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- Author or Editor: Frank M. Andrews x
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Abstract
Objective—To assess antiulcerogenic properties of 3 dietary oils.
Animals—8 healthy adult mares.
Procedure—A protocol to induce gastric ulcers was used and included 240 mL of water plus corn oil, refined rice bran oil, or crude rice bran oil administered each day for 6 weeks according to a 4 × 4 Latin square randomized crossover design with 5-week washout intervals. A 7-day alternating feed deprivation period was included between weeks 5 and 6. Omeprazole was administered daily for the last 14 days of each washout interval. Endoscopic examinations of the stomach were performed at 0, 5, and 6 weeks, and the number (0 to 4 scale) and severity (0 to 5 scale) of ulcers were scored. Gastric fluid was collected at 0 and 5 weeks.
Results—Median body weight significantly increased by 29 kg (range, 10 to 50 kg). Mean ± SE gastric fluid pH significantly decreased from 4.9 ± 0.4 to 3.1 ± 0.3 over 5 weeks, and total volatile fatty acid concentration significantly decreased over time. Mean ± SE severity of nonglandular ulcers significantly increased from 0.4 ± 0.1 to 1.2 ± 0.2 over 5 weeks. Nonglandular ulcers significantly increased in number (mean ± SE, 1.3 ± 0.2 to 3.0 ± 0.2) and severity (mean ± SE, 1.2 ± 0.2 to 2.6 ± 0.2) during the 7-day alternating feed deprivation period. No effects of treatment were detected.
Conclusions and Clinical Relevance—In this model dietary oils did not prevent gastric ulcers from forming in the nonglandular portion of the stomach of horses. (Am J Vet Res 2005;66:2006–2011)
Abstract
Objective
To measure total body water (TBW) content in horses, using deuterium oxide (D20) dilution.
Animals
Six 8- to 10-year-old healthy untrained mixed-breed horses, weighing (mean ± SD) 503.4 ± 64.0 kg.
Procedure
After a 12-hour nonfeeding period, 6 horses were given D2O (0.14 g/kg of body weight) via nasogastric tube. Blood samples were collected from a preplaced indwelling jugular vein catheter prior to and 1 to 8, 10, 12, 14, and 24 hours after administration of D2O. Blood samples were centrifuged immediately, and plasma was collected and stored at −70 C until analysis. The D2O content in plasma was measured by zinc reduction to deuterium gas. The resulting gas was measured, using an isotope ratio mass spectrometer.
Results
Deuterium oxide was rapidly absorbed from the gastrointestinal tract of all horses, and reached peak (mean ± SD) plasma concentration (1,454.4 ± 163 delta D/ml or parts/thousand) 1 hour after administration. Plasma concentration decreased slowly during the next 2 to 3 hours, then remained statistically constant from 2 to 5 hours (early plateau phase) and 3 to 7 hours (late plateau phase) after administration. Mean ± SEM TBW content was 623.0 ± 2.2 ml/kg (62.3% of body weight) for the early plateau phase and 630.3 ± 2.2 ml/kg (63.0% of body weight) for the late plateau phase.
Conclusion
Deuterium oxide dilution appears to be of value for measurement of TBW content in horses, and has a 4-hour plateau effect. Equilibration of D2O with large intestinal water may be the reason for the prolonged equilibrium time and plateau effect seen in these horses.
Clinical Relevance
Deuterium oxide appears safe and efficacious for determining TBW content in horses and may be helpful for determining changes in TBW content during exercise and disease. (Am J Vet Res 1997;58:1060–1064)
Abstract
Objective—To determine whether expression of mRNA for sodium-potassium adenosine-triphosphatase (NAKA) and sodium-hydrogen exchanger (NHE) in samples of the nonglandular portion of the equine gastric mucosa was altered by exposure to volatile fatty acids (VFAs) in an acidic environment.
Animals—10 horses (5 ≤ 5 years old and 5 ≥ 12 years old).
Procedures—Samples of the nonglandular portion of the gastric mucosa were collected and exposed in Ussing chambers to Ringer's solution (control samples), Ringer's solution containing a mixture of VFAs (pH, 1.5 or 4.0), or Ringer's solution containing acetic acid (pH, 1.5 or 4.0). Expression of mRNA for the gene for the β1 subunit of NAKA and the gene for the NHE-3 isoform was determined by means of real-time PCR assays.
