Serum vitamin D concentrations at dry-off and close-up predict increased postpartum urine ketone concentrations in dairy cattle.

Vitamin D is commonly supplemented to dairy cows as vitamin D3 to support calcium homeostasis and in times of low sunlight exposure. Vitamin D has beneficial immunomodulatory and anti-inflammatory properties. Serum 25-hydroxyvitamin D [25(OH)D] concentrations fluctuated during lactation, with the lowest concentrations measured in healthy cows within 7 d of calving. However, it is unknown if serum 25(OH)D concentrations measured during the previous lactation are associated with transition diseases or health risk factors in dairy cattle. We collected serum samples from 279 dairy cattle from 5 commercial dairy herds in Michigan at dry-off, close-up, and 2-10 d in milk (DIM). Vitamin D concentrations were determined by measuring serum 25(OH)D by radioimmunoassay. Total serum calcium was measured by colorimetric methods. Body condition scores (BCS) were assigned at the time of blood collection. Clinical disease incidence was monitored until 30 d postparturition. Separate bivariable logistic regression analyses were used to determine if serum 25(OH)D at dry-off, close-up, and 2-10 DIM was associated with various clinical diseases including mastitis, lameness, and uterine disorders (classified as metritis, retained placenta, or both) and increased urine ketone concentrations at P < 0.05. Among all significant bivariable analyses, multivariable logistic regression analyses were built to adjust for potential confounding variables including parity, BCS, season, and calcium. Receiver operator characteristic (ROC) curve analyses were used to determine optimal concentrations of serum 25(OH)D. We found that higher serum 25(OH)D concentrations at dry-off and close-up predicted increased urine ketone concentrations in early lactation, even after adjustment for confounders. Alternatively, we found that lower serum 25(OH)D at 2-10 DIM was associated with uterine diseases. Optimal concentrations for serum 25(OH)D at dry-off and close-up for lower risk of increased urine ketone concentrations were below 103.4 and 91.1 ng/mL, respectively. The optimal concentration for serum 25(OH)D at 2-10 DIM for uterine diseases was above 71.4 ng/mL. These results indicate that serum 25(OH)D at dry-off and close-up may be a novel predictive biomarker for increased urine ketone concentrations during early lactation. Increased urine ketone concentrations are not necessarily harmful or diagnostic for ketosis but do indicate development of negative energy balance, metabolic stress, and increased risk of early lactation diseases. Predicting that dairy cattle are at increased risk of disease facilitates implementation of intervention strategies that may lower disease incidence. Future studies should confirm these findings and determine the utility of serum 25(OH)D concentrations as a predictive biomarker for clinical and subclinical ketosis.

Reproductive careers of Thoroughbred broodmares before and after surgical correction of ≥360 degree large colon volvulus.

BACKGROUND: Limited data exist describing broodmare longevity and reproductive efficiency after surgical correction of ≥360 degree large colon volvulus (° LCV). OBJECTIVES: Compare career duration and foals delivered for broodmares before and after ≥360° LCV surgery. STUDY DESIGN: Retrospective case series. METHODS: Broodmares registered with The Jockey Club that had surgical correction of ≥360° LCV and survived to hospital discharge at Rood and Riddle Equine Hospital from 1 January 2000 to 31 December 2015 were included. Information was collected from the hospital's medical data base and The Jockey Club produce records about the mares' reproductive careers. Data were evaluated using parametric and nonparametric tests, P≤0.05. RESULTS: Mares that were bred but never foaled prior to surgery (n = 19) had shorter careers (mean ± standard deviation [s.d.]), 4.4 ± 4.5 years, and fewer foals, 3.1 ± 3.3, compared with mares that delivered ≥1 foal before surgery (n = 565), 10.4 ± 4.5 years and 7.4 ± 3.4 foals, respectively, P<0.001. Broodmares that delivered foals before surgery produced more foals in the years before surgery, 4.8 ± 3.0, than after surgery, 2.6 ± 2.4, P<0.001, and had longer breeding careers, 5.9 ± 3.8 vs. 4.5 ± 3.3 years before compared with after surgery, P<0.001. No significant differences in career length or number of foals delivered were detected for mares with a single compared with multiple LCV surgeries. Mares that were 3-11 years old at the time of surgery had significantly more foals after surgery compared with mares ≥12 years old, P<0.001, as expected. MAIN LIMITATIONS: Retrospective collection of data. CONCLUSIONS: Broodmares had productive careers following surgery for ≥360° LCV that were largely influenced by the mares' age at the time of surgery.

