Characterization of immune responses and immunopathology in turkeys experimentally infected with clostridial dermatitis-producing strains of Clostridium septicum.

Clostridium septicum is one of the major causative agents of clostridial dermatitis (CD), an emerging disease of turkeys, characterized by sudden deaths and necrotic dermatitis. Despite its economic burden on the poultry industry, the immunopathological changes and pathogen-specific immune responses are poorly characterized. Here, we used three strains of C. septicum, namely Str. A1, Str. B1 and Str. C1, isolated from CD field outbreaks, to experimentally infect turkeys to evaluate local (skin and muscle) and systemic (spleen) pathological and immunological responses. Results showed that while all three strains produced an acute disease, Str. A1 and B1 caused significantly higher mortality when compared to Str. C1. Gross and histopathology evaluation showed that birds infected with Str. A1 and B1 had severe inflammatory, edematous, granulomatous and necrotic lesions in the skin, muscle and spleen, while these lesions produced by Str. C1 were relatively less severe and mostly confined to skin and/or muscle. Immune gene expression in these tissues showed that Str. B1-infected birds had significantly higher expression of interleukin (IL)-1ß, IL-6 and interferon (IFN)γ genes compared to uninfected control, suggesting a robust inflammatory response both locally as well as systemically. The transcription of IL-1ß and IFNγ in the muscle or spleen of Str. A1-infected birds and IL-1ß in the skin of Str. C1-infected group was also significantly higher than control. Additionally, Str. A1 or B1-infected groups also had significantly higher IL-4 transcription in these tissues, while birds infected with all three strains developed C. septicum-specific serum antibodies. Furthermore, splenic cellular immunophenotyping in the infected turkeys showed a marked reduction in CD4+ cells. Collectively, it can be inferred that host responses against C. septicum involve an acute inflammatory response along with antibody production and that the disease severity seem to depend on the strain of C. septicum involved in CD in turkeys.

Mucosal and systemic lymphoid immune responses against Clostridium perfringens strains with variable virulence in the production of necrotic enteritis in broiler chickens.

Necrotic enteritis (NE), caused by Clostridium perfringens, is an economically important disease of chickens. Although NE pathogenesis is moderately well studied, the host immune responses against C. perfringens are poorly understood. The present study used an experimental NE model to characterize lymphoid immune responses in the caecal tonsils (CT), bursa of Fabricius, Harderian gland (HG) and spleen tissues of broiler chickens infected with four netB+ C. perfringens strains (CP1, CP5, CP18, and CP26), of which CP18 and CP26 strains also carried the tpeL gene. The gross and histopathological lesions in chickens revealed CP5 to be avirulent, while CP1, CP18, and CP26 strains were virulent with CP26 being "very virulent". Gene expression analysis showed that, while the virulent strains induced a significantly upregulated expression of pro-inflammatory IL-1ß gene in CT, the CP26-infected birds had significantly higher CT transcription of IFNγ and IL-6 pro-inflammatory genes compared to CP5-infected or uninfected chickens. Furthermore, CP26 infection also led to significantly increased bursal and HG expression of the anti-inflammatory/regulatory genes, IL-10 or TGFß, compared to control, CP5 and CP1 groups. Additionally, the splenic pro- and anti-inflammatory transcriptional changes were observed only in the CP26-infected chickens. An antibody-mediated response, as characterized by increased IL-4 and/or IL-13 transcription and elevated IgM levels in birds infected with virulent strains, particularly in the CP26-infected group compared to uninfected controls, was also evident. Collectively, our findings suggest that lymphoid immune responses during NE in chickens are spatially regulated such that the inflammatory responses against C. perfringens depend on the virulence of the strain.

Necrotizing Hepatitis Associated with Clostridium perfringens in Broiler Chicks.

