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Currently, intraoperative tumour margin imaging is not routinely utilized in veterinary medicine. Optical coherence tomography (OCT) allows for real‐time assessment of tissue morphology of 1–2 mm depth. The aims of this study were (1) to compare the histologic and OCT features of excised canine skin and subcutaneous specimens, and (2) to determine the diagnostic accuracy of OCT for surgical margin evaluation. The authors hypothesized that OCT imaging would correlate well with histopathology and that OCT would be sensitive for detection of incomplete margins. Eighty dogs were prospectively enrolled. Tumours were excised, and the surgical margins were imaged using a spectral domain OCT system. The tumour type and completeness of excision were determined by histopathology. Nine blinded observers received training in OCT image interpretation and were then given a set of OCT images and videos. The observers assigned each image/video a grade from 1 (no tumour) to 4 (tumour) and the results were compared to histopathology. The overall median sensitivity and specificity of OCT imaging for detection of incomplete margins were 86.7% and 84.6%, respectively. A potential limitation is that observers had varied experience with OCT image interpretation, ranging from no prior experience to participating in a previous OCT project. OCT is sensitive for detection of incomplete margins and could be a promising real‐time surgical margin imaging modality. Further study is needed to evaluate intraoperative applications of OCT and its impact on tumour recurrence and long‐term outcome. [ABSTRACT FROM AUTHOR]

Background: The influenza A virus (IAV) binds to α‐2,3‐ and α‐2,6‐linked sialic acid (SA) receptors expressed by Madin‐Darby canine kidney (MDCK) cells. The receptor distribution may therefore be important in regulating IAV propagation. Serum‐free medium (SFM) avoids variability in conventional culture medium containing fetal bovine serum (FBS), which can have variable composition and may contain endotoxins. However, little is known about the distribution of SA receptors on cells maintained in SFM. Objectives: We assessed the influence of culture media on MDCK cell SA receptor distribution along with the effect of SA receptor distribution on IAV recovery. We hypothesized that SFM would increase the proportion of α‐2,6‐linked SA receptors present and alter isolate recovery. Methods: Madin‐Darby canine kidney cells were cultured in medium containing FBS and two SFMs. Cell surface distribution of α‐2,6‐ and α‐2,3‐linked receptors was determined using flow cytometry. Recovery of swine‐ and avian‐lineage IAVs from MDCK cells maintained in each medium was quantified as TCID50. Results: Madin‐Darby canine kidney cells cultured in UltraMDCK SFM expressed both SA receptors and supported the growth of both swine‐ and avian‐lineage IAVs. Cells maintained in other medium inconsistently expressed each receptor and the avian IAV grew to lower titers in cells cultured with FBS. Conclusions: Medium conditions altered the distribution of SA receptors present on MDCK cells and affected IAV recovery. Culture in UltraMDCK SFM resulted in cells expressing both receptors and IAVs grew to higher titers than in the other culture condition, indicating that this medium may be useful for culturing IAV from multiple species. [ABSTRACT FROM AUTHOR]