Carney Jackson

Prevalence of latent, neuropathogenic equine herpesvirus-1 in the Thoroughbred broodmare population of central Kentucky

REASON FOR PERFORMING STUDY An emerging problem of equine herpesvirus-1 (EHV-1) infection in horses in the USA is a high-mortality myeloencephalopathy that commonly occurs where large numbers of horses are stabled. EHV-1 isolates recovered from recent neurological outbreaks represent a mutant virus strain that possesses enhanced neuropathogenicity. A central question of EHV-1 myeloencephalopathy is the latency carriage rate for these mutants of EHV-1 in USA horse populations. OBJECTIVE To estimate the prevalence of neuropathogenic strains of EHV-1 as latent infections in the Thoroughbred broodmare population of central Kentucky. METHODS Submandibular lymph nodes (SMLN) were collected during post mortem examination of 132 Thoroughbred broodmares. Total DNA purified from SMLN tissue was tested for the presence of latent EHV-1 DNA by an ultrasensitive magnetic bead-based, sequence-capture, nested PCR method. Differentiation of active from latent infections by EHV-1 was achieved by detection of transcripts of EHV-1 glycoprotein B by reverse transcription PCR. RESULTS Latent EHV-1 DNA was detected in the SMLN tissues of 71 (54%) of the 132 mares submitted for necropsy. Thirteen (18%) of the 71 latently infected horses harboured the neuropathogenic biovar of EHV-1. Of the 13 horses latently infected with an ORF30 mutant strain of EHV-1, 11 also carried a latent, wild-type strain of the virus in their SMLN tissues. CONCLUSIONS Neuropathogenic strains of EHV-1 have established a significant presence in the Thoroughbred broodmare population of central Kentucky as latently infected carrier horses. The data also indicate that a highly sensitive DNA detection method is required to identify many instances of EHV-1 latency. POTENTIAL RELEVANCE The presence of a relatively large biological reservoir of latent, neuropathogenic EHV-1 has the potential for posing emerging equine health and economic threats to the future prosperity of the USA horse industry.

The efficacy of gadobenate dimeglumine (Gd-BOPTA) at 3 Tesla in brain magnetic resonance imaging: comparison to 1.5 Tesla and a standard gadolinium chelate using a rat brain tumor model.

Objectives:The objectives of this study were to analyze the differences in contrast enhancement using gadobenate dimeglumine (Gd-BOPTA or MultiHance) at 3 T versus 1.5 T and to compare Gd-BOPTA with a standard gadolinium chelate, gadopentetate dimeglumine (Gd-DTPA or Magnevist), at 3 T in a rat glioma model. Materials and Methods:Twelve rats with surgically implanted gliomas were randomized to either comparing Gd-BOPTA at 1.5 T versus 3 T (n = 7) or comparing Gd-BOPTA and Gd-DTPA at 3 T (n = 5). Matched T1-weighted spin-echo techniques were used for both comparisons and the order of examinations was randomized. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and lesion enhancement (LE) were evaluated using a region-of-interest analysis. A veterinary histopathologist evaluated all brain specimens. Results:In the evaluation of Gd-BOPTA at 3 T and 1.5 T, there were significant increases in SNR, LE, and CNR at 3 T. Average increases in brain and tumor SNR were 93% (P < 0.0001) and 92% (P < 0.0001), respectively. CNR increased by 121% (P < 0.0001). Comparison of Gd-BOPTA and Gd-DTPA at 3 T demonstrated significantly higher CNR and LE with Gd-BOPTA. CNR increased by 35% (P = 0.002). LE increased by 44% (P = 0.03). Conclusions:Gd-BOPTA provides significantly higher CNR at 3 T compared with 1.5 T and also demonstrates significantly higher CNR when compared with a standard Gd-chelate at 3 T. As a result of transient protein binding, Gd-BOPTA may be superior to standard gadolinium chelates in neurologic imaging at 3 T.

Brain tumor enhancement in magnetic resonance imaging: comparison of signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) at 1.5 versus 3 tesla.