In this retrospective study we describe unusual cases of clostridial hepatitis associated with high mortality in young broiler chicks. Eleven cases of necrotizing hepatitis in broiler chicks from four companies were submitted to the Poultry Diagnostic and Research Center or the Georgia Poultry Laboratory Network between 2017 and 2020. In most flocks, increased 3-day mortality was followed by an elevated 7-day mortality. Gross lesions included green to dark brown discoloration of the liver, congested lungs, serosanguineous fluid in the caudoventral aspect of the abdomen, and emphysema in the yolk sacs. In birds older than a week of age, disease with neurologic signs became evident and consisted of tremors, stargazing, and incoordination. Histopathologic evaluation revealed multifocal to coalescing fibrinoheterophilic and necrotizing hepatitis associated with gram-positive, long, rod-shaped bacteria. Formalin-fixed liver samples from six cases out of eight cases tested were positive for Clostridium perfringens by immunohistochemistry. Liver samples from two cases were culture positive for Clostridium spp., and C. perfringens was isolated from one sample. Toxinotyping by PCR performed in seven samples revealed the presence of the genes that code for alpha toxin phospholipase C (cpa or plc) and necrotic enteritis toxin B-like (netB) in six samples and as well as C. perfringens large cytotoxin (tpeL) in one sample. Broiler breeders are the suspected source of the infection, and testing revealed C. perfringens in hatchery samples and among broiler breeder flocks. Antimicrobial therapy was coupled with enhanced sanitation at the farm and hatchery in that company, markedly decreasing the mortality and clinical signs. This is the first comprehensive evaluation of clostridial necrotizing hepatitis in newly hatched chicks, and the second ever reported in the literature.

Hepatitis necrotizante asociada con Clostridium perfringens en pollos de engorde En este estudio retrospectivo se describen casos inusuales de hepatitis clostridial asociados con una alta mortalidad en pollos de engorde jóvenes. Once casos de hepatitis necrotizante en pollos de engorde de cuatro empresas se enviaron al Centro de Investigación y Diagnóstico Avícola o a la Red de Laboratorios Avícolas del Estado Georgia entre los años 2017 y 2020. En la mayoría de las parvadas, el aumento de la mortalidad a los tres días fue seguido por una mortalidad elevada a los siete días. Las lesiones macroscópicas incluyeron coloración del hígado de verde a marrón oscuro, pulmones congestionados, líquido serosanguinolento en la cara caudoventral del abdomen y enfisema en los sacos vitelinos. En aves mayores de una semana de edad, la enfermedad con signos neurológicos se hizo evidente y consistía en temblores, torticolis (aves como observando a las estrellas) y falta de coordinación. La evaluación histopatológica reveló hepatitis multifocal a fibrinoheterófila coalescente y necrotizante asociada con bacterias grampositivas largas en forma de bastón. Las muestras de hígado fijadas en formalina de seis casos de los ocho casos analizados dieron positivo para Clostridium perfringens por inmunohistoquímica. Las muestras de hígado de dos casos dieron positivo en cultivo para Clostridium spp., y se aisló C. perfringens de una muestra. La tipificación por el tipo de toxina mediante PCR realizado en siete muestras reveló la presencia de los genes que codifican la toxina alfa fosfolipasa C (cpa, plc) y la toxina de enteritis necrótica similar a la toxina B (netB) en seis muestras, así como la citotoxina grande de C. perfringens (tpeL) en una muestra. Se sospecha que las reproductoras de pollos de engorde son la fuente de la infección, y las pruebas revelaron C. perfringens en las muestras de las incubadoras y entre las parvadas de reproductoras de pollos de engorde. La terapia antimicrobiana se combinó con un saneamiento mejorado en la granja y en la incubadora de esa empresa, lo que redujo notablemente la mortalidad y los signos clínicos. Esta es la primera evaluación exhaustiva de la hepatitis necrosante por clostridios en pollitos recién nacidos y la segunda que se ha informado en la literatura.

Clinicopathologic, Gross Necropsy, and Histopathologic Effects of High-Dose, Repeated Meloxicam Administration in Rhode Island Red Chickens (Gallus gallus domesticus).

