Establishment of the body condition score for adult female Xenopus laevis

• Published in: PloS one 2023-04, Vol.18 (4), p.e0280000
• Main Authors: Tix, Leonie, Ernst, Lisa, Bungardt, Britta, Talbot, Steven R, Hilken, Gero, Tolba, René H
• Format: Article
• Language: English
• Subjects: Adipose Tissue; Adipose tissues; Amphibians; Anatomy & physiology; Animal protection; Animal welfare; Animals; Behavior; Biology and Life Sciences; Body weight; Eggs; Experiments; Fat body; Female; Females; Football (College); Frogs; Health problems; Housing conditions; Laboratory animals; Mammals; Medicine and Health Sciences; Nutrition assessment; Nutritional status; Physical Sciences; Physiology; Reptiles & amphibians; Research and Analysis Methods; Subcutaneous Fat; Surgery, Plastic; Water temperature; Xenopus; Xenopus laevis
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0280000

The assessment of animals' health and nutritional status using a Body Condition Score (BCS) has become a common and reliable tool in lab-animal science. It enables a simple, semi-objective, and non-invasive assessment (palpation of osteal prominences and subcutaneous fat tissue) in routine examination of an animal. In mammals, the BCS classification contains 5 levels: A low score describes a poor nutritional condition (BCS 1-2). A BCS of 3 to 4 is considered optimum, whereas a high score (BCS = 5) is associated with obesity. While BCS are published for most common laboratory mammals, these assessment criteria are not directly applicable to clawed frogs (Xenopus laevis) due to their intracoelomic fat body instead of subcutaneous fat tissue. Therefore, this assessment tool is still missing for Xenopus laevis. The present study aimed to establish a species-specific BCS for clawed frogs in terms of housing refinement in lab-animal facilities. Accordingly, 62 adult female Xenopus laevis were weighed and sized. Further, the body contour was defined, classified, and assigned to BCS groups. A BCS 5 was associated with a mean body weight of 193.3 g (± 27.6 g), whereas a BCS 4 ranged at 163.1 g (±16.0 g). Animals with a BCS = 3 had an average body weight of 114.7 g (±16.7 g). A BCS = 2 was determined in 3 animals (103 g, 110 g, and 111 g). One animal had a BCS = 1 (83 g), equivalent to a humane endpoint. In conclusion, individual examination using the presented visual BCS provides a quick and easy assessment of the nutritional status and overall health of adult female Xenopus laevis. Due to their ectothermic nature and the associated special metabolic situation, it can be assumed that a BCS ≥3 is to be preferred for female Xenopus laevis. In addition, BCS assessment may indicate underlying subclinical health problems that require further diagnostic investigation.