Neoplasia in an assurance population of Puerto Rican crested toads (Peltophryne lemur).

Disease monitoring of amphibian assurance populations is an important buffer against ongoing global extinctions. This study documents a high incidence of neoplasia in a zoo-managed assurance population of Puerto Rican crested toads (Peltophryne lemur; PRCTs). Over 5 years, neoplasia was diagnosed in 17/49 (35%) submitted adult PRCTs and was the cause of death or euthanasia in 13/17 (72%). Most toads were male (16/17; 94%) and 6 to 11-years-old (average 8.1 years). Notably, seven toads (41%) had multiple neoplasms. Of the 29 neoplasms identified, 17 (59%) were cutaneous or subcutaneous. The most common neoplasms included mast cell tumors (MCTs; 8/29; 28%), histiocytic sarcomas (6/29; 21%), lymphoma/leukemia (4/29; 14%), and squamous cell carcinomas (3/29; 10%). Distant metastases were documented in 6/8 (75%) toads with MCTs. Causes for neoplasia in this population were not determined though may include genetic or environmental factors. Continued investigations of managed endangered amphibians will help elucidate mechanisms of carcinogenesis.

In vivo and in vitro phenotypic differences between Great Lakes VHSV genotype IVb isolates with sequence types vcG001 and vcG002.

Viral hemorrhagic septicemia virus (VHSV) is an aquatic rhabdovirus first recognized in farmed rainbow trout in Denmark. In the past decade, a new genotype of this virus, IVb was discovered in the Laurentian Great Lakes basin and has caused several massive die-offs in some of the 28 species of susceptible North American freshwater fishes. Since its colonization of the Great Lakes, several closely related sequence types within genotype IVb have been reported, the two most common of which are vcG001 and vcG002. These sequence types have different spatial distributions in the Great Lakes. The aim of this study was to determine whether the genotypic differences between representative vcG001 (isolate MI03) and vcG002 (isolate 2010-030 #91) isolates correspond to phenotypic differences in terms of virulence using both an in vitro and in vivo approach. In vitro infection of epithelioma papulosum cyprini (EPC), bluegill fry (BF-2), and Chinook salmon embryo (CHSE) cells demonstrated some differences in onset and rate of growth in EPC and BF-2 cells, without any difference in the quantity of RNA produced. In vivo infection of round gobies (Neogobius melanostomus) via immersion exposure to different concentrations of vcG001 or vcG002 caused a significantly greater mortality in round gobies exposed to 102 plaque forming units ml-1 of vcG001. These experiments suggest that there are phenotypic differences between Great Lakes isolates of VHSV genotype IVb.

Pathologic impacts of contaminants in freshwater fish of Cook County IL.

Mercury (Hg) and polychlorinated biphenyls (PCBs) are widespread environmental toxicants in urban environments with negative impacts to fish health. The present study evaluated the potential association between muscle tissue contaminant (total Hg and total PCB) concentrations and indicators of health in benthic and predatory fish collected from four Forest Preserves of Cook County lakes in the Chicago metropolitan area. Common carp (carp; Cyprinus carpio) and largemouth bass (LMB; Micropterus salmoides) were sampled three times a year (spring, summer, fall) during 2019 and 2020. Water quality analyses (temperature, color, turbidity, dissolved oxygen, total alkalinity, pH, chloride, nitrate, phosphate, ammonium, and pH) were performed concurrently with fish collections. Tissue (skin-on fillet) contaminant concentrations were compared between lake types and fish species and assessed for any relationship with fish morphometric data and pathologic lesions. Main health indicator endpoints included muscle lipid content, parasite burden, and pathologic lesions. Mean total PCB concentrations were greater in carp (203.1 ± 152 µg/kg, wet weight), and mean Hg concentrations were greater in LMB (0.11 ± 0.1 mg/kg, wet weight). In most fish, concentrations of both toxicants surpassed the EPA's lowest threshold to restrict fish consumption for sensitive cohorts (0.029 mg/kg for Hg and 1.5 µg/kg for PCBs). In both species, Hg positively correlated with splenic pigmented macrophage aggregate area (P < 0.001). In carp, Hg also positively correlated with hepatocellular pigmentation (P < 0.01). Mercury correlated with standard length in both species (LMB: P < 0.001, carp: P = 0.95), but polychlorinated biphenyls only correlated with standard length in carp (P < 0.001). No association was found between intraspecific contaminant concentrations and parasite burden, year, or lake type, though differences were noted among individual lakes. The contaminant burden appeared well-tolerated with only mild Hg-associated and no appreciable PCB-associated lesions. However, possible effects on reproduction or behavior were not fully assessed, and future studies are warranted.

Epitheliotropic T-cell lymphoma in 2 half-sibling bontebok.

We diagnosed epitheliotropic T-cell lymphoma of the forestomachs in 2 aged, half-sibling, zoo-managed bontebok (Damaliscus pygargus pygargus). One bontebok also had mesenteric lymph node and cutaneous involvement. Both animals had a history of chronic abdominal distension and diminished body condition that resulted in euthanasia. At autopsy, both animals had marked ruminal distension with diffusely blunted ruminal papillae and reticular crests. In case 1, there was an increased amount and particle length of the ruminoreticular fibrous material with scant fluid, and a 2-cm diameter focus of cutaneous crusting adjacent to a mammary teat. In case 2, the rumen and reticulum were fluid-distended with decreased fibrous material. Histologically in case 1, the rumen, reticulum, omasum, and skin had intraepithelial nests and sheets of neoplastic small lymphocytes; in case 2, the rumen and reticulum had a similar neoplastic cell population. Immunohistochemically, neoplastic lymphocytes were immunoreactive for CD3 and negative for CD20, confirming the diagnosis of epitheliotropic T-cell lymphoma.