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Wildlife

CSI North Yorkshire

17 Dec, 15 | by gmills

By Tim Hopkins

Raptor persecution is an emotive issue in Britain. In an attempt to increase the population of gamebirds, some unscrupulous gamekeepers (sometimes directed by managers and employers) continue to illegally kill raptors. For conservationists and welfare groups, the shooting, trapping and poisoning of these wild birds represents the worst of the gamebird industry. Aside from the welfare concerns (for both game and raptor) and the disease risks from the release of many millions of captive birds annually, persecution continues to have a significant conservation impact on a number of species, in particular the hen harrier (Circus cyaneus) and golden eagle (Aquila chrysaetos). Historically, some British species were pushed to extinction due to such pressure, although all have since returned to breeding. Parts of the gamebird industry continue to dispute the scale and impact of raptor persecution and believe that the conservationists and welfare bodies are attempting to piecemeal outlaw their traditional hunting sport. For any given incident, the reliability and transparency of a postmortem investigation is paramount.

Veterinary pathologists, police and NGOs are hindered in confirming shooting by decomposition, scavenging and concealment of the carcase by the perpetrator. Furthermore, the identification of ballistic objects within a carcase is rarely enough to prove cause of death – it is often an incidental finding. An article published recently in Veterinary Record Case Reports details a confirmed shooting in an otherwise ambiguous postmortem examination of a hen harrier using advanced imaging techniques.

The bird was fitted with a tracking device as part of Natural England’s Hen Harrier Recovery Project, which enabled its recovery after death. Despite the advanced state of decomposition, a postmortem examination was performed at the Zoological Society of London’s Institute of Zoology. The bird had a broken tibiotarsus, which was radiographed, and minute metallic radio-opacities noted. Without an obvious gross ballistic remnant, the authors needed a diagnostic tool that would determine the composition of the foreign object and its effect on the surrounding tissue. Several modalities were considered but ultimately rejected as they failed to preserve both the foreign body and the microscopic structure of the bone. Histology, for instance, would have provided accurate descriptions of the bony trauma but no information about the chemistry of the object. Conversely, many spectroscopic techniques would have provided accurate descriptions of the metallic object atomic makeup but destroyed the surrounding bone in the process. Scanning Electron Microscopy with x-ray Dispersive Spectroscopy (SEM-EDX) was the only tool that fitted the bill.

 

Fig 1: Plain craniocaudal radiograph of the left tibiotarsus and tarsometatarsus showing three radiodense objects (white and black arrowheads)

Fig 1: Plain craniocaudal radiograph of the left tibiotarsus and tarsometatarsus showing three radiodense objects (white and black arrowheads)

 

SEM-EDX was carried out at the University College London’s Institute of Orthopaedic and Musculoskeletal Science. With great care, the bone was prepared for imaging, which included a thin coat of gold palladium to reduce scatter during scanning. The images were spectacular and conclusive. The fragment had tunnelled into the cortex of the tibiotarsus, fracturing the bone and trabeculae. On its way, it had disintegrated. The fragment was predominantly lead on EDX. The lack of any significant bone resorption or remodelling suggested this injury had resulted in rapid death. Case closed.

That was until we noticed that there were minute amounts of niobium on the spectrum. Niobium is not used in ammunition or firearms manufacture, so where had it come from? The explanation took several months. EDX, like any diagnostic tool, is subject to artefacts, operator error and sensitivity and specificity constraints. After consulting with the University of Bristol’s Department of Earth Sciences, the authors ran the scan data through third party software – DTSA II (Desktop Spectrum Analyser, National Institute for Standards and Technology). DTSA was able to discriminate the spectral peaks and showed that the aforementioned niobium was a misread of the peaks caused by the gold palladium coating. Additionally, it revealed the presence of arsenic and antimony, common additives in lead ammunition manufacture.

This case demonstrates the application of a novel forensic modality to the veterinary field. SEM-EDX has also been used in human forensic science to demonstrate gun shot residue (GSR) – microscopic remnants of the ammunition primer and propellant – on victims, shooters and firearms. This information often forms a vital piece of the investigative puzzle. In the future, it may be possible to determine that an animal was shot by a particular firearm or person by matching the GSR EDX data.

