Surgical repair of a meningoencephalocoele in a kākāpō (Strigops habroptilus)

CASE HISTORY

A kākāpō (Strigops habroptilus) chick hatched on an off-shore island of New Zealand with a small white mass protruding through the cranial skin of the head. The chick's growth followed a normal pattern for kākāpō but at 3 weeks of age the cranium mass was non-reducible and fixed in place and the chick was removed from the island for diagnostic imaging and hand-rearing.

CLINICAL FINDINGS AND TREATMENT

A computed tomography (CT) examination revealed a full-thickness circular defect in the central cranium with suspected herniation of brain and dura. Surgery was performed at 37 days of age, and the herniated dura was dissected from the open fontanelle. Attempts to reduce the herniated tissue were unsuccessful, so the herniated dura and cortex were clamped and resected. The dura was closed and the periosteum of the skull was scarified and monofilament polypropylene mesh was secured tautly over the fontanelle. The mesh graft was infused with autologous bone marrow harvested from the ulna in an attempt to stimulate osteogenesis in the mesh repair. The skin flap was then closed. Post-operative recovery and healing were without complication. A CT examination 4 weeks after surgery showed no recurrence of the hernia, and a composite of mesh and scar over the open fontanelle which had reduced in diameter. The chick was released back onto an off-shore island with a radio transmitter and it continues to be monitored regularly.

PATHOLOGICAL FINDINGS

The tissue resected at surgery consisted of a cylindrical core of cerebral parenchyma overlain by a mildly hyperplastic epidermis, and large amounts of oedematous fibrovascular tissue arising from the leptomeninges.

DIAGNOSIS

Rostral parietal meningoencephalocoele.

CLINICAL RELEVANCE

This is the first report of successful surgical resolution of a meningoencephalocoele in any bird. Techniques from human neurosurgery were adapted for the unique anatomical features of the avian skull. The risks of the procedure included increased intra-cranial pressure resulting in anaesthetic complications or death, cerebrospinal fluid leakage, meningitis or recurrence of the meningoencephalocoele. In the longer term, there was a risk of developmental deficits in cognition or behaviour. None of these complications eventuated in the short to medium term, probably due to the small size of the meningoencephalocoele.

Causes of adult mortality in two populations of New Zealand sea lions (Phocarctos hookeri)

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Infectious disease, including tuberculosis, was the most common cause of death.

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Anthropogenic trauma caused 26% of deaths in mainland sea lions.

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Trauma inflicted by adult male conspecifics caused 24% of deaths.

The New Zealand sea lion is an endangered species endemic to New Zealand. While causes of death are well described for pups of this species, mortality in adults is poorly characterised. This study investigated causes of death in 136 New Zealand sea lions in two different populations: a major breeding site on remote, uninhabited Enderby Island in the sub-Antarctic, and a slowly increasing recolonising population on the inhabited mainland. For animals with at least a partial diagnostic investigation (n = 112), the most frequently diagnosed causes of mortality were infectious disease (41/112; 37%), particularly tuberculosis due to M. pinnipedii (20/112; 18%), and conspecific trauma (27/112; 24%). Anthropogenic trauma was an important cause of death in mainland sea lions (9/33; 26%). Deliberate anthropogenic mortality has previously been identified as the greatest potential threat to population recovery for mainland sea lions, and as human and pinniped populations increase, managing interactions between these species will become increasingly important.

Cases of mortality in little penguins (Eudyptula minor) in New Zealand associated with avian malaria

CASE HISTORY A little penguin (Eudyptula minor) of wild origin, in captivity at Wellington Zoo, became inappetent and lethargic in March 2013. Despite supportive care in the zoo's wildlife hospital, the bird died within 24 hours. CLINICAL FINDINGS Weight loss, dehydration, pale mucous membranes, weakness, increased respiratory effort and biliverdinuria were apparent on physical examination. Microscopic evaluation of blood smears revealed intra-erythrocytic stages of Plasmodium spp. and a regenerative reticulocytosis in the absence of anaemia. PATHOLOGICAL FINDINGS Post-mortem findings included reduced body condition, dehydration, pulmonary congestion and oedema, hepatomegaly, splenomegaly, hydropericardium and subcutaneous oedema. Histopathological findings included protozoal organisms in sections of lung, liver and spleen. A marked, diffuse, sub-acute interstitial histiocytic pneumonia was present. Accumulation of haemosiderin was noted in the Kupffer cells of the liver and in histiocytic-type cells in the spleen. MOLECULAR TESTING DNA was extracted from frozen portions of the liver. Nested PCR results and DNA sequencing confirmed infection of the deceased little penguin with Plasmodium (Huffia) elongatum lineage GRW06. DIAGNOSIS Avian malaria due to Plasmodium (Huffia) elongatum GRW06 RETROSPECTIVE INVESTIGATION A retrospective analysis of 294 little penguin cases in the Massey University post-mortem database revealed three other potential avian malaria cases. Analysis of archived tissues using a nested PCR for Plasmodium spp. followed by DNA sequencing revealed that a little penguin which died at Auckland Zoo was infected with P. elongatum GRW06 and two wild little penguins found dead on New Zealand beaches were infected with P. relictum SGS1 and Plasmodium. sp. lineage LINN1. Therefore, the overall frequency of deaths in little penguins associated with avian malaria was 4/295 (1.36%). CLINICAL RELEVANCE Our results suggest that avian malaria is associated with sporadic mortality in New Zealand's little penguins both in the wild and in captivity, but there is no evidence of mass mortality events due to Plasmodium spp. infection.

Ventral dermatitis in rowi (Apteryx rowi) due to cutaneous larval migrans

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Rowi on a crèche island showed loss of feathers and dermatitis.

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We identified cutaneous larval migrans, possibly due to Trichostrongylus.

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This is the first instance of cutaneous larval migrans to be recorded in birds.

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Fatal complications resulted in the death of eight birds from aspergillosis.

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Intensive conservation management can result in pathways for novel infections.

The rowi is a critically endangered species of kiwi. Young birds on a crèche island showed loss of feathers from the ventral abdomen and a scurfy dermatitis of the abdominal skin and vent margin. Histology of skin biopsies identified cutaneous larval migrans, which was shown by molecular sequencing to be possibly from a species of Trichostrongylus as a cause of ventral dermatitis and occasional ulcerative vent dermatitis. The predisposing factors that led to this disease are suspected to be the novel exposure of the rowi to parasites from seabirds or marine mammals due to the island crèche and the limited management of roost boxes. This is the first instance of cutaneous larval migrans to be recorded in birds. Severe and fatal complications of the investigation resulted in the death of eight birds of aspergillosis and pulmonary complications associated with the use of bark as a substrate in hospital. Another bird died of renal failure during the period of hospitalisation despite oral and intravenous fluid therapy. The initiating cause of the renal failure was not determined. These complications have the potential to undermine the working relationship between wildlife veterinarians and conservation managers. This case highlights that intensive conservation management can result in increased opportunities for novel routes of cross-species pathogen transmission.