Reduced serum vitamin D concentrations in healthy early-lactation dairy cattle.

Cattle obtain vitamin D by ingestion or cutaneous exposure to UV light. Dairy cattle diets are frequently supplemented with vitamin D to compensate for limited sun exposure or during times of increased metabolic demands, such as the periparturient period, to maintain calcium homeostasis. Whether housing and supplemental vitamin D practices supply adequate amounts of vitamin D to optimally support the transition from gestation to lactation in dairy cattle is unknown. Our objective was to determine how serum vitamin D concentrations of dairy cows change with season, age, parity, and stage of lactation. Clinically healthy cows (n = 183) from 5 commercial dairies were enrolled in the study. Serum samples were collected at dry off, within 7 d of entering the close-up group, and within 7 d after calving (calving+7). Vitamin D status was determined by measuring serum 25-hydroxyvitamin D [25(OH)D] by radioimmunoassay. We performed repeated-measures mixed-effects linear regression to determine the effects of season, age, parity, and lactation stage (dry off, close-up, and calving+7) on 25(OH)D concentrations in serum. Bivariable analysis indicated that parity, age, and season were not associated with serum 25(OH)D concentrations. Sample period affected 25(OH)D concentrations, with the highest 25(OH)D levels at dry off (99.7 ± 1.9 ng/mL) followed by close up (93.8 ± 2.1 ng/mL), with the lowest levels at calving+7 (82.6 ± 1.7 ng/mL). These data showed a large depletion of 25(OH)D in dairy cattle postpartum compared with late prepartum, although the biological significance of this change in these healthy cattle is unclear. Consumption of serum 25(OH)D by immune system functions and calcium homeostasis in early lactation likely caused the reduction in serum 25(OH)D concentrations after calving. These results suggest that determining whether serum 25(OH)D concentrations are associated with the incidence of transition period disease is an appropriate next step. Assessing the effects of enhanced vitamin D supplementation of cows in early lactation on postpartum diseases may be warranted.

Laryngeal advancement surgery improves swallowing function in a reversible equine dysphagia model.

REASONS FOR PERFORMING STUDY: Pharyngeal dysphagia is a debilitating, sometimes fatal condition in horses, with multiple aetiologies. The pathophysiology is complex and not fully understood. Treatment is largely supportive. Laryngeal advancement surgery may diminish symptoms of dysphagia and improve swallowing in affected horses. OBJECTIVES: 1) to induce reversible moderate and marked pharyngeal dysphagia by regional anaesthesia of branches of the glossopharyngeal (IX), vagus (X) and hypoglossal (XII) nerves; 2) to characterise the dysphagia produced by each model; and 3) to determine whether laryngeal advancement surgery improves swallowing in these models. STUDY DESIGN: Experimental design using 6 adult horses. METHODS: Two dysphagia models were produced by blocking IX, the pharyngeal branch of X and XII unilaterally (moderate model) and only the pharyngeal branch of X bilaterally (marked model) within the guttural pouches. Both models were performed on each horse before and after surgery in order to assess the effectiveness of the surgical procedure as a potential treatment for pharyngeal dysphagia. Dysphagia was scored by partly blinded observers on a scale of 0-12 based on observations of eating (nonblinded), endoscopic examinations and fluoroscopic swallowing (blinded), where 0 = normal swallow and 12 = severe dysphagia with tracheal aspiration. Data were analysed by 3-factor ANOVA, with significance taken as P<0.05. RESULTS: Dysphagia models were reversible, and horses swallowed normally within 3 h of model induction. The marked dysphagia model impaired movement of feed from the base of the tongue to the oesophagus and caused severe airway contamination. The average dysphagia score (mean ± s.d.) for the marked dysphagia model was 10.6 ± 1.1 before surgery and 6.1 ± 4.3 after surgery (P = 0.007). Laryngeal advancement surgery did not significantly improve the dysphagia scores in the moderate model (P = 0.5). CONCLUSIONS: Laryngeal advancement surgery may improve swallowing and reduce aspiration in horses affected with diseases that cause pharyngeal dysphagia.

