Small intestinal explants from weaned pigs were cultured under a variety of conditions. Explants maintained villus-to-crypt ratio between 1:1 and 1.5:1 for 48 hours. The mucosal epithelium remained well preserved and retained good cellular morphologic features, as determined by light and electron microscopy. Between 48 and 72 hours, considerable mucosal degeneration was evident. Best results were obtained when the explants were cultured on a rocking platform placed in an atmosphere of 95% O2 and 5% CO2, using supplemented RPMI 1640 cell culture medium.

Four consecutive 6-hour urine sample collections were performed on 7 healthy adult Holstein cows fed a diet of coastal Bermuda hay with ad libitum water consumption. Urine (via indwelling urinary catheter) and venous blood samples were collected at 6, 12, 18, and 24 hours. Total 24-hour urine production for the 7 cows ranged from 4,515 to 7,130 ml/d (mean +/- SD, 5,633 +/- 946 ml/d) or 0.02 to 0.04 ml/kg of body weight/d (mean +/- SD, 0.03 +/- 0.007 ml/kg/d). Renal clearance (C) of creatinine (Cr), sodium (Na), calcium (Ca), and magnesium (Mg) varied significantly (P less than 0.05) among individuals, but did not vary significantly among the four 6-hour collection periods. Clearance of chloride (Cl) and phosphorous (P) did not vary significantly either among individuals or among the four 6-hour periods. Clearance of potassium (K) varied significantly (P less than 0.05) among individuals and among the four 6-hour periods. Creatinine clearance was significantly (P less than 0.01) correlated with CCl, CCa, CP, and CMg when all data were considered. Significant (P less than 0.05) correlations were also found between CCl, and CK, CCa, CP, and CMg; between CCa and CP and CMg; and between CP and CMg. Fractional excretion (FE) of Na, K, Cl, Ca, P, and Mg did not vary significantly among the four 6-hour periods. Fractional excretion of Na, Ca, and Mg (P less than 0.01) and K and P (P less than 0.05) varied significantly within individuals among the 6-hour periods. Mean FE values, calculated by averaging values for each of the 4 collection periods for all 7 cows, ranged from 0.05 to 0.78% for FENa; 129.33 to 670.40% for FEK; 1.23 to 6.23% for FECl; 0.17 to 4.44% for FECa; 0.36 to 1.14 for FEP; and 4.96 to 11.73% for FEMg. Linear relationships between the clearance and fractional excretion of electrolytes were observed on base-10 logarithmically transformed data for Na, Ca, P, and Mg. Linear relationship was not found between CK and FEK or between CCl and FECl.

Naturally acquired gram-negative bacterial intramammary infections (n = 160) were studied in 99 cows over a 2-year period. Escherichia coli, Klebsiella spp, Serratia spp, Enterobacter spp, and unidentified gram-negative bacteria were isolated from 28.8, 39.4, 9.4, 5.0, and 11.2%, respectively, of infected mammary glands. A majority (61%) of intramammary infections were first detected during the nonlactating period. Gram-negative bacteria isolated during the first half of the nonlactating period were predominantly Klebsiella spp, Serratia spp, and Enterobacter spp. Onset of E coli intramammary infections was more prevalent during the second half of the nonlactating period and during the first 7 days of lactation. The majority (59%) of infections were <28 days in duration, but Klebsiella spp and Serratia spp infections were of significantly (P <0.05) greater duration than infections with E coli. The greatest percentage (47%) of gram-negative bacterial intramammary infections were first detected during the summer.