Objective:The objective of this study was to compare the difference in lesion enhancement between 1.5 and 3 T using an extracellular gadolinium chelate in a rat brain glioma model. Methods:Five rats (CDF Fischer 344) with implanted C6/LacZ brain gliomas were evaluated using matched T1-weighted spin echo techniques and hardware configurations at 1.5 and 3 T. Serial imaging over 10 minutes after gadoteridol (ProHance) administration was performed. Contrast enhancement (CE), signal-to-noise ratios (SNR) for brain and tumor, as well as contrast-to-noise ratios (CNR) were evaluated using region-of-interest (ROI) analysis at both field strengths. All gliomas were also evaluated by histopathology. Results:CE at 3 T increased by 106% to 137% (all P < 0.05) with maximum CE occurring at 5 minutes for both 1.5 and 3 T (9.8 ± 2.2 vs 21.1 ± 3.5; P = 0.0004). At 3 T, SNR increased for normal brain by 66% to 76% (P < 0.01) and SNR for tumor increased by 70% to 89% (P < 0.01). CNR increased by 101% to 137% (P < 0.05) depending on the time postcontrast. The highest CNR for both 1.5 T and 3 T occurred 5 minutes after contrast (1.5 T: 9.4 ± 1.1 vs 3 T: 20.3 ± 2.4; P < 0.0004). Conclusion:Using a standardized animal model and matched scan techniques, this study shows a significant benefit of 3 T compared with 1.5 T in contrast-enhanced brain tumor magnetic resonance imaging.

Comparative evaluation of lesion enhancement using 1 M gadobutrol vs. 2 conventional gadolinium chelates, all at a dose of 0.1 mmol/kg, in a rat brain tumor model at 3 T.

Purpose:The purpose of this study is to compare the differences in contrast enhancement using 0.1 mmol/kg body weight 1 M gadobutrol versus 2 standard gadolinium chelates, both formulated at 0.5 M, (gadopentetate dimeglumine and gadoterate meglumine) in a standardized rat brain glioma model at 3 T. Materials and Methods:A total of 19 rats were evaluated, divided into 2 groups. Group 1 (n = 10) was examined using gadobutrol and gadopentetate dimeglumine and group 2 (n = 9) was examined using gadobutrol and gadoterate meglumine. The time between the intraindividual injections was at least 24 hours and contrast agent injections were performed in a randomized order. All agents were applied at a dose of 0.1 mmol/kg body weight.Image acquisition was performed using a T1-weighted 2D TSE technique (repetition time/echo time (TE) 500/16, FA 180°) with an acquisition time of 1:47 minutes:seconds. At a field-of-view of 75 × 75 mm2 and a matrix size of 320 × 320, a voxel size of 0.2 × 0.2 × 2.0 mm3 was achieved. Data acquisition was performed before and at 5 consecutive time points every 2 minutes after contrast agent injection. Signal-to-noise ratios (SNRs) of tumor and normal contralateral brain as well as contrast-to-noise ratio (CNR) measurements were performed using region of interest analysis. Results:The increase in tumor contrast enhancement, ranged between 19.6% and 35.9% for gadobutrol versus gadopentetate dimeglumine (group 1) and between 23.2% and 27.8% for gadobutrol versus gadoterate meglumine (group 2). Overall, CNR was statistically significantly higher for gadobutrol in both groups (P < 0.0001). CNR values for gadobutrol were 25.5 ± 8.2 in group 1 and 27.1 ± 8.3 in group 2 with respective CNR values for gadopentetate dimeglumine of 18.6 ± 5.6 and gadoterate meglumine of 19.2 ± 5.3. At each acquired time point mean values of tumor SNR were higher for gadobutrol (group 1: SNRmean range from 78.7–89.1 vs. 74.3–80.8; group 2: SNRmean range from 79.9–88.9 vs. 74.2–80.8). Tumor SNR was statistically significant different at all measured time points in group 2 (P < 0.05). In group 1, the difference of tumor SNR was also statistically significant for the gadobutrol/gadopentetate dimeglumine comparison (P < 0.05) with exception of time point at 9 minutes postcontrast (P = 0.07). Conclusion:The results of this study show significantly higher brain tumor SNR and CNR postcontrast for gadobutrol compared with gadopentetate dimeglumine and gadoterate meglumine at 3 T. Injecting the same gadolinium chelate dose on a weight basis, tumor mean SNR gains were superior for gadobutrol at all acquired postcontrast time points. This result with gadobutrol may facilitate better brain tumor detection in the presence of blood–brain barrier disruption.

