Sows intramammarily inoculated with Escherichia coli at parturition: I. Functional capacity of granulocytes in sows affected or non-affected by clinical mastitis

Bacteriological investigation of milk samples and biopsies from the mammary gland of healthy sows

OBJECTIVE

Milk samples from clinically healthy sows often contain a similar bacterial content as samples from mastitic sows. To verify whether contamination during sample collection is a possible reason for this or bacterial content in the mammary gland postpartum is a regular finding, the aim of the present study was to compare the suitability of milk samples and mammary gland biopsies for assessing the bacteriological status of healthy sows.

MATERIAL AND METHODS

Twenty-five clinically healthy sows of different parities were selected. The mammary skin and teats were cleaned and disinfected before biopsies and milk samples were taken from the second mammary gland on the left udder side one day postpartum. Needle biopsies were performed after local anaesthesia. Samples were investigated bacteriologically for aerobic bacteria and a semi-quantitative classification of bacterial growth was carried out. Additionally, formalin-fixed paraffin-embedded biopsies from 18 of the healthy sows were stained and scored for inflammatory cells.

RESULTS

A low bacterial content could be found in 96 % of milk samples and in 92 % of biopsies from the healthy sows. Both Gram-positive (mostly streptococci and staphylococci) and Gram-negative bacteria (Escherichia coli) were detected. Histopathological examination revealed mild inflammatory cell infiltration with mainly plasma cells and lymphocytes, in rare cases neutrophilic granulocytes.

CONCLUSION

Biopsies of the mammary gland provided similar results with regard to bacteriological investigation compared to milk sampling although these were collected under aseptic conditions. Therefore, it is assumed that ubiquitous bacteria are regularly present in the colostrum and in the mammary gland tissue of clinically healthy sows after parturition. Histopathological findings were not entirely uneventful.

CLINICAL RELEVANCE

Milk samples and biopsies from the thoroughly cleaned and disinfected mammary gland indicate a regular bacterial load of the gland postpartum; biopsies do not provide advantages with regard to hygienic conditions.

Lack of evidence of mastitis as a causal factor for postpartum dysgalactia syndrome in sows

To investigate the prevalence of mastitis in sows suffering from postpartum dysgalactia syndrome (PDS), we examined milk constituents and concentrations of lipopolysaccharides (LPS) obtained from the udder vein (v. epigastrica). As part of a case-cohort study, 109 sows were monitored daily from 60 h antepartum (a.p.) to 36 h postpartum (p.p.). Over time, 38 sows were diagnosed with PDS (PDS+) and were retrospectively matched with 38 healthy sows (PDS-). The study period was divided into 7 smaller time periods (A, B, C, D, E, F, G, H, and E), allowing the studied values, in period B to G, to be compared with period A that served as a baseline, and PDS+ and PDS- sows were compared within the time periods. All sows were subjected to a thorough daily clinical examination and blood was sampled from v. epigastrica for LPS detection. Milk samples were obtained for bacteriological evaluation and detection of N-acetyl-beta-d-glucosaminidase (NAGase), lactate dehydrogenase (LDH), β-glucuronidase (β-glu; for evaluation of mastitis), isocitrate (isoC), free glucose, uric acid (UA; for evaluation of the mammary energy status), β-hydroxybutyrate acid (BHBA; for evaluation of ketosis), and milk urea (for evaluation of the protein status). The results revealed that PDS+ sows had decreased concentrations of UA in milk (P < 0.0001), increased heart rates (P < 0.01), increased mammary edema (P < 0.05), and prolonged capillary refill time in the vulvar mucosa (P < 0.01) compared with PDS- sows. Compared with baseline, feces became more solid 0 to 36 h p.p. (P < 0.0001) and the respiration rate decreased 12 to 24 h p.p. (P < 0.0001) for both PDS+ and PDS- sows. No differences were found between PDS+ and PDS- sows for severe bacterial infections, concentrations of LPS in blood or LDH, NAGase, BHBA, free glucose, isoC, or urea in milk. Concentrations of LPS in blood were not associated with signs of mastitis or edema in the mammary glands. However, a difference over time was seen for redness (P < 0.0001), warmth (P < 0.0001), and hardness (P < 0.05) of the 6 most anterior glands in both PDS+ and PDS- sows from 60 h a.p to 36 h p.p. The PDS- sows had greater concentrations of β-glu than the PDS+ sows, but no change over time was demonstrated for this marker. In conclusion, signs of mastitis were not consistently linked to PDS in sows. However, the cardiovascular system seemed to be compromised in PDS+ sows and the cause should be investigated to elucidate the pathogenesis of PDS.

