Teat disorders predispose ewes to clinical mastitis after challenge with Mannheimia haemolytica.

Faculty of Veterinary Science, University of Thessaly, PO Box 199, 43100 Karditsa, Greece.
Veterinary Research (Impact Factor: 3.43). 01/2006; 37(1):89-105. DOI: 10.1051/vetres:2005042
Source: PubMed

ABSTRACT 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.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The study was carried out in Mytilene breed dairy ewes, which were allocated into two groups, 2 months before their first mating. All animals were given a diet based on dried alfalfa hay and concentrate compound feed with no added vitamin A or copper, hence making the diet poor in β-carotene and vitamin A. Ewes in group A were administered intramuscularly 150,000 IU of vitamin A at 3-month intervals, whilst animals in group B remained untreated. After lambing and on five occasions in total during their first lactation period, milk samples were collected from animals for somatic cell counting. Samples with somatic cell counts ≥0.5 × 106 cells mL−1, as well as samples from clinical cases of mastitis were examined bacteriologically. Significantly (P < 0.05) fewer cases of clinical or subclinical mastitis were recorded in group A animals, compared to group B ones. Coagulase negative staphylococci were the most frequently isolated bacteria from secretion samples of ewes with clinical or subclinical mastitis. Somatic cell counts of milk of group A ewes were significantly smaller than those of group B on the first four sampling occasions (P < 0.05), but not on the one at the end of the lactation period (P > 0.05). It is suggested that vitamin A deficiency may lead to increased incidence risk of clinical and subclinical mastitis in and to increased milk somatic cell counts in dairy ewes.
    Small Ruminant Research 03/2013; 110(s 2–3):120–123. · 1.12 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of the present paper is to review the significance of administration of antibiotics at the end of a lactation period/beginning of the dry-period in ewes. During the stage of active involution, there is an increased risk of new mastitis cases and recrudescence of subclinical infections that had occurred during the previous lactation period. The main pathogens involved in the so-called 'dry-period mastitis' are coagulase-negative staphylococci. The principle of antibiotic administration at the end of a lactation period involves the intramammary infusion of a preparation to both mammary glands of ewes in the flock. Although a variety of products is licensed for administration in ewes, preferably the product for administration should be selected on the results of susceptibility testing of bacteria to be isolated from samples from ewes in the flock. In many clinical studies from around the world, performed in dairy- or mutton-production flocks, administration of antimicrobial agents at the end of a lactation period has been found beneficial in curing intramammary infections present at cessation of a lactation period, as well as in minimising the risk for intramammary infections during the dry-period. In dairy flocks, there are also benefits from increase in milk yield and decrease flock bulk milk mean somatic cell counts during the subsequent lactation period. Antibiotic administration at drying-off may be performed to all animals in a flock ('complete') or only to those considered to be infected ('selective'). In all cases, after administration of the antibiotic, definite and complete cessation of the lactation period is essential for success of the procedure. Moreover, maintenance of the prescribed withdrawal periods is essential to safeguard public health. The procedure should always be applied as part of a strategic udder health management plan in a flock; implementation improves the welfare of animals and affords significant financial benefits to the farmer. A mastitis prevention scheme during lactation will minimise the incidence of the disease; effective treatment of cases of the disease during lactation will decrease the bacterial populations in the flock and limit risk of infection of other animals. Administration of antibiotics at the end of a lactation period will complement the above procedures and will contribute to improved mammary health for the forthcoming lactation period.
    Journal of Dairy Research 10/2013; · 1.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective was to investigate if trematode infections predispose ewes to mastitis and/or metritis. We used 80 trematode-infected ewes: primigravidae in group P-A and multigravidae in M-A remained untreated, primigravidae in P-B and multigravidae in M-B were drenched with netobimin and multigravidae in M-C were given rafoxanide. We collected faecal samples for parasitological examination, blood samples for β-hydroxybutyrate concentration measurement and uterine content, teat duct material and milk samples for bacteriological examination. We found significant differences in blood β-hydroxybutyrate concentrations between M-A, M-B and M-C during pregnancy (P⩽0.002). We did not observe significant differences between groups regarding development of metritis (P>0.83). We found that for M-A, M-B and M-C ewes, respectively, median time to first case of mastitis was 5.75, 21 and 6.75days after lambing (P=0.003) and incidence risk of mastitis was 0.308, 0.069 and 0.222 (P=0.047). We postulate that trematode infections predispose ewes to mastitis; perhaps, increased β-hydroxybutyrate blood concentrations adversely affect mammary cellular defences. This is the first report associating parasitic infections with mastitis in sheep.
    Research in Veterinary Science 12/2013; · 1.77 Impact Factor

Full-text (2 Sources)

Available from
May 23, 2014