Cholelithiasis in adult bearded dragons: retrospective study of nine adult bearded dragons (Pogona vitticeps) with cholelithiasis between 2013 and 2015 in southern Germany.

With an increased number of pet reptiles, many diseases occur due to nutritional disorders. Between 2013 and 2015, irregular gallbladder contents (sludge/choleliths) in adult bearded dragons (Pogona vitticeps) were recorded in many of the routinely conducted necropsies at the reptile rescue station in Munich (Auffangstation für Reptilien, München e.V., Munich, Germany). Nine animals, six from the rescue station and three from an associated veterinary practice (Tierärztliche Praxis für Exoten, Augsburg, Germany), were studied. Gallbladder contents from all animals were analysed at the Institute for Clinical Chemistry in Zurich, Switzerland. In three of nine animals, one cholelith composed of 100% calcium carbonate (CaCO3 ) was detected and it precipitated either as pure calcite or as a calcite:vaterite combination. In the remaining six animals, analyses suggested a protein-based material. The detection of choleliths/sludge was not anticipated at necropsy or surgery in eight of nine animals. The diet of the six animals from the rescue station was retrospectively described as mainly insects, whereas the diet of the three animals from the veterinary practice also contained little plant matter. Fed insect species were mealworm larva (Tenebrio molitor), house cricket (Acheta domestica), migratory locust (Locusta migratoria) and zophobas larva (Zophobas morio), all high in protein and fat. In other species, a nidus must be present for CaCO3 to precipitate. As a protein-based sludge was detected in six gallbladders, it is possible that a high-protein diet could lead to such a nidus and subsequently to cholelith formation. Cholelithiasis seems to be a rising problem in adult bearded dragons and is likely underdiagnosed, as many choleliths were found at necropsy. This rise in cholelithiasis may correlate with an unnatural high-protein, high-fat insect-based diet instead of a balanced plant-based diet.