Hormonal and metabolic indicators before and after farrowing in sows affected with postpartum dysgalactia syndrome

BACKGROUND

Postpartum dysgalactia syndrome (PDS) in sows is difficult to diagnose and the pathogenesis is obscure. Hormonal changes related to the disease are often difficult to distinguish from those found in the normal transition period from gestation to lactation. The study aimed to investigate metabolic and hormonal changes related to PDS with the goal of identifying potential biomarkers in sows suffering from PDS (PDS+). Selected biomarkers were examined by comparing 38 PDS+ sows with 38 PDS negative (PDS-) sows. The sows were sampled every 24 h from 60 h ante partum (a.p.) to 36 h post partum (p.p.).

RESULTS

Compared to the baseline (60 to 36 h a.p.), cortisol in serum and saliva and fasting blood glucose concentrations increased in PDS+ as well as PDS- sows. C-peptide decreased relative to the baseline in PDS+ sows, and prolactin and 8-epi prostaglandin F2 alpha (8-epi-PGF2α) decreased in PDS- sows. Concentrations of cortisol in serum and saliva, salivary chromogranin A (CgA), fasting blood glucose, C-peptide, and 8-epi-PGF2α differed significantly between PDS+ and PDS- sows, with levels of cortisol in serum and saliva, salivary CgA, and 8-epi-PGF2α in serum being different in the two groups already before parturition. Concentrations of salivary CgA were significantly lower in PDS- sows than in PDS+ sows during the entire study period.

CONCLUSIONS

The results suggest that salivary CgA, cortisol and serum 8-epi-PGF2α may potentially serve as early diagnostic indicators for PDS. The consistently higher salivary CgA concentration in PDS+ sows compared to PDS- sows may indicate that homeostatic disturbances are present between 36 to 60 h before parturition in sows developing PDS. The higher serum and saliva cortisol concentration in PDS+ sows compared to PDS- sows could reflect an early sign of inflammation or stress. The significantly lower C-peptide in PDS+ sows compared to PDS- sows may reflect a lower food intake. Our results contribute to the understanding of the pathogenesis of PDS, and the homeostatic disturbances detected before parturition warrants further investigation. The diagnostic potential of the markers identified in this study should be investigated further in a larger population of sows.

Inflammatory markers before and after farrowing in healthy sows and in sows affected with postpartum dysgalactia syndrome

Background

The pathogenesis of postpartum dysgalactia syndrome (PDS) in sows is not fully elucidated and affected sows often present vague clinical signs. Accurate and timely diagnosis is difficult, and PDS is often recognized with a delay once piglets begin to starve. Increased rectal temperature of the sow is an important diagnostic parameter, but it may also be influenced by a number of other parameters and is thus difficult to interpret. Inflammatory markers may be important adjuncts to the clinical assessment of sows with PDS, but such markers have only been studied to a limited extent. The objective was to characterize the inflammatory response in healthy sows and in sows suffering from PDS, and to identify biomarkers that may assist in early identification of PDS-affected sows.

Results

Thirty-eight PDS-affected (PDS+) and 38 healthy (PDS-) sows underwent clinical examination and blood sampling every 24 h, from 60 h before the first piglet was born to 36 h after parturition. In both groups, inflammatory markers changed in relation to parturition. Most inflammatory markers changed 12-36 h after parturition [white blood cell counts (WBC), neutrophil counts, lymphocyte counts, tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), serum amyloid A (SAA), C-reactive protein (CRP), haptoglobin (Hp), iron (Fe) and albumin (ALB)]. Changes in neutrophil counts, lymphocyte counts, CRP, Fe and ALB were observed -12 to 0 h before parturition. WBC, neutrophil and lymphocyte counts, serum concentrations of TNF-α, IL-6, Hp and Fe differed between PDS+ and PDS- sows. These differences were mainly apparent 12 to 36 h after parturition, but already at 12 h before parturition, PDS+ sows had lower lymphocyte counts than PDS- sows.

