Search Results

You are looking at 1 - 5 of 5 items for

  • Author or Editor: Christopher J. Thomas x
  • Refine by Access: All Content x
Clear All Modify Search


Objective—To compare shedding patterns and serologic responses to bovine coronavirus (BCV) in feedlot calves shipped from a single ranch in New Mexico (NM calves) versus calves assembled from local sale barns in Arkansas (AR calves) and to evaluate the role of BCV on disease and performance.

Animals—103 feedlot calves from New Mexico and 100 from Arkansas.

Procedures—Calves were studied from before shipping to 35 days after arrival at the feedlot. Nasal swab specimens, fecal samples, and serum samples were obtained before shipping, at arrival, and periodically thereafter. Bovine coronavirus antigen and antibodies were detected by use of an ELISA.

Results—NM calves had a high geometric mean titer for BCV antibody at arrival (GMT, 1,928); only 2% shed BCV in nasal secretions and 1% in feces. In contrast, AR calves had low antibody titers against BCV at arrival (GMT, 102) and 64% shed BCV in nasal secretions and 65% in feces. Detection of BCV in nasal secretions preceded detection in feces before shipping AR calves, but at arrival, 73% of AR calves were shedding BCV in nasal secretions and feces. Bovine coronavirus infection was significantly associated with respiratory tract disease and decreased growth performance in AR calves.

Conclusions and Clinical Relevance—Replication and shedding of BCV may start in the upper respiratory tract and spread to the gastrointestinal tract. Vaccination of calves against BCV before shipping to feedlots may provide protection against BCV infection and its effects with other pathogens in the induction of respiratory tract disease.

Full access
in American Journal of Veterinary Research


Objective—To determine the prevalence, fecal shedding pattern, and association of bovine torovirus (BoTV) with diarrhea in veal calves at time of arrival and periodically throughout the first 35 days after their arrival on a veal farm.

Animals—62 veal calves.

Procedure—Fecal samples collected on days 0, 4, 14, and 35 after arrival were tested for BoTV by use of ELISA and reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Paired serum samples obtained from blood collected on days 0 and 35 were analyzed for BoTV antibodies with a hemagglutination inhibition assay. Fecal samples were also screened for other enteric pathogens, including rotavirus, coronavirus, and Cryptosporidium spp.

Results—Fecal shedding of BoTV was detected in 15 of 62 (24%) calves by use of ELISA and RT-PCR assay, with peak shedding on day 4. A significant independent association between BoTV shedding and diarrhea was observed. In addition, calves shedding ≥ 2 enteric pathogens were more likely to have diarrhea than calves shedding ≤ 1 pathogen. Calves that were seronegative or had low antibody titers against BoTV (≤ 1:10 hemagglutination inhibition units) at arrival seroconverted to BoTV (> 4-fold increase in titer); these calves were more likely to shed virus than calves that were seropositive against BoTV at arrival.

Conclusions and Clinical Relevance—Shedding of BoTV was strongly associated with diarrhea in neonatal veal calves during the first week after arrival at the farm. These data provide evidence that BoTV is an important pathogen of neonatal veal calves. (Am J Vet Res 2003;64:485–490)

Full access
in American Journal of Veterinary Research


To determine whether intracameral injection of carbachol at the completion of phacoemulsification in dogs would prevent the increase in intraocular pressure (IOP) that can develop during the first 24 hours after surgery.


Randomized controlled trial.


32 adult dogs undergoing elective unilateral or bilateral phacoemulsification.


Dogs were randomly assigned to 1 of 4 groups with 8 dogs/group: phacoemulsification and intracameral administration of 0.5 ml of 0.01 % carbachol at the end of surgery; phacoemulsification, intraocular lens implantation, and intracameral administration of 0.5 ml of 0.01 % carbachol; phacoemulsification and intracameral administration of 0.5 ml of balanced salt solution; and phacoemulsification, intraocular lens implantation, and intracameral administration of 0.5 ml of balanced salt solution. Intraocular pressure was measured at 3 and 6 hours and the morning after surgery. Aqueous flare was also measured 6 hours and the morning after surgery.


