Megan Curnow

A 2-year-old female spayed British Shorthair cat presented for investigation of chronic small intestinal diarrhoea, which was determined to be attributable to ionised hypercalcaemia. A cranial mediastinal mass was identified on computed tomography; median sternotomy was performed, and the mediastinal mass was excised. Histopathology, including immunohistochemistry, diagnosed the mediastinal mass as being remnant thymic tissue. Subsequent follow-up 10 months postoperatively showed restoration of normocalcaemia and concurrent resolution of gastrointestinal symptoms. To the authors' knowledge, this is the first case to report remnant thymic tissue as a cause of hypercalcaemia. This case report aims to describe the clinical presentation, computed tomography description, histopathological findings and treatment outcome of a thymic remnant causing hypercalcaemia in a cat.

The Australian livestock industry, including the beef cattle, dairy, sheep, pig and poultry industries, account for 45% of the gross value of Australian agricultural output and generated in excess of AUD$22 billion in 2015-2016 for the Australian economy.1 Farming enterprises in Australia provide direct employment for approximately 140,000 persons nationally. The livestock industry also generates significant indirect employment and economic activity through advisory and technical services, road transport, energy, veterinary and pharmaceutical products, finance and insurance, and a wide range of manufactured goods.1 Livestock disease investigations are an integral part of protecting that industry and all other livestock industries in Australia on several levels. In 2016, WA turned-off 757 000 head of cattle with just under half of these destined for live export (A$400m).2 Many of Australia’s trading partners have very strict import requirements and require evidence that any product entering their country is free of certain diseases and residues. Livestock disease investigations in Australia provide valuable data and evidence of our freedom from these diseases, keeping these export markets open to the Australian economy. Many of the diseases exotic to Western Australia, including diseases like Foot and Mouth disease (FMD) and Classical and African Swine fever (CSF and ASF), would devastate the Australian livestock industry if they were to breach our borders. Everyday livestock disease investigations are a primary method of detection of exotic disease in this country. Consequently, it’s vital that veterinarians in the field know not only how to recognise these diseases but also how to maximise the chances of an accurate and rapid diagnosis by sampling appropriately. While it’s vital to be able to rapidly and accurately diagnose or exclude the relevant exotic disease, it is also beneficial to the veterinarian, the producer and the Western Australian government to make an accurate endemic diagnosis whenever possible. This paper presents guidelines for sampling during a livestock disease investigation that maximise the chances of a reliable exotic disease exclusion and a useful endemic diagnosis with the same sample set. This paper will also provide a brief update on the status of several exotic diseases across the globe.

A one-year-old Suffolk ram was evaluated after a fourmonth history of intermittent left-sided bloating and regurgitation. The ram had been slowly losing condition while other sheep in the cohort were gaining weight. Severe megaoesophagus was confirmed on lateral thoracic and neck radiographs and a firm, 6-cm mass at the oesophageal sphincter was palpated during standing exploratory laparotomy. Postmortem examination confirmed an abscess was the cause of the partial oesophageal obstruction. The abscess yielded pure light growth of Streptococcus alactolyticus, an organism not reported to be associated with infection in sheep. Intermittent bloating is an unusual presentation in ruminants, and acquired megaoesophagus has been reported only very occasionally in sheep. This case report expands the list of differential diagnoses for abnormal regurgitation and intermittent bloating, and provides another specific cause of obstructive gastrointestinal disease in sheep. Acquired megaoesophagus was an unusual sequela of this primary disease.