Conclusions

Parturition itself caused significant inflammatory changes, but PDS+ sows showed a more severe response than PDS- sows. WBC, neutrophil and lymphocyte counts, and concentrations of TNF-α, IL-6, Hp and Fe can be potential biomarkers for PDS. Lymphocyte counts may be used to detect PDS at pre-partum. To assess their diagnostic potential, these markers must be investigated further and most likely combined with assessment of clinical parameters and other biomarkers for improved identification of sows at risk of developing PDS.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1382-7) contains supplementary material, which is available to authorized users.

USO DE ÓLEOS ESSENCIAIS NO CONTROLE DOS SINAIS CLÍNICOS DAS DIARREIAS NEONATAIS EM LEITÕES NASCIDOS DE FÊMEAS COM DIFERENTES ORDENS DE PARTO

Este estudo avaliou a emulsão líquida de óleos essenciais de orégano (Origanum vulgare) e alecrim (Rosmarinus officinalis labiatae) no controle dos sinais clínicos da diarreia neonatal em leitões. Foram monitorados 1.334 leitões lactentes, com peso vivo médio inicial de 1,5kg, quanto aos sinais clínicos de diarreia neonatal. O delineamento experimental foi o inteiramente casualizado e com três tratamentos (T): (T1) controle (solução fisiológica), (T2) mescla dos óleos essenciais e (T3) enrofloxacina. Os animais que receberam o T1 apresentaram sinais clínicos característicos de diarreia diferindo (P<0,01) dos demais tratamentos. O percentual de cura da diarreia dos leitões não diferiu (P>0,01) entre os tratamentos, independente da ordem de partos (OP) das mães. Já leitões com sinais clínicos de diarreia, nascidos de fêmeas com OP inferior a três apresentaram maior percentual de cura (74,6%), se comparados aos leitões diarreicos de fêmeas com OP entre três e cinco (68,2%) e superior a cinco (56,4%). As análises microbiológicas das fezes e histológicas do epitélio ileal não apresentaram diferenças (P>0,01) entre os tratamentos. A emulsão com óleos essenciais de orégano e alecrim (2mL kg-1), para leitões entre zero e o oito dias de vida, pode vir a substituir a enrofloxacina no controle dos sinais clínicos das diarreias neonatais.

Effects of meloxicam (Metacam®) on post-farrowing sow behaviour and piglet performance

Farrowing is an intrinsically risky process for both the sow and the piglets that can cause welfare and economic problems. The effects of the non-steroidal anti-inflammatory drug meloxicam on post-farrowing behaviour of sows, and the performance of piglets were investigated. A total of 48 sows were randomly allocated at the day of farrowing (day 0) into two homogeneous groups regarding parity, and treated with either meloxicam or saline solution as placebo. For each sow, number of position changes, total time lying and standing or sitting, feed intake and rectal temperature (RT) were recorded during 3 days after farrowing. Piglets were individually weighed at farrowing and at weaning. The number of position changes did not show significant differences between treatments (P = 0.79). Sows spent significantly less time lying during day +3 after farrowing in the meloxicam group than in the placebo group (P = 0.04). Feed intake and RT showed a parity effect (P < 0.001 in both cases); however, no treatment effect was observed (P = 0.67 and P = 0.47, respectively). Pre-weaning mortality rate in piglets was not affected by treatment. In litters from multiparous sows, piglets of low birth weight (defined as percentile 15: BW <1180 g) had an average daily gain significantly higher in the meloxicam group than in the placebo group (196.6 ± 7.2 v. 166.6 ± 9.1 g/day; P = 0.03). Although the administration of meloxicam 90 min after farrowing showed a positive effect on the total time lying of the sows, additional investigations are required to better qualify relevant indicators of pain following farrowing in sows and to specify the analgesic effects of meloxicam on piglet performance.

