Although reproductive and adrenal endocrine patterns of the male giant panda (Ailuropoda melanoleuca) have been established, the metabolic changes that facilitate these activities are unknown.1 Because thyroid hormones (triiodothyronine [T3]; thyroxine [T4]) regulate metabolism and reproduction,4 understanding their activity in the giant panda would benefit species care and management. Additionally, a hypothyroid-like condition in nearly 15% of the captive population drives a need to understand thyroid activity in giant pandas.2 By utilizing a novel non-invasive approach, we sought to create a normative database of seasonal T3 and T4 in the male giant panda. Fresh fecal samples (∼2000) were collected for 1 yr (three samples/wk) from eight male giant pandas (age 4–21 yr) at the Chengdu Breeding Base of the Giant Panda. Feces were freeze-dried, crushed, and frozen prior to storage.3 Thyroid hormone metabolites were extracted in 70% ethyl alcohol (10 ml) and double-antibody enzyme immunoassay was used to quantify the T3 and T4 metabolites (L. Graham, University of Guelph).5 Excreted T3 and T4 were greatest (p<0.05) in the pre-breeding period (October 1–January 31), declined as the breeding season progressed (February 1–May 31), and increased again in the non-breeding period (June 1–September 30). These are the first thyroid hormone data on the male giant panda and most interestingly conform to the seasonal reproductive cycle of the species. These data lay a contextual foundation for veterinarians and animal care managers to appreciate thyroid hormone levels in clinical presentation and normal physiology.
The authors thank Allison Rowland, Kristina Ridge, and the staff at the Chengdu Research Base of Giant Panda Breeding, specifically, Hou Rong, Luo Li, Wang Chengdong and Zhang Zhihe. Project funding was provided by Zoo Atlanta and student funding was provided by Merial Veterinary Scholars Program.
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