Meloxicam is a commonly prescribed non-steroidal anti-inflammatory drug for backyard poultry that has demonstrated pharmacodynamic efficacy at a single high dose of 5 mg/ kg. This study characterized the adverse effects of meloxicam administered in chickens at an approximate dose of 5 mg/kg orally twice daily for 5 days. Twenty-one adult Rhode Island Red hens (Gallus gallus domesticus), judged to be healthy based on an external physical examination, complete blood count (CBC), and plasma biochemistry panel, were recruited for this study. The subject birds were randomly assigned to a treatment (n = 11) or control group (n = 10) and received a 15-mg tablet of meloxicam or a nonmedicated feed pellet, respectively, orally twice daily. Physical examinations and body weight measurements were performed daily, and observation for clinical signs occurred twice daily. Following completion of the 5-day treatment course, an external physical examination, blood collection for a CBC and plasma biochemistry panel, euthanasia, necropsy, and measurement of meloxicam tissue residues were performed. During the treatment course, 1 hen from the treatment group died with peracute clinical signs, 2 hens from the treatment group died suddenly with no clinical signs, and 1 hen from the treatment group became acutely lethargic and was euthanized. Within the meloxicam group, 7 out of 11 hens had gross and histologic evidence of varying levels of renal acute tubular injury and gout. Plasma uric acid concentrations were above the species reference intervals in all affected hens in the treatment group that were still available for testing. The control group had no evidence of renal injury or gout based on postmortem examinations. Based on the results of this study, repeated oral dosing of meloxicam in chickens at 5 mg/kg twice daily is not recommended.

The effectiveness of a dietary direct-fed microbial and mannan oligosaccharide on ultrastructural changes of intestinal mucosa of turkey poults infected with Salmonella and Campylobacter.

Salmonella and Campylobacter are considered major public health burdens worldwide, and poultry are known to be one of the main reservoirs for these zoonotic pathogens. This study was conducted to evaluate the effect of a commercial probiotic or direct-fed microbial (DFM) Calsporin (CSP), and prebiotic or mannan oligosaccharide (MOS) (IMW50) on ultrastructural changes and the villous integrity of intestinal mucosa in turkey poults challenged with Salmonella and Campylobacter. A 21-day battery cage study was conducted using 4 dietary treatments including a basal diet (corn and soybean-based) nonsupplemented and uninfected as a negative control (NC); basal diet supplemented with 0.05% DFM (CSP); basal diet supplemented with 0.05% MOS (IMW50); and basal diet supplemented with 0.05% mixture of DFM and MOS at equal proportions. Female large white turkey poults aged 336 days were obtained from a local commercial hatchery and randomly distributed in electrically heated battery cages with 12 treatments of 4 replicates per treatment containing 7 poults per pen. The first 16 pens were not infected with bacteria, poults in pens 17-32 were orally challenged at day 7 with 105 cfu Salmonella Heidelberg, and the poults in pens 33-48 were orally challenged at day 7 with 105 cfu Campylobacter jejuni. Feed and water were provided ad libitum throughout the study. At day 21, ileal tissue samples from 1 bird per cage were collected for intestinal integrity and ultrastructural examination by scanning and electron microscopy. DFM and MOS supplementation was effective in both challenged and nonchallenged (not infected with Salmonella and Campylobacter) birds. Goblet cells and mucus were increased, with the presence of large numbers of segmented filamentous bacteria in DFM- and MOS-supplemented groups compared with birds in control treatments. The number and size of villi were reduced in poults exposed to Salmonella and Campylobacter. Results show that CSP and IMW50 provide protection of ileal mucosal integrity in poults exposed to Salmonella or Campylobacter.

Effect of a direct-fed microbial and prebiotic on performance and intestinal histomorophology of turkey poults challenged with Salmonella and Campylobacter.

Salmonella and Campylobacter are leading human foodborne pathogens commonly associated with poultry and poultry products, and several methods to control these pathogens have been applied to poultry production. This study was conducted to evaluate the effect of CALSPORIN, (CSP), a direct-fed microbial (DFM), and yeast cell wall (Saccharomyces cervisiae, IMW50, a mannanoligosaccharide (MOS)-based prebiotic, on performance, levels of Salmonella and Campylobacter in the feces, and intestinal histomorphometry in turkey poults. A 21-day battery cage study was conducted using 4 dietary treatments, including: an unsupplemented basal diet (corn and soybean-based) as negative control (NC); basal diet supplemented with 0.05% DFM; basal diet supplemented with 0.05% MOS; and basal diet supplemented with 0.05% mixture of DFM and MOS at equal proportions. Female Large White turkey poults (n = 336) were randomly distributed in 6 electrically-heated battery cages with 4 treatments and 12 replicates per treatment (7 poults per replicate pen). The first 16 pens were not inoculated with bacteria, while poults in pens 17 to 32 were orally challenged at day 7 with 105 CFU Salmonella Heidelberg and the poults in pens 33 to 48 were orally challenged at day 7 with 105 CFU Campylobacter jejuni. Feed consumption, body weight, and feed conversion ratio were measured weekly and at the end of the experiment. At day 21, fresh fecal samples from each pen were collected for Salmonella and Campylobacter enumeration and ileal tissue samples were collected from 1 bird per pen for histomorphology examination. DFM and MOS supplementation was accompanied with reduced levels of Salmonella shed by the treated birds compared to the control group, and with increased body weight (P ≤ 0.05). The surface area of villi increased in the MOS-supplemented group compared to the control group (P ≤ 0.05). There was a significant difference in V:C ratio between supplemented groups and control group (P ≤ 0.05). Based on these results, there is potential for CALSPORIN and IMW50 to reduce Salmonella shedding in feces, enhance ileal mucosal health, and improve growth performance of turkey poults.

