Free-ranging avifauna as a source of generalist parasites for captive birds in zoological settings: An overview of parasite records and potential for cross-transmission

Captive birds in zoological settings often harbor parasites, but little information is available about the potential for free-ranging avifauna to act as a source of infection. This review summarizes the gastrointestinal parasites found in zoo birds globally and in seven common free-ranging avian species [mallard (Anas platyrhynchos), Eurasian blackbird (Turdus merula), common starling (Sturnus vulgaris), Eurasian jackdaw (Corvus monedula), house sparrow (Passer domesticus), European robin (Erithacus rubecula), and rock dove (Columba livia)] to identify the overlap and discuss the potential for cross-species transmission. Over 70 references were assessed, and papers spanned over 90 years from 1925 to 2019. A total of 60 studies from 1987 to 2019 met the eligibility criteria. All examined free-ranging avifauna harbored parasite species that were also reported in zoo birds, except for the European jackdaw. Parasites reported in captive and free-ranging birds include nematodes (Capillaria caudinflata, Dispharynx nasuta, Ornithostrongylus quadriradiatus, Strongyloides avium, Syngamus trachea, and Tetrameres fissispina), cestodes (Dicranotaenia coronula, Diorchis stefanskii, Fimbriaria fasciolaris, and Raillietina cesticillus, Sobolevicanthus gracilis), trematode (Echinostoma revolutum), and protozoa (Cryptosporidium baileyi). Although no study effectively proved cross-transmission either experimentally or by genetic analysis, these parasites demonstrate low host specificity and a high potential for parasite sharing. There is potential for parasite sharing whenever determinants such as host specificity, life cycle, and husbandry are favorable. More research should be carried out to describe parasites in both captive and free-ranging birds in zoological settings and the likelihood of cross-infection. Such information would contribute to evidence-based control measures, enhancing effective husbandry and preventive medicine protocols.

Caesarean delivery of a Western Lowland gorilla with fetal distress and suspected pre-eclampsia

Pre-eclampsia is a well-recognised complication of human pregnancy however case reports suggest that it also affects non-human primates. The authors present the case of a primigravid western lowland gorilla (Gorilla gorilla gorilla) who developed behavioural changes, significant proteinuria, and ultrasound features of suspected fetal distress at term, three days prior to her estimated due date. A working diagnosis of pre-eclampsia was made, and the baby was delivered by emergency caesarean section. In spite of a prolonged recovery complicated by sepsis, anaemia and persistent proteinuria in the mother, both mother and baby made a good recovery. This case highlights how the application of basic principles of obstetric medicine and collaboration between obstetricians and veterinarians in the care of captive gorillas resulted in the successful management of pregnancy complications.

Neuroaxonal Dystrophy in a Flock of Pied Imperial Pigeons (Ducula bicolor)

Five juvenile pied imperial pigeons (Ducula bicolor) presented with neurological signs including torticollis, ataxia and poor flying ability. All were humanely destroyed and submitted for post-mortem examination. Microscopically, the most significant findings were in the brain and spinal cord. Spheroid formation was evident within the medulla, pons, diencephalon, cortical grey and subcortical white matter, spinal cord white and grey matter and the granular and molecular cell layers of the cerebellum. There was no evidence of associated inflammation. Immunohistochemistry revealed positive labelling within the spheroids for S100 axons and phosphorylated neurofilaments including SMI31, neurofilament cocktail and microtubule-associated protein 2. Transmission electron microscopy confirmed the light microscopical findings of frequent axonal spheroids. These results are consistent with neuroaxonal dystrophy, which has not been described previously in pigeons. This highlights the importance of considering neuroaxonal dystrophy in juvenile birds with neurological signs. A genetic basis is suspected in this group.

Mycobacterial Arthritis and Synovitis in Painted Reed Frogs (Hyperolius marmoratus)

Several species of atypical mycobacteria have been isolated from wild and captive amphibians. In captive anurans, cutaneous and visceral mycobacteriosis are common and can result in significant mortality, particularly when animals are immunocompromised. Mycobacterial arthritis and synovitis are reported rarely in amphibians. We describe 20 cases in painted reed frogs (Hyperolius marmoratus), which presented with cachexia, limb paresis or paralysis or 'spindly leg syndrome'. Histopathology revealed multifocal histiocytic to granulomatous synovitis affecting appendicular, rib or spinal intervertebral joints. Periarticular granulomata, granulomatous cellulitis and skeletal muscle atrophy, necrosis and degeneration were also present. In one case, granulomatous spinal osteomyelitis was recorded. Ziehl-Neelsen stains showed large numbers of acid-fast bacteria in macrophages and histiocytes. The mycobacterial isolates obtained from culture were identified as members of the Mycobacterium chelonae complex (either M. chelonae or Mycobacterium abscessus). This was confirmed by 5'-16S ribosomal ribonucleic acid (rRNA) sequencing. In 17 cases mycobacterial lesions were present only in the joints and skeleton, highlighting the importance of not ruling out mycobacterial infection on the basis of absence of cutaneous or visceral lesions.