Increased serum nonesterified fatty acid and low ionised calcium concentrations are associated with post partum colic in mares.

REASONS FOR PERFORMING STUDY: Increased serum nonesterified fatty acids (NEFA) and decreased serum electrolytes are linked to abdomasal displacements in post partum dairy cattle. Post partum colic in mares may be associated with metabolic changes specific to pregnancy and the periparturient period. OBJECTIVES: To determine if fluctuations in serum NEFA, ionised calcium (iCa) and magnesium (iMg) occurred in periparturient mares and if these alterations were associated with post partum colic. STUDY DESIGN: Longitudinal observational study. METHODS: Mares from 3 farms in central Kentucky were enrolled. Blood samples were collected 14 days prior to the estimated foaling date, within 4 days post parturition, and 14 and 28 days after foaling for batch analysis of serum NEFA, iCa and iMg. Health information was provided by farm managers and veterinarians. Data were analysed using Kruskal-Wallis χ(2) statistic for nonparametric data and a matched case/control approach. Repeated measures logistic regression models were developed. RESULTS: Serum NEFAs were higher at 14-1 day before foaling (mean ± s.d., mmol/l), 0.28 ± 0.12, P = 0.04 and from foaling to 4 days after foaling, 0.29 ± 0.20 (P = 0.05) in mares that developed colic compared with those that did not colic, 0.19 ± 0.05 and 0.21 ± 0.14, respectively. Ionised calcium was lower at 15-28 days post foaling in mares that showed colic, 1.50 ± 0.17 compared to mares that did not colic, 1.60 ± 0.12, P = 0.02. Risk of colic in post partum mares increased 38% for each 0.1 mmol/l increase in serum NEFA (odds ratio = 1.38, 95% confidence interval 1.06-1.81, P = 0.02). CONCLUSIONS: Mares with post partum colic had significantly higher serum NEFA and lower iCa prior to the colic episode compared with mares that did not develop colic. Monitoring these metabolic alterations may lead to predictive and preventive colic strategies for post partum mares.

Changes in the faecal microbiota of mares precede the development of post partum colic.

REASONS FOR PERFORMING STUDY: Disruptions in the gastrointestinal microbiota may trigger development of post partum colic. OBJECTIVES: To determine the effects of the periparturient period on the faecal microbiome and identify associations between the faecal microbiota and post partum colic. STUDY DESIGN: Longitudinal case-control study. METHODS: Pre- and post partum faecal samples were collected from mares on 3 farms in central Kentucky. Next generation sequencing of the V4 region of the 16S rRNA gene was performed on samples from 13 mares that developed colic, 13 mares that did not display colic and 5 nonpregnant controls. RESULTS: There were 4,523,727 sequences from 85 samples evaluated (mean ± s.d. 53,220 ± 29,160, range 8442-122,535). Twenty-five phyla were identified, although only Firmicutes, Verrucomicrobia, Actinobacteria and Proteobacteria were present at a relative abundance of 1% or greater. The faecal microbiota of late-term mares differed from nonpregnant mares, with differences in microbial community membership and structure but not the relative abundance of major phyla. There was limited impact of foaling and the post partum period on the faecal microbiome. Faecal samples obtained from mares prior to episodes of colic had significantly higher relative abundance of Proteobacteria (8.2%, P = 0.0006) compared with samples from mares that did not display colic (3.7%). All samples with a relative abundance of Firmicutes of ≤50% preceded colic, as did 6/7 (86%) samples with >4% Proteobacteria. Differences in microbiota membership and structure were also present between mares that developed large colon volvulus and matched controls that did not have colic. Sixty-one indicator operational taxon units were identified for the control (vs. volvulus) samples, and these were dominated by Lachnospiraceae (n = 38) and Ruminococcaceae (n = 8). CONCLUSIONS: Foaling had minimal effects on the mares' faecal microbiota. Numerous differences in the faecal microbiota preceded colic. Associations between Firmicutes (particularly Lachnospiraceae and Ruminococcaceae) and Proteobacteria and development of colic could lead to measures to predict and prevent colic. The Summary is available in Chinese - see Supporting information.

Prophylactic digital cryotherapy is associated with decreased incidence of laminitis in horses diagnosed with colitis.

