AORTIC ANEURYSM, DISSECTION, AND RUPTURE IN SIX BILE-FARMED BEARS

Comparative thoracic radiography in healthy and tuberculosis-positive sun bears (Helarctos malayanus)

Early and accurate diagnosis of pulmonary tuberculosis (TB) is key to effective outbreak management, and in humans thoracic radiography is used extensively for screening purposes. In wildlife TB radiography is a relatively accessible diagnostic tool, particularly in under-resourced settings, however its use is limited by body size. Sun bears are susceptible to human-associated TB, and their small body size makes thoracic radiography feasible. However, there are no established guidelines on normal thoracic radiographs or radiographic manifestations of TB in this species. We provide a first description of thoracic radiographs from healthy and TB affected sun bears at a bear rescue sanctuary, including correlation with postmortem results for a subset of bears. Findings of two veterinary radiologists, blinded to clinical information, revealed high agreement on broad categorization of radiographic studies as normal, abnormal, or needing correlation with further information. Agreement was lower for the presence of specific lung patterns, reflecting inherent subjectivity when classifying these features. Very few studies were identified as definitively normal, however definitively abnormal studies were significantly associated with TB cases. Diffuse bronchial and/or bronchointerstitital lung patterns were commonly reported, with a high proportion needing correlation with age and/or clinical signs to further interpret. Interstitial, interstitial-to-alveolar, alveolar and nodular lung patterns, along with radiographic signs of lymphadenomegaly and pleural fluid, were almost exclusively found in TB cases, however the sensitivity of the presence of any of these changes for detecting TB was below 70%. Radiographic reporting of thoracic lymph node enlargement detected at postmortem was low (4/17; 23%), and aortic outflow tract dilation and positional atelectasis were differential diagnoses for radiographic changes that could also represent TB. Together these findings demonstrate the importance of developing species-specific criteria for interpretation, to differentiate between common findings and manifestations of TB, and to highlight areas where radiographic techniques can be optimized to assist this. Given TB remains a global health challenge in humans and other animals (wild or domestic), and detection is key to control, we recommend development of standardized approaches to radiographic studies and their interpretation to bolster diagnostic pathways for detecting TB in sun bears, and other novel or understudied hosts.

Sudden death due to aortic rupture in New Zealand sheep

CASE HISTORY

Over a period of 2 months in the spring and early summer of 2021, 13 cases of sudden death in cull ewes due to aortic rupture were diagnosed at a small number of New Zealand abattoirs.

CLINICAL FINDINGS

In 12/13 (92%) cases, a large blood clot was present in the thorax, and in one case the blood clot was seen in the tissues dorsal to the heart. There were no obvious signs of external trauma. The pluck (heart and lungs) or fixed aorta was submitted for histological examination in seven cases and in all of these, a tear in the aorta was found. Comparing the microscopic appearance of the proximal aorta in these seven cases to three clinically normal ewes from unaffected farms, the aortic wall thickness appeared thinner in the case ewes than the unaffected ewes. Subjectively, there was increased collagen in the tunica media in 3/7 and decreased elastin fibres in 5/7 case ewes compared to the control ewes. Further investigations on the index farm (where the first cases originated), found that the mean liver and serum Cu concentrations in 10 similarly aged, clinically normal ewes were within the normal reference range for New Zealand sheep. Similarly, the liver Cu concentrations of the seven case ewes were within the normal reference range.

DIAGNOSIS

Aortic rupture due to an unknown aetiology.

CLINICAL RELEVANCE

Clinicians should be aware of this condition as a differential diagnosis for sudden death in older sheep and to assist the Ministry for Primary Industries in establishing the extent of this problem in New Zealand.

Modification of Domestic Animal Lameness Scales for Use in Asiatic Black Bears (Ursus thibetanus)

Lameness in animals is a welfare concern as it can be an indicator of pain. A standardized bear lameness scale would significantly improve the ability of facilities that house bears to monitor, manage, and treat lameness in their animals. The Animals Asia bear rescue center in Vietnam holds over 180 rescued bears with varying health and mobility conditions as a result of the illegal bear bile trade, and a reliable lameness assessment system was needed. Bear locomotion includes a lumbering gait, which differs from domestic animal locomotion, necessitating the modification of domestic animal lameness scales, and a five-point lameness scale was developed. Professionals from various veterinary-related backgrounds scored bear lameness videos to assess interobserver reliability and the intraclass correlation coefficient indicated good to excellent reliability. A 15-min training video with examples of lameness and grades was provided before assessment. The lameness scale developed herein addresses the lack of a published lameness scale for bears, and, due to the similar locomotion of the genus, can be used on any bear species. This scale is a consistent and reliable tool for evaluating and documenting lameness in addition to monitoring response to treatment. It will benefit bear welfare by indirectly characterizing the level of pain a bear is experiencing due to lameness as well as serving to document trends in pain status.