Oral Squamous Cell Carcinoma in Three Related Kowari (Dasyuroides byrnei)

We report three kowari (Dasyuroides byrnei) with squamous cell carcinoma affecting the gingiva. These cases occurred in rapid succession in a related group of individuals of similar age, suggesting a familial tendency to this condition and a typical age of presentation. Other conditions affecting the oral cavity can mimic the appearance of oral squamous cell carcinoma in this species, and so knowledge of this condition can assist the veterinarian in making rapid decisions regarding prognosis and improving the welfare of these animals.

Thoracic limb morphology of the red panda (Ailurus fulgens) evidenced by osteology and radiography

The red panda (Ailurus fulgens) is distributed primarily in the Himalayas and southern China. It is classified as a vulnerable species by the International Union for Conservation of Nature. The aim of this study was to describe the normal osteology and radiographic anatomy of the thoracic limb of the red panda. Radiography of the right thoracic limb was performed in seven captive adult red pandas. Radiographic findings were correlated with bone specimens from three adult animals. The scapula was wide craniocaudally and presented with a large area for the origin of the teres major muscle. The square-shaped major tubercle did not extend proximal to the head of the humerus. The medial epicondyle was prominent. A supracondylar foramen was present. The radial tuberosity and sesamoid bone for the abductor digiti I longus were prominent. The accessory carpal bone was directed palmarolaterally. Metacarpal bones were widely spread. The thoracic limb morphology of the red panda evidenced by osteology and radiography indicated flexibility of the thoracic limb joints and well-developed flexor and supinator muscles, which are important in arboreal quadrupedal locomotion. Knowledge gained during this study may prove useful in identifying skeletal material or remains and diagnosing musculoskeletal diseases and injuries of the thoracic limb.

Morphology of the pelvis and hind limb of the red panda (Ailurus fulgens) evidenced by gross osteology, radiography and computed tomography

The red panda (Ailurus fulgens) is a quadrupedal arboreal animal primarily distributed in the Himalayas and southern China. It is a species commonly kept in zoological collections. This study was carried out to describe the morphology of the pelvis and hind limb of the red panda evidenced by gross osteology, radiography and computed tomography as a reference for clinical use and identification of skeletons. Radiography of the pelvis and right hind limb was performed in nine and seven animals, respectively. Radiographic findings were correlated with bone specimens from three adult animals. Computed tomography of the torso and hind limb was performed in one animal. The pelvic bone had a wide ventromedial surface of the ilium. The trochlea of the femur was wide and shallow. The patella was similar to that seen in feline species. The medial fabella was not seen radiographically in any animal. The cochlea grooves of the tibia were shallow with a poorly defined intermediate ridge. The trochlea of the talus was shallow and presented with an almost flattened medial ridge. The tarsal sesamoid bone was always present. The lateral process of the base of the fifth metatarsal (MT) bone was directed laterally. The MT bones were widely spaced. The morphology of the pelvis and hind limb of the red panda indicated flexibility of the pelvis and hind limb joints as an adaptation to an arboreal quadrupedal lifestyle.

Osteology and radiographic anatomy of the pelvis and hind limb of healthy ring-tailed lemurs (Lemur catta)

In family Lemuridae, anatomical variations exist. Considering its conservation status (near threatened) and presence of similarities between strepsirrhines and primitive animals, it was thought to be beneficial to describe the gross osteology and radiographic anatomy of the pelvis and hind limb of ring-tailed lemurs (Lemur catta) as a reference for clinical use and species identification. Radiography was performed in 14 captive adult ring-tailed lemurs. The radiographic findings were correlated with bone specimens from two adult animals. Additionally, computed tomography of the hind limbs was performed in one animal. The pelvic bone has a well-developed caudal ventral iliac spine. The patella has a prominent tuberosity on the cranial surface. The first metatarsal bone and digit 1 are markedly stouter than the other metatarsal bones and digits with medial divergence from the rest of the metatarsal bones and digits. Ossicles were seen in the lateral meniscus, inter-phalangeal joint of digit 1 and in the infrapatellar fat pad. Areas of mineral opacity were seen within the external genitalia, which are believed to be the os penis and os clitoris. Variations exist in the normal osteology and radiographic appearance of the pelvis and hind limb of different animal species. The use of only atlases from domestic cats and dogs for interpretative purposes may be misleading.

Toxoplasmosis in a colony of sugar gliders (Petaurus breviceps)

Eleven of a group of 16 sugar gliders died acutely over a period of 2 to 3 weeks. Histopathologic examination revealed a protozoal infection with tachyzoites present in multiple organs, including the intestine, heart, brain, spleen, pancreas, adrenal gland, and kidney. Immunostaining confirmed disseminated toxoplasmosis. Marsupials are susceptible to toxoplasmosis. It was thought that the sugar gliders acquired the infection through foraging in wood chips used as a substrate that were contaminated with feline fecal material.