REASONS FOR PERFORMING THE STUDY: Recent research suggested that prophylactic digital cryotherapy (ICE) improved lameness scores, diminished histological changes and early laminar inflammatory signalling in horses following oligofructose administration. In clinical practice, horses at risk for sepsis-associated laminitis receive ICE. Evidence to support this practice is lacking. OBJECTIVES: To determine factors associated with development of laminitis in horses diagnosed with colitis, including ICE. STUDY DESIGN: Multicentre retrospective case series. METHODS: Medical records for horses admitted to 2 university hospitals diagnosed with colitis with evidence of systemic inflammatory response from 2002 to 2012 were reviewed. Horses were excluded if they exhibited signs of laminitis at admission, were ponies, miniature or draught breeds, or <2 years old. Data were analysed using univariate and multivariate logistic regression. RESULTS: Twenty-seven of 130 horses (21%) developed laminitis. Seven of 69 (10%) horses treated with ICE developed laminitis compared with 20/61 (33%) horses that developed laminitis but did not receive ICE. Factors associated with laminitis included site of hospitalisation, admission respiratory rate (↑) and blood L-lactate (↑), and ICE (↓), P<0.05. Horses treated with ICE had 10 times less odds of developing laminitis compared with horses treated without ICE (odds ratio 0.11, 95% confidence limit 0.03-0.44). Sixteen horses (16/130, 12%) were subjected to euthanasia in hospital. Fourteen of these horses had laminitis and 2 did not develop laminitis. Survival for horses with colitis that developed laminitis was 13/27 (48%) compared with survival for horses with colitis that did not develop laminitis, 101/103 (98%). CONCLUSION: Laminitis occurred in more clinically compromised horses. Use of ICE reduced the incidence of clinical laminitis in the study population suggesting that digital cryotherapy is an effective prophylactic strategy for the prevention of laminitis in horses with colitis.

Results of upper airway radiography and ultrasonography predict dynamic laryngeal collapse in affected horses.

REASONS FOR PERFORMING STUDY: The pathogenesis of dynamic bilateral laryngeal collapse (DLC) associated with poll flexion is unknown. Diagnosis is dependent upon exercise endoscopy while replicating the flexed head position harness racehorses experience during racing. OBJECTIVES: To describe the effects of poll flexion on rostrocaudal laryngeal positioning and laryngeal lumen width in resting horses diagnosed with DLC compared to controls, and to establish diagnostic criteria for DLC by use of diagnostic imaging. STUDY DESIGN: Case-control study. METHODS: Fifty harness racehorses were prospectively included in the study: 25 cases diagnosed with DLC by treadmill endoscopy and 25 controls in which treadmill endoscopy revealed no abnormal findings. Laryngeal radiography and ultrasonography were obtained in neutral and flexed head positions. Laryngeal positioning and laryngohyoid conformation were compared between the groups and head positions. RESULTS: Poll flexion induced a greater rostral advancement of the larynx in relation to the hyoid apparatus in resting harness racehorses affected with DLC compared to controls (P = 0.007). At the level of the vocal folds, poll flexion resulted in a smaller laryngeal lumen width in horses affected with DLC compared to controls (P = 0.04). Horses were significantly more likely to be affected with DLC when the thyrohyoid bone to thyroid cartilage distance was ≥12 mm in poll flexion (odds ratio 21.3, 95% confidence interval 3.65-124.8, P = 0.004) and when laryngeal lumen width at the level of the vocal folds was less in poll flexion than in the neutral head position (odds ratio 8.4; 95% confidence interval 1.6-44.1, P = 0.012). CONCLUSIONS AND POTENTIAL RELEVANCE: In DLC horses, poll flexion advanced the larynx more rostrally and resulted in a decreased airway lumen width compared to control horses. Laryngeal ultrasound and radiography may facilitate the diagnosis of DLC at rest.

Local airborne particulate concentration is associated with visible tracheal mucus in Thoroughbred racehorses.

