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Variation in environmental chemistry affects animal health and demographics. For instance, acidification of aquatic ecosystems (e.g., due to acid rain) can have consequences for organismal fitness. Elevated atmospheric concentrations of CO2, which reacts with water to produce carbonic acid, may affect aquatic animal physiology in multiple ways, including via reductions in pH. Such impacts have been assessed to a large extent in marine systems. Similar effects are also likely occurring in freshwater ecosystems but are relatively understudied. The goal of this project was to determine how changes in pH and CO2 concentrations influence traits and survival of animals in freshwater systems, using larval American Bullfrogs (Lithobates catesbeianus (also known as Rana catesbeiana) [Shaw, 1802]) as a model. We hypothesized that elevated CO2 concentrations and reduced pH negatively affect larval frog immune function, growth, and survival, which we tested in a laboratory aquarium experiment. Over the 27-d experiment, tadpoles were exposed to 4 treatments: 1) near-neutral pH and no gas addition (mean ± SE pH = 7.17 ± 0.05), 2) CO2 gas sparged into aquariums (pH = 5.32 ± 0.04), 3) acidified water without gas addition (pH = 6.29 ± 0.08), and 4) ambient air sparged into aquariums (control for effects of gas addition) at near-neutral pH (pH = 7.46 ± 0.03). We measured tadpole innate immune response, growth, and survival. Results from the experiment partially supported our hypothesis, with lower immune function in tadpoles exposed to acidified water or elevated CO2 compared with the control treatments and lower final mass and survival under elevated CO2. These findings motivate additional research on pH and CO2 effects on freshwater animals and suggest that increased environmental acidity and elevated CO2 can lead to negative impacts, which could contribute to reductions in wildlife health and population declines in light of ongoing environmental changes. [ABSTRACT FROM AUTHOR]

OBJECTIVE To use CT measurements to define the body surface area (BSA) formula in American bullfrogs (Lithobates catesbeianus) and calculate the species-specific shape constant (K) to suggest chemotherapeutic doses. ANIMALS 12 American bullfrogs owned by the North Carolina State College of Veterinary Medicine Department of Laboratory Animal Resources underwent CT scans without anesthesia or sedation in November 2022. METHODS As part of this prospective study, each American bullfrog underwent a complete physical exam and CT scan. 3-D surface models were created using CT data, and the resulting measurements were used for BSA calculations. Animals were grouped by sex. Nonlinear regression analysis of BSA versus body weight was performed, and a speciesspecific formula was derived for calculating BSA in American bullfrogs. RESULTS The mean body weight of the bullfrogs was 354 grams. The mean CT-derived BSA was 414.92 cm2. The calculated K constant was 8.28 for the 12 American bullfrogs, and the CT-derived BSA formula was BSA in cm2 = 8.28 X (body weight in g)2/3. The K constant was 8.07 for females and 8.44 for males and was not significantly different between sexes (P = .5). CLINICAL RELEVANCE Results indicated that the species-specific K constant for American bullfrogs is 8.28. This is the first calculated K constant that exists for amphibians to our knowledge. [ABSTRACT FROM AUTHOR]

Introduced fungal pathogens have caused declines and extinctions of naïve wildlife populations across vertebrate classes. Consequences of introduced pathogens to hosts with small ranges might be especially severe because of limited redundancy to rescue populations and lower abundance that may limit the resilience of populations to perturbations like disease introduction. As a complement to biosecurity measures to prevent the spread of pathogens, surveillance programs may enable early detection of pathogens, when management actions to limit the effects of pathogens on naïve hosts might be most beneficial. We analyzed surveillance data for the endangered and narrowly endemic Dixie Valley toad (Anaxyrus [= Bufo] williamsi) from two time periods (2011-2014 and 2019-2021) to estimate the minimum detectable prevalence of the amphibian fungal pathogen Batrachochytrium dendrobatidis (Bd). We assessed if detection efficiency could be improved by using samples from both Dixie Valley toads and co-occurring introduced American bullfrogs (Lithobates catesbeianus) and literature-derived surveillance weights. We further evaluated a weighted surveillance design to increase the efficiency of surveillance efforts for Bd within the toad's small (<6 km²) range. We found that monitoring adult and larval American bullfrogs would probably detect Bd more efficiently than monitoring Dixie Valley toads alone. Given that no Bd was detected, minimum detectable prevalence of Bd was <3% in 2011-2014, and <5% (Dixie Valley toads only) and <10% (American bullfrogs only) in 2019-2021. Optimal management for Bd depends on the mechanisms underlying its apparent absence from the range of Dixie Valley toads, but a balanced surveillance scheme that includes sampling American bullfrogs to increase the likelihood of detecting Bd, and adult Dixie Valley toads to ensure broad spatial coverage where American bullfrogs do not occur, would probably result in efficient surveillance, which might permit timely management of Bd if it is detected. [ABSTRACT FROM AUTHOR]

