USE OF COMPUTED TOMOGRAPHY (CT) TO DETERMINE THE SENSITIVITY OF CLINICAL SIGNS AS A DIAGNOSTIC TOOL FOR RESPIRATORY DISEASE IN BORNEAN ORANGUTANS (PONGO PYGMAEUS).

Orangutans are noteworthy among great apes in their predilection for chronic, insidious, and ultimately fatal respiratory disease. Termed Orangutan Respiratory Disease Syndrome (ORDS), this cystic fibrosis-like disease is characterized by comorbid conditions of sinusitis, mastoiditis, airsacculitis, bronchiectasis, and recurrent pneumonia. The aim of this retrospective study was to determine the sensitivity of clinical signs in the diagnosis of ORDS in Bornean orangutans (Pongo pygmaeus) compared with the gold standard for diagnosis via computed tomography (CT). We retrospectively compared observed clinical signs with CT imaging in a population of clinically affected animals at an orangutan rescue center in southeastern Borneo. From August 2017 to 2019, this center housed 21 ORDS-affected animals, all of which underwent CT imaging to delineate which areas of the respiratory tract were affected. We reviewed clinical signs recorded in medical records and keeper observation notes for each individual for the period of 2 years prior to the date of the CT scan. A chi-square test of association was used to assess whether the observed clinical signs could predict the results of CT imaging. Results show that clinical signs may not be sensitive indicators in predicting respiratory disease identified by CT imaging. Based on the results of this study, clinical signs appear to be very poor predictors of underlying respiratory pathology in orangutans, based on high P-values, low sensitivity, and low specificity. This result is observed even with clinical signs data gathered over a full 24-mo period prior to CT scan performance. The findings of this study suggest the need for advanced imaging to properly diagnose and manage the most common health issue of captive orangutans.

EVALUATING THE EFFICACY OF HUMAN BRONCHIECTASISBASED ANTIBIOTIC THERAPY IN THE TREATMENT OF ORANGUTAN RESPIRATORY DISEASE SYNDROME.

Unique among apes, orangutans (Pongo spp.) develop a chronic respiratory disease called orangutan respiratory disease syndrome (ORDS). The authors define ORDS as intermittent bacterial infection and chronic inflammation of any region or combination of regions of the respiratory tract, including the sinuses, air sacs, cranial bones, airways, and lung parenchyma. Infection in any of these areas can present acutely but then becomes recurrent, chronic, progressive, and ultimately fatal. The closest model to this disease is cystic fibrosis (CF) in people. We hypothesized that use of a 4-8-wk course of combined oral antibiotics used in the treatment of bronchiectasis in CF patients would lead to prolonged symptomatic and computed tomography (CT) scan improvement in orangutans experiencing early signs of ORDS. Nine adult Bornean orangutans (Pongo pygmaeus, eight males, one female, 18-29 yr of age) diagnosed with early ORDS-like respiratory disease underwent CT scan before initiation of treatment. Each animal received a combined course of azithromycin (400 mg 3/wk, mean 7 mg/kg) and levofloxacin (500 mg PO q24h, mean 8.75 mg/kg) for a period of 4-8 wk. CT scan was repeated 6-14 mon after completion of antibiotic treatment. Pretreatment CT showed that six of nine animals had lower respiratory pathology (airway disease, pneumonia, or both). All six orangutans had concurrent sinusitis, mastoiditis, airsacculitis, or a combination of these conditions. Upper respiratory disease alone was observed in three animals. CT showed improvement or resolution in four of five sinusitis cases, improvement in one of two instances of mastoiditis, resolution in five of six instances of airsacculitis, improvement or resolution in six of six instance of lower airway disease (P = 0.03, 95% CI 0.54-1.0], and resolution in five of five cases of pneumonia. Resolution of pretreatment clinical signs was observed in all nine animals. Two developed signs not present at pretreatment. These results show that combination antibiotic therapy with azithromycin and levofloxacin provides improvement in clinical signs and CT evidence of ORDS-related pathology, resulting in symptom-free status in some animals for up to 33 mon.