Evaluation of factors influencing the development of late Marek's disease virus-induced immunosuppression: virus pathotype and host sex.

Marek's disease virus (MDV) is a herpesvirus that induces lymphoma and immunosuppression in chickens. MDV-induced immunosuppression (MDV-IS) is complex and can be divided into two phases: early-MDV-IS associated with cytolytic infection in the lymphoid organs in chickens lacking maternal antibodies against MDV (MAbs) and late-MDV-IS that appears later in the pathogenesis and occurs even in chickens bearing MAbs. We have recently developed a model to reproduce late-MDV-IS under laboratory conditions. This model evaluates late-MDV-IS indirectly by assessing the effect of MDV infection on the efficacy of infectious laryngotracheitis (ILT) vaccines against challenge with ILT virus. In the present study, we have used this model to investigate the role of two factors (MDV pathotype and host sex) on the development of late-MDV-IS. Five MDV strains representing three different pathotypes: virulent (vMDV; 617A, GA), very virulent (vvMDV; Md5), and very virulent plus (vv+MDV; 648A, 686), were evaluated. Only vv+ strains were able to induce late-MDV-IS. An immunosuppression rank (IS-rank) was established based on the ability of MDV to reduce the efficacy of chicken embryo origin vaccine (values go from 0 to 100, with 100 being the highest immunosuppressive ability). The IS-rank of the evaluated MDV strains ranged from 5.97 (GA) to 20.8 (617A) in the vMDV strains, 5.97 to 16.24 in the vvMDV strain Md5, and 39.08 to 68.2 in the vv+ strains 648A and 686. In this study both male and female chickens were equally susceptible to MDV-IS by vv+MDV 686. Our findings suggest that late-MDV-IS is a unique feature of vv+ strains.

Early infection with Marek's disease virus can jeopardize protection conferred by laryngotracheitis vaccines: a method to study MDV-induced immunosuppression.

Marek's disease virus (MDV) is a herpesvirus that induces lymphomas and immunosuppression in chickens. MDV-induced immunosuppression (MDV-IS) is divided into two phases: early-MDV-IS occurring mainly in chickens lacking maternal antibodies (MAb) against MDV and associated with lymphoid organ atrophy; and late-MDV-IS occurring once MDV enters latency and during tumour development. Our objectives were to document the impact of late-MDV-IS on commercial poultry (meat-type chickens bearing MAb against MDV and that were vaccinated or unvaccinated against MD) and to optimize a model to study late-MDV-IS under laboratory conditions. The impact of late-MDV-IS was evaluated by assessing the effect of early infection (day of age) with a very virulent plus MDV (vv+MDV) on the efficacy of chicken-embryo-origin (CEO) infectious laryngotracheitis (ILT) virus vaccine against ILT challenge. The CEO ILT vaccine was administered in water at 14 days of age and ILT virus (ILTV) challenge was done intratracheally at 30 days of age. Development of ILT was monitored by daily evaluation of clinical signs, development of gross and histological lesions in trachea, and quantification of ILTV transcripts in trachea. Infection with vv+MDV strain 648A resulted in total abrogation of protection conferred by the CEO vaccine against ILTV challenge even in chickens vaccinated at 1 day of age with either HVT, HVT+SB-1, or CVI988. Chickens exposed to vv+MDV prior to vaccination with CEO ILTV vaccine had similar (P < 0.05) clinical scores, gross lesions, histopathologic lesion scores, and load of ILTV transcripts in trachea after ILTV challenge, as chickens that were not vaccinated with CEO ILTV vaccine.