Novel modalities are increasingly important for NGOs and police seeking to stamp out illegal persecution. Confirmation of shooting in such ambiguous cases may increase pressure on the game industry to reform its practices. The imminent use of GSR EDX to match individuals with shooting incidents may be enough to dissuade gamekeepers too.

More details about this case can be found here

 

 

 

Wombat fatigue: marsupial regains mobility after pioneering surgery

20 Feb, 15 | by Assistant Editor

 

If you are ever faced with a juvenile hairy-nosed wombat with a limp, the recently published case report by Gail Anderson and colleagues (published in Veterinary Record Case Reports and found here) should contain a salutary lesson.

The authors were presented with a male juvenile hand-raised southern hairy-nosed wombat, which weighed 7.5 kg and was approximately 13 months old. He had been rescued from his dead mother’s pouch about seven months earlier and raised by a carer using southern hairy-nosed wombat milk replacer (yes – it does exist!). His carer had noted he was reluctant to walk and this lameness became progressively worse.

 

Haarnasenwombat_(Lasiorhinus_krefftii)

A southern hairy-nosed wombat. Photo: Eva Hejda

 

Clinical observation showed that he was reluctant to move and, when encouraged to do so, he had severe lameness in both hindlimbs and a ‘shuffling’ gait. The wombat was placed under general anaesthesia and palpation of the stifles elicited crepitus on both sides but no obvious joint effusion. It was not possible to fully extend the stifles. No other abnormalities were found on clinical examination. Stifle radiographs revealed displacement of the distal femoral metaphyses due to bilateral type 1 Salter-Harris epiphyseal fractures.

Distal femoral metaphyses have a mottled, radiolucent, appearance. Proximal femoral epiphyses were flattened and showed delayed development consistent with epiphyseal dysplasia. The right proximal femoral epiphysis was slightly more irregular and flattened compared with the left proximal femoral epiphysis. The lower lumbar spine was normal according to radiographs.

 

F1.large

The left (top) and right (bottom) stifle joints of the wombat before surgery.

 

 

Radiographs of a normal southern hairy-nosed wombat of the same age were not available for comparison and, to the author’s knowledge, are not available in the literature. This situation is a common problem for veterinarians treating lesser-studied wildlife species.

After discussion with his carer, he was scheduled for surgery to attempt to reduce the epiphyseal fractures. If left untreated, it was unlikely that he would have regained normal mobility and function. The wombat was, however, given a guarded prognosis, partly because the injury appeared to be chronic and other radiographic changes had been observed.

Induction of anaesthesia was somewhat problematic as endotracheal intubation was difficult, probably due to the relatively small diameter of a wombat’s trachea and excessive mucus production.

The surgical procedure was similar to that commonly used for the repair of comparable fractures in dogs. Using a small osteotome and mallet, the cartilaginous and bony epiphyseal piece was elevated and freed from its caudally displaced position and gently levered back into a position more cranially. Once reduced, the epiphyseal piece was secured with two 1.5 mm diameter Kirschner wires.

 

F5.large

Radiograph of the right stifle following surgery. The white cross shows the K-wires used to immobilise the fracture. The left side looked the same as this after surgery.

 

The wombat recovered quickly and uneventfully from general anaesthesia and was given postoperative analgesia. Once he was moving freely and starting to hide in its custom-made pouch (a fleece-lined pillowcase), he was left in a quiet, dimly lit cage and closely supervised.

The wombat was discharged to his carer once he was moving normally in his pouch, with instructions to restrict his activity for two weeks. He continued to eat well, although he showed initial discomfort and limited mobility. However, he continued to improve and by four months after surgery, he was walking with good extension of his hindlimbs and normal action. His carer felt that he had made a complete recovery.

A video of the wombat four months after surgery showing excellent recovery and mobility can be viewed here: www.youtube.com/watch?v=HqstN5sS8Hg.

Similar hindlimb injuries in pouch young have been frequently observed by vets working in Australia. It is thought that forcible removal of a juvenile wombat from its dead mother’s pouch is the usual cause. However, this report, adding as it does to the limited resources available for this species, shows that excellent outcomes can be achieved following this type of injury in wombats.

More details, images and discussion about this case can be found at Veterinary Record Case Reportshttp://vetrecordcasereports.bmj.com/content/3/1/e000099.abstract

 

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