Teat disorders predispose ewes to mastitis after challenge with Mannheimia haemolytica

Faculty of Veterinary Science, University of Thessaly, PO Box 199, 43100 Karditsa, Greece.
Veterinary Research (Impact Factor: 2.82). 01/2006; 37(1):89-105. DOI: 10.1051/vetres:2005042
Source: PubMed


In order to study the effects of sheep teat disorders on the protection of the mammary gland, we used a Mannheimia haemolytica isolate, which did not cause clinical mastitis when deposited into intact teats. In the first experiment, this was deposited into the duct of teats with orf (Group A, n=5) or papilloma (Group B, n=3). In the second, teats were chapped and then, the organism was deposited into the duct (Group C, n=7) or on the skin (Group D, n=4). Ewes with healthy teats were controls (Group E, deposition into duct, n=5; Group F, deposition on skin, n=2). The ewes in Groups A, B or C developed clinical mastitis 5 h later, whilst the ewes in Group D developed it 2 d later; no control ewe developed clinical mastitis. In ewes with teat lesions, the organism was isolated from secretion samples and the California Mastitis Test became positive 5 h after challenge; neutrophils and lymphocytes were seen in Giemsa-stained secretion films from Group A or B ewes, whilst macrophages, neutrophils and lymphocytes in films from Group C or D ewes; neutrophils were predominating in films from Group E or F ewes. Inside the teats of Group A, B, C or D ewes, folds, hyperaemia and mucosal thickness were seen; histologically, subepithelial leucocytic infiltration was seen. In Group A or B ewes, no evidence of lymphoid tissue at the teat duct-cistern border was found. In Group C or D ewes, intense erosion and ulceration of the teat skin and conspicuous lymphoid tissue at the teat duct-cistern border, were evident; lesions characteristic of haemorrhagic mastitis were in the mammary parenchyma. In control ewes, subepithelial leucocytic infiltration in the teat duct and lymphoid tissue as above, were evident. We postulate that teat lesions can be predisposing factor to mastitis, by adversely affecting defences and speeding the process of infection and making it more severe.

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Available from: Ioannis Taitzoglou, Feb 21, 2014
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    • "These focal lymphoid accumulations were later characterised and found to contain CD79 + , CD3 + , γδ T cells, CD68 + and MHC-II + cells (Mavrogianni et al., 2007; Fragkou et al., 2010). However, in cases of Orf Virus infection in the teats, these structures could not be observed (Mavrogianni et al. 2006a), as was also the case in chapped teats (Fragkou et al., 2007a). In these cases, bacterial deposition even at the tip of the teat resulted in clinical mastitis, confirming the protective role of these structures. "
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    ABSTRACT: Bacterial mastitis is a significant welfare and financial problem in sheep flocks. This paper reviews the recently published literature, including publications that highlight the significance and virulence factors of the causal agents, especially Staphylococcus aureus and Mannheimia haemolytica, the primary causes of the disease. Research has also contributed to the understanding of risk factors, including genetic susceptibility of animals to infections, supporting future strategies for sustainable disease control. Pathogenetic mechanisms, including the role of the local defenses in the teat, have also been described and can assist formulation of strategies that induce local immune responses in the teat of ewes. Further to well-established diagnostic techniques, i.e., bacteriological tests and somatic cell counting, advanced methodologies, e.g., proteomics technologies, will likely contribute to more rapid and accurate diagnostics, in turn enhancing mastitis control efforts. Copyright © 2015 Elsevier B.V. All rights reserved.
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    • "Mortality associated with CE is low, but unless proper care is given to infected animals, mortality can increase, as complications such as fly infestation of affected tissues and secondary infections can be quite common [4]. Depending upon the location of the lesions, infected animals may be unwilling to nurse, eat, or walk [5], and in lactating ewes, udder lesions may also cause mastitis [6]. Infected lambs or kids may need to be hand-fed, as they can transmit the disease by suckling other females. "
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    • "However, in all cases, pregnancy was carried to term in all affected animals. In the second outbreak, animals from the flock infected with the 'GRE-2 teat 2004' strain were subsequently used in an experimental study, where it was shown that Orf virus infection in teats of ewes leads to depletion of local mammary defences and predisposes animals to mastitis [24]. Those experimental findings were allied to the clinical evidence recorded in the same farm, where higher frequency of mastitis was recorded among the Orf virus-infected animals [25]. "
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