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1.
Colloids are fluids containing large molecular weight molecules that do not readily cross the capillary membrane. Colloid replacement is becoming increasingly more common in the equine intensive care unit. Advantages of colloid therapy include improved oncotic pressure, rapid intravascular volume replacement, and improved microvascular perfusion. Edema formation is minimized through the use of colloids, rather than crystalloids, in the volume resuscitation of hypoproteinemic animals. Available colloids include both natural (biologic) and synthetic formulations. Plasma is the most common biologic colloid utilized in horses, and offers the advantage of providing a broad range of proteins in addition to its principle colloid, albumin. These additional proteins include coagulation factors, antithrombin, and immunoglobulins. The most widely used synthetic colloid in horses is hydroxyethyl starch (hetastarch). Side effects of hetastarch include dose-dependent effects on coagulation, primarily because of decreases in factor VIII and von Willebrand factor concentrations. Other synthetic or semisynthetic colloids include pentastarch, dextrans, and a polymerized ultrapurified bovine hemoglobin product. Monitoring of patients receiving colloid therapy should include direct colloid osmometry. Indirect estimates of colloid osmotic pressure are not reliable in critically ill patients and in those receiving synthetic colloids. Total protein measurements do not account for the oncotic contribution of synthetic colloids.  相似文献   

2.
Equine albumin solution can be a good therapeutic option in fluid replacement for treatment of horses with colic. The purpose of this study was to evaluate the effects of initial fluid therapy with equine albumin solution in horses presenting with colic and mild-to-moderate dehydration, and to compare this therapy with fluid therapy based on crystalloids alone. Nineteen horses of both genders presenting with colic and mild-to-moderate dehydration were used. Animals were randomly assigned to one of two groups (control: fluid therapy based on crystalloid solutions; experimental: fluid therapy based on equine albumin and crystalloid solutions). Physical examination, hematocrit determination, blood gas analysis, serum biochemistry, blood and peritoneal lactate assessment, and measurement of colloid osmotic and arterial pressure were performed at predetermined times. Good results were obtained with equine albumin solution. More fluid is attracted into and maintained in the intravascular compartment, despite infusion of small volumes, as indicated by higher arterial pressure, lower capillary refill time, lower hematocrit and serum protein concentrations, lower colloid osmotic pressure, and better skin turgor. Equine albumin solution has good oncotic action and is a safe fluid therapy option for horses with colic and mild-to-moderate dehydration. Our results suggest it can be a good choice of fluid for correction of severe dehydration, although further research is necessary to determine the adequate dose in such cases.  相似文献   

3.
The purpose of this study was to determine the duration of action of a single dose of hetastarch, a synthetic colloid, in hypoalbuminemic dogs. Thirty hypoalbuminemic dogs (albumin concentration, 2,0 g/dL) received 1 dose of hetastarch each, with an average dose of 18.1 mL/kg. Doses ranged from 7.7 to 43.9 mL/kg, with the majority of doses (n = 26) in the range of 10 to 25 mL/kg. Dogs were allotted to one of several groups: all dogs, dogs with acute gastrointestinal protein loss, dogs with chronic gastrointestinal protein loss, all dogs with gastrointestinal protein loss, and dogs with nongastrointestinal protein loss. Colloid oncotic pressure was measured immediately before and immediately after hetastarch administration, and 12 hours after hetastarch administration. There was a significant ( P < .001) increase in the mean colloid oncotic pressure after hetastarch treatment in all groups, except in the group with acute gastrointestinal protein loss. Twelve hours after hetastarch treatment, the mean colloid oncotic pressure had decreased significantly ( P < .001) from the immediate post-treatment value in all groups, except in dogs in the groups with acute and chronic gastrointestinal protein loss. Twelve hours after hetastarch treatment the mean colloid oncotic pressure was not significantly ( P < .001) different from the baseline mean colloid oncotic pressure in any of the groups. Twenty-three dogs (77%) survived their illness and were sent home, whereas, 7 (23%) died or were euthanized. The effect of a single dose of hetastarch on raising colloid oncotic pressure in dogs with hypoalbuminemia decreases significantly within 12 hours of administration, and is no longer significantly above baseline values. We conclude that multiple dosing is necessary to prolong the beneficial effects of hetastarch.  相似文献   

