Publications by authors named "Abigail R Armwood"

9 Publications

  • Page 1 of 1

Pathology in Practice.

J Am Vet Med Assoc 2021 Dec;259(S2):1-4

In collaboration with the American College of Veterinary Pathologists.
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http://dx.doi.org/10.2460/javma.19.07.0356DOI Listing
December 2021

A novel herpes-like virus inducing branchial lesions in a tiger shark ().

Vet Pathol 2021 Nov 18:3009858211052662. Epub 2021 Nov 18.

University of Georgia, Athens, GA, USA.

A juvenile, male tiger shark () developed illness after capture in Florida waters and was euthanized. Gross lesions included mild skin abrasions, hepatic atrophy, and coelomic fluid. Histologically, gills contained multifocal lamellar epithelial cell necrosis and thromboses. Scattered gill and esophageal epithelial cells had large, basophilic, intracytoplasmic, and intranuclear inclusions. Ultrastructurally, lamellar epithelial cells contained arrays of intracytoplasmic viral particles and scattered intranuclear nucleocapsids. Capsulated virions were 148 ± 11 nm with an 84 ± 8 nm icosahedral nucleocapsid and an electron-dense core. Next-generation sequencing, quantitative polymerase chain reaction, and in situ hybridization performed on formalin-fixed tissue confirmed a herpes-like viral infection. The viral polymerase shared 24% to 31% protein homology with other alloherpesviruses of fish, indicating a divergent virus. This report documents the pathologic findings associated with a molecularly confirmed novel herpes-like virus in an elasmobranch.
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http://dx.doi.org/10.1177/03009858211052662DOI Listing
November 2021

Genetic variability of Edwardsiella piscicida isolates from Mississippi catfish aquaculture with an assessment of virulence in channel and channel × blue hybrid catfish.

J Fish Dis 2021 Nov 12;44(11):1725-1751. Epub 2021 Jul 12.

Department of Wildlife, Fisheries and Aquaculture, College of Forest Resources, Mississippi State University, Starkville, MS, USA.

The bacterium Edwardsiella piscicida causes significant losses in global aquaculture, particularly channel (Ictalurus punctatus) × blue (I. furcatus) hybrid catfish cultured in the south-eastern United States. Emergence of E. piscicida in hybrid catfish is worrisome given current industry trends towards increased hybrid production. The project objectives were to assess intraspecific genetic variability of E. piscicida isolates recovered from diseased channel and hybrid catfish in Mississippi; and determine virulence associations among genetic variants. Repetitive extragenic palindromic sequence-based PCR (rep-PCR) using ERIC I and II primers was used to screen 158 E. piscicida diagnostic case isolates. A subsample of 39 E. piscicida isolates, representing predominant rep-PCR profiles, was further characterized using BOX and (GTG) rep-PCR primers, virulence gene assessment and multilocus sequence analysis (MLSA) targeting housekeeping genes gyrb, pgi and phoU. The MLSA provided greater resolution than rep-PCR, revealing 5 discrete phylogroups that correlated similarly with virulence gene profiles. Virulence assessments using E. piscicida representatives from each MLSA group resulted in 14-day cumulative mortality ranging from 22% to 54% and 63 to 72% in channel and hybrid fingerlings, respectively. Across all phylogroups, mortality was higher in hybrid catfish (p < .05), supporting previous work indicating E. piscicida is an emerging threat to hybrid catfish aquaculture in the south-eastern United States.
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http://dx.doi.org/10.1111/jfd.13491DOI Listing
November 2021

Retrospective study of phaeohyphomycosis in aquarium-housed fish, with first descriptions of Exophiala lecanii-corni and Neodevriesia cladophorae in fish.

J Fish Dis 2021 Oct 20;44(10):1563-1577. Epub 2021 Jun 20.

Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.