None of the dogs treated with carbachol developed postoperative ocular hypertension (ie, IOP > 27 mm of Hg), whereas 12 of 16 control dogs had ocular hypertension 3 hours after surgery. Intraocular pressure 3 hours after surgery was not significantly associated with phacoemulsification time or phacoemulsification power or with whether the dog received an intraocular lens implant. Severity of aqueous flare was similar for treated and control dogs.

Clinical Implications

Results suggested that intracameral administration of 0.01 % carbachol at the end of surgery was a safe and efficacious method of preventing the postoperative increase in IOP associated with phacoemulsification in dogs. (J Am Vet Med Assoc 1998;212:1885–1888)

Free access
in Journal of the American Veterinary Medical Association


Objective—To investigate the effect of opsonization of Rhodococcus equi with R equi-specific antibodies in plasma on bacterial viability and phagocyte activation in a cell culture model of infection.

Sample—Neutrophils and monocyte-derived macrophages from 6 healthy 1-week-old foals and 1 adult horse.

Procedures—Foal and adult horse phagocytes were incubated with either opsonized or nonopsonized bacteria. Opsonization was achieved by use of plasma containing high or low concentrations of R equi-specific antibodies. Phagocyte oxidative burst activity was measured by use of flow cytometry, and macrophage tumor necrosis factor (TNF)-α production was measured via an ELISA. Extracellular and intracellular bacterial viability was measured with a novel R equi-luciferase construct that used a luminometer.

Results—Opsonized bacteria increased oxidative burst activity in adult horse phagocytes, and neutrophil activity was dependent on the concentration of specific antibody. Secretion of TNF-α was higher in macrophages infected with opsonized bacteria. Opsonization had no significant effect on bacterial viability in macrophages; however, extracellular bacterial viability was decreased in broth containing plasma with R equi-specific antibodies, compared with viability in broth alone.

Conclusions and Clinical Relevance—The use of plasma enriched with specific antibodies for the opsonization of R equi increased the activation of phagocytes and decreased bacterial viability in the extracellular space. Although opsonized R equi increased TNF-α secretion and oxidative burst in macrophages, additional factors may be necessary for effective intracellular bacterial killing. These data have suggested a possible role of plasma antibody in protection of foals from R equi pneumonia.

Full access
in American Journal of Veterinary Research


Objective—To determine sensitivity and specificity of radiography, ultrasonography, and antegrade pyelography for detection of ureteral obstructions in cats.

Design—Retrospective study.

Animals—11 cats.

Procedure—Medical records of cats that had radiography, ultrasonography, and antegrade pyelography performed for suspected ureteral obstructions were examined. Ultrasound-guided pyelocentesis and fluoroscopic- assisted antegrade pyelography were performed on 18 kidneys in 11 cats. Obstructive ureteral lesions were confirmed in all cats by surgical or necropsy examination. Sensitivity and specificity of survey radiography, ultrasonography, and antegrade pyelography for identification of ureteral obstructions were calculated. Surgical or necropsy findings were used as the standard for comparison.

Results—All cats were azotemic. Mean ± SD serum creatinine and BUN concentrations were 10.2 ± 6.1 and 149 ± 82 mg/dL, respectively. Fifteen of 18 ureters were found to be obstructed at surgery or necropsy. Sensitivity and specificity were 60 and 100% for radiography and 100 and 33% for ultrasonography, respectively, in identification of ureteral obstructions. Leakage of contrast material developed in 8 of 18 kidneys during antegrade pyelography and prevented diagnostic interpretation in 5 of 18 studies. For the 13 diagnostic studies, specificity and sensitivity were 100% by use of the antegrade pyelography technique. Correct identification of the anatomic location of the ureteral obstruction was obtained in 100% of diagnostic antegrade pyelography studies and in 60% of radiography or ultrasonography studies.

Conclusions and Clinical Relevance—Antegrade pyelography can be a useful alternative in the diagnosis and localization of ureteral obstructions in azotemic cats, although leakage of contrast material may prevent interpretation of the study. (J Am Vet Med Assoc 2003;222:1576–1581)

Full access
in Journal of the American Veterinary Medical Association