4.
The relationship between colloid osmotic pressure (COP) and protein concentration was investigated for purified proteins and plasma samples obtained from cattle, horses, dogs, and cats. At equivalent concentrations, bovine albumin exerted a COP that exceeded that of gamma-globulins by a mean factor of 4.4. Similar relationships between COP and protein were observed in the other species. Consequently, for a given total protein concentration, COP was dependent on the albumin/gamma-globulins ratio. A commonly used nomogram for estimating COP from protein concentration, the Landis-Pappenheimer equation, did not provide reliable results for plasma samples from these species.  相似文献   

5.
The last decade has led to major shifts in opinions on the use of hydroxyethyl starch (HES) solutions in fluid therapy, specifically in human patients with sepsis. The majority of evidence documenting adverse effects of HES solutions on coagulation and renal health come from studies in people. However, these findings have led to investigation into the safety of HES solutions in veterinary species. While there are now studies investigating the effects of HES solutions on coagulation and renal health in dogs, cats and horses, information regarding long-term follow-up, clinical significance of these changes and use of these solutions in critically ill animals is still lacking. The information presented here serves to review the physiology of oncotic pressure and the rationale behind colloid use, specifically HES solutions. Additionally, the foundation of arguments against the use of HES and the available literature regarding HES use in animals will be summarised.  相似文献   

6.
A normal plasma colloid osmotic pressure (COP) interval was established for foals and compared to values for adult horses. Plasma samples were obtained from 38 Thoroughbred foals that had normal findings on postfoaling examination and 10 healthy Thoroughbred adult horses. Samples were analyzed using a commercially available colloid osmometer. Fifty samples were obtained from 38 foals. Twelve foals had 2 samples taken, 1 during the 1st 24 hours of life and the 2nd between 24 and 72 hours of life. For foals with 2 samples, only 1 randomly selected value was used in group analysis. Total plasma protein, albumin, and globulin concentrations were measured on all samples from foals. The mean measured plasma COP for foals was 18.8 +/- 1.9 mm Hg for the 38 samples analyzed. Measured plasma COP did not differ significantly over the time period examined for either the 12 paired samples (P = .13) or with regression analysis of the 38 samples (P = .13). Calculation of mean COP, based on previously published quadratic equations using total protein, albumin, and globulin concentrations, underestimated mean measured foal COP values except for when total protein measured by refractometer was used in the Landis-Pappenheimer equation. In conclusion, the plasma COP interval (95% CI: 15.0 mm Hg, 22.6 mm Hg) obtained for healthy foals in this study was found to be lower than that of healthy adult Thoroughbreds (20.6 +/- 0.7 mm Hg, P = .006).  相似文献   

7.
BACKGROUND: Small volume resuscitation has been advocated as a beneficial therapy for endotoxemia in horses but this therapy has not been investigated in a prospective manner. The objective of this study was to determine the cardiopulmonary effects of small-volume resuscitation using hypertonic saline solution (HSS) plus Hetastarch (HES) during experimental endotoxemia in anesthetized horses. HYPOTHESIS: Treatment of horses with induced endotoxemia using HES-HSS does not alter the response of various cardiopulmonary indices when compared to treatment with either small- or large-volume isotonic crystalloid solutions. ANIMALS: Eighteen healthy horses were randomly assigned to 1 of 3 groups. Anesthesia was maintained with halothane. Endotoxemia was induced by administering 50 microg/kg of Escherichia coli endotoxin IV. The horses were treated over 30 minutes with 15 mL/kg of balanced polyionic crystalloid solution (control), 60 mL/kg of balanced polyionic crystalloid solution (ISO), or 5 mL/kg of HSS followed by 10 mL/kg of HES (HSS-HES). METHODS: Prospective randomized trial. RESULTS: Cardiac output (CO) after endotoxin infusion increased significantly (P < .05) from baseline in all groups, whereas mean central venous pressure increased significantly (P < .05) in the ISO group only. Mean pulmonary artery pressure increased from baseline (P < .05) in horses treated with isotonic fluids and HSS-HES. There was no effect of treatment with HSS-HES on CO, systemic vascular resistance (SVR), mean arterial pressure, blood lactate concentrations, or arterial oxygenation. CONCLUSIONS AND CLINICAL IMPORTANCE: The use of HSS-HES failed to ameliorate the deleterious hemodynamic responses associated with endotoxemia in horses. The clinical value of this treatment in horses with endotoxemia remains unconfirmed.  相似文献   