Evaluation of gadobutrol, a macrocyclic, nonionic gadolinium chelate in a brain glioma model: Comparison with gadoterate meglumine and gadopentetate dimeglumine at 1.5 T, combined with an assessment of field strength dependence, specifically 1.5 versus 3 T

To evaluate in a rat brain glioma model intraindividual tumor enhancement at 1.5 T using gadobutrol (Gadovist), a nonionic, macrocyclic chelate currently in clinical trials in the United States, in comparison with both an ionic macrocyclic chelate, gadoterate meglumine (Dotarem), and an ionic linear chelate, gadopentetate dimeglumine (Magnevist), and to compare the degree of tumor enhancement with gadobutrol at 1.5 and 3 T.

Brain tumor enhancement in magnetic resonance imaging at 3 tesla: intraindividual comparison of two high relaxivity macromolecular contrast media with a standard extracellular gd-chelate in a rat brain tumor model.

Objectives:The aim of this study was to evaluate lesion enhancement (LE) and contrast-to-noise ratio (CNR) properties of P846, a new intermediate sized, high relaxivity Gd-based contrast agent at 3 Tesla in a rat brain glioma model, and to compare this contrast agent with a high relaxivity, macromolecular compound (P792), and a standard extracellular Gd-chelate (Gd-DOTA). Materials and Methods:Seven rats with experimental induced brain glioma were evaluated using 3 different contrast agents, with each MR examination separated by at least 24 hours. The time between injections assured sufficient clearance of the agent from the tumor, before the next examination. P792 (Gadomelitol, Guerbet, France) and P846 (a new compound from Guerbet Research) are macromolecular and high relaxivity contrast agents with no protein binding, and were compared with the extracellular agent Gd-DOTA (Dotarem, Guerbet, France). T1w gradient echo sequences (TR/TE 200 milliseconds/7.38 milliseconds, flip angle = 90°, acquisition time: 1:42 minutes:sec, voxel size: 0.2 × 0.2 × 2.0 mm3, FOV = 40 mm, acquisition matrix: 256 × 256) were acquired before and at 5 consecutive time points after each intravenous contrast injection in the identical slice orientation, using a dedicated 4-channel head array animal coil. The order of contrast media injection was randomized, with however Gd-DOTA used either as the first or second contrast agent. Contrast agent dose was adjusted to compensate for the different T1 relaxivities of the 3 agents. Signal-to-noise ratio, CNR, and LE were evaluated using region-of-interest analysis. A veterinary histopathologist confirmed the presence of a glioma in each subject, after completion of the imaging study. Results:P792 showed significantly less LE as compared with Gd-DOTA within the first 7 minutes after contrast agent injection (P < 0.05) with, however, reaching comparable LE values at 9 minutes after injection (P = 0.07). However, P792 provided significantly less CNR as compared with Gd-DOTA (P < 0.05) for all examination time points. P846 provided comparable but persistent LE as compared with Gd-DOTA (P < 0.05) and demonstrated significantly greater LE and CNR when compared with P792 (P < 0.05). No statistically significant differences between CNR values for Gd-DOTA and P846 were noted for all examination time points (P < 0.05), with P846 administered at one-fourth the dose as compared with Gd-DOTA. Conclusion:The intravascular contrast medium P792 showed significantly less LE and CNR in comparison to Gd-DOTA and P846, suggesting that it does not show marked extravasation from tumor neocapillaries and does not significantly cross the disrupted blood brain-barrier in this rat glioma model. In distinction, P846 provides comparable enhancement properties at a field strength of 3 Tesla to the extracellular contrast agent Gd-DOTA, using the adjusted dose, suggesting that it crosses the disrupted blood-brain-barrier and tumor capillaries, most likely based on the decreased molecular weight as compared with P792. At the same time, the high relaxivity of this compound allows for decreasing the injected gadolinium dose by a factor of 4 whereas providing comparable enhancement properties when compared with a standard extracellular Gd-chelate (Gd-DOTA) at a dose of 0.1 mmol/kg body weight.

