Pituitary cells, collected from five healthy dogs, were cultured and treated with various doses of ovine corticotropin-releasing hormone (CRH), arginine vasopressin (AVP), oxytocin (OT), or angiotensin II (AII) to determine which of these hypothalamic peptides affected adrenocorticotropin (ACTH) secretion. Of the 4 peptides, only CRH significantly increased ACTH secretion from cultured canine anterior pituitary cells. The lowest dose of CRH tested, 0.01 nM, significantly stimulated ACTH release. Co-addition of AVP, OT, or AII with CRH did not increase ACTH secretion beyond that caused by addition of CRH alone. Similarly, neither co-addition of AVP with OT, AVP with AII, or OT with AII significantly stimulated ACTH secretion. These results support a role for CRH in the physiologic regulation of ACTH secretion from the canine anterior pituitary, but do not support regulatory roles for AVP, OT, or AII.

Bronchoalveolar lavage (BAL) fluid was analyzed in healthy horses, using different lavage fluid volumes and lung sites. The only significant difference in the cellular composition of BAL fluid between the right and left lungs was the mast cell numbers, which were significantly higher in the left lung. Total cell count ranged from 34 to 330 cells/microliter for the right lung and 43 to 330 cells/microliter for the left lung. Percentage of neutrophils ranged from 1 to 7% in the right lung and 1 to 5% in the left lung. The small-volume (50 ml) lavage had a greater percentage of neutrophils and a lesser percentage of mast cells in the large-volume (350 ml) lavage. Statistical difference in the composition of BAL fluid recovered was not detected between the 3 sequential 100-ml lavages and a single 300-ml lavage, except that macrophages were significantly higher in the 3 sequential 100-ml lavages. Values for BAL fluid analysis in healthy horses have varied considerably and this variation is from a failure to adhere to any standard technique for volume of fluid infused.

We evaluated the efficacy of 3 treatments for chronic obstructive pulmonary disease in horses: prednisone (400 mg/horse, PO, daily; n = 7), methyl sulfonmethane (10 g/horse, PO, q 12 h; n = 6), and clenbuterol hydrochloride (0.4 mg/horse, PO, q 12 h; n = 7). A fourth group acted as controls (n = 6) and was not treated. The treatment period lasted 10 days. Each horse was a member of 2 different groups for 10 days, separated by an 18-day interval of no treatment. All horses were housed together in an outdoor pen without bedding. Horses were fed alfalfa/grass hay mix ad libitum from a large feeder. The same batch of hay was fed throughout the study. Multiple physical and laboratory variables were monitored prior to, during, and at the end of each 10-day trial period. Changes in lung sounds, respiratory effort, degree of anal movement, nasal discharge, temperature, respiratory rate, or heart rate were not significant. Changes in arterial blood gas tensions, tracheal wash or bronchoalveolar lavage cytologic findings, or phagocyte function were not significant. All horses were tachypneic and most were tachycardic. The median value for Pao2 was below normal for all horses. All tracheal wash and most bronchoalveolar lavage cytologic findings represented a suppurative response. Negative linear correlation was observed between Pao2 and degree of respiratory effort in these horses (eg, as Pao2 decreased, the degree of respiratory effort increased).

A model of bovine pneumonic pasteurellosis, using an indwelling bronchial catheter for inoculation and subsequent lavage of a single main stem bronchus of the lung, was evaluated in a preliminary efficacy trial of an experimental therapeutic compound, Inoculation of 10(7) Pasteurella haemolytica organisms into the bronchus consistently induced a focal pneumonic lesion with typical morphology of pneumonic pasteurellosis in the left or right caudal lung lobe. The experimental treatment caused significant (P < 0.05) reduction in lung lesion volume, compared with that of a saline-treated control. It also caused significant (P < 0.05) reduction in lavage fluid bacterial counts at 48 hours after inoculation, compared with counts in the controls. The inflammatory cell count and the percentage of neutrophils increased markedly in lavage fluids 8 hours after inoculation, but differences were not detected between treatments. Significant differences between treatments were not found in clinical signs, rectal temperature, or histologic changes. This model appears to be a sensitive indicator of treatment efficacy and has the advantage over previous models of pneumonic pasteurellosis of allowing sequential monitoring of the primary lesion site.