REASON FOR PERFORMING STUDY: Accumulations of tracheal mucus assessed by endoscopic examination are associated with poor performance in racehorses. The air quality in horses' stalls may contribute to this visible tracheal mucus. OBJECTIVES: To determine whether the concentration and number of airborne particulates in stalls are associated with visible accumulations of tracheal mucus and with the number of inflammatory cells in tracheal aspirates. METHODS: We studied 107 racehorses from 3 stables, in 3 different months, and measured airborne particulate matter 3 times daily in each of the stalls. On each monthly visit, horse airways were examined endoscopically and assigned a mucus score, and tracheal lavage was performed. Bivariate procedures, general estimating equations and linear mixed models were applied to estimate the association between PM and the presence of accumulations of mucus and number of inflammatory cells. RESULTS: Stable, stall, month and PM were all significantly associated with the presence of accumulations of tracheal mucus, which had an overall prevalence of 67%. The odds of horses having visible accumulation of mucus were increased when horses occupied enclosed stables or stalls with higher particulate concentrations, and when concentrations of larger particles (≤ 10 µm in diameter) were elevated. Sixty-eight percent of tracheal wash samples contained more than 20% neutrophils. Increased numbers of neutrophils were associated with the concentration of smaller particles (≤ 2.5 µm in diameter). POTENTIAL RELEVANCE: Careful consideration of stable construction and management practices focused on maintaining the lowest possible dust concentrations throughout the day should reduce the prevalence of visible accumulations of tracheal mucus, potentially improving racing performance.

Ethyl pyruvate diminishes the inflammatory response to lipopolysaccharide infusion in horses.

REASONS FOR PERFORMING THE STUDY: Endotoxaemia contributes to morbidity and mortality in horses with colic due to inflammatory cascade activation. Effective therapeutic interventions are limited for these horses. Ethyl pyruvate (EP), an anti-inflammatory agent that alters the expression of proinflammatory cytokines, improved survival and organ function in sepsis and gastrointestinal injury in rodents and swine. Therapeutic efficacy of EP is unknown in endotoxaemic horses. OBJECTIVES: Determine the effects of EP on signs of endotoxaemia and expression of proinflammatory cytokines following administration of lipopolysaccharide (LPS) in horses. METHODS: Horses received 30 ng/kg bwt LPS in saline to induce signs of endotoxaemia. Next, horses received lactated Ringer's solution (LRS), (n = 6), 150 mg/kg bwt EP in LRS, (n = 6), or 1.1 mg/kg bwt flunixin meglumine (FM), (n = 6). Controls received saline followed by LRS (n = 6). Physical examinations, behaviour pain scores and blood for clinical pathological testing and gene expression were obtained at predetermined intervals for 24 h. RESULTS: Lipopolysaccharide infusion produced clinical and clinicopathological signs of endotoxaemia and increased expression of tumour necrosis factor alpha (TNFα), interleukin 6 (IL-6) and IL-8 (P<0.001) compared with controls. Leucopenia and neutropenia occurred in all horses that received LPS. Horses treated with EP and FM had significantly (P<0.0001) reduced pain scores compared with horses receiving LPS followed by LRS. Flunixin meglumine was significantly more effective at ameliorating fever compared with EP. Both EP and FM significantly diminished TNFα expression. Ethyl pyruvate significantly decreased, but FM significantly increased, IL-6 expression. Neither EP nor FM altered IL-8 expression. CONCLUSIONS AND POTENTIAL RELEVANCE: Ethyl pyruvate administered following LPS diminished the clinical effects of endotoxaemia and decreased proinflammatory gene expression in horses. Ethyl pyruvate suppressed expression of proinflammatory cytokines better than FM. However, FM was a superior anti-pyretic compared with EP. Ethyl pyruvate may have therapeutic applications in endotoxaemic horses.

Dysphagia associated with presumed pharyngeal dysfunction in 16 neonatal foals.

