Effect of a commercial anionic dietary supplement on urinary pH and concentrations of electrolytes and pH in blood of horses.

Aims: To compare urine urinary pH, blood pH and concentration of electrolytes in blood of healthy horses fed an anionic salt supplement to achieve diets with a dietary cation-anion difference (DCAD) of -40 or 0 mEq/kg DM, with horses a fed a diet with a DCAD of 85 mEq/kg DM.Methods: Eight healthy horses received each of three diets in a randomised crossover design. Diets consisted of grass hay and concentrate feed, with a varying amount of an anionic supplement to achieve a DCAD of 85 (control), 0 or -40 mEq/kg DM. They were fed for 14 days each with a washout period of 7 days between. Urine pH was measured daily and blood samples were collected on Days 0, 7 and 14 of each study period for the measurement of pH and concentration of electrolytes.Results: Four horses voluntarily consumed the anionic supplement with their feed, but four horses required oral supplement administration via dose syringe. During the study period mean urine pH was lower in horses fed diets with a DCAD of 0 (6.91; SD 0.04) and -40 (6.83; SD 0.04) mEq/kg DM compared to the control diet (7.30; SD 0.04). Compared with horses fed the control diet, mean urine pH was lower in horses fed the 0 and -40 mEq/kg DM diets on Days 1-12 and 14 (p < 0.05) of the study period. On Day 13 it was only lower in horses fed the -40 mEq/kg DM diet (p < 0.01). Urine pH was similar for horses fed the 0 and -40 mEq/kg DM diets (p = 0.151). The DCAD of the diet had no effect on blood pH, ionised Ca or anion gap. Mean concentrations of bicarbonate in blood were affected by diet (p = 0.049); they were lower when horses were fed the 0 mEq/kg diet relative to the control diet on Day 14.Conclusions and clinical relevance: The anionic supplement reduced urine pH in horses fed diets with a DCAD of 0 or -40 mEq/kg DM compared with 85 mEq/kg DM. However as urinary pH did not fall below pH 6.5, the pH below which calcium carbonate uroliths do not form, this reduction in urine pH is unlikely to be clinically significant. The supplement was variably palatable and showed minimal promise as an effective urinary acidifier at the doses administered in this study.

Factors associated with long-term athletic outcome in Thoroughbred neonates admitted to an intensive care unit.

BACKGROUND: Limited information exists on the long-term outcome of foals that survive following hospitalisation for disease as a neonate. Significant financial investment is required to raise foals to racing age, therefore improved understanding of factors that affect long-term outcome and future athletic performance is important. OBJECTIVES: To analyse racing performance in Thoroughbred foals hospitalised as neonates, compared with their maternal siblings and to determine factors associated with failure to race and racing performance. STUDY DESIGN: Retrospective cohort study. METHODS: Medical records of Thoroughbred foals admitted to a neonatal intensive care unit between 1982 and 2008 were reviewed. Surviving foals of registered mares were included. Data including the foal's primary and concurrent diseases were extracted from the medical record. Racing records for foals and maternal siblings were evaluated. Multivariable logistic regression was used to identify disorders associated with failure to race and decreased racing performance. RESULTS: Two-hundred and sixty-nine of 454 previously hospitalised foals (59%) raced. Sixty-eight percent (269/394) of registered foals raced, compared with 79% (697/880) of registered siblings. Foals with prematurity/dysmaturity (P = 0.002) and those with orthopaedic disease (P = 0.007) were significantly less likely to race than their siblings. Premature/dysmature foals also had significantly fewer starts and wins and lower earnings than siblings. Foals with orthopaedic disorders had a lower percentage of wins, relative to their siblings. There was no significant association between racing performance and other disease categories. MAIN LIMITATIONS: Small sample size in some disease categories and retrospective nature of study. CONCLUSIONS: Foals hospitalised due to prematurity/dysmaturity or orthopaedic disorders were less likely to race than their maternal siblings and those that did race had decreased performance.

Genome-wide identification, in silico characterization and expression analysis of ZIP-like genes from Trichomonas vaginalis in response to Zinc and Iron.

