Potential Factors Related to Neonatal Mortality and Failure to Thrive in a Herd of Thomson’s Gazelles (Eudorcas thomsonii) Over a 12-Year Period
Neonatal mortality and failure to thrive in Thomson’s gazelles are common problems in AZA institutions with an average AZA population neonatal mortality rate of 36–38% over the last 20 years. To determine potential causes of this problem risk factors were assessed for one institution over a 12-year period. A total of 111 neonates were classified as normal [64% (n=71); survived with no hand rearing] or abnormal [36% (n=40); required hand rearing (n=10)] or died within 6 days of birth (n=30). Risk factors examined included: PCV, total solids, GGT, glutaraldehyde, birth weight, age at first handling, sex, sire, dam, handling, vaccination, venipuncture, rainfall, and mean low environmental temperature.
The most common cause of death was failure to nurse (n=23). A significant difference (p<0.05) was found between groups for: glucose, GGT, weight, rainfall, glutaraldehyde, and GGT grouping. A binary logistic regression analysis of the significant parameters revealed blood glucose to be a significant indicator for survival among all the neonates (p<0.05).
This study found no evidence of significant effects of human contact (handling, venipuncture, vaccination, or age at first handling), environmental temperature, or neonate sex or parentage on survival. Low birth weight and indicators of failure of passive transfer were associated with decreased survival rates. The correlation of rainfall and decreased survival could indicate a need for early intervention or heightened vigilance following rainy nights, and assessment of shelter availability and herd use.
The authors thank the Wildlife Conservation Society (WCS) animal care personnel who care for the Thomson’s gazelles, along with the veterinarians, veterinary technicians, laboratory staff, and pathology staff. A special thank you to Dr. Bonnie Raphael (WCS) for her encouragement during this project, Tracy Clegg from the University College Dublin for her assistance with statistical analysis, and Kevin Browne from the James San Jacinto Mountains Reserve for his assistance with procuring environmental data.