Estimation of variance components for postpartum dysgalactia syndrome in sows

The postpartum dysgalactia syndrome (PDS) represents one of the most important diseases after parturition in sows. The genetic background of the disease has been investigated some time ago and heritability estimates around 0.10 have been obtained. To compute current estimates, a dataset of 1680 sampled sows and their 2001 clinically examined litters was used for variance components estimation with a threshold liability model. Affected sows were defined through clinical examination 12-48 h after parturition. Posterior mean of additive genetic variance was 0.10 and estimated heritability for PDS averaged 0.0879 with a 95% confidence interval of 0.0876 and 0.0881. The results are in agreement with those of other studies and emphasize the importance of considering the genetic predisposition for susceptibility to PDS as well as of additional factors including hygiene and management conditions.

Morphometric analysis of proinflammatory cytokines in mammary glands of sows suggests an association between clinical mastitis and local production of IL-1beta, IL-6 and TNF-alpha

Twelve healthy primiparous sows received intramammary inoculation with Escherichia coli (serotype O127) during the 24-h period preceding parturition. Mammary gland biopsy samples were taken immediately before inoculation (0 h) and from the inoculated and the contralateral non-inoculated glands 24 h after inoculation. The analyses of interleukin-1 beta (IL-1beta), IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) by immunohistochemistry revealed that the production of these proinflammatory cytokines significantly increased in the inoculated mammary glands of sows that developed clinical signs of mastitis (affected group, n=4) 24 h after inoculation. This was also true for IL-8 in the inoculated mammary glands of sows that did not develop clinical signs of mastitis (nonaffected group, n=8). Sows that developed clinical signs of mastitis displayed significantly lower constitutive production of IL-1beta than did sows that remained clinically healthy. The data indicate that the development of clinical symptoms of coliform mastitis in the sow is associated with a locally increased proinflammatory cytokine production in response to intramammary E. coli infection.

Proinflammatory cytokine mRNA expression in mammary tissue of sows following intramammary inoculation with Escherichia coli

The expression of the proinflammatory cytokines interleukin-1beta (IL-1beta), IL-6, IL-8, and tumor necrosis factor-alpha (TNF-alpha) mRNAs was determined by reverse transcription-PCR (RT-PCR) analysis of biopsies from the mammary glands of sows. The biopsies were collected before and 24h after intramammary inoculation of 12 pregnant sows with Escherichia coli (E. coli). Four of the sows developed clinical signs of mastitis and these animals displayed significantly lower levels of IL-1beta mRNA before inoculation than those that remained clinically healthy. There was a significant increase in IL-1beta, IL-6, IL-8, and TNF-alpha mRNA expression in the inoculated mammary glands of sows that developed clinical signs of mastitis (affected group) 24h postinoculation. This was also true for IL-8 and TNF-alpha mRNA expression in the inoculated mammary glands of sows that did not develop clinical signs of mastitis (non-affected group). No significant differences were found in IL-1beta, IL-6, and TNF-alpha mRNA expression in the inoculated mammary glands between groups (affected versus non-affected) 24h postinoculation. Thus, a local production of proinflammatory cytokines in the mammary gland of sows was indicated by the induced expression of IL-1beta, IL-6, IL-8, and TNF-alpha mRNAs after intramammary inoculation with E. coli.

Influence of 17β-Estradiol, Progesterone, and Dexamethasone on Diapedesis and Viability of Bovine Blood Polymorphonuclear Leukocytes

The aim of the current study was to investigate whether polymorphonuclear leukocyte (PMN) diapedesis and viability are influenced by steroid hormones. Using an in vitro model with different types of cell layers (bovine mammary epithelial cells and fibroblasts), we investigate whether steroid hormone treatments (17beta-estradiol, progesterone, and dexamethasone) have an influence on the diapedesis capacity and viability of PMN. In addition, we studied apoptosis of PMN in the in vitro model and evaluated the influence of different types of cell layers and steroid hormone treatments on this process. A significant decrease in the number of viable PMN in the lower compartment of the in vitro model (i.e., number of migrated PMN x viability after migration) was found after 17beta-estradiol treatment, whereas no influence was detected after progesterone or dexamethasone treatment. The effect of 17beta-estradiol was not due to a lower viability before migration as none of the treatments caused a significant effect on the viability before diapedesis. This treatment effect was not influenced by endogenous 17beta-estradiol or progesterone levels before isolation because there was no correlation between these plasma levels and PMN diapedesis capacity or viability. Furthermore, migration through epithelial cells caused a significant decrease in viability of PMN due to increased apoptosis but not necrosis.