Trace elements such as Zinc and Iron are essential components of metalloproteins and serve as cofactors or structural elements for enzymes involved in several important biological processes in almost all organisms. Because either excess or insufficient levels of Zn and Fe can be harmful for the cells, the homeostatic levels of these trace minerals must be tightly regulated. The Zinc regulated transporter, Iron regulated transporter-like Proteins (ZIP) comprise a diverse family, with several paralogues in diverse organisms and are considered essential for the Zn and Fe uptake and homeostasis. Zn and Fe has been shown to regulate expression of proteins involved in metabolism and pathogenicity mechanisms in the protozoan pathogen Trichomonas vaginalis, in contrast high concentrations of these elements were also found to be toxic for T. vaginalis trophozoites. Nevertheless, Zn and Fe uptake and homeostasis mechanisms is not yet clear in this parasite. We performed a genome-wide analysis and localized the 8 members of the ZIP gene family in T. vaginalis (TvZIP1-8). The bioinformatic programs predicted that the TvZIP proteins are highly conserved and show similar properties to the reported in other ZIP orthologues. The expression patterns of TvZIP1, 3, 5 and 7 were diminished in presence of Zinc, while the rest of the TvZIP genes showed an unchanged profile in this condition. In addition, TvZIP2 and TvZIP4 showed a differential expression pattern in trophozoites growth under different Iron conditions. These results suggest that TvZIP genes encode membrane transporters that may be responsible for the Zn and Fe acquisition in T. vaginalis.

Pharmacokinetics of ceftiofur sodium in equine pregnancy.

Eleven pregnant pony mares (D270-326) were administered ceftiofur sodium intramuscularly at 2.2 mg/kg (n = 6) or 4.4 mg/kg (n = 5), once daily. Plasma was obtained prior to ceftiofur administration and at 0.5, 1, 2, 4, 8, 12, and 24 hr after administration. Eight pony mares were re-enrolled in the study at least 3 days from expected foaling to ensure steady-state concentrations of drug at the time of foaling. Mares were administered ceftiofur sodium (4.4 mg/kg, IM) daily until foaling. Parturition was induced using oxytocin 1 hr after ceftiofur sodium administration. Allantoic and amniotic fluid, plasma, and colostrum samples were collected at time of foaling. Serial foal plasma samples were obtained. Placental tissues were collected. Desfuroylceftiofur acetamide (DCA) concentrations were measured in samples by high-performance liquid chromatography (HPLC). Mean (±SD) peak serum concentrations of DCA were 3.97 ± 0.50 µg/ml (low dose) and 7.45 ± 1.05 µg/ml (high dose). Terminal half-life was significantly (p = .014) shorter after administration of the low dose (2.91 ± 0.59 hr) than after administration of the high dose (4.10 ± 0.72 hr). The mean serum concentration of DCA from mares at time of foaling was 7.96 ± 1.39 µg/ml. The mean DCA concentration in colostrum was 1.39 ± 0.70 µg/ml. DCA concentrations in allantoic fluid, amniotic fluid, placental tissues, and foal plasma were below the limit of quantification (<0.1 µg/ml) and below the minimum inhibitory concentration of ceftiofur against relevant pathogens. These results infer incomplete passage of DCA across fetal membranes after administration of ceftiofur sodium to normal pony mares.

Effects of clarithromycin, azithromycin and rifampicin on terbutaline-induced sweating in foals.

