Size of supernumerary teats in sheep correlates with complexity of the anatomy and microenvironment.
Journal of anatomy
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Hardwick, L., Phythian, C. J., Fowden, A., & Hughes, K. (2020). Size of supernumerary teats in sheep correlates with complexity of the anatomy and microenvironment.. Journal of anatomy, 236 (5), 954-962. https://doi.org/10.1111/joa.13149
Supernumerary nipples or teats (polythelia) are congenital accessory structures that may develop at any location along the milk line and have been implicated in the pathogenesis of mastitis. We describe the anatomy and histology of 27 spontaneously occurring supernumerary teats from 16 sheep, delineating two groups of teats – simple and anatomically complex – according to the complexity of the anatomy and microenvironment. Anatomically complex supernumerary teats exhibited significantly increased length and barrel diameter compared to simple supernumerary teats. A teat canal and/or teat cistern was present in anatomically complex teats, with smooth muscle fibres forming a variably well-organised encircling teat sphincter. Complex supernumerary teats also exhibited immune cell infiltrates similar to those of normal teats, including lymphoid follicle-like structures at the folds of the teat cistern – teat canal junction, and macrophages that infiltrated the peri-cisternal glandular tissue. One complex supernumerary teat exhibited teat end hyperkeratosis. These anatomical and histological features allow inference that supernumerary teats may be susceptible to bacterial ingress through the teat canal and we hypothesise that this may be more likely in those teats with less well-organised encircling smooth muscle. The teat cistern of anatomically complex teats may also constitute a focus of milk accumulation and thus a potential nidus for bacterial infection, potentially predisposing to mastitis. We suggest that size of the supernumerary teat, and relationship to the main teats, particularly in the case of ‘cluster teats’, should be considerations if surgical removal is contemplated.
British Veterinary Association Animal Welfare Foundation (BVA AWF) Norman Hayward Fund
External DOI: https://doi.org/10.1111/joa.13149
This record's URL: https://www.repository.cam.ac.uk/handle/1810/299895
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