Ferulic acid ameliorates concanavalin A-induced hepatic fibrosis in mice via suppressing TGF-ß/smad signaling.

BACKGROUND AND AIM: Hepatic fibrosis, one of the main reasons for death globally, is a serious complication of chronic liver disorders. However, the available therapies for liver fibrosis are limited, ineffective, and often associated with adverse events. Hence, seeking for a novel, effective therapy is warranted. Our objective was to investigate the potential efficacy of ferulic acid (FA), a phenolic phytochemical, at different doses in hindering the progress of concanavalin A (Con A)-induced hepatic fibrosis and explore the involved mechanisms. METHODS: Thirty-six mice were assorted into 6 groups (n = 6): Group I (control); group II received FA (20 mg/kg/day orally for 4 weeks); group III received Con A (6 mg/kg/week/i.v.) for 4 weeks; groups IV, V, and VI received Con A and were offered FA at 5, 10, and 20 mg/kg/day, respectively. RESULTS: The data showed the palliative effect of FA against Con A-induced fibrosis in a dose-dependent manner. This was obvious from the recovery of liver markers and hepatic architecture with the regression of fibrosis in FA-treated mice. FA abolished Con A-mediated oxidative insults and promoted the antioxidant enzyme activities, which run through the Nrf2/HO-1 signaling. Additionally, FA suppressed Con A-induced increase in NF-kB and IL-ß levels, and TNF-α immune-expression. The anti-fibrotic effect of FA was evident from the drop in TGF-ß, smad3 levels, α-SMA expression, and hydroxyproline content. CONCLUSION: FA attenuated Con A-induced liver fibrosis through stimulating Nrf2 signaling, suppressing NF-kB, and inhibiting the TGF-ß/smad3 signaling pathway. Thus FA can be considered as a promising therapy for combating liver fibrosis.

Current review of isoxazoline ectoparasiticides used in veterinary medicine.

The isoxazolines are a novel class of ectoparasiticides with potent inhibitory activity on glutamate- and gamma-aminobutyric acid-gated chloride channel located in nervous system of invertebrates. In recent years, studies have been performed to evaluate the efficacy and safety of isoxazolines against various types of ectoparasites, including fleas, ticks, and mites. As more single and combined isoxazoline products have been approved by the United States Food and Drug Administration and European Medicines Agency, a more comprehensive understanding of isoxazolines becomes essential for veterinary clinical practitioners. This article provides a complete review of isoxazolines with respect to pharmacodynamics, pharmacokinetics, ectoparasiticidal efficacy, and safety, which will provide veterinarians information to allow them to make the best choice of ectoparasiticide for their clients' specific needs.

Consuming Different Structural Parts of Bamboo Induce Gut Microbiome Changes in Captive Giant Pandas.

Giant pandas consume different structural parts of bamboo (shoots, leaves and culms) during different seasons. Previous research showed different bamboo parts have varying nutritional content and that a long-term diet consisting of a single part of bamboo resulted in remarkable metabolic changes within captive giant pandas. However, the effects on the gut microbiome of giant pandas, as a result of a single bamboo part diet, have not been investigated. Here, we evaluated the changes in gut microbial communities based on single bamboo part diets and their potential implications by using 16S rRNA gene-based amplicon sequencing and metagenome shotgun sequencing. We found that the composition and function of the gut microbiome from captive giant pandas fed exclusively culms were significantly different from that of individuals fed shoots or leaves. During the culm feeding period, the gut microbiome showed strongest digestive capabilities for cellulose, hemicellulose and starch, and had the highest potential abilities for the biosynthesis of bile acids, fatty acids and amino acids. This suggests the microbiome aids in breaking down culm, which is more difficult for giant pandas to digest, as a means to compensate for the nutrient poor content of the culm. Genes related to fatty acid metabolism and tricarboxylic acid cycle enzymes were more abundant during the leaf stage diet than that in the shoot and culm stages. Thus, the microbiome may help giant pandas, which typically have low lipase levels, with fat digestion. These results illustrate that adaptive changes in the gut microbiome community and function may be an important mechanism to aid giant panda digestion when consuming different structural parts of bamboo.

Effects of verapamil on the pharmacokinetics of ivermectin in rabbits.

