Clinical, ultrasonographic, bacteriological, cytological and histological findings during uterine involution in ewes with pregnancy toxaemia and subsequent reproductive efficiency.

Objectives were to evaluate characteristics of uterine involution in ewes with pregnancy toxaemia during gestation and to study effects on subsequent reproductive performance. Pregnancy toxaemia was induced in ewes (A) by feeding an energy-deficient diet as confirmed by detecting ß-hydroxybutyrate concentrations in blood indicative of this disorder. There was also a control group (C). Animals were evaluated until the 60th day post-partum using clinical and ultrasonographic examinations. Vaginal swab samples and uterine biopsy tissue samples were collected for bacteriological and cytological examination; biopsy samples were prepared for histological examination. Ewes were subsequently placed with rams and reproductive performance was ascertained. Post-partum, during the ultrasonographic examination of the uterus, ewes of Group A had caruncle and uterine lumen diameters, as well as a uterine thickness greater than ewes of Group C. Post-partum uterine blood flow volume was greater in ewes of the A than C group. Neutrophils predominated in vaginal samples, with the neutrophil proportion being less in ewes of Group A than C. There were no differences in the uterine involution process between groups. During the subsequent reproductive season, all the ewes of Group A lambed normally and produced viable lambs. It is concluded that there were no adverse effects on subsequent reproductive performance of ewes previously affected with pregnancy toxaemia, when appropriate health management was performed.

Experimental study for evaluation of the efficacy of a biofilm-embedded bacteria-based vaccine against Staphylococcus chromogenes-associated mastitis in sheep.

Although coagulase-negative staphylococci are the primary aetiological agents of subclinical mastitis in ewes, there is little information regarding vaccination against that infection. The objective of this study was to evaluate the efficacy of a vaccine against staphylococcal mastitis in ewes under experimental conditions. The antigen in the vaccine is based on a bacterin of Staphylococcus aureus strain, expressing the exopolysaccharide poly-N-acetylglucosamine (PNAG), which is involved in biofilm formation by these bacteria. Ewes in groups A (n = 17) or B (n = 6) were given an initial vaccination 5 weeks before expected lambing, followed by a repeat administration 21 days later. Ewes in groups C (n = 8) or D (n = 6) were unvaccinated controls. Ewes in group A (n = 17) or C (n = 8) were challenged with a biofilm-forming S. chromogenes; animals in subgroups A1 or C1 were challenged on the 10th and those in A2 or C2 on the 50th day after lambing. Ewes in groups B or D were uninoculated controls. Clinical examinations of ewes, ultrasonographic examinations of udder, milk yield measurements, blood sampling for detection of anti-PNAG specific antibodies and milk sample collection for bacteriological and cytological examinations were performed up to 52nd day post-challenge. Finally, biopsies were performed for mammary tissue collection for histopathological examination. Among group A ewes, 29% developed systemic signs and 59% signs in the inoculated gland; the respective figures for group C were 50% and 100% (P =  0.040 for mammary signs). The median total clinical score was 2.0 for A and 5.5 for C ewes (P =  0.025). For A, but not for C, clinical scores decreased progressively during the study (P =  0.018 and P =  0.47, respectively). The duration of mastitis was shorter in A (4 days) than in C (17.5 days) ewes (P =  0.022). Bacterial counts were lower in milk samples from A than from C ewes, for samples collected from the inoculated and the uninoculated (P <  0.01) mammary glands of these ewes. Somatic cell counts in samples from inoculated and uninoculated mammary glands of A ewes were higher than in samples of C ewes (P <  0.02). There were differences for gray-scale evaluations during ultrasonographic examination and for milk yield measurements between groups (P <  0.01). Median bacterial counts in tissue samples from A ewes (0 cfu g-1) were lower than in ones from C (6.5 cfu g-1) ewes (P =  0.041). The median score for histopathological findings in tissue samples from inoculated glands of A was lower than that for C ewes: 1 versus 2 (P =  0.014). It is concluded that mastitis was less severe in vaccinated animals, as indicated by a wide array of measures.

Comparative evaluation of metallic skin staples or polypropylene sutures for primary closure of teat wounds in sheep.

AIMS: To compare stainless steel staples and polypropylene suture material for primary closure of wounds after teat amputation in ewes and to assess progress of healing in the presence or absence of intramammary infection (IMI). METHODS: Chios-cross ewes, aged 3-5 years were randomly allocated to be infected in one teat with 1,200-1,500 cfu of Mannheimia haemolytica 5 days after parturition (groups A and B; n = 8 in each group) or remain uninfected (groups C and D; n = 4 in each group). On the following 4 days one teat from each ewe was amputated 2.5 cm from the teat end and the wound was closed using skin staples (groups A and C) or polypropylene sutures (groups B and D). Clinical evaluation of wound healing was performed between 1-21 days after surgery. On day 21 tissue sections were collected for tensiometric and histological evaluation. RESULTS: The mean interval from the start to finish of wound closure was shorter when staples were used than when sutures were used (p < 0.001). Healing scores were lower (improved) for ewes in group A than B between days 1-7 after surgery (p = 0.005), but were similar between days 10-21 (p = 0.43). Healing scores were similar in groups C and D (p = 0.98). The tensile strain at maximum load was higher in tissue from group A than B (p = 0.001) and D (p = 0.004), but all other tensiometric measures were similar between groups. Histologically, collagen density was higher in sections from group A than B (p = 0.05) and D (p = 0.01), and angiogenesis was lower in sections from group A than B (p = 0.03) and D (p = 0.01). CONCLUSIONS AND CLINICAL RELEVANCE: Skin staples and polypropylene sutures can be used effectively for primary closure of teat wounds, even in the presence of IMI. Skin staples had the advantage of a reduction in surgical time. ABBREVIATION: IMI: intramammary infection.

Trematode infections in pregnant ewes can predispose to mastitis during the subsequent lactation period.

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 ß-hydroxybutyrate concentration measurement and uterine content, teat duct material and milk samples for bacteriological examination. We found significant differences in blood ß-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 6.75 days 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 ß-hydroxybutyrate blood concentrations adversely affect mammary cellular defences. This is the first report associating parasitic infections with mastitis in sheep.