REASONS FOR PERFORMING STUDY: Dysphagia due to pharyngeal dysfunction occurs in human neonates and is associated with prematurity and hypoxic episodes. This syndrome probably occurs in neonatal foals but has not been reported. OBJECTIVES: The objectives of this study were to describe 1) a series of neonatal foals with dysphagia due to pharyngeal dysfunction; 2) the progression, treatment and resolution of the dysphagia; 3) the comorbidities; and 4) the prognosis for life and athleticism for affected foals. METHODS: Records from 3 referral equine hospitals were reviewed from neonatal foals with dysphagia of pharyngeal origin. Inclusion criteria were a normal to strong suckle, dysphagia evidenced by milk at the nostrils after nursing the dam, and endoscopic examination of the airway. Foals with mechanical reasons for dysphagia, botulism or hyperkalaemic periodic paralysis were not included. RESULTS: Sixteen neonatal foals qualified for the study. Eight (50%) were premature and/or diagnosed with hypoxic ischaemic encephalopathy. Twelve (75%) had aspiration pneumonia. Fifteen foals were discharged alive from the hospital, nursing the mare with no evidence of dysphagia (n = 14), or mild dysphagia (n = 1), a mean +/- s.d. of 7 +/- 6 days (median = 6.3 days, range 0-22 days) after hospital admission. One foal was subjectedto euthanasia in hospital. Follow-up nformation was available for 14 animals. Thirteen of 16 (81%) were alive and included one yearling and 12 horses >2 years old. Seven of the 14 (50%) were racing, training or in work, and 6 horses were pets, breeding animals or had unknown athletic status. Two had laryngeal deficits. One foal was subjected to euthanasia within weeks of discharge from the hospital due to aspiration pneumonia. CONCLUSION: Dysphagia related to pharyngeal dysfunction occurs in equine neonates and can resolve, but may require days to weeks of supportive care. Prognosis for life is favourable and for athleticism fair.

Particle mapping in stables at an American Thoroughbred racetrack.

REASONS FOR PERFORMING STUDY: Airway inflammation and mucus in the trachea are common in racehorses. Fine airborne particles can initiate and coarse particles can worsen airway inflammation in man and in animal models of airway disease. The regional and seasonal distribution of particles of different sizes has never been investigated in American racing stables. OBJECTIVES: To determine the regional and seasonal concentration and number of airborne particles of different sizes in racing stables. METHODS: Direct reading instruments were used to determine the mass concentration and numbers of particles 3 times daily (early morning, midday and late afternoon) in July, September and November, in 3 different racing stables. RESULTS: Average particle concentrations were lowest in July and highest in September and November. Early morning concentrations were significantly higher than those measured throughout the rest of the day. The completely enclosed stable with little natural ventilation, had significantly higher particulate concentrations than the open-sided stable. With regard to numbers of particles, those 2-5 µm were greatest in July and least in November; those 0.5-1.0 µm were greatest in September and least in November. Location of stall within stable also affected concentrations and numbers. CONCLUSIONS: The concentration and number of particles in sizes known to reach the lower airways varies with stable design/management, time of day, season of year and location of the stall within the stable. POTENTIAL RELEVANCE: Particle mapping is a useful tool in the identification of stables, season, and location of stalls within stables where horses may be at greater risk of exposure to offending particulates.

Preliminary safety and biological efficacy studies of ethyl pyruvate in normal mature horses.

REASONS FOR PERFORMING THE STUDY: Endotoxaemia causes substantial morbidity and mortality in horses with colic and sepsis. Ethyl pyruvate is a novel anti-inflammatory medication that improved survival in preclinical models of severe sepsis endotoxaemia and intestinal ischaemia and reperfusion in rodents, swine, sheep and dogs and may be a useful medication in horses. HYPOTHESIS: Ethyl pyruvate has no adverse effects in normal horses and is biologically active based on suppression of proinflammatory gene expression in endotoxin stimulated whole blood, in vitro. METHODS: Physical and neurological examinations, behaviour scores, electrocardiograms and clinicopathological tests were performed on 5 normal healthy horses receiving 4 different doses of ethyl pyruvate. Doses included 0, 50, 100 and 150 mg/kg bwt administered in a randomised crossover design with a 2 week washout period between doses. Biological efficacy was assessed by stimulating whole blood with endotoxin from the horses that received ethyl pyruvate prior to and 1 and 6 h after drug infusion. Gene expression for TNFα, IL-1ß and IL-6 was assessed. RESULTS: There were no effects of drug or dose (0, 50, 100 or 150 mg/kg bwt) on any of the physical or neurological examination, behaviour factors, electrocardiogram or clinical pathological results collected from any of the horses. All parameters measured remained within the normal reference range. There was a significant reduction in TNFα, IL-1ß and IL-6 gene expression in endotoxin stimulated whole blood from horses 6 h after receiving 150 mg/kg bwt ethyl pyruvate. There were no detectable effects on gene expression of any of the other doses of ethyl pyruvate tested. CONCLUSION: We were unable to detect any detrimental effects of ethyl pyruvate administration in normal horses. Ethyl pyruvate significantly decreased proinflammatory gene expression in endotoxin stimulated blood 6 h after drug administration. CLINICAL RELEVANCE: Ethyl pyruvate may be a safe, effective medication in endotoxaemic horses.