Formerly bile-farmed bears as a model of accelerated ageing

Bear bile-farming is common in East and Southeast Asia and this farming practice often results in irreversible health outcomes for the animals. We studied long-term effects of chronic bacterial and sterile hepatobiliary inflammation in 42 Asiatic black bears (Ursus thibetanus) rescued from Vietnamese bile farms. The bears were examined under anesthesia at least twice as part of essential medical interventions. All bears were diagnosed with chronic low-grade sterile or bacterial hepatobiliary inflammation along with pathologies from other systems. Our main finding was that the chronic low-grade inflammatory environment associated with bile extraction in conjunction with the suboptimal living conditions on the farms promoted and accelerated the development of age-related pathologies such as chronic kidney disease, obese sarcopenia, cardiovascular remodeling, and degenerative joint disease. Through a biomimetic approach, we identified similarities with inflammation related to premature aging in humans and found significant deviations from the healthy ursid phenotype. The pathological parallels with inflammageing and immuno-senescence induced conditions in humans suggest that bile-farmed bears may serve as animal models to investigate pathophysiology and deleterious effects of lifestyle-related diseases.

New insights into dietary management of polar bears (Ursus maritimus) and brown bears (U. arctos)

Although polar bears (Ursus maritimus) and brown bears (U. arctos) have been exhibited in zoological gardens for centuries, little is known about their nutritional needs. Multiple recent studies on both wild and captive polar bears and brown bears have found that they voluntarily select dietary macronutrient proportions resulting in much lower dietary protein and higher fat or digestible carbohydrate concentrations than are currently fed in most zoos. These lower protein concentrations selected by both species maximized growth rates and efficiencies of energy utilization in brown bears and may play a role in reducing kidney, liver, and cardiovascular diseases in both species. Therefore, we propose the need for the development of new dietary regimens for both species in managed care that better reflect their macronutrient needs. We developed a new kibble that is higher in fat and lower in protein than typical diets that have been fed in managed care, has a fatty acid profile more consistent with wild bear diets, and has been readily consumed by both brown bears and polar bears. The kibble can be fed as the sole diet or as part of more complex diets with additional fruits, meats, or vegetables. Because many nutritional deficiencies and related diseases can take months or years to appear, we urge caution and continued long-term monitoring of bears and their diets to ensure their optimal health.

Metabolic derangements and reduced survival of bile-extracted Asiatic black bears (Ursus thibetanus)

Background

Across China and Southeast Asia, an estimated 17,000 bears are currently farmed for bile, primarily for traditional medicines. Depending on country, bile is extracted daily via transabdominal gallbladder fistulas, indwelling catheters, or needle aspiration. Despite claims that bears do not develop adverse effects from bile extraction, health issues identified in bears removed from bile farms include bile-extraction site infections, abdominal hernias, peritonitis, cholecystitis, hepatic neoplasia, cardiac disease, skeletal abnormalities, and abnormal behaviors. We present a comprehensive assessment of the effects of bile farming by comparing serum biochemical and hematological values of bears from farms that were bile-extracted (BE) and bears from farms not bile-extracted (FNE) with bears from non-farm captive (ZOO) and free-range (FR) environments. We hypothesized BE bears would have significant laboratory abnormalities compared to all non-extracted bear groups. We also hypothesized BE bears would have reduced long-term survival compared to FNE bears despite removal from farms.

Results

BE bears exhibited the highest values and greatest variation (on a population level) in laboratory parameters compared to all non-extracted bear groups particularly for alanine transaminase, gamma glutamyltransferase (GGT), total bilirubin (TBIL), alkaline phosphatase (ALKP), blood urea nitrogen, creatinine (CREA), and total white blood cell count. Significant differences were detected between bear groups when accounting for season, sex, and/or age. BE bears exhibited greater mean serum GGT compared to all non-extracted bear groups, and the odds of having elevated TBIL were 7.3 times greater for BE bears, consistent with hepatobiliary disease. Biochemical parameter elevations in BE bears persisted up to 14 years post-rescue, consistent with long-term effects of bile-extraction. BE bears that arrived with elevated CREA and ALKP had median survival times of 1 and 4 years respectively, and regardless of laboratory abnormalities, BE bears had significantly shorter survival times compared to FNE bears.

Conclusions

Our results provide strong evidence that bile extraction practices not only represent a temporary constraint for bears’ welfare, but confer distinct long-term adverse health consequences. Routine laboratory panels may be insensitive to detect the extent of underlying illness in BE bears as these bears have significantly reduced survival regardless of biochemical assessment compared to FNE bears.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-2006-6) contains supplementary material, which is available to authorized users.