BACKGROUND: Erythromycin (ERY) induces anhidrosis in foals. Azithromycin (AZI) and clarithromycin (CLA), often combined with rifampicin (RIF), are commonly used to treat Rhodococcus equi infections, but effects on sweating have not been investigated. OBJECTIVE: To determine the effects of AZI, CLA and RIF on sweat responses in normal foals. STUDY DESIGN: Each experiment was a blinded, duplicated, six foal × three period counterbalanced within subjects design (12 foals/experiment). METHODS: Antimicrobials were given orally for 5 days. In Experiment 1, ERY, AZI and CLA were given. In Experiment 2, ERY, RIF and ERY/RIF combination were used. Quantitative intradermal terbutaline sweat tests were performed daily for 3 days before and 1, 2, 5, 9, 24, and 39 days after treatment. Data were analysed by repeated measures analysis of variance procedures. Significance was P≤0.05. RESULTS: In Experiment 1, all macrolides suppressed sweating although CLA and AZI were less potent than ERY. In Experiment 2, significant sweat suppression occurred in foals given ERY with or without RIF, but there was no effect of RIF alone. Rifampicin reduced sweat suppression by ERY on Day 1 of treatment but not thereafter. MAIN LIMITATIONS: Because ERY blood concentrations were not measured, effects of RIF on ERY-induced anhidrosis could not definitively be ascribed to altered ERY bioavailability. CONCLUSIONS: All macrolides commonly used to treat R. equi pneumonia, i.e. ERY, AZI and CLA, induce anhidrosis in foals. The potent anti-sudorific effect of ERY is delayed, but not substantially affected by concurrent RIF administration.

Factors associated with outcome in 94 hospitalised foals diagnosed with neonatal encephalopathy.

REASONS FOR PERFORMING STUDY: Neonatal encephalopathy is the most common neurological abnormality identified in neonatal foals, but its clinical course has been rarely characterised. OBJECTIVES: To describe factors associated with nonsurvival in a population of foals diagnosed with neonatal encephalopathy. STUDY DESIGN: Retrospective cross-sectional clinical study. METHODS: Cases were selected from equine neonatal (≤14 days of age) admissions between 1996 and 2007. Multivariable logistic regression was used to identify clinical parameters, laboratory variables and therapeutic interventions associated with nonsurvival. RESULTS: A total of 94 foals were included in the study. Median age at admission was 12 h (range 0-96 h). The most frequently identified clinical signs included abnormal udder seeking (59%), abnormal suckle (55%), inability to stand (42%), abnormal gastrointestinal motility (37%), abnormal consciousness (34%) and seizure activity (22%). Overall, 75 (79.8%) foals survived to be discharged from the hospital and 19 foals died or were subjected to euthanasia. Variables significantly associated with nonsurvival in the multivariable model were serum total calcium concentration, serum activity of alkaline phosphatase, recumbency, number of concurrent diseases, and use of vasopressors/inotropes. The model correctly classified 92.0% of cases. CONCLUSIONS: Overall survival was good and similar to previous reports. Vasopressors/inotropes were the only therapeutic intervention associated with nonsurvival, suggesting that persistent hypotension is associated with nonsurvival in the current population. Foals with concurrent disease, high total calcium and low alkaline phosphatase at admission, and that were recumbent or required treatment with vasopressors/inotropes during hospitalisation, were significantly less likely to survive.

Factors associated with outcome and gradual improvement in survival over time in 1065 equine neonates admitted to an intensive care unit.

REASONS FOR PERFORMING STUDY: There is a paucity of information regarding the association between common disorders and outcome over time in a large population of ill equine neonates. OBJECTIVES: To describe the relative frequency of neonatal disorders in a large population of foals admitted to a neonatal intensive care unit, to determine the disorders and factors associated with nonsurvival and determine if the outcome of ill neonatal foals has improved over time. STUDY DESIGN: Retrospective study. METHODS: Cases were selected from equine neonatal (≤14 days of age) admissions between 1982 and 2008. Multivariable logistic regression was used to identify the disorders, clinical parameters and laboratory variables associated with nonsurvival or natural death and assess survival over time after accounting for potential confounding variables. RESULTS: A total of 1065 foals were included in the study. Overall, 775 of 1065 (72.8%) foals survived to be discharged from the hospital and 290 (27.2%) foals were nonsurvivors. Age at admission, sepsis score, proportion of foals with positive blood cultures and proportion of survivors were significantly different (P<0.001) between primary disease categories. Variables retained in the multivariable model for nonsurvival included positive blood culture, neutrophils <2.28 × 109 /l, temperature ≤37.6°C, bicarbonate, PCO2 , presence of infectious orthopaedic disorders and sepsis score. The adjusted odds of survival for foals admitted in the 2000s were approximately 3.4 (95% CI = 1.9-6.0, P<0.001) times higher than that of foals admitted in the 1980s. CONCLUSIONS: Primary disorders, sepsis, temperature, acid base status and neutropenia are the main factors that affect outcome in this population of equine neonates. The survival of foals admitted to a neonatal intensive care unit has increased dramatically over a 26 year period.