Ethyl pyruvate diminishes the endotoxin-induced inflammatory response of bovine mammary endothelial cells.

The endotoxin-induced inflammatory response during coliform mastitis is difficult to control with the currently available therapeutics. Endothelial cells are among the first cell type to be engaged in the inflammatory response and can modulate the severity of inflammation by producing proinflammatory mediators upon endotoxin exposure. Ethyl pyruvate, an ethyl ester of pyruvic acid, can ameliorate endotoxin-induced inflammatory responses by inhibiting the production of proinflammatory mediators in several in vitro and in vivo endotoxemia models. The objective of this study was to determine the effect of ethyl pyruvate on the production of vascular proinflammatory mediators that are associated with the pathogenesis of coliform mastitis. The ability of ethyl pyruvate to reduce the expression of proinflammatory mediators was evaluated in cultured bovine mammary endothelial cells (BMEC) stimulated with endotoxin. Treatment of endotoxin-stimulated BMEC with ethyl pyruvate significantly reduced gene expression of IL-6, IL-8, and intercellular adhesion molecule 1 as well as expression of eicosanoid-producing enzymes, including cyclooxygenase 2 and 15-lipoxygenase 1. This is the first time that the effect of ethyl pyruvate was evaluated in an in vitro BMEC model of coliform mastitis. The ability of ethyl pyruvate to effectively inhibit gene and protein expression of potent vascular proinflammatory mediators in vitro warrants further investigations to assess in vivo efficacy. Ethyl pyruvate is safe for human consumption, and it may be an attractive candidate as a therapeutic in ameliorating the severe pathogenesis associated with coliform mastitis.

Cationic and neutral amino acid transporter transcript abundances are differentially expressed in the equine intestinal tract.

To test the hypothesis that AA transporter transcripts are present in the large intestine and similarly expressed along the intestinal tract, mRNA abundance of candidate AA transporter genes solute carrier (SLC) family 7, member 9 (SLC7A9), SLC7A1, SLC7A8, and SLC43A1 encoding for b(0,+)-type AA transporter (b(0,+)AT), cationic AA transporter-1 (CAT-1), L-type AA transporter-2 (LAT-2), and L-type AA transporter-3 (LAT-3), respectively, was determined in small and large intestinal segments of the horse. Mucosa was collected from the equine small (jejunum and ileum) and large intestine (cecum, left ventral colon, and left dorsal colon), flash frozen in liquid nitrogen, and stored at -80 degrees C. Messenger RNA was isolated from tissue samples, followed by manufacture of cDNA. Relative quantitative reverse transcription-PCR was conducted using the 2(-DeltaDeltaCT) method, with glyceraldehyde-3-phosphate dehydrogenase serving as the housekeeping gene. Compared with the jejunum, cationic and neutral AA transporter SLC7A9 mRNA abundance was similar in the ileum, cecum, and large intestinal segments. Compared with the jejunum, cationic AA transporter SLC7A1 mRNA abundance was similar in the ileum and decreased in the cecum, left ventral colon, and left dorsal colon (P < 0.001). Neutral AA transporter SLC7A8 mRNA abundance decreased from the cranial to caudal end of the intestinal tract (P < 0.001). Neutral AA transporter SLC43A1 mRNA abundance was similar in the ileum and left dorsal colon and increased in the cecum (P < 0.01) and left ventral colon (P < 0.1) compared with the jejunum. Cationic and neutral AA transporter SLC7A9 mRNA abundance was similarly expressed in the large compared with small intestine, whereas cationic AA transporter SLC7A1 was of low abundance in the large intestine; neutral AA transporters SLC7A8 and SLC43A1 were differentially expressed with decreased abundance of SLC7A8 and increased abundance of SLC43A1 in the large intestine. Results indicate that the large intestine might contribute to both cationic and neutral AA uptake and absorption predominantly via transporters LAT-3 and b(0,+)AT.

Effect of poll flexion and dynamic laryngeal collapse on tracheal pressure in Norwegian Coldblooded Trotter racehorses.

