The effects of famotidine, ranitidine and magnesium hydroxide/aluminium hydroxide on gastric fluid pH in adult horses.

Gastric fluid pH was measured in five adult horses following nasogastric administration of famotidine, 0.5, 1.0, and 2.0 mg/kg bodyweight (bwt); ranitidine, 4.4 and 6.6 mg/kg bwt and an antacid containing magnesium hydroxide (40 mg/ml) and aluminium hydroxide (45 mg/ml), 120 and 180 ml. Fluid was aspirated through a 16 French nasogastric feeding tube at 15 min intervals, and pH was measured using a pH meter. Basal gastric fluid pH was measured at 20 min intervals for 6 h in each horse and, with the exception of two measurements of 4.66 and 4.17, ranged from 1.42 to 2.41, with a mean pH of 1.88 +/- 0.18. The response to both ranitidine and famotidine was variable between horses and between dosages. The mean gastric fluid pH values following administration of a single dose of famotidine or ranitidine were famotidine, 0.5 mg/kg bwt, 3.63 +/- 1.72; famotidine, 1.0 mg/kg bwt, 3.41 +/- 1.40; famotidine, 2.0 mg/kg bwt, 4.18 +/- 2.06; ranitidine, 4.4 mg/kg bwt, 4.07 +/- 1.25; ranitidine 6.6 mg/kg bwt, 5.34 +/- 1.12. Differences in mean gastric fluid pH between famotidine dose levels and between ranitidine dose levels were not significant (P > 0.10). Gastric fluid pH increased to greater than 6 in three horses receiving 0.5 mg/kg bwt, five horses receiving 1.0 mg/kg bwt and three horses receiving 2.0 mg/kg bwt famotidine. Gastric fluid pH increased to greater than 6 in each of the five horses receiving 6.6 mg/kg bwt ranitidine and in four of five horses receiving 4.4 mg/kg bwt ranitidine. During the 6 h post administration, ranitidine tended to increase gastric fluid pH greater than 6 longer (166 +/- 106 mins) than famotidine (98 +/- 110 mins) and this difference was nearly significant (P = 0.054). The response to antacid was variable and consistently short-lived. The mean gastric fluid pH values for 6 h after administration of 120 ml or 180 ml were 2.42 +/- 0.71 and 2.44 +/- 0.47, respectively. Gastric fluid pH increased to greater than 6 in only two horses, for 15 and 30 mins, respectively. The increase in gastric fluid pH was significantly greater for ranitidine (P < 0.001) and famotidine (P < 0.02) than for antacid. The duration of the effect was significantly longer for ranitidine doses (P < 0.001) and nearly so for famotidine doses (P < 0.055) than for antacid.

Endoscopic evaluation of changes in gastric lesions of Thoroughbred foals.

Gastroendoscopic examinations were conducted on thirty-two 2- to 60-day-old Thoroughbred foals on 5 breeding farms. Repeat gastroendoscopic examinations were performed 35 to 135 days after the initial examination, with the age of foals ranging from 39 to 190 days. On initial endoscopic examination, lesions consisting of ulcers and/or erosions were most prevalent in the stratified squamous epithelial mucosa adjacent to the margo plicatus along the greater curvature of the stomach (15 of 32 foals), and were observed much less frequently at other sites within the stomach. In addition to ulcers and erosions, squamous epithelial desquamation at the margo plicatus was observed in 16 of 19 foals less than 30 days old and in 3 of 13 foals 30 to 60 days old, and was not seen in any foal on repeat endoscopy. At the time of repeat endoscopic examination, the frequency of ulcers and erosions at the margo plicatus was significantly (P less than 0.01) less than at initial examination (4 of 32 foals vs 15 of 32 foals). Lesions had healed in 14 of the 15 foals with lesions at the margo plicatus on the initial examination. Lesions were observed in the glandular mucosa of the fundus in 3 of 32 foals on initial examination and in 6 of 32 foals reexamined. Lesions in the glandular fundus observed on initial examination had healed in 2 of 3 foals, and of the 6 foals with glandular mucosal lesions on reexamination, 5 had developed lesions since the initial examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric ulcers in horses: a comparison of endoscopic findings in horses with and without clinical signs.