This study was aimed to investigate the influence of verapamil-mediated inhibition of P-glycoprotein (P-gp) on the pharmacokinetics of ivermectin (IVM) given orally and subcutaneously (SC) to rabbits. Twenty New Zealand rabbits were allotted to 4 groups (n = 5) and received IVM either orally or SC (0.4 mg/kg) alone or co-administered with verapamil (2 mg/kg SC, 3 times at a 12-hr interval). Plasma, fecal, and urine samples were collected over 30 days after medication to assess IVM concentrations in these samples. No significant differences were observed in the pharmacokinetic parameters of IVM between oral and SC administrations. The area under the plasma concentration-time curve was higher (p < .05) after IVM (oral)/verapamil treatment, compared with oral IVM alone. Moreover, the time to the Cmax of IVM was shorter (p < .05), whereas the elimination half-life and the mean residence time were longer (p < .05) in the presence of verapamil. The IVM/verapamil combination administered orally or SC reduced fecal IVM concentrations, compared with IVM alone. In conclusion, the significant changes by verapamil on the pharmacokinetics of IVM, likely due to the inhibition of a P-gp-mediated intestinal secretion, may change IVM's antinematodal activity.

Pharmacokinetics, tissue residues, and ex vivo pharmacodynamics of tylosin against Mycoplasma anatis in ducks.

The pharmacokinetics of tylosin were investigated in 3 groups of ducks (n = 6). They received a single dose of tylosin (50 mg/kg) by intravenous (IV), intramuscular (IM), and oral administrations, respectively. Plasma samples were collected at various time points to 24 hr post-administration to evaluate tylosin concentration over time. Additionally, tylosin residues in tissues and its withdrawal time were assessed using 30 ducks which received tylosin orally (50 mg/kg) once daily for 5 consecutive days. After IV administration, the volume of distribution, elimination half-life, area under the plasma concentration-time curve, and the total body clearance were 7.07 ± 1.98 L/kg, 2.04 hr, 19.47 µg hr/ml, and 2.82 L hr-1  kg-1 , respectively. After IM and oral administrations, the maximum plasma concentrations were 3.70 and 2.75 µg/ml achieved at 1 and 2 hr, and the bioavailability was 93.95% and 75.77%, respectively. The calculated withdrawal periods of tylosin were 13, 8, and 5 days for kidney, liver, and muscle, respectively. For the pharmacodynamic profile, the minimum inhibitory concentration for tylosin against M. anatis strain 1,340 was 1 µg/ml. The calculated optimal oral dose of tylosin against M. anatis in ducks based on the ex vivo pharmacokinetic/pharmacodynamic modeling was 61 mg kg-1  day-1 .

Identification of an antigenic domain in the N-terminal region of avian hepatitis E virus (HEV) capsid protein that is not common to swine and human HEVs.

The antigenic domains located in the C-terminal 268 amino acid residues of avian hepatitis E virus (HEV) capsid protein have been characterized. This region shares common epitopes with swine and human HEVs. However, epitopes in the N-terminal 338 amino acid residues have never been reported. In this study, an antigenic domain located between amino acids 23 and 85 was identified by indirect ELISA using the truncated recombinant capsid proteins as coating antigens and anti-avian HEV chicken sera as primary antibodies. In addition, this domain did not react with anti-swine and human HEV sera. These results indicated that the N-terminal 338 amino acid residues of avian HEV capsid protein do not share common epitopes with swine and human HEVs. This finding is important for our understanding of the antigenicity of the avian HEV capsid protein. Furthermore, it has important implications in the selection of viral antigens for serological diagnosis.

Increasing the number of masticatory cycles is associated with reduced appetite and altered postprandial plasma concentrations of gut hormones, insulin and glucose.

To determine the influence of masticatory efficiency on postprandial satiety and glycaemic response, twenty-one healthy males were recruited for this randomised cross-over trial. The participants consumed a fixed amount of pizza provided in equal-sized portions by chewing each portion either fifteen or forty times before swallowing. Subjective appetite was measured by appetite questionnaires at regular intervals for 3 h after the meal and plasma samples were collected for the measurement of selected satiety-related hormones, glucose, insulin and glucose-dependent insulinotropic peptide (GIP) concentrations. An ad libitum meal was provided shortly after the last blood sample was drawn and the amount eaten recorded. Compared with fifteen chews, chewing forty times per portion resulted in lower hunger (P= 0·009), preoccupation with food (P= 0·005) and desire to eat (P= 0·002). Meanwhile, plasma concentrations of glucose (P= 0·024), insulin (P< 0·001) and GIP (P< 0·001) were higher following the forty-chews meal. Chewing forty times before swallowing also resulted in a higher plasma cholecystokinin concentration (P= 0·045) and a trend towards a lower ghrelin concentration (P= 0·051). However, food intake at the subsequent test meal did not differ (P= 0·851). The results suggest that a higher number of masticatory cycles before swallowing may provide beneficial effects on satiety and facilitate glucose absorption.