We document eight cases of axanthism in Green Frogs (Lithobates clamitans) and one case in an American Bullfrog (Lithobates catesbeianus) in Maine. Although this mutation has been previously reported for both species, this is the first confirmed documentation of "blue" L. clamitans and L. catesbeianus from Maine. [ABSTRACT FROM AUTHOR]

The American bullfrog (Rana catesbeiana), recently named Lithobates catesbeianus is currently farmed for commercial purposes throughout various regions of Brazil. Stressful situations such as problems of management, inadequate facilities and environmental changes with consequent reduction of immunity are common in intensive production. The assessments of these situations of stress allow us detect these problems decreasing the injuries causes by confinement. The main objective of this study was to use the biological markers of plasma cortisol and glucose level and hematological parameters to evaluate the response of bullfrog tadpoles submitted to stressed mechanisms of capture and hypoxia. The animals were subjected to three treatments: stress due to individual capture with a hand net; stress due to batch capture with a hand net; and stress due to capture by emptying. The results obtained demonstrated that there were no statistically significant differences in the parameters tested when comparing the treatments with and without exposure to air (normoxia and hypoxia). Based on these results we can conclude that the stressful stimuli tested were not adequate to alter the biomarker tested. For the cortisol, probably this should have occurred due to the synergistic action between this hormone and thyroxin, which induces metamorphosis in these animals.A rã-touro americana (Rana catesbeiana) recentemente denominada Lithobates catesbeianus é cria da com propósito comercial em várias regiões do Brasil. Situações estressantes tais como problemas de manejo, criação inadequada e alterações ambientais com consequente redução da imunidade são comuns em produções intensivas. A avaliação destas situações de estresse permite-nos detectar estes probemas e diminuir as injurias causadas pelo confinamento. O principal objetivo deste estudo foi utilizar os marcadores biológicos de cortisol, glicemia e dados hematológicos para avaliar a resposta de girinos de rã-touro submetidos aos mecanismos estressores de captura e hipóxia. Os animais foram distribuídosem três tratamentos: estresse por captura individual com puçá; estresse por captura em massa com puçá e estresse por captura por escoamento. Os resultados obtidos demostraram não haver diferenças estatisticamente significativas entre os parametros avaliados quando comparou-se os grupos com e sem exposição ao ar (normoxia e hipoxia). Com base nestes resultados pode-se concluir que os estímulos estressores avaliados não foram adequados para alterar os valores plasmáticos dos marcadores biológicos testados. Para o cortisol, isto ocorreu provavelmente em virtude da ação sinérgica deste hormônio e a tiroxina, que induz a metamorfose nestes animais.

