RESUMO
Chinchillas are a relatively novel research model compared with other rodent species. They require special considerations when it comes to their husbandry and daily care. Chinchillas tend to be shy animals that are well adapted to masking clinical signs of illness. These characteristics can make them a difficult species to maintain in a research setting. The authors' institution has maintained chinchillas and established standardized daily animal care procedures for them. Chinchillas are most commonly used for auditory research. They are often used to study the mechanism of different induced auditory conditions or injuries as well as exploration for potential alleviating treatments. Often, tested therapeutics have demonstrated potentially beneficial effects but have not been applied in the specific condition or injury of interest. The development of new applications for therapeutics can lead to groundbreaking discoveries, but testing of new therapeutic applications is often initially performed in an animal model without knowing how the therapeutic will behave in the species. During testing, unexpected adverse events may manifest that require more focused monitoring and supportive care. This scenario occurred when adverse effects were observed in a chinchilla blast-injury model after receiving an acylated glucagon-like peptide-1 (GLP-1) receptor agonist. The study involved evaluation of this therapeutic over an extended amount of time after inducing a controlled pressurized blast-injury followed by multiple repeated hearing tests under anesthesia. Chinchillas enrolled in the study exhibited several clinical signs including weight loss, lethargy, labored breathing, neurologic abnormalities, decreased appetite or decreased fecal output, and otitis. Five primary abnormalities were reported on pathology: aspiration pneumonia, hepatic steatosis, right ventricular dilation, pancreatitis, and tubulointerstitial nephritis. Initially abnormal clinical signs, early mortality rates, and pathology were attributed to multiple anesthetic events. However, a retrospective analysis evaluating the association of different study variable exposures in a stratified comparison demonstrated that the early mortality rates were actually associated with the therapeutic drug given for the first time in this species. In this study, we describe the detailed findings of the retrospective analysis and explore different strategies that can be incorporated to maintain good animal welfare and decrease early animal loss.
RESUMO
The Amazon Molly (Poecilia formosa) reproduces by gynogenesis, a relatively rare form of asexual reproduction where sperm is required to trigger embryogenesis, but male genes are not incorporated into the genome of the embryo. Studying gynogenesis could isolate paternal non-genetic effects on reproduction. This study explored which of eleven related species can produce sperm to trigger gynogenesis through natural mating in P. formosa, and whether sympatry affects reproductive success in P. formosa. Reproductive outcomes measured were relative reproductive output (number of offspring in the first brood divided by female standard length), relative embryo output (number of embryos in the first brood divided by female standard length) and combined relative reproductive output (sum of relative reproductive output and relative embryo output). For large (>4 cm) P. formosa, combined relative reproductive output was higher with sympatric Atlantic Molly (Poecilia mexicana) males than with allopatric P. mexicana males. P. formosa produced live offspring or late-stage embryos with all species tested in the genera Poecilia and Limia but did not produce offspring or embryos with males from the genera Gambusia, Girardinus, Heterandria, Poeciliopsis, or Xiphophorus. This information, as well as the limitations characterized in this study, will set a foundation for use of P. formosa as a model for paternal effects and the species specificity of sperm on fertilization, embryogenesis, and reproductive success.
