A Retrospective Review of Post-Metamorphic Mountain Chicken Frog (Leptodactylus Fallax) Necropsy Findings From European Zoological Collections, 1998 to 2018

Abstract

The mountain chicken frog (Leptodactylus fallax) is the largest endemic amphibian species in the Western Hemisphere. Since 1998, this Critically Endangered species has been maintained as a European Endangered Species Programme (EEP) but low breeding success and a high mortality rate threatens the sustainability of the captive frog population. In the current study, we analyzed gross and histopathological post-mortem information from 212 mountain chicken frogs which died in European zoological collections, 1998 -2018. Thin body condition was the most commonly reported finding across all submissions, observed in 125 frogs. The gastrointestinal and urinary systems were reported to have the highest prevalence of pathological findings on gross and histopathological examination. Inflammatory disease was the most frequent diagnosis following histopathological examination of relevant tissues with intestinal inflammatory disease (n=76) followed by tubulointerstitial nephritis (n=26) most commonly reported. Neoplasia was reported in 42/212 (19.8%) frogs, all of which were adults. A defined cause of death, or reason for euthanasia, was proposed for 164/212 (77.4%) frogs with inflammatory diseases processes (74/212; 34.9%) most commonly implicated. Intestinal adenocarcinoma, seemingly restricted to the colon, caused the deaths of 31 adult frogs. Further investigations to determine factors contributing to the high incidence of inflammatory disease processes and neoplasia are advocated in order to help improve the health and sustainability of the captive mountain chicken frog population.

Activity budgets, responses to disturbance and novel behaviours in captive mountain chicken frogs Leptodactylus fallax

“…Health checks are imperative, particularly as mountain chickens are known to develop potentially fatal diseases within captivity (Ashpole et al, 2021), but our results show a clear tension between the need for health checks and the need for minimising disturbance. Importantly, the effects of disturbance were not limited to those dens including frogs that were captured, but were identified for some behaviours in dens that were indirectly disturbed by keepers catching frogs in neighbouring dens.…”

“…Although successful captive breeding has led to an increase in this captive population size (Jameson et al, https://doi.org/10.33256/33.2.4354 2019), managing mountain chickens in captivity has proven problematic, mainly due to the highly specific conditions required by this species in captivity (Tapley et al, 2015;Donaldson, 2019;Jameson et al, 2019). The physiological requirements of captive mountain chickens are becoming better understood (Fitzgerald et al, 2007;Dierenfeld et al, 2008;King et al, 2011;Jaffe et al, 2015;Tapley et al, 2015;Jayson et al, 2018;2018b;Croci et al, 2019;Donaldson, 2019;Jameson et al, 2019;Ashpole et al, 2021;Michaels et al, 2021;White et al, 2021). Although very basic information on habitat use and activity patterns is known from wild populations (Schwartz & Henderson, 1991;Daltry, 2002; see Jameson et al, 2019), detailed information on activity budgets and patterns is lacking for both wild and captive mountain chickens.…”