An adult female American bullfrog ( Lithobates catesbeianus) presented with an exophytic multilobular soft tissue mass involving the majority of the second left front digit. An excisional biopsy was performed under general anesthesia using a buffered tricaine methanesulfonate bath. The entire digit, including the distal, middle, and proximal phalanges, and associated mass were surgically removed by dislocation at the metacarpophalangeal joint. The incision was closed with 4-0 polydioxanone using two horizontal mattress sutures and the frog was recovered in a freshwater bath. Histological examination revealed a well-differentiated squamous cell carcinoma with a mitotic rate of less than one per high power field. Six months following surgery the frog was fully recovered and returned to use in an educational program. The frog survived four years postsurgery with no gross or histological evidence of neoplasm recurrence. [ABSTRACT FROM AUTHOR]

A 7-yr-old male captive American bullfrog ( Lithobates catesbeianus) presented with a 2-wk history of an enlarged, ulcerated nuptial pad on the mediopalmar surface of the first digit of the left carpus. A 3-mm wedge biopsy of the mass was not diagnostic and differentials included an epidermal inclusion cyst or squamous cell carcinoma. No fungal or acid-fast organisms were cultured or noted on impression smear. Wide surgical resection of the mass and associated first digit were performed. Histopathology confirmed squamous cell carcinoma associated with the dermal nuptial gland with neoplastic cells extending close to deep surgical margins. Two months after surgery, no recurrence was noted. Although experimental tumor studies in amphibians are well documented, clinical reports of cutaneous neoplasia management in captive amphibians are scarce. Squamous cell carcinoma should be considered as a differential diagnosis when male anurans present with nuptial gland enlargement. [ABSTRACT FROM AUTHOR]

We report three records of a rare blue American Bullfrog, Lithobates catesbeianus, from Nova Scotia, Canada. [ABSTRACT FROM AUTHOR]

The health of freshwater ecosystems is negatively affected by a multitude of pollutants. In northern latitudes, road deicing agents enter nearby ponds and waterways elevating chloride concentrations in winter and spring. Few studies have examined how amphibians respond to road salt contamination and no study has focused on the response of an invasive amphibian. We examined the effects of NaCl, the most commonly used deicing agent, on the embryos and tadpoles of the American bullfrog, Lithobates catesbeianus, a species that is invasive in many regions around the world. In the first experiment, we exposed L. catesbeianus embryos to ecologically relevant levels of chloride for 60 days. The second experiment examined the indirect consequences of chloride contamination by exposing L. catesbeianus tadpoles to dragonfly larvae. Lithobates catesbeianus did not experience reduced survival, growth, or ability to evade predation in elevated chloride concentrations compared to controls. The lack of a response by L. catesbeianus suggests that its population growth will not be negatively impacted by road salt contamination. This result may be good news for L. catesbeianus, but raises concern for sympatric amphibians that have to contend with negative impacts of both chloride contamination and non-native L. catesbeianus. [ABSTRACT FROM AUTHOR]

Exotic invasive bullfrogs ( Lithobates catesbeianus) are considered to exert a considerable negative impact on native amphibian communities. This can be due to competition and predation, but they are also a notorious source of the infectious diseases chytridiomycosis and ranavirosis, affecting amphibian populations globally. Little is known regarding their carriage of other microbial agents that might be transferred to humans or other animals. In this study we determined the occurrence of the amphibian pathogens Ranavirus and Batrachochytrium dendrobatidis and of the zoonotic agents Coxiella burnetii, Neospora caninum, Leptospira sp., Toxoplasma gondii, Mycoplasma sp., Campylobacter sp., Salmonella sp. and extended-spectrum beta-lactamase producing Escherichia coli in 164 bullfrogs from three populations in Belgium and The Netherlands. Although B. dendrobatidis was present at a high prevalence of 63%, mean infection loads were low with an average of 10.9 genomic equivalents (SD 35.5), confirming the role of bullfrogs as B. dendrobatidis carriers, but questioning their role as primary reservoirs for B. dendrobatidis transmission to native amphibian communities. All tested samples were negative for the other infectious agents examined. These results suggest a limited role of bullfrogs as carrier of these pathogens. [ABSTRACT FROM AUTHOR]

The article focuses on American bullfrog tadpoles' physiological response to capture and hypoxia. The authors used biological markers of plasma cortisol, glucose level and hematological parameters in getting the response of the American bullfrog in the aforementioned situations. The bullfrogs used in the study was subjected to three treatments that included stress due to individual capture, stress due to batch capture and stress due to capture by empty. The authors concluded that plasma cortisol and glucose levels are not affected by capture nor hypoxia.