8.
OBJECTIVE: To compare effects of oral supplementation with an experimental potassium-free sodium-abundant electrolyte mixture (EM-K) with that of oral supplementation with commercial potassium-rich mixtures (EM+K) on acid-base status and plasma ion concentrations in horses during an 80-km endurance ride. ANIMALS: 46 healthy horses. PROCEDURE: Blood samples were collected before the ride; at 21-, 37-, 56-, and 80-km inspection points; and during recovery (ie, 30-minute period after the ride). Consumed electrolytes were recorded. Blood was analyzed for pH, PvCO2, and Hct, and plasma was analyzed for Na+, K+, Cl-, Ca2+, Mg2+, lactate, albumin, phosphate, and total protein concentrations. Plasma concentrations of H+ and HCO3-, the strong ion difference (SID), and osmolarity were calculated. RESULTS: 34 (17 EM-K and 17 EM+K treated) horses finished the ride. Potassium intake was 33 g less and Na+ intake was 36 g greater for EM-K-treated horses, compared with EM+K-treated horses. With increasing distance, plasma osmolarity; H+, Na+, K+, Mg2+, phosphate, lactate, total protein, and albumin concentrations; and PvCO2 and Hct were increased in all horses. Plasma HCO3-, Ca2+, and Cl- concentrations were decreased. Plasma H+ concentration was significantly lower in EM-K-treated horses, compared with EM+K-treated horses. Plasma K+ concentrations at the 80-km inspection point and during recovery were significantly less in EM-K-treated horses, compared with EM+K-treated horses. CONCLUSIONS AND CLINICAL RELEVANCE: Increases in plasma H+ and K+ concentrations in this endurance ride were moderate and unlikely to contribute to signs of muscle fatigue and hyperexcitability in horses.  相似文献   

9.
Hydroxyethyl starch (HES) solution is an effective colloidal infusion solution in humans for treatment of hypovolaemic shock, but it has not been compared with fluids currently available for use in horses. On the basis of plasma-expanding effect of HES in normal horses, a 10% medium-molecular 200/0.5 solution of HES was subsequently tested in hypovolaemic horses. Six normal horses were given five protocols of a single infusion of HES at varying dosage rates (5, 10, 15 ml HES/kg), as well as isotonic saline (15 ml/kg) and hypertonic saline (4 ml/kg b.w.). Dehydrated horses suffering from acute colitis or those which had been treated surgically for ileus of the small or large intestine were given an i.v. infusion of 10 ml HES/kg in combination with 10 ml saline/kg. Clinical data and blood samples for testing were taken before the infusion, and then 10 min, 1 h, 2, 4, 6, 8, 10, 12 and 24 h after infusion (a.i.). A significant decrease in haematocrit was observed in protocol 1-5 for a period of up to 4, 4, 10 h, 10 min and up to 10 min; in group of colitis, during the entire 24-h testing period, and in groups of ileus of small intestine and of large intestine, up to 4 and 10 h a.i. HES decreases better and longer-lasting haematocrit and total protein than either isotonic or hypertonic saline. Half-life of HES increases due to higher dosage (5.83, 7.63 and 11.48 h) and distribution is exclusively intravascular. In normal horses of protocol 1-3 using HES aPTT, sodium and potassium were within the physiological range. Serum amylase activity is increased in horses using HES. On the basis of this clinical study, the decreasing effect of urea and creatinine in colic patients after surgery and fewer instances of postoperative ileus a dosage of 10 ml HES/kg could be recommended.  相似文献   

