In mammals, animal health professionals and researchers often use a system called a Body Condition Score – or BCS – to evaluate nutritional status and overall health. The method relies on gently feeling the animal’s bones, fat, and muscle to judge whether it is too thin, too heavy, or in good condition. It’s been adapted for many species, but it doesn’t work for frogs, as they store barely any fat under the skin. Instead, most fat is tucked away inside the body cavity, making the usual assessment methods impossible.

Dr Tix led a study to establish a BCS tailored specifically for the South African clawed frog. Working with 62 adult female frogs, her team combined careful measurements of body weight and length, with visual assessments of body shape and muscles.

From these observations, they created a five-point scoring system. At the lowest end, BCS 1 indicates severe emaciation and signals a humane endpoint – meaning the animal should no longer be kept in experiments. At the higher end, BCS 4 and 5 describe frogs in robust condition, with pear-shaped bodies and muscular limbs. Unlike in mammals where higher scores can mean obesity, in clawed frogs the upper scores usually represent the preferred condition, unless fluid-retention is present.

Importantly, the BCS can also serve as an early warning system: a frog with an unexpectedly high or low score might be developing health problems and should be further investigated by a veterinarian.

This new scoring system represents a meaningful step in refining laboratory animal care. It also highlights the importance of tailoring welfare practices to the biology of each species, rather than applying one-size-fits-all approaches. Thanks to Dr Tix and her team, animal health professionals and researchers now have a consistent and species-specific way to monitor the nutritional status of South African clawed frogs – a species that continues to provide invaluable insights into life’s most fundamental processes.