Foremilk, residual milk, and blood samples were studied for 10 days during acute mastitis episodes induced by endotoxin infused via the teat canal. Quarter milk and blood samples were collected frequently for 3 days after the infusion and thereafter once or twice daily. Leukocyte concentration in milk and blood was determined by flow cytometry. Within 2 hours after infusion of the endotoxin, clinical mastitis was observed. Total leukocyte concentration and proportion of neutrophils increased significantly (P < 0.05) by postinfusion hour (PIH) 2 in foremilk and by PIH 4 in residual milk. From PIH 2, serum albumin content and N-acetyl-beta-D-glucosaminidase activity were significantly increased in both fractions. Neutrophils were the predominant leukocyte population in both fractions until PIH 59. From PIH 72, lymphocytes were the predominant cell population until PIH 175 in foremilk and until PIH 223 in residual milk. Serum albumin content and N-acetyl-beta-D-glucosaminidase activity in residual milk was significantly lower than in foremilk from PIH 4 to 24 and from PIH 24 to 59, respectively. Regarding total and differential leukocyte counts, values for the 2 fractions followed the same pattern throughout the course of inflammation, probably owing to frequent sample collection. Total and differential cell counts tended to differ between the fractions during some periods, although differences were not statistically significant. When samples were taken less frequently, the total leukocyte concentration in residual milk was higher than that in foremilk. Although sample collections were frequent, clustering of immature neutrophils was not observed in the cytofluorogram of blood leukocytes in this study. Residual milk seems to be the fraction that best reflects the condition in the quarter at the particular time when the milk sample is taken. Results also indicate that residual milk reflects the condition of the secretory tissue, as well as the lower regions of the gland.

We evaluated the biochemical and hemodynamic response to hypertonic saline solution plus dextran in isoflurane-anesthetized pigs infused IV with Escherichia coli endotoxin (5 micrograms/kg of body weight for 0 to 1 hour + 2 micrograms/kg for 1 to 4 hours). After 120 minutes of endotoxemia, pigs were treated with a bolus (4 ml/kg over 3 minutes) of either normal saline solution (NSS; 0.9% NaCl), or hypertonic saline solution plus dextran (HSSD; 7.5% NaCl + 6% dextran-70). Administration of HSSD significantly (P < 0.05) increased serum osmolality and concentrations of sodium and chloride for approximately 2 hours during endotoxemia. Plasma total protein concentration decreased significantly (P < 0.05) for 2 hours after treatment with HSSD, indicating hemodilution and increased plasma volume. Although HSSD transiently increased cardiac index (CI) for approximately 15 minutes, this effect was not sustained; however, the endotoxin-induced decrease in CI was ameliorated from 120 to 180 minutes. In pigs of the endotoxin + NSS group from 180 to 240 minutes, CI decreased significantly (P < 0.05), compared with baseline and control values. The endotoxin-induced increases in mean pulmonary arterial pressure and pulmonary vascular resistance were not attenuated by HSSD. At 135 minutes, total peripheral vascular resistance was transiently lower (for approx 15 minutes) in pigs treated with HSSD, compared with control pigs. The endotoxin-induced increase in plasma lactate concentration was not attenuated by HSSD, indicating continued peripheral O2 debt. We conclude that, despite sustained increases in serum osmolality and concentrations of sodium and chloride, HSSD has only transiently beneficial cardiopulmonary effects during endotoxemia in pigs.