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A 6-year-old unilateral cryptorchid dog presented with episcleral haemorrhage and ecchymosis. The complete blood count was consistent with pancytopaenia. Abdominal imaging confirmed the presence of a caudal abdominal mass suspected to be a Sertoli cell tumour (SCT) with associated myelotoxicity. The presence of myelotoxicity induced thrombocytopaenia and the delay in obtaining serum oestradiol results could make it challenging to confirm hyperoestrogenism in suspected SCTs without overt feminisation. Preputial cytology was used as a rapid and simple way to diagnose hyperoestrogenism in a dog without overt signs of feminisation and where the risk of significant haemorrhage precluded abdominal mass sampling. This technique could potentially detect hyperoestrogenism before clinical signs of feminisation and can readily be carried out in first opinion practice. A postmortem examination following sudden deterioration confirmed the presence of an SCT in the retained testicle and intracranial haemorrhage secondary to thrombocytopaenia.

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Background:Tissue microarrays (TMAs), where each block (and thus section) contains multiple tissue cores from multiple blocks potentially allow more efficient use of tissue, reagents and time in neuropathology. New Method:The relationship between data from TMA cores and whole sections was investigated using 'virtual' TMA cores. This involved quantitative assessments of microglial pathology in white matter lesions and motor neuron disease, alongside qualitative TDP-43 inclusion status in motor neuron disease cases. Following this, a protocol was developed for TMA construction. Results:For microglial pathology we found good concordance between virtual cores and whole sections for volume density using one 1.75mm core (equivalent to a 2mm core after accounting for peripheral tissue loss). More sophisticated microglial cell size and measures required two cores. Qualitative results of pTDP-43 pathology showed use of one 1.75mm core gave a 100% sensitivity and specificity within grey matter, and 88.3% sensitivity and 100% specificity within white matter. A method of producing the TMAs was suitable for immunohistochemistry both manually and by autostainer, with the minimal core loss from the microscope slide. Comparison with Existing Methods:TMAs have been used infrequently in post mortem neuropathology research. However, we believe TMAs give comparable tissue assessment results and can be constructed, sectioned and stained with relative ease. We found TMAs could be used to assess both quantitative (microglial pathology) and qualitative pathology (TDP-43 proteinopathy) with greatly reduced quantities of tissue, time and reagents. These could be used for further work to improve data acquisition efficiency.