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Abstract

Objective

To determine whether there is variation attributable to reproductive stage in lymphocyte subsets and major histocompatibility complex (MHC) class II expressing cells in mammary glands of sows.

Animals

8 healthy primiparous crossbred sows that had been nursing piglets for 30 to 35 days.

Procedure

Needle biopsy of the mammary gland was performed after parturition, at midlactation, and after weaning. Various lymphocyte subsets and MHC class II expressing cells were detected immunohistochemically, using monoclonal antibodies.

Results

The number of CD8+ cells was significantly lower after parturition than after weaning but not significantly lower than at midlactation. The number of IgA-bearing cells was lower after parturition and after weaning than at midlactation. There were more B cells at midlactation than after weaning. There was no change over time in the number of CD4+ cells or MHC class II expressing cells. Immunohistochemically positive cells were detected only in interalveolar tissue.

Conclusions and Clinical Relevance

Certain lymphocyte subsets in mammary glands of sows are affected by reproductive stage. The data do not support the hypothesis that development of postparturient coliform mastitis may be the result of impaired mammary immune defenses at parturition. (Am J Vet Res 1999;60:546–548)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To compare the effect of oral and IV administrations of flunixin meglumine on the endotoxin-induced inflammatory response in heifers.

Design

The study was conducted in 2 experimental sets in which heifers were exposed to low IV doses of Escherichia coli endotoxin. Within each set, heifers were allocated to 3 treatment groups; pretreatment with flunixin meglumine orally and IV prior to endotoxin administration, or endotoxin administration only. The dose of flunixin used was the recommended therapeutic dose in cattle.

Animals

11 clinically normal heifers weighing from 400 to 640 kg.

Procedure

A permanent cannula was inserted into the jugular vein on the day prior to the experiment. Blood samples were collected regularly during the experiment and analyzed for the content of prostaglandin F metabolite, Cortisol, blood mononuclear cells, and polymorphonuclear neutrophilic leukocytes and rectal temperature was measured.

Results

Endotoxin administration caused clinical signs and hematologic changes characteristic of endotoxemia in cattle. Flunixin administered orally prior to experimentally induced endotoxemia exerted an effect equal to that after its IV administration. Significant increases in rectal temperature and prostaglandin F metabolite concentrations after administration of endotoxin were abrogated when the heifers were pretreated with flunixin, irrespective of route of administration. Cortisol concentrations were lower after pretreatment with flunixin. However, flunixin did not prevent the decrease in blood mononuclear cells and polymorphonuclear neutrophilic leukocytes seen after endotoxin administration.

Conclusion

Owing to no major difference in the inflammatory response between oral and IV flunixin dosing, flunixin granules may be an alternative to parenteral use in bovine practice.

Free access
in American Journal of Veterinary Research

Summary

Porcine blood mononuclear cells (bmc) were exposed to prepartum concentration of estrogen in gilts before acquisition (in vivo) and their subsequent reactivity (in vitro) was explored. In a cross-over experimental designed study, 6 ovariectomized gilts were injected once with 3.75 mg of estradiol-17β benzoate in arachidic oil or with arachidic oil only during 2 experiments. The ability of their bmc to proliferate in response to stimulation with phytohemagglutinin, concanavalin A, and pokeweed mitrogen was assayed in cultures of blood and in cultures of purified bmc. After 2 days of mitogen stimulation, activity of accessible interleukin 2 was quantified in supernatants obtained from cultures of purified bmc and supernatants of blood cultures stimulated with pokeweed mitogen. Also, production of immunoglobulins by purified bmc in response to polyclonal stimuli was measured.

Three days after treatment with estradiol, the proliferative response was suppressed in blood cultures stimulated with concanavalin A (P < 0.05) and phytohemagglutinin (P < 0.07). Effects of estradiol treatment were not found in any of the assays performed with purified bmc. We, therefore, assumed that in vivo exposure to estradiol can affect the function of porcine bmc; however, this was only evident when the in vitro assays were performed on blood cultures.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of porcine mammary secretions on polymorphonuclear (PMN) leukocyte function and to relate concentrations of estradiol-17β and cortisol in mammary secretions to PMN cell function.

Sample Population—Mammary secretions from 10 healthy sows and blood PMN leukocytes from 27 healthy sows.

Procedure—Mammary secretions were collected within 24 hours after parturition (colostrum) and 12 to 13 days later (milk). Chemoattractant properties were assessed by use of a cell migration assay. Phagocytic capacity of PMN cells in colostrum and milk was assessed by recording chemiluminescence following phagocytosis of Escherichia coli or zymosan. Estradiol-17β and cortisol concentrations were determined by use of radioimmunoassays.

Results—Chemoattractant properties of colostrum and milk were significantly greater than that of zymosan-activated serum. However, chemoattractant properties did not differ significantly between the 2 types of secretions. The capacity of PMN cells in colostrum to phagocytose either zymosan or E coli was less, compared with cells in milk, and the ability of cells in either type of mammary secretion to phagocytose E coli was greater than the ability to phagocytose zymosan. Concentrations of estradiol-17β and cortisol were greater in colostrum, compared with milk. No clear relation was evident between PMN cell activity and hormone concentrations in mammary secretions.