Results—For horses ≤ 5 years old, relative expression of mRNA for NAKA was significantly decreased and expression of mRNA for NHE was significantly increased following exposure to the mixture of VFAs or acetic acid, compared with expression in control samples. In contrast, for horses ≥ 12 years old, relative expression of mRNA for both NAKA and NHE was significantly increased following exposure to the mixture of VFAs or acetic acid, compared with expression in control samples.
Conclusions and Clinical Relevance—Results suggested that relative expression of mRNA for NAKA, but not NHE, in samples of the nonglandular portion of the equine gastric mucosa in response to exposure to VFAs in an acidic environment was an age-dependent event.
Abstract
Objective—To determine the effects of a 24-hour infusion of an isotonic electrolyte replacement fluid (IERF) on weight, serum and urine electrolyte concentrations, and other clinicopathologic variables in healthy neonatal foals.
Animals—4 healthy 4-day-old foals.
Design—Prospective study.
Procedure—An IERF was administered to each foal at an estimated rate of 80 mL/kg/d (36.4 mL/lb/d) for 24 hours. Body weight was measured before and after the infusion period. Urine was collected via catheter during 4-hour periods; blood samples were collected at 4-hour intervals. Variables including urine production; urine and serum osmolalities; sodium, potassium, and chloride concentrations in urine and serum; urine and serum creatinine concentrations; urine osmolality-to-serum osmolality ratio (OsmR); transtubular potassium gradient (TTKG); and percentage creatinine clearance (Crcl) of electrolytes were recorded at 0, 4, 8, 12, 16, 20, and 24 hours during the infusion period. Immediately after the study period, net fluid and whole-body electrolyte changes from baseline values were calculated.
Results—Compared with baseline values, urine and serum sodium and chloride serum concentrations, urine and serum osmolalities, OsmR, and percentage Crcl of sodium and chloride were significantly increased at various time points during the infusion; urine production did not change significantly. After 24 hours, weight, TTKG, serum creatinine concentration, and whole-body potassium had significantly decreased from baseline values.
Conclusions and Clinical Relevance—Results suggest that administration of an IERF containing a physiologic concentration of sodium may not be appropriate for use in neonatal foals that require maintenance fluid therapy. (J Am Vet Med Assoc 2005;227:1123–1129)
Summary
Blood viscosity (bv) was measured in 32 healthy horses at 6 spindle speeds (60, 30, 12, 6, 3, and 1.5 rpm) and for pcv of 40%, using a digital rotational cone and plate microviscometer. Also, in 7 of 32 horses, bv was measured 3 times each, for 3 pcv values (20, 40, and 60%), and at each spindle speed to determine effect of pcv on bv and machine and among-horse variations. Total plasma protein and fibrinogen concentrations were measured in all horses, using a standard refractometer and heat precipitation, respectively. In 7 of 32 horses, quantitative fibrinogen concentration was measured, using a quantitative fibrinogen assay. Plasma protein and fibrinogen concentrations were measured to determine their effect on bv.
Plasma total protein (6.0 to 7.5 g/dl) and fibrinogen (100 to 400 mg/dl) concentrations were within normal reference range for our laboratory. In this study of healthy horses, mean (± sd) bv values obtained for each pcv value and at each spindle speed were: for pcv of 20%, 2.39 ± 0.33 centipoise (cp) at 60 rpm, 2.52 ± 0.35 cp at 30 rpm, 2.80 ± 0.37 cp at 12 rpm, 2.96 ± 0.48 cp at 6 rpm, 3.04 ± 0.62 cp at 3 rpm, and 2.93 ± 0.96 cp at 1.5 rpm; for pcv of 40%, 3.98 ± 0.29 cp at 60 rpm, 4.40 ± 0.38 cp at 30 rpm, 5.26 ± 0.59 cp at 12 rpm, 6.36 ± 0.93 cp at 6 rpm, 7.34 ± 1.46 cp at 3 rpm, and 8.33 ± 2.61 cp at 1.5 rpm; and for pcv of 60%, 7.21 ± 0.91 cp at 60 rpm, 8.27 ± 1.05 cp at 30 rpm, 10.46 ± 1.38 cp at 12 rpm, 13.69 ± 1.82 cp at 6 rpm, 18.12 ± 2.81 cp at 3 rpm, and 23.44 ± 3.45 cp at 1.5 rpm.