A study was performed to determine whether equine peritoneal macrophages produce interleukin 6 (IL-6) in vitro in response to endotoxin. Peritoneal fluid was collected from 14 clinically normal adult horses and was used as the source of peritoneal macrophages. Macrophages from each horse were isolated and cultured separately in vitro in the absence or presence of various concentrations (0.5, 5, or 500 ng/ml) of endotoxin (lipopolysaccharide from Escherichia coli 055:B5). Culture medium supernatants were collected after 3, 6, 12, and 24 hours' incubation and were frozen at - 70 C until assayed for IL-6 activity. Supernatant IL-6 activity was determined by use of a modified colorimetric assay and the murine hybridoma cell line B13.29 clone B.9, which is dependent on IL-6 for survival. Results indicated that equine peritoneal macrophages produce IL-6 in vitro and that supernatant medium IL-6 activity was significantly (P < 0.05) increased by exposure to endotoxin. Significant (P < 0.05) time and treatment effects on macrophage IL-6 production were apparent. The IL-6 activity peaked at 6 or 12 hours' incubation, then remained high through 24 hours' incubation, regardless of endotoxin exposure. Medium IL-6 activity during 3 and 6 hours' incubation was significantly (P < 0.05) greater in macrophages exposed to 5 or 500 ng of endotoxin/ml than in those exposed to 0.5 ng of endotoxin/ml; however peak IL-6 activity was similar among all endotoxin concentrations. Endotoxin concentration did not have an effect on medium IL-6 activity from macrophages exposed to endotoxin for 12 or 24 hours.

Postoperative abdominal fluid changes were compared in 2 groups of horses; those undergoing double small-colon resection and anastomosis (n = 10) and those undergoing exploratory celiotomy alone (n = 5). Peritoneal fluid was collected before surgery and on postoperative days 1, 3, 5, and 7. Total and differential nucleated cell counts, RBC numbers, and total protein and fibrinogen concentrations were evaluated. In both groups, all values were significantly higher than normal on the first postoperative day (after small-colon resection and anastomoses, WBC = 130,350 +/- 23,310 cells/microliter, RBC 7,389,000 +/- 6,234,000 cells/microliter, total protein = 3.63 +/- 0.16 g/dl; after exploratory celiotomy alone, WBC = 166,620 +/- 34,340 cells/microliter, RBC = 295,000 +/- 86,070 cells/microliter, total protein 4.38 +/- 0.54 g/dl). The number of total peritoneal nucleated cells and RBC significantly decreased after the first postoperative day, whereas total protein and fibrinogen concentrations, percent neutrophils, and percent mononuclear cells remained unchanged. None of the values had returned to normal by postoperative day 7 (after small-colon resection and anastomoses, WBC = 45,600 +/- 8,765 cells/microliter, RBC = 95,390 +/- 53,380 cells/microliter, total protein = 4.39 +/- 0.23 g/dl; after exploratory celiotomy alone, WBC = 43,340 +/- 7,746 cells/microliter, RBC = 12,860 +/- 11,790 cells/microliter, total protein = 3.92 +/- 2.20 g/dl.) The resection and anastomosis group had a significantly lower total protein concentration on the first postoperative day and a significantly higher mean total RBC count over the entire 7-day postoperative evaluation than did horses that underwent celiotomy alone. Other values in the 2 groups of horses did not differ significantly. As a result, there was insufficient evidence to conclude that resection and anastomosis of the small colon in healthy horses causes a different inflammatory response than does manipulation of the intestine alone.

The aerobic bacterial flora of the genital tract was characterized in 15 stud dogs in an 18-month study. The dogs represented 4 breeds and were from 3 kennels. Bacterial samples from the prepuce and semen were collected every month, except in connection with matings, when they were collected weekly (464 samples). The dogs that were included all mated at least once during the study. The mean pregnancy rate, litter size, and pup mortality for the bitches with which they had mated were all within normal limits. The most frequent bacteria isolated from the prepuce and semen were Pasteurella multocida, beta-hemolytic streptococci, and Escherichia coli. There was a tendency for breeds to differ in frequency of the most common bacterial species. Bacterial culture yielded no aerobic growth in 14.2% of the preputial samples and 69.8% of the semen samples. Bacteria were transferred between dog and bitch at mating. In this study of healthy breeding dogs, neither the fertility of the dog nor that of the bitch was affected by the bacteria transferred.

