = 0.44. CONCLUSIONS AND CLINICAL RELEVANCE: Definitive evidence for passive transfer of lactoferrin via colostrum is lacking, because SLFC on day 2 or 4 were not significantly different than day 0. Relative efficiency of lactoferrin absorption was directly related to SLFC on day 6 but inversely related to SLFC on day 7.

Animals↗
PubMed2002

Tilmicosin reduces lipopolysaccharide-stimulated bovine alveolar macrophage prostaglandin E(2) production via a mechanism involving phospholipases.

Tilmicosin is a potent antimicrobial with broad-spectrum activity against the bacterial agents involved in the bovine respiratory disease complex. Recent studies indicate that in addition to being bactericidal, tilmicosin is capable of modulating inflammation in the lung. A series of experiments were designed to determine whether tilmicosin alters alveolar macrophage-prostaglandin E(2) (PGE(2)) production induced by Escherichia coli (O55:B5) lipopolysaccharide (LPS). Twenty-two healthy Holstein bull calves were used to study the effects of LPS-induced PGE(2) production of alveolar macrophages after in vivo or in vitro treatment with tilmicosin. In Experiment 1, tilmicosin was given by subcutaneous injection (15 mg/kg) twice, 48 hours apart, to four calves; four control calves received no treatment. Twenty-four hours after the second treatment, alveolar macrophages were stimulated with LPS in vitro. In Experiment 2, alveolar macrophages from five untreated calves were harvested and treated in vitro with tilmicosin, followed by LPS stimulation. In Experiment 3, the ability of in vitro tilmicosin treatment to alter the expression of LPS-induced cyclooxygenase-2 (COX-2) mRNA was evaluated. In Experiments 4 and 5, secretory phospholipase A(2) activity was examined in untreated calves. Treatment of calves with tilmicosin resulted in reduced LPS-induced alveolar macrophage PGE(2) production. Similar reductions in PGE(2) by LPS-stimulated alveolar macrophages after in vitro tilmicosin treatment were noted. This in vitro tilmicosin treatment was not associated with reduction of the expression of LPS-induced COX-2. Alveolar macrophage phospholipase A(2) activity induced by LPS was significantly reduced by prior tilmicosin treatment in vitro. Tilmicosin (in vivo and in vitro) appears to reduce the PGE(2) eicosanoid response of LPS-stimulated alveolar macrophages by reducing the in vitro substrate availability without altering in vitro COX-2 mRNA expression.

Actins↗