Macrolide-induced hyperthermia in foals: Role of impaired sweat responses.

REASONS FOR PERFORMING STUDY: The mechanism of hyperthermia, a potentially fatal adverse effect of erythromycin treatment of foals, is unknown. OBJECTIVES: To determine the cause of erythromycin-associated hyperthermia. It was hypothesised that the normal sweat response of foals is impaired by treatment with erythromycin. STUDY DESIGN: Blinded, crossover study in 10 healthy pony foals. METHODS: Foals kept in stalls were given either erythromycin (25 mg/kg bwt orally, 3 times daily) or control for 10 days then turned out for a further 10 days. Quantitative intradermal terbutaline sweat tests were performed on Days 1 (baseline), 3, 10 and 20. The effects on terbutaline-induced sweating of erythromycin, terbutaline concentration and treatment day were analysed by repeated-measures ANOVA with Bonferroni-corrected pairwise post hoc comparisons. Peak temperatures were compared by Wilcoxon's signed rank test and proportions by McNemar's related samples test. Significance was set at P<0.05. RESULTS: There were significant 2-factor interactions for treatment × terbutaline after baseline, treatment × day at every terbutaline concentration, and day × terbutaline for erythromycin (P<0.001) but not control (P = 0.9) treatment. Sweating was significantly reduced from baseline in erythromycin-treated foals at all subsequent days. Erythromycin-treated foals produced less sweat at all time-points than did control-treated foals (P<0.05). Peak rectal temperatures of erythromycin-treated foals were significantly higher (P = 0.02) than those of controls. During the first 3 days outside more erythromycin-treated than control-treated foals required treatment for hyperthermia (6 vs. 0; P = 0.03). CONCLUSIONS: We believe drug-induced anhidrosis is the likely cause of hyperthermia in some foals treated with erythromycin.

Physicochemical Approach to Determine the Mechanism for Acid-Base Disorders in 793 Hospitalized Foals.

BACKGROUND: The quantitative effect of strong electrolytes, unmeasured strong anions (UAs), pCO2, and plasma protein concentrations in determining plasma pH can be demonstrated using the physicochemical approach. Plasma anion gap (AG) and strong ion gap (SIG) are used to assess UAs in different species. HYPOTHESES: Strong ions are a major factor influencing changes in plasma pH of hospitalized foals. AG and SIG accurately predict severe hyper-L-lactatemia ([L-lac(-)] > 7 mmol/L). ANIMALS: Seven hundred and ninety three hospitalized foals < 7 days old. METHODS: Retrospective study. The relationship between measured pH and physicochemical variables, and the relationship between plasma [L-lac(-)] and AG and SIG, were determined using regression analyses. Optimal AG and SIG cut points to predict hyper-L-lactatemia were identified using an ROC curve analysis. RESULTS: Combined, the measured strong ion difference and SIG accounted for 54-69% of the changes in the measured arterial pH of hospitalized foals. AG and SIG were significantly associated with plasma [L-lac(-)] (P < .0001). The receiver operator characteristics (ROC) AUC of AG and SIG for prediction of severe hyper-L-lactatemia were 0.89 (95%CI, 0.8-0.95; P < .0001) and 0.90 (95%CI, 0.81-0.96; P < .0001), respectively. Severe hyper-L-lactatemia was best predicted by AG > 27 mmol/L (sensitivity 80%, 95%CI, 56-94, specificity 85%, 95%CI, 73-93; P < .0001) and SIG <-15 mmol/L (sensitivity 90%, 95%CI, 68-98; specificity 80%; 95%CI, 68-90; P < .0001). CONCLUSION AND CLINICAL RELEVANCE: Altered concentrations of strong ions (Na(+), K(+), Cl(-)) and UAs were the primary cause of acidemia of hospitalized foals. AG and SIG were good predictors of hyper-L-lactatemia and could be used as surrogate tests.