A broadening fish host range is affected by novel and known pigmented fungal pathogens. A review of 2,250 piscine submissions received by the Aquatic Pathology Service, University of Georgia, revealed 47 phaeohyphomycosis cases (2.1%), representing 34 bony and cartilaginous fish species. The majority involved bony fish (45/47, 95.7%) and were predominantly marine (41/47, 87.2%), with only a few freshwater species (4/47, 8.5%). Cartilaginous fish cases included two zebra sharks (Stegostoma fasciatum) (2/47, 4.3%). Northern seahorses (Hippocampus erectus) had the highest incidence overall (7/47, 14.9%). Culture and sequencing of the internal-transcribed spacer region of the rDNA (ITS), large ribosomal subunit gene D1/D2 domains (LSU) and the DNA polymerase II gene (RPB2) were performed for fungal identification when fresh tissue was obtainable. Exophiala, Ochroconis and Neodevriesia spp. were identified, with Exophiala as the most common fungal genus (8/11, 72.7%). Exophiala lecanii-corni and Neodevriesia cladophorae were described for the first time from fish. Microscopically, lesions were characterized by necrosis, granulomatous inflammation and angioinvasion most frequently affecting the skin/fin, skeletal muscle and kidneys. In this study of diverse aquarium-housed fish species, phaeohyphomycosis cases occurred sporadically and in rare outbreaks with variable pathologic presentations, tissue distributions and severities.
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http://dx.doi.org/10.1111/jfd.13477DOI Listing
October 2021

A Retrospective Study of Pathology in Bats Submitted to an Exotic and Zoo Animal Diagnostic Service in Georgia, USA (2008-2019).

J Comp Pathol 2021 May 28;185:96-107. Epub 2021 May 28.

Department of Pathology, Athens, Georgia, USA.

Pathology records of bats submitted to the University of Georgia from managed care settings were reviewed to identify naturally occurring diseases. Fifty-nine cases were evaluated during an 11-year period (2008-2019), including representatives from four families: Pteropodidae (Yinpterochiroptera), Phyllostomidae, Vespertilionidae and Molossidae (Yangochiroptera). Pathology reports were reviewed to determine the primary pathological process resulting in death or the decision to euthanize. Cases were categorized as non-infectious (34/59; 58%), infectious/inflammatory (17/59; 29%) or undetermined due to advanced autolysis (8/59; 14%). Musculoskeletal diseases and reproductive losses were the most frequent pathological processes. Among the infectious processes identified, bacterial infections of the reproductive and haemolymphatic systems were most frequently observed. The first two reports of neoplasia in small flying foxes (Pteropus hypomelanus) are described. Bats under managed care present with a wide range of histopathological lesions. In this cohort, non-infectious disease processes were common.
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http://dx.doi.org/10.1016/j.jcpa.2021.04.010DOI Listing
May 2021

Computed tomographic and ultrasonographic diagnosis with successful excision of a lipoma in a shusui koi .

J Am Vet Med Assoc 2020 Jun;256(12):1379-1385

Case Description: A client-owned 12-year-old 10.3-kg (22.7-lb) female shusui koi () was evaluated because of an ulcerated mass on the left body wall, hyporexia, and decreased activity.

Clinical Findings: The patient was anesthetized with a solution of eugenol in water for all examinations and procedures. An approximately 7 × 5-cm smooth, raised, ulcerated, and firm mass was present ventral and lateral to the dorsal fin on the left body wall. Whole-body CT images obtained before and after contrast administration revealed an encapsulated, homogeneous, fat-opaque mass within the muscle. The mass was fat echoic with poor vascularity on ultrasonographic examination. Histologic evaluation of an ultrasound-guided needle biopsy specimen was suggestive of a lipoma.

Treatment And Outcome: The mass was excised, and the fish was placed in water with 0.3% salinity for 3 weeks after surgery. Postoperative antimicrobial administration was not indicated, and additional postoperative analgesic administration was considered impractical. The patient had noticeable improvement in appetite and activity with no indication of discomfort immediately following surgery. Five weeks after surgery, the incision site had healed with minimal scarring, and evaluation of CT images revealed no evidence of mass regrowth or regional osteomyelitis.