The effect of food form on satiety.

To understand the influence of food form on satiety, 19 male participants attended two separate test sessions to consume either a liquid-solid meal (LS), which consisted of whole pieces of vegetable in a broth, or a liquid version of the same ingredients [liquid meal (LM)]. Following this meal, appetite questionnaires and blood samples were collected at regular intervals over 3 h. An ad libitum meal was then served and the amount eaten recorded. Fullness and preoccupation with food were higher following the LM compared with the LS (p = 0.001 and p = 0.031, respectively). Postprandial plasma concentration of cholecystokinin (p < 0.001) and insulin (p < 0.001) was higher and plasma glucose concentration was lower (p = 0.003) following the LM compared with the LS. However, there was no difference in the food intake at the subsequent meal. These results suggest that food form has a limited effect on satiety; however, the influence of the postprandial insulin response warrants further attention.

Should Airway Interstitial Fluid Be Used to Evaluate the Pharmacokinetics of Macrolide Antibiotics for Dose Regimen Determination in Respiratory Infection?

Macrolide antibiotics are important drugs to combat infections. The pharmacokinetics (PK) of these drugs are essential for the determination of their optimal dose regimens, which affect antimicrobial pharmacodynamics and treatment success. For most drugs, the measurement of their concentrations in plasma/serum is the surrogate for drug concentrations in target tissues for therapy. However, for macrolides, simple reliance on total or free drug concentrations in serum/plasma might be misleading. The macrolide antibiotic concentrations of serum/plasma, interstitial fluid (ISF), and target tissue itself usually yield very different PK results. In fact, the PK of a macrolide antibiotic based on serum/plasma concentrations alone is not an ideal predictor for the in vivo efficacy against respiratory pathogens. Instead, the PK based on drug concentrations at the site of infection or ISF provide much more clinically relevant information than serum/plasma concentrations. This review aims to summarize and compare/discuss the use of drug concentrations of serum/plasma, airway ISF, and tissues for computing the PK of macrolides. A better understanding of the PK of macrolide antibiotics based on airway ISF concentrations will help optimize the antibacterial dose regimen as well as minimizing toxicity and the emergence of drug resistance in clinical practice.

Probiotics and Postbiotics as an Alternative to Antibiotics: An Emphasis on Pigs.

Probiotics are being used as feed/food supplements as an alternative to antibiotics. It has been demonstrated that probiotics provide several health benefits, including preventing diarrhea, irritable bowel syndrome, and immunomodulation. Alongside probiotic bacteria-fermented foods, the different structural components, such as lipoteichoic acids, teichoic acids, peptidoglycans, and surface-layer proteins, offer several advantages. Probiotics can produce different antimicrobial components, enzymes, peptides, vitamins, and exopolysaccharides. Besides live probiotics, there has been growing interest in consuming inactivated probiotics in farm animals, including pigs. Several reports have shown that live and killed probiotics can boost immunity, modulate intestinal microbiota, improve feed efficiency and growth performance, and decrease the incidence of diarrhea, positioning them as an interesting strategy as a potential feed supplement for pigs. Therefore, effective selection and approach to the use of probiotics might provide essential features of using probiotics as an important functional feed for pigs. This review aimed to systematically investigate the potential effects of lactic acid bacteria in their live and inactivated forms on pigs.

Evaluation of Recent Intranasal Drug Delivery Systems to the Central Nervous System.