The role of decreased luteal activity in embryonic loss after induced endotoxemia was studied in mares 21 to 35 days pregnant. Fourteen pregnant mares were treated daily with 44 mg of altrenogest to compensate for the loss of endogenous progesterone secretion caused by prostaglandin F2 alpha, (PGF2 alpha) synthesis and release following intravenous administration of Salmonella typhimurium endotoxin. Altrenogest was administered daily from the day of endotoxin injection until day 40 of gestation (group 1; n = 7), until day 70 (group 2; n = 5), or until day 50 (group 3; n = 2). In all mares, secretion of PGF2 alpha, as determined by the plasma 15-keto-13,14-dihydro-PGF2 alpha concentrations, followed a biphasic pattern, with an initial peak at 30 minutes followed by a second, larger peak at 105 minutes after endotoxin injection. Plasma progesterone concentrations decreased in all mares to values < 1 ng/ml within 24 hours after endotoxin injection. In group 1, progesterone concentrations for all mares were < 1 ng/ml until the final day of altrenogest treatment. In 6 of 7 mares in group 1, the fetuses died within 4 days after the end of treatment, with progesterone concentrations < than 1 ng/ml at that time. In the mare that remained pregnant after the end of treatment, plasma progesterone concentration was 1.6 ng/ml on day 41 and increased to 4.4 ng/ml on day 44. In group 2, all mares remained pregnant, even though plasma progesterone concentrations were < 1 ng/ml in 4 of 5 mares from the day after endotoxin injection until after the end of altrenogest treatment. One group-2 mare appeared to develop a secondary corpus luteum before day 70, with progesterone concentrations greater than 1 ng/ml from day 36 through day 70. Daily altrenogest administration consistently prevented pregnancy loss, which usually follows induced endotoxemia. Altrenogest administration offers a reliable and practical treatment for the prevention of fetal loss following endotoxemia in mares < 2 months pregnant. One group-3 mare remained pregnant, and in the other mare, fetal death was diagnosed 8 days after endotoxin administration, although this mare was still being treated with altrenogest. In that case fetal death was believed to be unrelated to the treatment.

The role of prostaglandin F2 alpha (PGF2 alpha) in embryonic loss following induced endotoxemia was studied in mares that were 21 to 44 days pregnant. Thirteen pregnant mares were treated with a nonsteroidal anti-inflammatory drug, flunixin meglumine, to inhibit the synthesis of PGF2 alpha caused by Salmonella typhimurium endotoxin given IV. Flunixin meglumine was administered either before injection of the endotoxin (group 1, -10 min; n = 7), or after endotoxin injection into the mares (group 2, 1 hour, n = 3; group 3, 2 hours, n = 3); 12 pregnant mares (group 4) were given only S typhimurium endotoxin. In group 4, the secretion of PGF2 alpha, as determined by plasma 15-keto-13,14-dihydro-PGF2 alpha concentrations, was biphasic, initially peaking at 30 minutes followed by a second, larger peak approximately 105 minutes after the endotoxin was given IV. When flunixin meglumine was administered at -10 minutes, synthesis of PGF2 alpha was inhibited for several hours, after administration of flunixin meglumine at 1 hour, the second secretory surge of PGF2 alpha was blocked, and administration of the drug at 2 hours did not substantially modify the secretion of PGF2 alpha. Plasma progesterone concentrations were unchanged after endotoxin injections were given in group 1. In group 2, progesterone values decreased < 2 ng/ml and remained low for several days. In group 3 and group 4, progesterone concentrations decreased to values < 0.5 ng/ml by 48 hours after endotoxin injections were given. Pregnancy continued in all 7 mares in group 1; in group 2, pregnancy continued in 2 of 3 mares; and in group 3, none of the 3 mares was pregnant by 4 days after endotoxin administration. The abortifacient effect of endotoxemia in mares < 2 months pregnant is mediated indirectly through the secretion of PGF2 alpha; compromised luteal activity and inadequate progesterone secretion are the primary causes of fetal death. Although flunixin meglumine administration can be used to prevent loss of pregnancy in cases of endotoxemia, it must be initiated at an early stage of the endotoxemia, that is, when clinical signs are often not yet apparent.

The antebrachiocarpal and tarsocrural joints of 10 adult horses were randomly assigned to 1 of 4 groups. Groups were formulated and were treated as follows: group 1, control (arthrocentesis only); group 2, buffered lactated Ringer solution; group 3, 10% dimethyl sulfoxide (DMSO; w/v) in lactated Ringer solution; and group 4, 30% DMSO (w/v) in lactated Ringer solution. Joints were lavaged once with the respective solution. Prior to lavage and on days 1, 4, and 8 after lavage, all horses were evaluated for lameness and joint effusion; synovial fluid total and differential WBC counts, synovial fluid total protein concentration, and mucin clot quality were determined. Horses were euthanatized on day 8, and joints were evaluated grossly, histologically, and histochemically. Significant difference was not observed in effect of lactated Ringer solution, 10% DMSO, and 30% DMSO on any measured variable. At 24 hours after treatment, significant (P < 0.05) difference in synovial fluid WBC numbers and total protein concentration was detected between control and treated joints. Eighty percent of lavaged joints had effusion 24 hours after treatment, compared with 30% of control joints. Gross, histopathologic, or histochemical differences were not detected between treated and control joints. Results of the study indicate that buffered lactated Ringer, 10% DMSO, and 30% DMSO solutions induce similar inflammatory changes in articular structures and significantly greater inflammatory reaction than does arthrocentesis alone.