10.
OBJECTIVE: To quantify plasma and urine nitric oxide (NO) concentrations before and after low-dose endotoxin infusion in horses. ANIMALS: 11 healthy adult female horses. Procedure-Eight horses were given endotoxin (35 ng/kg of body weight,i.v.) over 30 minutes. Three sentinel horses received an equivalent volume of saline (0.9% NaCl) solution over the same time. Clinical signs of disease and hemodynamic variables were recorded, and urine and plasma samples were obtained to measure NO concentrations prior to endotoxin infusion (t = 0) and every hour until postinfusion hour (PIH) 6, then every 2 hours until PIH 24. Blood for hematologic and metabolic analyses and for serum cytokine bioassays were collected at 0 hour, every hour until PIH 6, every 2 hours through PIH 12, and finally, every 6 hours until PIH 24. RESULTS: Differences in plasma NO concentrations across time were not apparent, but urine NO concentrations significantly decreased at 4 and 20 to 24 hours in endotoxin-treated horses. Also in endotoxin-treated horses, alterations in clinical signs of disease, and hemodynamic, metabolic, and hematologic variables were significant and characteristic of endotoxemia. Serum interleukin-6 (IL-6) activity and tumor necrosis factor (TNF) concentrations were increased above baseline values from 1 to 8 hours and 1 to 2 hours, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Plasma and urine NO concentrations did not increase in horses after administration of a low dose of endotoxin, despite induction of an inflammatory response, which was confirmed by increased TNF and IL-6 values characteristic alterations in clinical signs of disease, and hematologic, hemodynamic and metabolic variables.  相似文献   

11.
Background: Direct colloid osmometry provides an objective assessment of the oncotic effects of crystalloid or colloidal fluid therapy, which is especially useful in monitoring fluid therapy of critically ill camelids due to their tendency toward nonspecific hypoproteinemia with increased risk of developing edema and ascites. Objectives: The aims of this study were to measure colloid osmotic pressure (COP) of alpacas and llamas, determine its correlation with concentrations of total protein (TP) and total solids (TS), as well as both albumin (A) and globulin (G) concentrations in the same model (A+G), and evaluate the effects of sample type and storage conditions on COP. Methods: Blood was collected from clinically healthy alpacas (n=23) and llamas (n=22) into heparin tubes. COP of fresh whole blood (COPFB) and plasma (COPFP) was determined using a membrane osmometer. For 20 alpacas, COP of refrigerated whole blood (COPRB) and frozen plasma (COPFrP) was also measured. Correlations between COPFB and TS, TP, and A+G concentrations were assessed by simple and multiple regression analysis to model potential predictors. Results: Median COPFB from alpacas (24.6 mmHg, range 19.3–28.1) was not significantly different from that of llamas (25.3 mmHg, range 22.5–33.7). Sample type or storage conditions did not affect COP. Measured COP had a strong positive linear correlation with TS, TP, and A+G concentrations in alpacas (r2=.7, .74, and .88, respectively). In llamas, COP correlated best with TS concentration (r2=.59), whereas correlation with TP and A+G concentrations was poor (r2=.19 and .25, respectively). Conclusion: COP can be measured using heparinized whole blood or plasma, either fresh or stored. Direct measurement is recommended whenever quantitative knowledge of COP is required in clinical or research setting. Further studies are needed to verify if the poor association of COP with TP found in this study can be generalized to llamas.  相似文献   

12.
The synthetic colloids, dextran and hydroxyethyl starch, have only recently enjoyed widespread use in critically ill veterinary patients. Plasma proteins normally provide colloid oncotic pressure and, thereby, are the primary force responsible for retaining fluid within the vasculature. Abnormally low plasma protein concentrations, common in the critically ill patient, are associated with excessive fluid loss from capillaries and development of peripheral or pulmonary edema. Infusion of colloid solutions decreases the potential for and severity of edema in hypooncotic states. Dextran and hydroxyethyl starch solutions also provide other positive hemodynamic benefits and are a preferable alternative to crystalloid usage in the resuscitation of selected patients from hypotensive and hypovolemic states. Potential side effects of synthetic colloid infusion include anaphylactoid reactions, increased risk of bleeding, interference with cross matching, and acute renal failure. Knowledge of the mechanisms responsible for these adverse effects minimizes their occurrence.  相似文献   