Re-evaluation of the sepsis score in equine neonates.

REASONS FOR PERFORMING STUDY: The modified sepsis scoring system provides a method to identify sepsis in foals early in the disease process, but inconsistent results have been obtained from its clinical application in previous studies. OBJECTIVES: To evaluate the sensitivity and specificity of the modified sepsis score in a larger population of foals. A secondary objective was to identify factors associated with sepsis. STUDY DESIGN: Retrospective cohort study. METHODS: Records were retrospectively analysed for neonatal admissions to the University of Florida Large Animal Hospital from 1982 to 2008. Backwards stepwise multivariable logistic regression was used to evaluate objective clinical factors associated with sepsis. Receiver operating chararacteristic ROC curve analysis was performed on the modified sepsis score and used to determine an optimal cut point. RESULTS: A total of 1065 foals were included in the study. The modified sepsis score had a sensitivity of 56.4% and specificity of 73.4% for the originally suggested cut point (>11). Receiver operating chararacteristic analysis revealed an optimal cut point of >7 (sensitivity 84.4%, specificity 41.8%). The modified sepsis score performed better than the generated regression model which included age, creatinine, lymphocytes, potassium and IgG>8 g/l (P = 0.026). Diagnostic performance of the modified sepsis score did not change significantly over time. CONCLUSIONS: Sensitivity and specificity of the modified sepsis score were not as high as previously documented, but the score still outperformed a regression model derived from objective clinical data. The Summary is available in Chinese - see Supporting information.

Pain control in horses: what do we really know?

Currently, approaches to pain control in horses are a mixture of art and science. Recognition of overt pain behaviours, such as rolling, kicking at the abdomen, flank watching, lameness or blepharospasm, may be obvious; subtle signs of pain can include changes in facial expression or head position, location in the stall and response to palpation or human interaction. Nonsteroidal anti-inflammatory drugs (i.e. phenylbutazone, flunixin meglumine and firocoxib), opioids (i.e. butorphanol, morphine and buprenorphine) and α2 -adrenergic agonists (i.e. xylazine, detomidine, romifidine and medetomidine) are the most commonly used therapeutic options. Multimodal therapy using constant-rate infusions of lidocaine, ketamine and/or butorphanol has gained popularity for severe pain in hospitalised cases. Drugs targeting neuropathic pain, such as gabapentin, are increasingly used for conditions such as laminitis. Optimal strategies for management of pain are based upon severity and chronicity, including special considerations for use of intra-articular or epidural delivery and therapy in foals. Strategies that aim to mitigate adverse effects associated with use of various analgesic agents are briefly discussed.

Effect of butorphanol on thermal nociceptive threshold in healthy pony foals.

REASONS FOR PERFORMING STUDY: Pain management is an important component of foal nursing care, and no objective data currently exist regarding the analgesic efficacy of opioids in foals. OBJECTIVES: To evaluate the somatic antinociceptive effects of 2 commonly used doses of intravenous (i.v.) butorphanol in healthy foals. Our hypothesis was that thermal nociceptive threshold would increase following i.v. butorphanol in a dose-dependent manner in both neonatal and older pony foals. METHODS: Seven healthy neonatal pony foals (age 1-2 weeks), and 11 healthy older pony foals (age 4-8 weeks). Five foals were used during both age periods. Treatments, which included saline (0.5 ml), butorphanol (0.05 mg/kg bwt) and butorphanol (0.1 mg/kg bwt), were administered i.v. in a randomised crossover design with at least 2 days between treatments. Response variables included thermal nociceptive threshold, skin temperature and behaviour score. Data within each age period were analysed using a 2-way repeated measures ANOVA, followed by a Holm-Sidak multiple comparison procedure if warranted. RESULTS: There was a significant (P<0.05) increase in thermal threshold, relative to Time 0, following butorphanol (0.1 mg/kg bwt) administration in both age groups. No significant time or treatment effects were apparent for skin temperature. Significant time, but not treatment, effects were evident for behaviour score in both age groups. CONCLUSIONS: Butorphanol (0.1 mg/kg bwt, but not 0.05 mg/kg bwt) significantly increased thermal nociceptive threshold in neonatal and older foals without apparent adverse behavioural effects. POTENTIAL RELEVANCE: Butorphanol shows analgesic potential in foals for management of somatic painful conditions.