Neurological diseases continue to increase in prevalence worldwide. Combined with the lack of modifiable risk factors or strongly efficacious therapies, these disorders pose a significant and growing burden on healthcare systems and societies. The development of neuroprotective or curative therapies is limited by a variety of factors, but none more than the highly selective blood-brain barrier. Intranasal administration can bypass this barrier completely and allow direct access to brain tissues, enabling a large number of potential new therapies ranging from bioactive peptides to stem cells. Current research indicates that merely administering simple solutions is inefficient and may limit therapeutic success. While many therapies can be delivered to some degree without carrier molecules or significant modification, a growing body of research has indicated several methods of improving the safety and efficacy of this administration route, such as nasal permeability enhancers, gelling agents, or nanocarrier formulations. This review shall discuss promising delivery systems and their role in expanding the clinical efficacy of this novel administration route. Optimization of intranasal administration will be crucial as novel therapies continue to be studied in clinical trials and approved to meet the growing demand for the treatment of patients with neurological diseases.

Antagonism of cadmium-induced liver injury in ducks by α-bisabolol.

Cadmium (Cd) is an ecological pollutant which causes hazardous effects in animals and humans. The aim of this study was to investigate the role of α-bisabolol (BISA) in antagonizing the Cd-induced hepatotoxicity in ducks. Two-week old ducks were allocated into 8 groups (10 ducks/group): Group I received basal diet and was gavaged with sunflower oil (BISA vehicle, 1.1 mL/kg/day); group II was administered BISA orally (50 mg/kg/day; diluted with sunflower oil); groups III, IV, and V were fed the basal diet mixed with CdCl2 at 37.5, 75, and 150 mg/kg diet, respectively, and were gavaged with sunflower oil; group VI, VII, and VIII were given basal diet containing CdCl2 at the aforementioned consecutive doses plus BISA. All treatments were provided daily for 4 weeks. Exposure to CdCl2 induced mortality in ducks, increased hepatic Cd content and serum levels of hepatopathic biomarkers, and caused oxidative stress and morphological alterations in ducks' liver. Furthermore, exposure to Cd caused upregulation of the mRNA of proinflammatory cytokine tumor necrosis factor-α and apoptotic gene Bax, and that of cyclooxygenase-2 protein in the liver. All effects of Cd were dose-dependent. BISA antagonized all of the aforementioned CdCl2-induced changes. These findings suggested that BISA exert the hepatoprotective effect against Cd toxicity through reducing the hepatic content of Cd as well as antagonizing oxidative insults, inflammation, and apoptosis. Thus, BISA has a great potential to be used as an antidote in the control of Cd poisoning.

Pharmacokinetic/Pharmacodynamic Modeling of Spiramycin against Mycoplasma synoviae in Chickens.

This research aimed to assess the pharmacokinetics/pharmacodynamics (PK/PD) and tissue residues of spiramycin in chickens. The PK of spiramycin were determined in 12 chickens using a parallel study design in which each group of chickens (n = 6) received a single dose of spiramycin at 17 mg/kg intravenously (IV) or orally. Plasma samples were collected at assigned times for up to 48 h to measure spiramycin concentrations. Additionally, a tissue depletion study was performed in 42 chickens receiving spiramycin at 17 mg/kg/day orally for 7 days. The area under the plasma concentration-time curve values were 29.94 ± 4.74 and 23.11 ± 1.83 µg*h/mL after IV and oral administrations, respectively. The oral bioavailability was 77.18%. The computed withdrawal periods of spiramycin were 11, 10, and 7 days for liver, muscle, and skin and fat, respectively. The minimum inhibitory concentration for spiramycin against Mycoplasma synoviae (M. synoviae) strain 1853 was 0.0625 µg/mL. Using the PK/PD integration, the appropriate oral dose of spiramycin against M. synoviae was estimated to be 15.6 mg/kg. Thus, we recommend an oral dose of 15.6 mg spiramycin/kg against M. synoviae in chickens and a withdrawal period of 11 days following oral treatment with 17 mg spiramycin/kg/day for 7 days.

Protective Effect of Pyrus ussuriensis Maxim. Extract against Ethanol-Induced Gastritis in Rats.