Dietary toxicity of soluble and insoluble molybdenum to northern bobwhite quail (Colinus virginianus).

Limited data are available on the effects of molybdenum (Mo) on avian wildlife, which impairs evaluation of ecological exposure and risk. While Mo is an essential trace nutrient in birds, little is known of its toxicity to birds exposed to molybdenum disulfide (MoS2), the predominant form found in molybdenite ore. The chemical form and bioavailability of Mo is important in determining its toxicity. Avian toxicity tests typically involve a soluble form of Mo, such as sodium molybdate dihydrate (SMD, Na2MoO4·2H2O); however MoS2 is generally insoluble, with low bioaccessibility under most environmental conditions. The current study monitored survival and general health (body weight and food consumption) of 9-day old northern bobwhite exposed to soluble Mo (SMD) and ore-related Mo (MoS2) in their diet for 30 days. Toxicity and bioavailability (e.g. tissue distribution) of the two Mo forms were compared. Histopathology evaluations and serum, kidney, liver, and bone tissue sample analyses were conducted. Copper, a nutrient integrally associated with Mo toxicity, was also measured in the diet and tissue. No treatment-related mortality occurred and no treatment-related lesions were recorded for either Mo form. Tissue analyses detected increased Mo concentrations in serum, kidney, liver, and bone tissues following exposure to SMD, with decreasing concentrations following a post-exposure period. For the soluble form, a No-Observed-Adverse-Effect Concentration (NOAEC) of 1200 mg Mo as SMD/kg feed (134 mg SMD/kg body weight/day) was identified based on body weight and food consumption. No adverse effects were observed in birds exposed to MoS2 at the maximum dose of 5000 mg MoS2/kg feed (545 mg MoS2/kg body weight/day). These results show that effects associated with MoS2, the more environmentally prevalent and less bioavailable Mo form, are much less than those observed for SMD. These data should support more realistic representations of exposure and risks to avian receptors from environmental Mo.

History of the Journal of Veterinary Medical Education.

The Journal of Veterinary Medical Education (JVME), with the leadership of seven editors and two interim editors, grew from 33 pages of mostly news and commentary to become the premier source for information exchange in veterinary medical education. The first national publication of the Association of American Veterinary Medical Colleges (AAVMC) was a 21-page newsletter published in December 1973. This one-time newsletter was followed by volume 1, issue 1 of JVME, published in spring 1974 and edited by William W. Armistead. Richard Talbot was the second and longest serving editor, and under his leadership, JVME grew in the number and quality of papers. Lester Crawford and John Hubbell served as interim editors, maintaining quality and keeping JVME on track until a new editor was in place. Robert Wilson, Billy Hooper, Donal Walsh, Henry Baker, and the current editor, Daryl Buss, are major contributors to the success of JVME. The early history of the journal is described by Billy Hooper and followed by a brief history of the periods of each of the editors. This history concludes with objective and subjective evaluations of the impacts of JVME.

Instruction and Curriculum in Veterinary Medical Education: A 50-Year Perspective.

Our knowledge of veterinary medicine has expanded greatly over the past 50 years. To keep pace with these changes and produce competent professionals ready to meet evolving societal needs, instruction within veterinary medical curricula has undergone a parallel evolution. The curriculum of 1966 has given way, shifting away from lecture-laboratory model with few visual aids to a program of active learning, significant increases in case- or problem-based activities, and applications of technology, including computers, that were unimaginable 50 years ago. Curricula in veterinary colleges no longer keep all students in lockstep or limit clinical experiences to the fourth year, and instead have moved towards core electives with clinical activities provided from year 1. Provided here are examples of change within veterinary medical education that, in the view of the authors, had positive impacts on the evolution of instruction and curriculum. These improvements in both how and what we teach are now being made at a more rapid pace than at any other time in history and are based on the work of many faculty and administrators over the past 50 years.

Epithelial cell tumors of the hen reproductive tract.