Tracheobronchial aspirates obtained from 66 healthy Thoroughbred racehorses in training at the same track were examined. Twenty-seven percent of the horses had > 20% neutrophils in the aspirate. Eosinophils, mast cells, giant cells, and Curschmann's spirals of mucus were observed in 94, 83, 65, and 42% of the horses, respectively. Hemosiderophages were observed in 86% of the horses, half of which had previous confirmation of exercise-induced pulmonary hemorrhage. Although fungal elements were seen in 70% of the horses, bacteria were detected in only 3% of the horses. The authors conclude that inflammatory airway disease is widespread in the racing Thoroughbred population.

Because articular chondrocytes are a target for drugs that can influence the integrity of cartilage, we investigated the effects of 3 antiarthritic drugs, glycosaminoglycan polysulfate, diclofenac-Na, and S-adenosylmethionine sulfate p-toluenesulfonate on total protein, fibronectin, and DNA synthesis, as well as on extradomain-A fibronectin and keratan sulfate content. Glycosaminoglycan polysulfate stimulated dose-dependent incorporation of [35S]methionine into protein and fibronectin, whereas incorporation of [3H]thymidine into DNA was unaffected. Total fibronectin, extradomain-A fibronectin, and keratan sulfate content were high in chondrocyte cultures treated with glycosaminoglycan polysulfate. In contrast, fibronectin and DNA synthesis, as well as extradomain-A fibronectin and keratan sulfate content were unaffected by diclofenac-Na. S-adenosylmethionine decreased dose-dependently the synthesis of fibronectin, as well as the content of fibronectin and keratan sulfate. At the highest concentration of S-adenosylmethionine tested, findings suggest that cell viability was impaired as assessed by the release of lactate dehydrogenase into the media.

In 8 Holstein cows, 50 colony-forming units (CFU) Of Escherichia coli was administered into 1 mammary gland. Infections were established in all inoculated glands. In 4 of the 8 cows, 500 mg of gentamicin sulfate was administered by intramammary infusion 14 hours after inoculation; the other 4 cows were untreated controls. Infusions of gentamicin also were given after each of the 3 successive milkings after the initial infusion, so that a total dose of 2 g of gentamicin was given to each of the treated cows. During the 33-hour treatment period and for the first milking after the last infusion of gentamicin, the treated cows had a mean gentamicin concentration of greater than or equal to 31.0 microgram/ml in milk samples that were collected from inoculated quarters immediately before each milking. Concentrations of 0.34 and 0.69 microgram of gentamicin were detected in milk from 2 cows at 8 days after inoculation with E coli. Mean serum concentrations of gentamicin were > 0.37 microgram/ml throughout the treatment period and the first 12 hours after the last infusion, with a mean peak concentration of 0.96 microgram/ml at 24.4 hours. The range of peak concentration of gentamicin detected in urine from all treated cows was 42 to 74.4 microgram/ml. Peak concentration of E coli in milk in the treated cows (6.08 +/- 1.02 log10 CFU/ml) did not significantly (P > 0.05) differ from that of the control cows (5.26 +/- 1.00 log10 CFU/ml). Similarly, mean duration of infection in the treated cows (54 hours) did not differ significantly from that of the control cows (48 hours). The treatment groups also did not differ significantly in peak concentrations of albumin or IgG1 in milk, although mean concentrations of albumin and IgG1 at 16 hours after inoculation, and of albumin at 20 hours, was significantly (P < 0.05) higher in the milk from control cows than from the treated cows. Mean values of peak rectal temperature and of mean rectal temperature throughout the trial did not differ between the groups. At the end of the 4-week trial, 1 of 4 inoculated glands in treated cows and 3 of 4 in control cows had somatic cell counts less than or equal to preinoculation concentrations (5.18 log10 cells/ml). Intramammary administration of gentamicin did not affect the duration or severity of experimentally induced E coli mastitis. In addition, substantial concentrations of gentamicin were detected in the serum of treated cows, suggesting that intramammary treatment may result in prolonged drug residues in tissue.