In order to better understand cholelithiasis in callitrichids, a questionnaire was sent to callitrichid-holding European zoos.
The response rate to this questionnaire was 20.7%, which represented a study population of 1306 animals (535 Saguinus sp., 431 Callithrix sp., 225 Leontopithecus sp., and 115 Callimico goeldii). This population is not statistically representative of the European population due to an overrepresentation of Leontopithecus species.
Twenty-eight (28) individual cases of cholelithiasis were recorded (3 Callithrix sp., 25 Leontopithecus sp.). The results suggest that Leontopithecus species are significantly predisposed to cholelithiasis whereas Saguinus and Callimico species do not develop this disease; which is consistent with the genus repartition found in the literature.5-7 The mean age at diagnosis of cholelithiasis was 18 years, supporting a predilection towards older individuals being affected by this disease. A multiseptate gallbladder was present in 55.6% of the cholelithiasis cases. Gender, weight, or nutrition were not identified as risk factors.
Cholelithiasis is difficult to diagnose, as 21.5% of cases were asymptomatic. When present, clinical signs were not specific (emaciation, weakness, and chronic intermittent diarrhea). Icterus was present in only 21.4% of the cases. Radiography and ultrasonography are complementary when used together, increasing the likelihood of detection. Elevations in alkaline phosphatase, bilirubin, and GGT were the most consistent biochemistry markers in affected individuals.
Pigment choleliths accounted for all callitrichid choleliths described in the survey, which is distinct from the more commonly described cholesterol choleliths seen in other primate species.1,4 Although the etiology of callitrichid pigment cholelithiasis is currently unknown, hemolytic anemia and infections of the gallbladder have been associated with the formation of certain types of pigment choleliths in humans.2,3,8 Enterobacter sakazakii, Escherichia coli, Clostridium sp., and Proteus sp. were cultured from the bile in two cases. E. coli is often associated with human brown pigment stones.3,8
As a conclusion, cholelithiasis should be included in differential diagnosis for non-specific symptoms in aged Leontopithecus tamarins.
The authors would like to thank the callitrichid TAG, all the callitrichid EEP coordinators and all the zoological institutions that answered to this study.
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