Clinical Relevance: Antemortem evaluation and diagnosis of a lipoma in a teleost with subsequent excision was described. This report highlighted the logistic challenges associated with anesthesia, advanced diagnostic imaging, and surgery in fish and showed that they can be successfully overcome so that high-level medical care can be provided to such patients.
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http://dx.doi.org/10.2460/javma.256.12.1379DOI Listing
June 2020

Primary intracranial fibrosarcoma in a southern sea otter Enhydra lutris nereis.

Dis Aquat Organ 2020 Mar 26;138:207-213. Epub 2020 Mar 26.

Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.

Southern sea otters Enhydra lutris nereis, a threatened marine mammal species, face numerous environmental and infectious disease challenges in their native habitat of coastal California, USA. However, there are few published cases describing neoplasia in sea otters despite their relatively long life span when cared for in aquarium settings. An 18 yr old neutered male southern sea otter, born and raised in human care, presented with an acute onset of seizures and dull mentation. Magnetic resonance imaging of the head revealed a large, central brain lesion. After no improvement with treatment, euthanasia was elected due to a poor prognosis. Grossly, a poorly demarcated, granular, tan mass expanded the cranial meninges in the longitudinal fissure at the level of the cruciate sulcus and extended into the underlying gray matter and superficial white matter. Histologically, the mass was composed of spindle cells, forming haphazardly arranged interlacing bundles and herringbone patterns, with a high mitotic count, moderate cellular pleomorphism, and prominent vascularization. Neoplastic cells demonstrated positive immunoreactivity for vimentin and negative immunoreactivity for smooth muscle actin, factor VIII-related antigen, S100, melan-A, E-cadherin, desmin, glial fibrillary acidic protein, and cytokeratin AE1/AE3. Based on gross, histologic, and immunohistochemical findings, the mass was most consistent with a primary intracranial fibrosarcoma (PIF). PIFs are a rare neoplasm in both humans and other animals with few reports in the veterinary literature. This is the first recorded case of a PIF in a sea otter.
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http://dx.doi.org/10.3354/dao03457DOI Listing
March 2020

Description of sp. nov., an emergent fish pathogen, and assessment of virulence using a tiger barb () infection model.

Int J Syst Evol Microbiol 2020 Feb;70(2):857-867

Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, 2108 Tupper Hall, Davis, CA 95616-5270, USA.

A recently described emergent disease of ornamental fish has been associated with an species positive for the surface protective antigen () C gene. Whole genome sequencing was performed on five isolates from diseased ornamental fish. In addition, these isolates were compared to and other -positive species isolated from terrestrial and marine mammals, birds and fish using multi-locus sequence analysis (MLSA). The genomes of fish pathogenic isolates were genetically distinct from , sharing 86.61-86.94 % average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of 31.6-32.2 %, but 99.01-99.11 % ANI and 90.8-91.9 % dDDH values with the uncharacterized -positive sp. strain 2 isolated from swine. The findings indicate the -positive fish and swine isolates are conspecific and represent a previously unrecognized taxon. While phylogenies inferred from MLSA sequences confirm this conclusion, slight genetic differences between the fish isolates and swine strain 2 were indicated. Bath immersion challenge trials were conducted using tiger barbs () exposed by immersion to 10 c.f.u. ml of three fish pathogenic species, and three and two isolates as a model of infection. Thirty days post-challenge, cumulative mean percentage survival was 37 % for the , 100 % for the and 13 % for the isolates, revealing differences in virulence among the various genotypes in fish. Genetic findings and observed differences in virulence demonstrate the fish pathogenic isolates represent a novel species, for which the name sp. nov. is proposed. The type strain is 15TAL0474 (=NRRL B-65533=ATCC-TSD-175=DSM 110099).
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http://dx.doi.org/10.1099/ijsem.0.003838DOI Listing
February 2020

Pathologic changes in cultured Nile tilapia (Oreochromis niloticus) associated with an outbreak of Edwardsiella anguillarum.

J Fish Dis 2019 10 15;42(10):1463-1469. Epub 2019 Jul 15.

Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, USA.

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http://dx.doi.org/10.1111/jfd.13058DOI Listing
October 2019
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