Pyrus ussuriensis Maxim (Korean pear) has been used for hundreds of years as a traditional herbal medicine for asthma, cough, and atopic dermatitis in Korea and China. Although it was originally shown to possess anti-inflammatory, antioxidant, and antiatopic properties, its gastroprotective effects have not been investigated. In the present study, we evaluated the protective effects of Pyrus ussuriensis Maxim extract (PUE) against ethanol-induced gastritis in rats. The bioactive compound profile of PUE was determined by gas chromatography mass spectroscopy (GC-MS) and high-performance liquid chromatography (HPLC). The gastroprotection of PUE at different doses (250 and 500 mg/kg body weight) prior to ethanol ingestion was evaluated using an in vivo gastritis rat model. Several endpoints were evaluated, including gastric mucosal lesions, cellular degeneration, intracellular damage, and immunohistochemical localization of leucocyte common antigen. The gastric mucosal injury and ulcer score were determined by evaluating the inflamed gastric mucosa and by histological examination. To identify the mechanisms of gastroprotection by PUE, antisecretory action and plasma prostaglandin E2 (PGE2), gastric mucosal cyclic adenosine monophosphate (cAMP), and histamine levels were measured. PUE exhibited significant antioxidant effects with IC50 values of 56.18 and 22.49 µg/mL for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'- azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) inhibition (%), respectively. In addition, GC/MS and HPLC analyses revealed several bioactive compounds of PUE. Pretreatment with PUE significantly (p < 0.05) decreased the ulcer index by preventing gastric mucosal lesions, erosion, and cellular degeneration. An immunohistochemical analysis revealed that PUE markedly attenuated leucocyte infiltration in a dose-dependent manner. The enhancement of PGE2 levels and attenuation of cAMP levels along with the inhibition of histamine release following PUE pretreatment was associated with the cytoprotective and healing effects of PUE. In contrast, the downregulation of the H+/K+ ATPase pathway as well as muscarinic receptor (M3R) and histamine receptor (H2R) inhibition was also involved in the gastroprotective effects of PUE; however, the expression of cholecystokinin-2 receptors (CCK2R) was unchanged. Finally, no signs of toxicity were observed following PUE treatment. Based on our results, we conclude that PUE represents an effective therapeutic option to reduce the risk of gastritis and warrants further study.

Characterization of Nuclear Progesterone Receptor Isoforms in the Term Equine Placenta.

In equine parturition, the role of progestins along with the nuclear progesterone receptor (nPR) signaling pathway in the placenta is not completely clarified. The progestins play an integral role in maintaining myometrial quiescence during the late stage of pregnancy via acting on nPR isoforms (PRA and PRB; PRB is more active than PRA). The current study aimed to determine the PRA and PRB expressions in the term equine placenta at the gene and protein levels. Six term equine placentas were used in this study. Reverse transcription polymerase chain reaction (RT-PCR) was used to quantify the mRNA expression for PRA and PRB. The protein expression was detected using the Western Blot technique. The results revealed that the mRNA and protein expressions for PRA were significantly higher (P < 0.0001) in the term equine placental tissue compared to the mRNA and protein expressions of PRB. These results demonstrated that nPRs are detectable in the term placenta of mares and PRA is the dominant isoform expressed. The present findings raised the possibility that the PRA plays an important role in the parturition process and expulsion of the placenta in mares.

Review of extralabel use of isoxazolines for treatment of demodicosis in dogs and cats.

Amitraz is presently the only FDA-approved treatment for demodicosis in dogs in the United States. Amitraz treatment involves a protracted course of administration and risks of severe adverse effects such as sedation, bradycardia, and respiratory depression, which are caused by activation of α2-adrenergic receptors. Other treatment options include macrocyclic lactones and lime sulfur, but these products have varied efficacy and high risks of adverse effects. Several recent studies have indicated that isoxazolines are capable of reducing Demodex mite counts in canine and feline patients with demodicosis by ≥ 99% in as little as 1 month with few adverse effects. This article reviews the status of isoxazolines in regard to labeled uses in dogs and cats in the United States, extralabel clinical use for treatment of demodicosis in these species, and safety of orally administered formulations of these drugs.

The Effect of Soluble Fiber Dextrin on Subjective and Physiological Markers of Appetite: A Randomized Trial.

