Gastrointestinal torsions and intussusception in northern koalas (Phascolarctos cinereus) at San Diego Zoo (1976-2012).

The recent classification as threatened status of the northern koala (Phascolarctos cinereus) by the Australian Government highlights the importance of the conservation and health management of this iconic Australian marsupial. This case series describes gastrointestinal torsion and intussusception in six northern koalas (three males, three females, 2-11 yr old) at the San Diego Zoo from 1976 to 2012. Two koalas died shortly after presentation. Diagnoses of ileocecal intussusception, resulting from enteritis in one case and cecal torsion in the other, were made at postmortem examination. One koala died 4 days after an exploratory laparotomy, with negative findings, and an acute double colonic intussusception was diagnosed at postmortem examination. Two small intestinal mesenteric torsion and one proximal colon mesenteric torsion cases were successfully corrected surgically. In the case of colonic mesenteric torsion, the koala had recurrent clinical signs 2 wk later, and a second surgery requiring resection and anastomosis of ischemic jejunum was performed, with the koala dying shortly afterward. One koala with small intestinal torsion had a recurrence of torsion 22 mo later and subsequently died. The koala with the second case of small intestinal torsion remains alive 14 mo postsurgical correction. All six koalas presented with signs of colic that included anorexia, lethargy, depression, acute abdominal distension, abdominal stretching, decreased fecal output, open-mouth gasping, or a combination of symptoms. Abdominal radiographs may show stacked gastrointestinal linear gas patterns and contrast stasis. Prevalence of torsion and intussusception is low at this institution (2%), although recurrence in individuals is common (50%) and overall survival is poor (83%), which emphasizes the importance of timely recognition, surgical correction, and postoperative management. While inciting etiologies were unable to be determined in these cases, monitoring generalized gastrointestinal health and differing Eucalyptus sp. effects on individual koala's gastrointestinal function, parasite control, and stress minimization through standardized husbandry practices are likely important.

Dietary specialization and Eucalyptus species preferences in Queensland koalas (Phascolarctos cinereus).

Koalas specialize on Eucalyptus leaves, but also feed selectively. Food choice is not random, but depends on various factors that are not well understood, although most research has focused on the role of secondary plant compounds. We studied the feeding choices of four adult male koalas housed at the San Diego Zoo. All subjects had a choice of nine types of Eucalyptus leaves over the eight-week study. The most preferred species was E. camuldulensis, but individual males exhibited different feeding preferences. We conclude that food selectivity among koalas is probably due to multiple factors, rather than only a consequence of secondary plant chemicals. A combination of intrinsic factors, such as developmental trajectory and reproductive state, as well as extrinsic factors, such as leaf chemical fingerprint and moisture, probably interact to shape koala foraging preferences. Koalas forage almost exclusively on Eucalyptus species, but have evolved an adaptive flexibility, enabling them to exploit various Eucalyptus species.

Evaluating the utility of an accelerometer and urinary hormone analysis as indicators of estrus in a Zoo-housed koala (Phascolarctos cinereus).

Induced ovulators, such as the koala, do not always have overt signs of estrus, which makes pairing these animals for breeding purposes difficult to achieve in a zoo setting. This study examined the possibility of using alternative methods to behavioral sampling and weight fluctuations for monitoring estrus in a female koala of reproductive age. We attempt to gain an improved understanding of koala estrus and enhance our ability to detect it by combining a noninvasive technique for hormone analysis with a newer method for recording activity level. The findings suggest that activity levels were accurately measured using an accelerometer and increased activity was associated with one estrus behavior, bellowing. Weekly weight declines occur with increases in activity registered from the accelerometer. We also validated an assay to detect progesterone and estradiol in female koala urine in an attempt to detect an estrus spike. However, neither urinary concentrations of estradiol nor progesterone was associated with behavioral cues of estrus in our subject. We suggest that increased female activity, bellowing, and weight loss all indicate a pro-estrus state that requires proper male stimulation in order to achieve a full estrus display.