Trans-Coelomic Ultrasound for Reproductive Monitoring in a Female Fijian Banded Iguana (Brachylophus bulabula)
The Fijian banded iguana (Brachylophus bulabula) is a highly arboreal, endangered iguana that is rarely encountered in the wild. Yolk coelomitis is an important cause of death in captive female iguanas, though much about this disease physiology remains poorly understood. Affected iguanas often present with non-specific or no clinical signs of illness, and plasma biochemistry results are difficult to distinguish from those of normally gravid females.
The Houston Zoo houses 2.1 iguanas, with one pair and one single male housed separately. The female iguana has been monitored closely via monthly trans-coelomic ultrasounds from 3 to 7 years of age (June 2008 to May 2012). Ultrasounds are performed under manual restraint in a warm water bath, using a Sonosite 180 Vet Plus ultrasound machine and 10–5 MHz linear transducer. The iguana laid one clutch before ultrasounds began in 2007, and laid 5 more clutches between June 2010 and May 2012. Despite being in a breeding situation, none of the clutches have produced fertile eggs. Monthly average follicular diameters ranged from 0 cm (no structures seen) to over 4 cm when ova are mature, just before oviposition. Ten blood samples taken over the 4-year time period show intermittent marked elevations in total WBC and in plasma levels of calcium, phosphorus and protein, with the lowest values occurring shortly after eggs are laid. Routine, non-invasive monitoring of the Fiji iguana has helped to establish expected cycling patterns and has the potential to predict when ovostasis and possibly yolk coelomitis are likely to develop.