Significant (P < 0.05) correlation between total plasma protein concentration and bv was found for pcv of 40% at all spindle speeds. Furthermore, significant (P < 0.05) correlation between quantitative plasma fibrinogen concentration and bv was found for pcv of 60% at the lower spindle speeds (6, 3, and 1.5 rpm).
The sd of measurement error and the among-horse sd for the digital rotational cone and plate microviscometer were greatest at the low spindle speeds for all pcv. The least variation was found for pcv of 20%.
The digital rotational cone and plate microviscometer is an accurate instrument for measuring bv at multiple pcv and spindle speeds in horses. Packed cell volume, plasma protein concentration, and fibrinogen concentration appear to affect bv in horses. Blood viscosity values obtained in this study will give insights into factors affecting bv in horses and will serve as a baseline for comparison with values in diseased horses.
Abstract
Objective—To characterize the physiologic response to IV bolus injection of glucose and insulin for development of a combined glucose-insulin test (CGIT) in horses.
Animals—6 healthy mares and 1 mare each with pituitary adenoma and urolithiasis.
Procedure—Horses were given a CGIT (glucose, 150 mg/kg; insulin, 0.1 U/kg); results were compared with a singular IV glucose tolerance test (GTT; 150 mg/kg) and a singular IV insulin sensitivity test (IST; 0.1 U/kg). Healthy horses were also given a CGIT after receiving xylazine and undergoing stress.
Results—Physiologically, the CGIT resulted in a 2-phase curve with positive (hyperglycemic) and negative (hypoglycemic) portions; the positive phase came first (250% of baseline at 1 minute). The descending segment declined linearly to baseline by approximately 30 minutes and to a nadir at 58% of baseline by 75 minutes. After a 35-minute valley, a linear ascent to baseline began. Addition of insulin in the CGIT increased glucose utilization by approximately 4.5 times during the positive phase but not during the negative phase. The diseases' effects and experimental inhibition of insulin secretion with xylazine and stress were detectable by use of the 2 phases of the CGIT. Only a single positive phase resulted from the GTT and a single negative phase from the IST.
Conclusions and Clinical Relevance—The CGIT resulted in a consistent, well-defined glycemia profile, which can be disrupted experimentally or by a disease process. The CGIT has clinical potential because it provides integrated information and more information than either the singular GTT or IST. (Am J Vet Res 2005;66:1598–1604)
Abstract
Objective—To compare the effects of hydrochloric acid (HCl) and various concentrations of volatile fatty acids (VFAs) on tissue bioelectric properties of equine stomach nonglandular (NG) mucosa.
Sample Population—Gastric tissues obtained from 48 adult horses.
Procedures—NG gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference (PD) were measured and electrical resistance (R) and conductance calculated for tissues after addition of HCl and VFAs (5, 10, 20, and 40mM) in normal Ringer's solution (NRS).
Results—Mucosa exposed to HCl in NRS (pH of 1.5 and, to a lesser extent, 4.0) had a significant decrease in Isc, PD, and R, whereas tissues exposed to acetic acid at a pH of < 4.0, propionic and butyric acids at a pH of ≤ 4.0, and valeric acid at a pH of ≤ 7.0 induced a concentration-dependent effect on reduction in these same values. Values for Isc returned to baseline (recovery of sodium transport) after addition of calcium carbonate in tissues exposed to all concentrations of VFAs except the higher concentrations of valeric acid at a pH of ≤ 4.0. Histologic examination revealed cell swelling in the mucosal layers below and adjacent to the stratum corneum in tissues exposed to HCl and VFAs at a pH of ≤ 4.0.
Conclusions and Clinical Relevance—The VFAs, especially acetic acid, in the presence of HCl at a pH of ≤ 4.0 appear to be important in the pathogenesis of NG mucosal ulcers in horses.
Abstract
Objective—To characterize the response of skin of nonallergic horses following ID injection of polyclonal rabbit anti-canine IgE (anti-IgE) and rabbit IgG.
Animals—6 healthy horses.
Procedures—Skin in the cervical area was injected ID with anti-IgE and IgG. Wheal measurements and skin biopsy specimens were obtained before and 20 minutes and 6, 24, and 48 hours after injection. Tissue sections were evaluated for inflammatory cells at 4 dermal depths. Immunohistochemical analysis for CD3, CD4, and CD8 was performed, and cell counts were evaluated.