13.
A randomized, controlled, blinded clinical trial was performed to determine whether butorphanol administered by continuous rate infusion (CRI) for 24 hours after abdominal surgery would decrease pain and surgical stress responses and improve recovery in horses. Thirty-one horses undergoing exploratory celiotomy for abdominal pain were randomly assigned to receive butorphanol CRI (13 microg/kg/h for 24 hours after surgery; treatment) or isotonic saline (control). All horses received flunixin meglumine (1.1 mg/kg IV q12h). There were no significant differences between treatment and control horses in preoperative or operative variables. Treatment horses had significantly lower plasma cortisol concentration compared with control horses at 2, 8, 12, 24, 36, and 48 hours after surgery. Mean weight loss while hospitalized was significantly less for treatment horses than control horses, whether expressed as total decrease in body weight (13.9+/-3.4 and 27.9+/-4.5 kg, respectively) or as a percentage decrease in body weight (2.6+/-0.7 and 6.3+/-1.1%, respectively). Treatment horses were significantly delayed in time to first passage of feces (median times of 15 and 4 hours, respectively). Treatment horses had significantly improved behavior scores during the first 24 hours after surgery, consistent with the conclusion that they experienced less pain during that time. Butorphanol CRI during the immediate postoperative period significantly decreased plasma cortisol concentrations and improved recovery characteristics in horses undergoing abdominal surgery.  相似文献   

14.
Veterinary patients are treated with colloid solutions for plasma volume expansion and maintenance of plasma colloid oncotic pressure (COP). In practice COP is usually extrapolated from measurement of albumin, total protein, or refractometric total solids (TS) as an estimate of total protein. The objective of this study was to determine if refractometer readings accurately reflect levels of synthetic colloid in the blood. Serial dilutions of synthetic colloids Dextran 70 and hetastarch into 2.5% and 5% human serum albumin (HSA) were prepared, and COP and TS measurements were performed. Synthetic colloids were found to produce a significant increase in measured COP, without a significant change in refractometric TS readings. Measured COP correlated well with concentration of synthetic colloid. In clinical patients, treatment of decreased COP with synthetic colloids should be monitored by direct measurement of COP or by observing resolution of clinical signs of hypovolemia or edema. (Vet Emerg & Crit Care, 1998; 8: 21–26)  相似文献   

15.
OBJECTIVE: To determine an infusion rate of butorphanol tartrate in horses that would maintain therapeutic plasma drug concentrations while minimizing development of adverse behavioral and gastrointestinal tract effects. ANIMALS: 10 healthy adult horses. PROCEDURE: Plasma butorphanol concentrations were determined by use of high-performance liquid chromatography following administration of butorphanol by single IV injection (0.1 to 0.13 mg/kg of body weight) or continuous IV infusion (loading dose, 17.8 microg/kg; infusion dosage, 23.7 microg/kg/h for 24 hours). Pharmacokinetic variables were calculated, and changes in physical examination data, gastrointestinal tract transit time, and behavior were determined over time. RESULTS: A single IV injection of butorphanol was associated with adverse behavioral and gastrointestinal tract effects including ataxia, decreased borborygmi, and decreased defecation. Elimination half-life of butorphanol was brief (44.37 minutes). Adverse gastrointestinal tract effects were less apparent during continuous 24-hour infusion of butorphanol at a dosage that resulted in a mean plasma concentration of 29 ng/ml, compared with effects after a single IV injection. No adverse behavioral effects were observed during or after continuous infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Continuous IV infusion of butorphanol for 24 hours maintained plasma butorphanol concentrations within a range associated with analgesia. Adverse behavioral and gastrointestinal tract effects were minimized during infusion, compared with a single injection of butorphanol. Continuous infusion of butorphanol may be a useful treatment to induce analgesia in horses.  相似文献   