Disposition of desfuroylceftiofur acetamide in serum, placental tissue, fetal fluids, and fetal tissues after administration of ceftiofur crystalline free acid (CCFA) to pony mares with placentitis.

The objective of this study was to determine the pharmacokinetics of CCFA in mares with placentitis and evaluate the disposition of the drug in fetal fluids, fetal membranes, colostrum, and serum of foals. A secondary objective was to obtain pilot data regarding the efficacy of CCFA for improving foal survival in mares with placentitis. Twelve pregnant pony mares were enrolled in the study, inoculated with Streptococcus zooepidemicus, intracervically and assigned to one of three groups: CEFT (n = 3; administered CCFA only; 6.6 mg/kg, i.m., q96h); COMBO (n = 6; administered combination therapy of CCFA, altrenogest, and pentoxifylline); UNTREAT (n = 3, no treatment). Treatment was initiated at the onset of clinical signs. Concentrations of desfuroylceftiofur acetamide (DCA), the acetamide derivative of ceftiofur and desfuroylceftiofur metabolites, were measured using high-performance liquid chromatography. Maximum and minimum serum concentrations of DCA at steady state in treated mares were 2.40±0.40 µg/mL and 1.06±0.29 µg/mL, respectively. Concentration of DCA in colostrum was 1.51±0.60 µg/mL. DCA concentrations in placenta and fetal tissues were very low (median = 0.03 µg/mL) and below the minimum inhibitory concentration of relevant pathogens. DCA was not detected in amniotic fluid or foal serum. Treatment did not appear to improve foal survival (CEFT: 0/3; COMBO: 2/6; UNTREAT: 2/3). Bacteria were recovered from the uterus of most mares postpartum and from blood cultures of most foals regardless of treatment.

Prevalence of gastric and duodenal ulceration in 691 nonsurviving foals (1995-2006).

REASON FOR PERFORMING STUDY: Gastric ulcer disease is reported to be a significant cause of morbidity in foals, but the prevalence of ulcers in this population has not recently been evaluated. OBJECTIVES: To determine the prevalence of gastric and duodenal ulceration in nonsurviving foals, and the association of ulceration with the body system of primary diagnosis. Secondary objectives were to evaluate a potential association between age and ulcer prevalence and to evaluate the use of antacid medication in the neonatal hospital population during the study years. METHODS: Necropsy records were searched for all equine accessions from 1995 to 2006. Foals aged from one day to 6 months were included. Year, age, breed, sex, diagnosis and the presence of glandular, nonglandularand/or duodenal ulceration were recorded. Diagnoses were divided into groups based on the body system of primary diagnosis, with multiple diagnoses possible. A computerised database was searched for antacid treatment of all neonatal admissions. RESULTS: The overall prevalence of ulcers was 22%, with nonglandular ulcers predominating. Ulceration was significantly associated with gastrointestinal disease. There was no significant change in ulcer prevalence over time, although there was a significant decrease in the use of antacid medications in the later study years. Neonatal foals (< 1 month) had a lower ulcer prevalence than olderfoals. CONCLUSIONS: The prevalence of ulcers in foals, although low, has remained stable over time. Gastric or duodenal ulcers are associated with a primary diagnosis of gastrointestinal disease and are less prevalent in neonates. POTENTIAL RELEVANCE: The prevalence of ulcers in nonsurviving foals is low. Foals with gastrointestinal disease are more likely to have ulcers than foals with other primary diagnoses, and older foals are more likely to have ulceration than neonates. The prevalence of ulceration did not appear to be related to hospital-wide antacid medication use in neonates.

Treatment with histamine-type 2 receptor antagonists and omeprazole increase the risk of diarrhoea in neonatal foals treated in intensive care units.