Results—Anti-IgE wheals were significantly larger than IgG wheals at 20 minutes and 6 and 24 hours after injection. There were significantly more degranulated mast cells after anti-IgE injection than after IgG injection. There were significantly more eosinophils at 6, 24, and 48 hours and neutrophils at 6 hours after anti-IgE injection, compared with cell numbers at those same times after IgG injection. There were significantly more eosinophils in the deeper dermis of anti-IgE samples, compared with results for IgG samples. No significant differences between treatments were detected for CD3+, CD4+, or CD8+ cells.
Conclusions and Clinical Relevance—Injection of anti-IgE antibodies was associated with the development of gross and microscopic inflammation characterized by mast cell degranulation and accumulation of inflammatory cells, particularly eosinophils and neutrophils. This pattern appeared to be similar to that of horses with naturally developing allergic skin disease, although lymphocytes were not increased; thus, ID injection of anti-IgE in horses may be of use for evaluating allergic skin diseases of horses.
Abstract
Objective—To measure pH, volatile fatty acid (VFA) concentrations, and lactate concentrations in stomach contents and determine number and severity of gastric lesions in horses fed bromegrass hay and alfalfa hay-grain diets.
Animals—Six 7-year-old horses.
Procedure—A gastric cannula was inserted in each horse. Horses were fed each diet, using a randomized crossover design. Stomach contents were collected immediately after feeding and 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, and 24 hours after feeding on day 14. The pH and VFA and lactate concentrations were measured in gastric juice. Number and severity of gastric lesions were scored during endoscopic examinations.
Results—The alfalfa hay-grain diet caused significantly higher pH in gastric juice during the first 5 hours after feeding, compared with that for bromegrass hay. Concentrations of acetic, propionic, and isovaleric acid were significantly higher in gastric juice, and number and severity of nonglandular squamous gastric lesions were significantly lower in horses fed alfalfa hay-grain. Valeric acid, butyric acid, and propionic acid concentrations and pH were useful in predicting severity of nonglandular squamous gastric lesions in horses fed alfalfa hay-grain, whereas valeric acid concentrations and butyric acid were useful in predicting severity of those lesions in horses fed bromegrass hay.
Conclusions and Clinical Relevance—An alfalfa haygrain diet induced significantly higher pH and VFA concentrations in gastric juice than did bromegrass hay. However, number and severity of nonglandular squamous gastric lesions were significantly lower in horses fed alfalfa hay-grain. An alfalfa hay-grain diet may buffer stomach acid in horses. (Am J Vet Res 2000;61: 784–790)
Abstract
Objective—To identify the pathogenesis of gastric ulcers by comparing injury to the nonglandular gastric mucosa of horses caused by hydrochloric acid (HCl) or volatile fatty acids (VFAs).
Sample Population—Gastric tissues from 30 horses.
Procedure—Nonglandular gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference were measured and electrical resistance calculated for tissues after addition of HCl and VFAs to normal Ringer's solution (NRS). Tissues were examined histologically.
Results—Mucosa exposed to HCl in NRS (pH, 1.5) had a significant decrease in Isc, compared with Isc for mucosa exposed to NRS at pH 4.0 or 7.0. Also, exposure to 60mM acetic, propionic, and butyric acids (pH, 4.0 or 1.5) caused an immediate significant decrease in Isc. Recovery of sodium transport was detected only in samples exposed to acetic acid at pH 4.0. Recovery of sodium transport was not seen in other mucosal samples exposed to VFAs at pH ≤ 4.0.
Conclusions and Clinical Relevance—Acetic, butyric, and propionic acids and, to a lesser extent, HCl caused decreases in mucosal barrier function of the nonglandular portion of the equine stomach. Because of their lipid solubility at pH ≤ 4.0, undissociated VFAs penetrate cells in the nonglandular gastric mucosa, which causes acidification of cellular contents, inhibition of sodium transport, and cellular swelling. Results indicate that HCl alone or in combination with VFAs at gastric pH ≤ 4.0 may be important in the pathogenesis of gastric ulcers in the nonglandular portion of the stomach of horses. (Am J Vet Res 2003;64:404–412)
