High neonatal mortality among red pandas (Ailurus fulgens) challenges the long-term sustainability of the SSP population.2,3,5 The majority of neonatal deaths are due to pneumonia and trauma; however, cause of death is unknown in 25% of cases.2 Congenital hypothyroidism is a rare condition in domestic animals, typically due to an inherited genetic defect.1,4 Non-goiterous congenital hypothyroidism was presumptively diagnosed in red panda neonates from three successive litters, with identical parentage. The index case was a 5-month-old cub with hypoplastic thyroids and cretin dwarf appearance on necropsy. The following two litters were each composed of a pair of cubs. A cub died in litter one at 3 weeks, and litter two at 3 days; both had hypoplastic thyroids, although cause of death was unrelated. The two surviving cubs (one from each litter) were diagnosed with suspected hypothyroidism at 12 and 9 weeks due to failure to grow, elevated TSH, and low total T4, free T4, and total T3. The cubs were treated with levothyroxine (0.022 mg/kg PO, BID until 6 months of age and then changed to SID). The more severely affected cub was hand-reared and had pronounced delays in development: ataxia, bladder atony, gastrointestinal ileus, and cretin appearance. Both cases had excellent response to treatment and matured to normal adult size and appearance. These cases demonstrate the importance of collecting thyroid tissue (or proximal trachea/larynx if gross visualization is not possible) in neonates for histopathology. Further investigation into the role of thyroid disease in neonatal red panda mortality is warranted.
The authors thank the staff at Binder Park Zoo for their dedication in caring for these animals.
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