16.
OBJECTIVE: To compare gentamicin concentrations achieved in synovial fluid and joint tissues during IV administration and continuous intra-articular (IA) infusion of the tarsocrural joint in horses. ANIMALS: 18 horses with clinically normal tarsocrural joints. PROCEDURE: Horses were assigned to 3 groups (6 horses/group) and administered gentamicin (6.6 mg/kg, IV, q 24 h for 4 days; group 1), a continuous IA infusion of gentamicin into the tarsocrural joint (50 mg/h for 73 hours; group 2), or both treatments (group 3). Serum, synovial fluid, and joint tissue samples were collected for measurement of gentamicin at various time points during and 73 hours after initiation of treatment. Gentamicin concentrations were compared by use of a Kruskal-Wallis ANOVA. RESULTS: At 73 hours, mean +/- SE gentamicin concentrations in synovial fluid, synovial membrane, joint capsule, subchondral bone, and collateral ligament of group 1 horses were 11.5 +/- 1.5 microg/mL, 21.1 +/- 3.0 microg/g, 17.1 +/- 1.4 microg/g, 9.8 +/- 2.0 microg/g, and 5.9 +/- 0.7 microg/g, respectively. Corresponding concentrations in group 2 horses were 458.7 +/- 130.3 microg/mL, 496.8 +/- 126.5 microg/g, 128.5 +/- 74.2 microg/g, 99.4 +/- 47.3 microg/g, and 13.5 +/- 7.6 microg/g, respectively. Gentamicin concentrations in synovial fluid, synovial membrane, and joint capsule of group 1 horses were significantly lower than concentrations in those samples for horses in groups 2 and 3. CONCLUSIONS AND CLINICAL RELEVANCE: Continuous IA infusion of gentamicin achieves higher drug concentrations in joint tissues of normal tarsocrural joints of horses, compared with concentrations after IV administration.  相似文献   

17.
An equine antiserum to core lipopolysaccharide was produced by inoculation of 6 horses with a boiled cell bacterin made from the J-5 mutant of Escherichia coli O111:B4. The antiserum immunoglobulin G titer to J-5 mutant E coli, as determined by enzyme-linked immunosorbent assay, was 1:15,006. Pooled serum prepared before inoculation (preimmune serum) had a J-5 immunoglobulin G titer of 1:350. The J-5 antiserum was tested for its protective efficacy in sublethal endotoxemia in 14 horses. Four horses served as nontreated controls and were given nothing before endotoxin challenge exposure (10 micrograms/kg of body weight, IV). Pooled preimmune serum (3 ml/kg, IV) was administered to 5 horses and J-5 antiserum (3 ml/kg, IV) was administered to 5 other horses 2 to 15 hours before endotoxin challenge exposure. During the 24 hours postendotoxin challenge exposure, endotoxemia was accompanied by significant (P less than 0.05) time-related changes in temperature, heart rate, pulse character, respiratory rate and character, capillary refill time, mucous membrane color, fecal composition, attitude, PCV, total plasma protein, WBC count, platelet count, plasma fibrinogen, prothrombin time, activated partial thromboplastin time, fibrinolytic degradation products, plasma glucose, and plasma lactate in all horses. There were no apparent treatment vs time interactions (P greater than 0.05). Two horses (1 control and 1 given J-5 antiserum) died suddenly from unknown causes immediately after endotoxin challenge exposure. Seemingly, equine antiserum to core lipopolysaccharide did not provide protection from the adverse effects of experimental endotoxemia produced by bolus IV infusion of 10 micrograms of endotoxin/kg.  相似文献   