Conclusions and Clinical Relevance—Although chemoattractant properties of colostrum and milk did not differ, the phagocytic capacity of PMN cells in colostrum was significantly less than that of cells in milk. This may predispose sows to coliform mastitis during the early postparturient period. (Am J Vet Res 2001;62:1250–1254)

Full access
in American Journal of Veterinary Research

Abstract

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 coli).

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)-α, 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-α, 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-α 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-α 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. (Am J Vet Res 2004;65:1434–1439)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To investigate whether the procedure used to snare and restrain pigs during collection of blood samples would alter in vitro functional capacity of leukocytes in the samples.

Animals

8 gilts.

Procedure

Catheters were surgically inserted into the jugular vein of gilts to enable blood sample collection without restraint. After collection of a control sample, gilts were restrained by use of a snare and samples were collected at 0.5, 3.5, and 6.5 minutes after start of restraint (0 minutes). At each time point, plasma β-endorphin and cortisol concentrations as well as WBC counts were recorded, and functional capacity of leukocytes in cultures of whole blood was assessed by means of mitogen-induced proliferation and interleukin-2 activity, virus-induced interferon-α concentration, and phagocytosis of zymosan particles.

Results

Concentrations of plasma β-endorphin and cortisol were increased at 3.5 and 6.5 minutes after start of restraint. At these times, virus-induced interferon-α concentration was decreased, whereas proliferative response to Concanavalin A and phytohemagglutinin increased in samples collected at 6.5 minutes.

Conclusion and Clinical Relevance

It was possible to snare pigs for the purpose of collecting blood samples and restrain them without causing excessive stress that would affect immunologic variables, provided that the collection procedure was completed within a few minutes. (Am J Vet Res 1998;59:421–425)

Free access
in American Journal of Veterinary Research

SUMMARY

The effects of short-term restraint stress, by means of snaring, on plasma concentrations of catecholamines, β-endorphin, and cortisol were studied in 6 gilts. A catheter was inserted into the jugular vein, and 2 blood samples were collected before onset of stress. Thereafter, a hog snare was applied, and blood samples were collected at 0.5,2, and 3.5 minutes after the start of snaring. Plasma epinephrine and norepinephrine concentrations increased (P < 0.001) within 0.5 minute after start of restraint and decreased thereafter. Plasma concentration of β-endorphin increased (P < 0.05) within 2 minutes after start of restraint, whereas that of cortisol increased (P < 0.05) 3.5 minutes after start of restraint. Taken together, short-term stress, such as snaring, may increase the plasma concentration of catecholamines, β-endorphin, and cortisol in pigs.

Free access
in American Journal of Veterinary Research

Summary

The effect of mimicking prepartum concentration of estradiol-17β on the inflammatory response to endotoxin in gilts was studied. The study was performed in a split-litter design and comprised 5 pairs of littermates. A catheter was inserted into the jugular vein 2 days prior to the start of the study. In each pair, 1 littermate was treated im with 2.5 mg of estradiol-17β/75 kg of body weight, and the other littermate was given peanut oil im as a control. The day after treatment, all gilts were challenge-exposed with a Salmonella typhimurium-derived endotoxin (1 µg/kg, iv) and the inflammatory response to challenge exposure was monitored. There was no effect of estradiol treatment on the transient clinical signs of endotoxemia or on the increase in rectal temperature. The increase in blood concentrations of prostaglandin F metabolite and cortisol after endotoxin challenge exposure was not affected by estradiol. Decrease in number of circulating blood mononuclear cells and polymorphonuclear leukocytes was not changed by estradiol treatment. Taken together, mimicking prepartum concentration of estradiol did not affect either the magnitude or the kinetics of the inflammatory response to endotoxin in gilts. Relevance of these findings to development of endotoxinmediated diseases, such as the postpartum agalactia syndrome, needs further study.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate effect of age and parity on distribution and number of cells expressing major histocompatibility complex (MHC) class II, CD4, or CD8 molecules in the endometrium of mares during estrus.

Animals

32 gynecologically healthy mares, categorized as young (3 to 8 years; n = 17) or old (9 to 16 years; 15) and nulliparous (n = 6), nulliparous embryo donors (16), or parous (10).

Procedures

Endometrial specimens collected from the uterine body and horns during estrus were stained by use of the avidin-biotin-peroxidase method, using monoclonal antibodies against equine MHC class II, CD4, and CD8 molecules. Labeled cells in the stratum compactum within 5 randomly selected fields at 400× magnification (total area = 0.31 mm2) were counted, and numbers were compared among groups and between locations.

Results

Age did not affect cell numbers within the 3 cell subsets examined. Numbers in each subset were higher in the uterine body than in the horns, although the difference was not significant for cells expressing MHC class II. Significantly more cells expressing MHC class II molecules were detected in the uterine body of nulliparous and parous mares than in embryo donors, whereas in the horns, these cells were significantly higher in number only in parous mares. Parity did not affect number of CD4+ or CD8+ cells.

Conclusions and Clinical Relevance

The increased likelihood for endometritis to develop in mares as they age cannot be explained by a decrease in number of cells expressing MHC class II, CD4, or CD8 molecules within the endometrium. However, greater number of cells within these 3 subsets detected in the uterine body, compared with the horns, during estrus suggests a local readiness to act against microorganisms or semen introduced during mating or insemination. (Am J Vet Res 1999;60:1531–1535)

Free access
in American Journal of Veterinary Research