There is a paucity of preclinical models that simulate the development of ovarian tumors in humans. At present, the egg-laying hen appears to be the most promising model to study the spontaneous occurrence of ovarian tumors in the clinical setting. Although gross classification and histologic grade of tumors have been used prognostically in women with ovarian tumors, there is currently no single system that is universally used to classify reproductive tumors in the hen. Four hundred and one 192-wk-old egg-laying hens were necropsied to determine the incidence of reproductive tumors using both gross pathology and histologic classification. Gross pathologic classifications were designated as follows: birds presenting with ovarian tumors only (class 1), those presenting with oviductal and ovarian tumors (class 2), those with ovarian and oviductal tumors that metastasized to the gastrointestinal tract (class 3), those with ovarian and oviductal tumors that metastasized to the gastrointestinal tract and other distant organs (class 4), those with oviductal tumors only (class 5), those with oviductal tumors that metastasized to other organs with no ovarian involvement (class 6), and those with ovarian tumors that metastasized to other organs with no oviductal involvement (class 7), including birds with gastrointestinal tumors and no reproductive involvement (GI only) and those with no tumors (normal). Histopathologic classifications range from grades 1 to 3 and are based on mitotic developments and cellular differentiation. An updated gross pathology and histologic classification systems for the hen reproductive malignancies provides a method to report the range of reproductive tumors revealed in a flock of aged laying hens.

Reovirus infections in young broiler chickens.

Selected 10-to-21-day-old broiler chickens from flocks undergoing runting-stunting syndrome were found to have significant pancreatic damage, grossly and histologically. Six reoviruses, with sequences that varied, both from each other and from S1133 reovirus, were isolated from these pancreases and from pancreases of specific-pathogen-free leghorn sentinels placed on two of the broiler farms for 7 days.

Cost effective and time efficient measurement of CD4, CD8, major histocompatibility complex Class II, and macrophage antigen expression in the lungs of chickens.

Cells expressing CD4, CD8, major histocompatibility complex (MHC) Class II, and macrophage biomarkers in lungs of chickens were quantified by measuring total area of antigen expressed using imageJ, a software program developed at the National Institutes of Health and available at no cost. The procedures reported here were rapid, and reproducible. Total area of antigen expressed had positive correlation with manual counts of cells expressing CD4 and CD8 biomarkers after inoculation with serotype 1 Marek's disease virus (MDV) vaccines. Visual inspection and overlays prepared from outlines of cells counted by imageJ confirmed agreement between antigen expression and area measured. Total area measured was not dependent on time of image acquisition from randomly selected fields from the same slides. Total area values were not computer specific, but acquisition of the original images required standardization of microscope used and camera setup. All steps in the process from sample collection through sectioning, staining, and image acquisition must be standardized as much as possible. Chickens infected with a very virulent+ (vv(+)) isolate of MDV (648A) had increased CD4, CD8, MHC Class II, and macrophage biomarker expression compared to noninfected control chickens at 10 days post infection, but variable responses depending on the specific biomarker measured at 3 and 5 days post infection. The procedure described here is faster and more reproducible than manual counting in cases (CD4 and CD8) where the number of positive cells is low enough for manual counts. Manual counting is not possible with MHC Class II and macrophage antigens nor when CD4(+) cells are present in large numbers following proliferation to tumors, thus subjective systems are used for scoring in these conditions. Using imageJ as described eliminates the need for subjective and less reproducible methods for measuring expression of these antigens.

Transmissible viral proventriculitis identified in broiler breeder and layer hens.

Transmissible viral proventriculitis (TVP) is a recognized cause of production losses in broiler chickens, but previously it has not been reported in broiler breeder and commercial layer hens. In this study, TVP was identified in broiler breeder and commercial layer hens, 9-20 wk of age, based on histopathologic detection of characteristic microscopic lesions. Microscopic lesions in proventriculi of affected hens consisted of glandular epithelial necrosis, ductal epithelial hyperplasia, replacement of glandular epithelium with ductal epithelium, and diffuse interstitial lymphoid infiltration. Additionally, chicken proventricular necrosis virus (CPNV), a virus previously identified as the etiology of TVP in broiler chickens, was detected in proventriculi of TVP-affected hens using a reverse transcriptase-polymerase chain reaction procedure. The findings identify TVP as a potential cause of production losses in broiler breeder and commercial layer hens and provide additional evidence for etiologic involvement in TVP by CPNV.

Myocarditis in 9- and 11-day-old broiler breeder chicks associated with a reovirus infection.