18.
Responses of jejunal transcapillary and transmucosal fluid fluxes to IV infusion of crystalloid or colloid solutions were evaluated in 12 dogs. One isolated intestinal segment in each dog was used as the control segment, and 2 segments were distended to a intraluminal hydrostatic pressure of 10 cm of H2O. The artery supplying 1 of the 2 distended (autoperfused) segments was cannulated and perfused with blood from the femoral artery. One of the 2 distended segments was autoperfused from the femoral artery. Intraluminal pressure was increased in the autoperfused segment and in 1 other segment for three, 20-minute periods after administration of the crystalloid or colloid solution. Net transmucosal fluid flux was estimated, using a volume recovery method. In each autoperfused segment, blood flow, capillary pressure, lymph flow, and plasma protein and lymph protein concentrations were measured during each 20-minute distention period. Systemic arterial pressure was monitored throughout the procedure. Plasma and tissue oncotic pressures were calculated from the plasma protein and lymph protein concentrations. Total vascular resistance and precapillary and postcapillary resistances were determined. Capillary pressure increased after infusion with colloids and crystalloids, with the effects being more prolonged in the colloid group. Plasma oncotic pressure transiently increased after infusion with colloids and decreased after infusion with crystalloids. Lymph flow increased only in crystalloid-treated dogs. Due to alterations in transcapillary fluid filtration, crystalloids induced a net loss of fluid into the intestinal lumen, whereas the fluid absorptive capacity of the jejunum was unaltered by colloid treatment.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
OBJECTIVE: To measure and compare the concentration and composition of very low-density lipoprotein (VLDL) in plasma and selected lipids in serum of horses fed mixed grass hay ad libitum or denied feed for 36 hours. ANIMALS: 4 healthy adult mares. PROCEDURE: Mares were either fed mixed grass hay ad libitum or denied feed for 36 hours beginning at 8:00 AM. Blood samples were collected every 2 hours during the study period and analyzed for nonesterified fatty acid (NEFA), triglyceride (TG), VLDL, and glucose concentrations and composition of VLDL. RESULTS: Withholding feed significantly increased mean serum concentrations of NEFA. By 36 hours, a 16-fold increase in mean serum NEFA concentration and 2-fold increase in mean plasma VLDL concentration, compared with baseline values, were detected. Mean plasma TG concentrations significantly increased with time in feed-deprived horses. Significantly lower overall mean plasma glucose concentrations were detected in feed-deprived horses. Mean percentage of protein in VLDL was significantly lower in feed-deprived horses. Plasma VLDL concentrations varied widely among horses in response to withholding feed. Plasma TG and VLDL concentrations remained unaltered in 2 horses. CONCLUSIONS AND CLINICAL RELEVANCE: Withholding feed significantly increases blood lipid concentrations in horses, but individual horses respond differently. Serum NEFA concentrations were increased in all 4 horses denied feed, indicating mobilization of tissue triglyceride stores. Variation in plasma VLDL concentration in response to withholding feed suggests that its metabolism is strongly influenced by other, as yet undetermined, factors in horses. Differences in the plasma VLDL concentrations among horses in response to withholding feed may be used as an indication of susceptibility to the hyperlipemic syndrome of Equidae.  相似文献   

20.
OBJECTIVE: To characterize the plasma pharmacokinetics and clinical effects of pirfenidone administered IV in healthy horses. ANIMALS: 6 adult horses. PROCEDURES: A 15 mg/kg dose of pirfenidone was administered IV over 5 minutes. Physical variables were recorded and blood samples collected prior to infusion; 2.5 minutes after beginning infusion; at the end of infusion; and at 3, 6, 9, 12, 15, 20, 25, 30, 40, 50, 60, 75, and 90 minutes and 2, 2.5, 3, 4, 6, 8, 12, and 24 hours after completion of infusion. Plasma concentrations of pirfenidone and its metabolites were determined. RESULTS: Mild clinical effects, including tachycardia and muscle fasciculations, were observed during drug administration but stopped at the end of the infusion. Pirfenidone and 2 metabolites, hydroxypirfenidone and carboxypirfenidone, were detected by the end of the 5-minute infusion. Mean peak plasma concentration of pirfenidone was 182.5 micromol/L, detected at the end of the infusion. Mean peak plasma concentrations of hydroxypirfenidone and carboxypirfenidone were 1.07 and 3.4 micromol/L, respectively, at 40 minutes after infusion. No parent drug or metabolites were detected at 24 hours. Distribution of pirfenidone best fit a 2-compartment model, and the drug had mean +/- SEM elimination half-life of 86.0 +/- 4.7 minutes, mean body clearance of 6.54 +/- 0.45 mL/kg/min, and apparent volume of distribution at steady state of 0.791 +/- 0.056 L/kg. CONCLUSIONS AND CLINICAL RELEVANCE: Intravenous administration of pirfenidone was tolerated with transient adverse affects during infusion, and drug clearance was rapid.  相似文献   

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