A study was conducted to determine whether dietary supplements with alpha-linolenic acid altered the ability of equine peritoneal macrophages to produce tumor necrosis factor (TNF) in response to endotoxin. Peritoneal macrophages were harvested from 6 healthy adult horses before and after the horses were fed a nutritionally balanced ration that contained 8% linseed oil as a source of alpha-linolenic acid. The macrophages were cultured in media containing no additives (control), endotoxin (0.5 to 50 ng/ml), or the calcium ionophore, A23187. Macrophage supernatants were collected after 6 and 24 hours' incubation and stored at -70 C. Tumor necrosis factor activity was estimated by a modified in vitro cytotoxicity bioassay, using the murine fibrosarcoma cell line, WEHI 164 clone 13. The TNF activity after 6 and 24 hours' incubation was greater in culture media of macrophages exposed to endotoxin than in media from control macrophages. For macrophages cultured in media that contained endotoxin, neither the concentration of endotoxin nor incubation time had any effect on TNF activity. Endotoxin-induced macrophage production of TNF, as determined by measurement of TNF activity, was significantly less after horses were fed the alpha-linolenic acid-rich ration for 8 weeks.

The type of plasminogen activator (PA) produced by bovine milk macrophages has been determined. Macrophages produce a PA protein with molecular weight of 28,000 and isoelectic point of 8.5, and with enzymatic activity independent of fibrin. These characteristics are identical to those reported for bovine urokinase-PA. Although blood monocytes and milk macrophages produce PA after stimulation with lipopolysaccharide, mammary macrophages are clearly limited in their ability to release PA. At maximal stimulation, 78% of the PA produced by milk macrophages remained cell-associated. In marked contrast, blood monocytes released 76% of the PA produced into the culture medium. Macrophages isolated from mastitic quarters produced higher (2.5 times) amounts of PA, compared with those produced by macrophages isolated from healthy quarters. However, in both cases, macrophages were unable to secrete the protein already produced. The limited PA secretion by milk macrophages might be a residual function of a differentiated macrophage population.

In a dorsal plane, an improved ultrasonographic off-set system was used to obtain serial ultrasonographic images with enhanced anatomic and pathologic detail of the tendons, ligaments, and associated structures of the limbs of 100 horses. The off-set provided good acoustic coupling between a linear array ultrasonographic transducer and the horse's skin. A water-soluble gel contained within the off-set had acoustic properties similar to those of mammalian soft tissues.

Fourteen adult beavers (Castor canadensis) weighing 16.5 +/- 4.14 kg (mean +/- SD) were anesthetized for surgical implantation of radio telemetry devices. Beavers were anesthetized with diazepam (0.1 mg/kg) and ketamine (25 mg/kg) administered IM, which provided smooth anesthetic induction and facilitated tracheal intubation. Anesthesia was maintained with halothane in oxygen via a semiclosed circle anesthetic circuit. Values for heart rate, respiratory rate, esophageal temperature, direct arterial blood pressure, end-tidal halothane concentration, and end-tidal CO2 tension were recorded every 15 minutes during the surgical procedure. Arterial blood samples were collected every 30 minutes to determine pH, PaO2, and PaCO2. Values for plasma bicarbonate, total CO2, and base excess were calculated. Ventilation was spontaneous in 7 beavers and controlled to maintain normocapnia (PaCO2 approx 40 mm of Hg) in 7 others. Vaporizer settings were adjusted to maintain a light surgical plane of anesthesia. Throughout the surgical procedure, all beavers had mean arterial pressure < 60 mm of Hg and esophageal temperature < 35 C. Mean values for arterial pH, end-tidal CO2, PaO2, and PaCO2 were significantly (P < 0.05) different in spontaneously ventilating beavers, compared with those in which ventilation was controlled. Respiratory acidosis during halothane anesthesia was observed in spontaneously ventilating beavers, but not in beavers maintained with controlled ventilation. All beavers recovered unremarkably from anesthesia.