Equine abortion and premature birth associated with Cellulosimicrobium cellulans infection

During the 2002 and 2003 foaling seasons, Cellulosimicrobium (Cellumonas) cellulans (formerly Oerskovia xanthineolytica) was the principal microorganism isolated from fetal tissues or placentas from cases of equine abortion, premature birth, and term pregnancies. Significant pathologic findings included chronic placentitis and pyogranulomatous pneumonia. In addition, microscopic and macroscopic alterations in the allantochorion from 4 of 7 cases of placentitis were similar to those caused by Crossiella equi and other nocardioform bacteria. This report confirms a causative role of C. cellulans infection in equine abortion.

Bartonella bovis isolated from a cow with endocarditis

A 7-year-old pregnant Angus cow was found dead in the field. At necropsy, the aortic valve was expanded by moderate fibrous connective tissue and acidophilic coagulum containing multifocal marked bacteria, mineral, neutrophils, and red blood cells. Numerous tiny grayish, opaque bacterial colonies were detected on blood agar plates at 7 days after inoculation with a swab of the heart valve of the cow. The bacterium was a Gram-negative, very small coccobacillus that was catalase, oxidase, and urease negative, and did not change litmus milk, triple sugar iron agar, and sulfide-indole-motility medium. The bacterium was negative for esculin hydrolysis, phenylalanine deaminase, nitrate reduction, and gelatin hydrolysis. The isolate did not produce acid from glycerol, inulin, lactose, maltose, mannose, raffinose, salicin, sorbitol, sucrose, trehalose, glycogen, ribose, or starch. Polymerase chain reaction tests for the gltA, ssrA, ftsZ, ribC, rpoB, and 16S ribosomal RNA genes of Bartonella species were positive for the isolate. Amplicons were sequenced, and the gltA, ribC, ssrA, and 16S ribosomal RNA gene sequences were found to have 100% homology to the type strain of Bartonella bovis, whereas the fts and rpoB sequences showed 99.9% and 99.6% homology, respectively, to the type strain of Bartonella bovis. Diagnosticians should be aware of slow-growing microorganisms, and culture media should be incubated beyond the standard period to enhance the recovery of Bartonella species.

A diagnostic evaluation of real-time PCR, fluorescent antibody and microscopic agglutination tests in cases of equine leptospiral abortion

REASONS FOR PERFORMING STUDY A comprehensive evaluation of the real-time PCR assay for leptospirosis in comparison with other diagnostic assays on a large-scale basis is fundamental in validating the assay and determining the causes of equine abortions. OBJECTIVES To compare and evaluate the diagnostic value of real-time PCR assay for leptospirosis with traditional methods in equine leptospiral abortions. STUDY DESIGN Cross-sectional observational study. METHODS A Leptospira spp. fluorescent antibody test (FAT), microscopic agglutination test (MAT) and real-time PCR (targeting the LipL32 gene) were compared and evaluated in equine fetal necropsy specimens (placenta, kidney, liver and heart blood) and maternal serum (when available) in 339 equine fetuses. RESULTS From a total of 339 equine fetuses necropsied, 21 cases (6.19%) were diagnosed as leptospiral abortion. The majority of leptospiral abortions occurred in January (8 cases) and February (5 cases). Real-time PCR detected 21 of 21 cases, whereas MAT and FAT detected 19 and 18 (including 2 suspicious cases) cases, respectively. Comparing tissues, placenta yielded somewhat similar cycle of threshold values by real-time PCR compared with kidney, whereas kidney was the best specimen for the diagnosis of leptospirosis by the FAT test. In all MAT positive cases, the predominant titre in fetal heart blood was to serovar Pomona (ranging 1:100 to 1:204,800) with little or no cross-reaction to serovar Grippotyphosa. CONCLUSIONS The results indicate that real-time PCR is an effective method for the diagnosis of leptospiral abortion in horses. However, MAT should continue to be used in clinical cases for serovar determination.

Complete Diphallia, Imperforate Ani (Type 2 Atresia Ani), and an Accessory Scrotum in a 5-Day-Old Calf

A 5-day-old Angus calf was submitted to the necropsy service at the University of Kentucky Livestock Disease Diagnostic Center. At birth, the calf was noted to have 2 scrota. Five days post-calving the calf developed severe tenesmus and an umbilical infection. Clinical examination revealed atresia ani. At necropsy, complete diphallus, imperforate ani (type 2 atresia ani), and remnants of 2 scrota were identified. This report describes the gross pathologic appearance of a rare case of complete diphallia, imperforate ani (type 2 atresia ani), and an accessory scrotum in a 5-day-old calf.