Obesity is a leading public health problem throughout the world. The development of foods that increase satiety and reduce food may aid weight management. This study determined the effect of consuming soluble fiber dextrin (SFD) on appetite, appetitive hormones, breath hydrogen and food intake in adults. Forty-three participants completed this study. For each treatment, 50% of the SFD was provided in liquid form as part of breakfast and 50% in solid form as a morning snack. Appetite questionnaires, blood and breath samples were collected immediately before breakfast and at regular intervals during the test session. The participants consumed an ad libitum lunch meal, afternoon snack and dinner meal, and the amount eaten was recorded. Following dinner, participants left the laboratory but were required to keep a diet diary for the remainder of the day. Breath hydrogen concentration was significantly higher following the consumption of SFD compared to control (p < 0.05). There was no observed overall treatment effect of consuming SFD on GLP-1 (Glucagon-Like-Peptide-1), ghrelin, CCK-8 (Cholecystokinin) or PYY3-36 (Petptide YY) (p > 0.05). Moreover, consuming foods containing SFD had no effect on subjective appetite or food intake (p > 0.05). Consuming foods containing SFD increased breath hydrogen but did not influence food intake, appetite or appetitive hormones. However, the limitations of this study may have individually or collectively masked an effect of SFD on food intake and appetite.

Comparative genomics reveals bamboo feeding adaptability in the giant panda (Ailuropoda melanoleuca).

The giant panda (Ailuropoda melanoleuca) is one of the world's most endangered mammals and remains threatened as a result of intense environmental and anthropogenic pressure. The transformation and specialization of the giant panda's diet into a herbivorous diet have resulted in unique adaptabilities in many aspects of their biology, physiology and behavior. However, little is known about their adaptability at the molecular level. Through comparative analysis of the giant panda's genome with those of nine other mammalian species, we found some genetic characteristics of the giant panda that can be associated with adaptive changes for effective digestion of plant material. We also found that giant pandas have similar genetic characteristics to carnivores in terms of olfactory perception but have similar genetic characteristics to herbivores in terms of immunity and hydrolytic enzyme activity. Through the analysis of gene family expansion, 3752 gene families were found, which were enriched in functions such as digestion. A total of 93 genes under positive selection were screened out and gene enrichment identified these genes for the following processes: negative regulation of cellular metabolic process, negative regulation of nitrogen compound metabolic process, negative regulation of macromolecule metabolic process and negative regulation of metabolic process. Combined with the KEGG pathway, it was found that genes such as CREB3L1, CYP450 2S1, HSD11B2, LRPAP1 play a key role in digestion. These genes may have played a key role in the pandas' adaptation to its bamboo diet.

Tissue Residues and Pharmacokinetic/Pharmacodynamic Modeling of Tiamulin Against Mycoplasma anatis in Ducks.

The pharmacokinetics of tiamulin were studied in 2 groups of ducks (n = 6) after its oral administration at 2 different doses (30 and 60 mg/kg, respectively). Plasma concentrations of tiamulin were measured by high performance liquid chromatography at different time points up to 24 h post-administration. The maximum plasma concentrations were 0.77 and 2.32 µg/mL attained at 2 h (Tmax) for 30 and 60 mg/kg, respectively. The elimination half-lives for these 2 doses were 3.54 and 6.34 h, respectively. The minimum inhibitory concentration for tiamulin against Mycoplasma anatis (M. anatis) strain 1340 was determined to be 0.06 µg/mL. The proper oral dose of tiamulin against M. anatis in ducks was calculated to be 35 mg/kg/day using the pharmacokinetic/pharmacodynamic modeling. Tiamulin was administered orally (40 mg/kg/day) to 30 ducks for 3 successive days to determine its residues in edible tissues and its preslaughter withdrawal time. The highest tiamulin residues were detected in the liver, followed by the muscle, whereas lower concentrations were detected in the skin and fat. The estimated withdrawal periods of tiamulin were 6, 5, 3, and 3 days for liver, muscle, skin, and fat, respectively. Therefore, an oral dosage regimen of 35 mg/kg/day should be adequate for tiamulin against M. anatis. We recommend a preslaughter withdrawal period of 6 days when ducks are treated with 40 mg tiamulin/kg/day, orally, for 3 days.

Baseline plasma cortisol and ACTH concentrations and response to low-dose ACTH stimulation testing in ill foals.

OBJECTIVE: To evaluate baseline plasma cortisol and ACTH concentrations and responses to low-dose ACTH stimulation testing in ill foals. DESIGN: Cross-sectional study. ANIMALS: 58 ill foals. PROCEDURES: Baseline cortisol and ACTH concentrations and cortisol concentrations after administration of a low dose of cosyntropin were determined within 6 hours after admission. Foals were assigned to 4 groups on the basis of age (