Reference values for serum chemistry of wild Amazon river dolphins (Inia geoffrensis) from the central Amazon

Blood values of wild cetacean population are a valuable tool to drive proper management of threatened species. Reference intervals of 26 serum analytes were determined from 107 apparently healthy Amazon river dolphins (Inia geoffrensis) wild-caught in the Mamiraua Sustainable Development Reserve (3 degrees 3 ' S, 64 degrees 51 ' W), central Amazon, Brazil. No differences were detected between males and females or between pregnant and nonpregnant females. Calves had higher serum calcium than juveniles and adults, and alkaline phosphatase activity was higher in calves and juveniles than adults as a result of bone growth. Adults showed higher creatinine levels than juveniles due to higher body mass, and higher urea than calves. Positive correlation was found between body length and body weight with creatinine, urea, and alanine aminotransferase activity; whereas calcium and alkaline phosphatase and creatine kinase (CK) activities negatively correlated with these body parameters. Cardiac rate and respiratory frequency appear to have not correlated with any serum analyte, while stress level positively correlated with CK. Storage of frozen samples for 60 days at -80 degrees C significantly altered 10 of the 19 analytes after one freeze-thaw cycle. Important differences were detected among age classes, stress level, and sample storage and should be taken into account before any clinical or physiological interpretations.

Automated summary

Blood values of wild Amazon river dolphins varied among different age groups, with serum calcium related to bone growth, and levels of creatinine and urea increasing with body weight. Prolonged storage of frozen samples may alter certain analytes, emphasizing the need to consider age classes, stress levels, and sample storage conditions in clinical or physiological interpretations.