Gastroendoscopic examinations were performed on 187 horses, ranging from one to 24 years. Eighty-seven horses had clinical problems including chronic, recurrent colic for seven or more days (25), one or more episodes of colic within the previous seven days (13), or acute colic (10), diminished appetite (53), poor bodily condition (40), and/or chronic diarrhoea (9). One hundred horses that had no signs of gastrointestinal problems were examined as part of a gastroendoscopic survey. Lesions observed in the squamous fundus, squamous mucosa adjacent to the margo plicatus along the greater curvature, glandular fundus, and the squamous mucosa along the lesser curvature were scored on a scale of 0-4, with 0 representing no lesions and 4 representing the most severe lesions. The mean endoscopic scores for the squamous fundus, margo plicatus and lesser curvature were significantly greater (P < 0.001) in horses with clinical signs than those without signs. This was because of the greater number of horses with lesions in the symptomatic group (80/87) compared to those without signs (52/100), and the greater severity of lesions in the horses with clinical signs. Of the horses, 74 were in race training. There was a significantly (P < 0.01) greater prevalence and severity of lesions at all sites except the glandular fundus in horses in training compared to those not in training, and in the horses in training with clinical signs (n = 37) compared to those in training without clinical signs (n = 37).

Regional gastric pH measurement in horses and foals.

The pH of the gastric mucosal surface and gastric content was measured in 18 foals (mean age: 20 days) and 27 horses (mean age: 2.9 years) with a pH electrode passed through an endoscope biopsy channel. A reference electrode was attached to a shaved area on the neck. pH Measurements of the gastric mucosal surface at the dorsal squamous fundus (SF), squamous mucosa adjacent to the margo plicatus (MP), glandular fundus (GF) and the fluid or feed contents of the stomach were recorded in duplicate for each animal. In adult horses, the SF pH was greatest (5.46 +/- 1.82), with a decreasing pH ventrally toward the MP (4.12 +/- 1.62), to the glandular fundic mucosa (3.09 +/- 1.90), and fluid contents (2.72 +/- 1.86). The differences in pH at each site within the stomach were significant (P < 0.05). In foals, mean pH measurement of the SF was 4.88 +/- 1.30, the MP was 4.92 +/- 1.29, the GF was 2.10 +/- 1.45, milk and fluid contents was 1.85 +/- 0.53 (six foals), and feed contents was 3.39 +/- 1.77 (12 foals). The pH of the SF and MP were significantly greater (P < 0.05) than that of feed contents, which was significantly greater (P < 0.05) than that of the glandular mucosal surface and fluid contents. The results indicate a dorsal to ventral pH gradient of the gastric mucosal surface in adult horses, and that gastric acid secretion is competent in young foals.

Breast lesions: differential diagnosis using digital subtraction angiography.

To evaluate its potential for differentiating benign from malignant breast lesions, digital subtraction angiography of the breast (DSAB) was performed in 23 women with mammographic evidence of disease, and the results were compared with surgical biopsy findings. The DSAB technique employed breast immobilization with modest compression and bolus injection; following the injection of contrast material, 30-40 sequential subtraction images were obtained over a 5-minute interval. The average technical settings were 50 k Vp and 10 mAs, resulting in an estimated radiation dose to the breast of 0.05 mrad (0.5 mu Gy) per exposure. DSAB consistently demonstrated retention of contrast material and abnormal vasculature in malignant lesions but not in benign lesions. In the 22 breast lesions for which there was histopathologic correlation, DSAB correctly categorized eight of nine malignant and 11 of 13 benign lesions. Although this series is small, the initial results of DSAB suggest its potential for differentiating benign from malignant lesions.