REASONS FOR PERFORMING STUDY: The use of anti-ulcer medication in the neonatal intensive care unit (ICU) is common due to the concern for development of catastrophic gastric ulcerdisease. In man, however, the use of acid-suppressive medication has been shown in some studies to be a substantial riskfactorfor the development of Clostridium difficile-associated diarrhoea (CDAD), bacteraemia and neonatal sepsis. OBJECTIVE: The purpose of the study reported herein is to evaluate the influence of anti-ulcer medications on the development of diarrhoea in the neonatalfoal. HYPOTHESIS: The use of anti-ulcer medication does not alter the incidence of diarrhoea in foals treated in an ICU. METHODS: The records of 1710 foals from 6 different equine hospitals were examined and the use of anti-ulcer drugs was recorded. The presence of in-hospital acquired diarrhoea, CDAD, Clostridium perfringens-associated diarrhoea, neonatal sepsis and salmonellosis were documented. In addition, the presence of gastric ulceration, duration of hospital stay and short-term outcome were examined. RESULTS: The use of anti-ulcer medications increased the odds of in-hospital diarrhoea by 2.0 (95% CI 1.4-2.9; P < 0.0001), relative to the use of no anti-ulcer medication. There was no significant association of anti-ulcer medication with CDAD (P = 0.3189) (OR 2.0; 95% CI 0.4-9.5). Further, results indicated that decreased prevalence of gastric ulceration was not associated with use of anti-ulcer drugs among foals in the study for which these data were known (P = 0.5522). CONCLUSIONS: Use of anti-ulcer drugs increases the odds of developing diarrhoea, and may not reduce the incidence of gastric ulceration in hospitalised equine neonates. POTENTIAL RELEVANCE: The use of anti-ulcer drugs in neonatal foals being treated in a hospital setting should be carefully evaluated on an individual basis to determine if such use is warranted.

Cranial mediastinal liposarcoma in a horse.

A 23-year-old Anglo-Arabian mare was presented with tachypnea, dyspnea, and pitting edema of the ventral thoracic subcutis. On necropsy, a tan to red, friable, irregularly shaped mass (23 × 20 × 18 cm) occupied the cranial mediastinum. Histologically, the mass was classified as a liposarcoma and was composed of short interlacing bundles of spindle-shaped to irregularly rounded cells with discrete, variably sized, clear cytoplasmic vacuoles, which were stained with oil red O in frozen sections of formalin-fixed tissue.

A review of foal diarrhoea from birth to weaning.

Diarrhoea is among the most common clinical complaints in foals. Aetiologies, diagnostic testing and recommended interventions for specific causes of enterocolitis are summarised. Many mild to moderately affected foals can be managed in an ambulatory setting, while others will benefit from more intensive care at a referral centre.

Ultrastructural changes in the equine colonic mucosa after ischaemia and reperfusion.

REASON FOR PERFORMING STUDY: Ultrastructural changes in the epithelium can provide information on early changes in barrier properties, repair and inflammation in equine colon after ischaemia and reperfusion (I/R). OBJECTIVES: To describe the morphology and ultrastructure of the epithelium in equine large colonic mucosa after I/R, and the response of inflammatory cells to injury. METHODS: Ischaemia was induced for 1 h followed by 4 h of reperfusion in a 40 cm segment of the pelvic flexure in 6 horses. Mucosal biopsies before and after ischaemia, and after 1, 2 and 4 h of reperfusion were fixed in glutaraldehyde/paraformaldehyde and osmium tetroxide, and embedded in epon. Morphological and ultrastructural changes were evaluated in toluidine blue-stained semithin sections by light microscopy and in thin sections stained with uranyl acetate/lead citrate by transmission electron microscopy. RESULTS: Ischaemia caused swelling of epithelial cells and their organelles, opening of tight junctions, detachment from the basement membrane, early apoptosis and single cell necrosis. Autophagy was a prominent feature in epithelial cells after ischaemia. Reperfusion was characterised by apoptosis, epithelial regeneration and restoration of apical cell junctions. Phagocytic-like vacuoles containing cellular debris and bacteria were evident in epithelial cells after reperfusion. Paracellular and subepithelial clefts formed, accompanied by infiltration of neutrophils, lymphocytes and eosinophils into the epithelium. Subepithelial macrophages and luminal neutrophils had increased phagocytic activity. CONCLUSIONS: Ischaemia caused ultrastructural damage to the colonic epithelium, but epithelial cells recovered during reperfusion. POTENTIAL RELEVANCE: Transmission electron microscopy can demonstrate subtle ultrastructural damage to epithelial cells and evidence of recovery after I/R in equine colon.