Tumor necrosis factor-, interleukin-6, serum amyloid A, haptoglobin, and cortisol concentrations in sows following intramammary inoculation of Escherichia coli

OBJECTIVE

To determine whether concentrations of proinflammatory cytokines, acute-phase proteins, and cortisol differ at parturition among 3 categories of sows (noninoculated, clinically affected and nonaffected following intramammary inoculation with Escherichia coll).

ANIMALS

16 sows.

PROCEDURE

Sows were allocated to inoculated (n = 12) or noninoculated (4) groups. Inoculated sows received intramammary administration of E coli (serotype O127) during the 24-hour period preceding parturition. Blood samples were collected from noninoculated and inoculated sows for 3 consecutive days within 3 to 11 days before farrowing and inoculation. Samples were also collected 0, 24, 48, 72, and 96 hours after farrowing and inoculation. Inoculated sows were further categorized as affected (4 sows) or nonaffected (8 sows) based on clinical signs of disease. Serum tumor necrosis factor (TNF)-alpha, plasma interleukin (IL)-6, and serum amyloid A (SAA) concentrations were measured by use of ELISA; serum haptoglobin concentration was assayed by use of a hemoglobin-binding method; and plasma cortisol concentration was determined by use of radioimmunoassay.

RESULTS

Plasma or serum concentrations of TNF-alpha, IL-6, and SAA of both categories of inoculated sows were significantly increased by 24 hours after intramammary inoculation of E coli, compared with concentrations in noninoculated sows. Concentrations of serum TNF-alpha and plasma IL-6 were significantly higher in inoculated sows that developed clinical mastitis than in nonaffected inoculated sows.

CONCLUSIONS AND CLINICAL RELEVANCE

Concentrations of TNF-alpha and IL-6 are promising markers for the identification of periparturient sows with subclinical coliform mastitis. Identification of such sows should help improve the health and survival of piglets.

Sows intramammarily inoculated with Escherichia coli at parturition. II. Effects on the densities of MHC class II(+), CD4(+) and CD8(+) cells in the mammary gland

The aim of this study was to determine the density of MHC class II, CD4 and CD8 positive cells in mammary glands of sows around parturition, and whether the densities were altered following intramammary inoculation with Escherichia coli prior to parturition. Also, animals developing clinical disease after inoculation were compared with animals not developing clinical disease. Fourteen cross-bred primiparous sows were subject to intramammary inoculation with E. coli bacteria 24h before estimated parturition. Mammary gland biopsies were collected and clinical observations were made. Four sows were categorised as clinically ill based on general condition, body temperature and gross mammary affection. There were no changes in density of MHC class II, CD4 and CD8 positive cells in non-inoculated glands around parturition, while significant changes in densities were shown in inoculated glands. Here, the density of MHC class II, CD4 and CD8 positive cells reached a peak at 72 h post-inoculation (p<0.01). In sows developing clinical disease, there was a tendency to an over all lower density (p=0.07) of MHC class II positive cells in inoculated glands compared with sows not developing clinical disease. When comparing the categories with respect to the density of CD4 and CD8 positive cells, the sows developing clinical disease showed a higher density (p=0.03) of CD4 and CD8 positive cells in inoculated glands than sows not developing disease. No differences were shown between categories in non-inoculated glands. It is concluded that the density of MHC class II, CD4 and CD8 positive cells seems to be unaltered around parturition. However, there is a rapid increase in density of these cells following intramammary inoculation with E. coli. Also, the data suggest that there is a difference between sows developing and sows not developing clinical disease after inoculation with respect to the increase in density of MHC class II, CD4 and CD8 positive cells in the mammary gland.