Nine- and 11-day-old male broiler breeder chicks from a flock with excessively high mortality were found to have ascites, fibrotic and necrotic livers, and round, thin-walled hearts. Virus isolation on liver homogenates and sequencing of PCR products of the isolate identified a reovirus whose sequence varied from sequences of other published reoviruses. Histopathology supported a diagnosis of reovirus-associated myocarditis and myocardial necrosis. This virus was possibly transmitted vertically from the primary breeder flock.

Selected blood chemistry values in mobility-impaired broiler breeder hens with suspected calcium tetany using the i-STAT handheld clinical analyzer.

Calcium tetany is a poorly defined disease of broiler breeder hens that results from acute hypocalcemia. It is characterized by impaired mobility, increased mortality, and absence of gross lesions that would explain the impaired mobility. To evaluate if hens with impaired mobility had calcium tetany or other abnormalities, blood values from normal and affected hens were determined using the i-STAT handheld clinical analyzer. Three flocks were evaluated weekly prior to peak production (range 25-30 wk of age) comparing normal hens to hens with clinically apparent calcium tetany. Calcium tetany suspect (CaTS) hens from four additional flocks were also evaluated. Significant hypocalcemia (P < 0.001) was observed in CaTS hens (average = 1.14 mmol/L ionized calcium [iCa]) compared to normal hens (average = 1.53 mmol/L iCa) in only one of three flocks sampled weekly. Clinically affected hens from one of the other four flocks also had hypocalcemia. Blood value abnormalities in mobility-impaired hens without hypocalcemia included hypernatremia. Findings in this study indicate calcium tetany is one cause of impaired mobility in breeder hens, but mobility impairment without hypocalcemia can also occur. Calcium tetany should be confirmed by finding significantly decreased levels of iCa in the blood, as diagnosis based on clinical presentation and necropsy results can be inaccurate. The i-STAT handheld clinical analyzer is an efficient, relatively low-cost method to determine iCa and other blood chemistry values that may be associated with impaired mobility in broiler breeder hens.

Macrorhabdus ornithogaster (Megabacterium) infection in adult hobby chickens in North America.

A field investigation was conducted on a flock of adult hobby chickens showing intermittent signs of enteritis. Roosters examined in the initial field visit and postmortem had cecal worms, roundworms, tetratrichomonads, and coccidiosis. Macrorhabdus ornithogaster was diagnosed histologically in the mucosal isthmus of the proventriculus and ventriculus. Three roosters and two hens were examined in a follow-up investigation of the flock conducted 9 days later. Macrorhabdus ornithogaster was confirmed in one hen.

Detection of chicken proventricular necrosis virus (R11/3 virus) in experimental and naturally occurring cases of transmissible viral proventriculitis with the use of a reverse transcriptase-PCR procedure.

A reverse-transcriptase-polymerase-chain-reaction (RT-PCR) procedure was evaluated for detection of chicken proventricular necrosis virus (CPNV) in transmissible viral proventriculitis (TVP) -affected chickens. The RT-PCR procedure was compared with indirect immunofluorescence (IFA) and virus isolation for detection of CPNV in experimentally infected chickens. Microscopic lesions characteristic of TVP were detected on days 5-35 postexposure (PE) in CPNV-infected chickens; CPNV was detected by RT-PCR on days 3-14 PE in freshly collected proventriculi, and on days 1-14 PE in formalin-fixed paraffin-embedded (FFPE) proventriculi. CPNV was detected in proventriculi of experimentally infected chickens by IFA on days 3-10 PE, and by virus isolation on days 1-14 PE. With IFA used as a reference, sensitivity of the RT-PCR procedure with freshly collected and FFPE proventriculi was 88% and 100%, respectively; specificity was 83% and 86%, respectively. Proventriculi (FFPE) obtained from suspect TVP cases (n=19) were evaluated for presence of CPNV by RT-PCR and microscopic lesions consistentwith TVP. CPNV was detected by RT-PCR in proventriculi from 8/11 TVP (+) cases (24/36 tissue sections). TVP (+) cases were defined by microscopic lesions characteristic of TVP; CPNV was not detected in proventriculi (0/8 cases, 0/32 tissue sections) in the absence of these lesions. The association between presence of TVP-characteristic microscopic lesions and presence of CPNV was highly significant (P = 0.0014). These findings indicate the utility of the RT-PCR procedure for detection of CPNV and provide additional evidence for an etiologic role for this virus in TVP.