Systemic effects of a prolonged continuous infusion of ketamine in healthy horses.

BACKGROUND: Ketamine as continuous rate infusion (CRI) provides analgesia in hospitalized horses. OBJECTIVE: Determine effects of prolonged CRI of ketamine on gastrointestinal transit time, fecal weight, vital parameters, gastrointestinal borborygmi, and behavior scores in healthy adult horses. ANIMALS: Seven adult Thoroughbred or Thoroughbred cross horses, with permanently implanted gastric cannulae. METHODS: Nonblinded trial. Random assignment to 1 of 2 crossover designed treatments. Ketamine (0.55 mg/kg IV over 15 minutes followed by 1.2 mg/kg/h) or lactated Ringer's solution (50 mL IV over 15 minutes followed by 0.15 mL/kg/h) treatments. Two hundred 3 × 5 mm plastic beads administered by nasogastric tube before drug administration. Every 2 hours vital parameters, behavior scores recorded, feces collected and weighed, and beads retrieved. Every 6 hours gastrointestinal borborygmi scores recorded. Study terminated upon retrieval of 180 beads (minimum 34 hours) or maximum 96 hours. Nontransit time data analyzed between hours 0 and 34. RESULTS: No significant (P < .05) differences detected between treatments in vital signs or gastrointestinal borborygmi. Significant (P = .002) increase in behavior score during ketamine infusion (0.381) from hours 24-34 compared with placebo (0). Ketamine caused significant delay in passage of 25, 50, and 75% of beads (ketamine = 30.6 ± 5.3, 41.4 ± 8.4, 65.3 ± 13.5 hours versus placebo = 26.8 ± 7.9, 34.3 ± 11.1, 45.8 ± 19.4 hours), and significant (P < .05) decrease in fecal weight from hours 22 (12.6 ± 3.2 versus 14.5 ± 3.8 kg) through 34 (18.5 ± 3.9 versus 12.8 ± 6.4 kg) of infusion. CONCLUSIONS AND CLINICAL IMPORTANCE: Ketamine CRI delayed gastrointestinal transit time in healthy horses without effect on vital parameters.

The effects of deferoxamine mesylate on iron elimination after blood transfusion in neonatal foals.

BACKGROUND: Hepatic failure is one of the more common complications in foals requiring blood transfusion to treat neonatal isoerythrolysis. Iron intoxication is likely the cause of hepatic injury. OBJECTIVES: To determine the effects of deferoxamine on iron elimination in normal foals. ANIMALS: Thirteen neonatal foals. METHODS: Randomized-controlled trial. At 1-3 days of age, foals received either 3 L of washed packed dam's red blood cells (RBC) or 3 L of saline IV once. Foals were treated with deferoxamine (1 g) or saline (5 mL) SC twice daily for 14 days. Foals were randomly assigned to 1 of 3 groups: RBC/deferoxamine (deferoxamine), RBC/saline (placebo), or saline/saline (control). Blood and urine samples and liver biopsy specimens were collected for measurement of hematological, biochemical, and iron metabolism variables. RESULTS: There was a significant (P<.05) increase in hematocrit, RBC count, and hemoglobin in the groups transfused with packed RBC as compared with controls at all times. Biochemical variables and liver biopsy scores were not significantly different between groups at any time. Urine iron concentrations and fractional excretion of iron were significantly higher in deferoxamine treated foals. By 14 days after transfusion, liver iron concentrations in foals treated with deferoxamine (79.9±30.9 ppm) were significantly lower than that of foals receiving placebo (145±53.0 ppm) and similar to that of controls (44.8±4.09 ppm). CONCLUSIONS AND CLINICAL IMPORTANCE: Deferoxamine enhances urinary iron elimination and decreases hepatic iron accumulation after blood transfusion in foals.