REASON FOR PERFORMING STUDY: Dynamic laryngeal collapse (DLC) associated with poll flexion is a newly diagnosed upper respiratory tract obstructive disorder that causes poor racing performance. OBJECTIVES: To determine if Norwegian Coldblooded Trotters (NCTs) affected with DLC associated with poll flexion differ from normal, elite NCTs based on simple airway mechanics measurements. METHODS: Five normal elite NCTs and 6 NCTs diagnosed previously with DLC underwent treadmill videoendoscopy while tracheal pressures were measured continuously. Alternating head positions were used such that horses were exercised with free head carriage and induced poll flexion at heart rates >200 beats/min. RESULTS: Peak inspiratory tracheal pressures were significantly more negative for horses with DLC compared to the elite horses. This difference was only significant during the exercise phases when the poll region was flexed, P = 0.0015. Head position significantly affected peak inspiratory pressure for both elite and affected horses, P < 0.0001. CONCLUSIONS AND CLINICAL RELEVANCE: Induced poll flexion significantly affected peak inspiratory pressure (PIP) in all horses; however, PIPs were significantly more negative in those affected with DLC. Based upon the tracheal pressure measurements recorded in this study, DLC in NCTs is a severe obstructive upper respiratory tract disorder that is induced by poll flexion.

Incidence of transfusion reactions and retention of procoagulant and anticoagulant factor activities in equine plasma.

BACKGROUND: The extent of preservation of clotting factors and incidence of transfusion reactions to noncommercial equine plasma is not documented. HYPOTHESIS: Equine frozen plasma would retain its coagulation factor activity within the reference range and the incidence of transfusion reactions would be low. ANIMALS: Ten plasma donor horses. Fifty clinically ill hospitalized horses receiving plasma were reviewed to determine the incidence of reactions. METHODS: In vitro study and retrospective case review. Plasma was prepared by gravity sedimentation from whole blood refrigerated for 48 hours. The activities of factors VII through XII, antithrombin (AT), and Protein C were measured. Factor activities were compared for plasma samples obtained before blood collection (S0), after 48 hours of gravity sedimentation at 5 degrees C and after plasma separation (S1), and after 90 days of storage at -20 degrees C (S90). The medical records of 50 consecutive clinically ill horses receiving frozen plasma were reviewed to determine the incidence of transfusion reactions. RESULTS: The combined effect of plasma harvest, gravity sedimentation, decantation, and freezing caused significant reductions in factors IX, (43%P= .0013), X, (33%P= .0001), XI, (48%P= .0008), AT, (10%P= .02), and Protein C (26%P= .0001). Activities for all factors analyzed, except factor X, remained within the reference ranges. Transfusion reactions were recorded for 5/50 horses. CONCLUSIONS AND CLINICAL RELEVANCE: Clotting factors, AT, and Protein C were well preserved. The incidence of reactions to frozen plasma was 10%.

Surgical treatment of colic in the miniature horse: a retrospective study of 57 cases (1993-2006).

REASONS FOR PERFORMING STUDY: It has been suggested that the rate of post operative abdominal adhesions in miniature horses is higher than that for other breeds. However, few reports exist in the veterinary literature describing complications and long-term survival following surgical treatment of colic in these horses. OBJECTIVES: To determine the prevalence of surgical lesions in miniature horses with acute abdominal disease in terms of clinical signs, surgical management, post operative treatment and complications, as well as short- and long-term survival. METHODS: Medical records of 57 American Miniature Horses undergoing surgical treatment for acute abdominal pain at the Michigan State University Large Animal Veterinary Teaching Hospital 1993-2006 were evaluated for clinical information. Owners and trainers were contacted to gain information regarding long-term survival. RESULTS: The most common surgical lesion was a faecalith (38/57 cases) located primarily within the descending colon and most frequently diagnosed in horses age <6 months (19/38 cases). Short-term survival to hospital discharge for horses recovered from anaesthesia was 98% (55/56) with the most common post operative complications being diarrhoea and inappetance. Intra-abdominal adhesions were identified in 2/8 horses requiring a second celiotomy. Long-term follow-up was available for 45 horses and 87% (39/45) were alive at least 12 months after surgery. CONCLUSIONS: As previously reported, faecalith obstruction is a frequent surgical lesion in the miniature horse and is most common in miniature horses age <6 months. The incidence of adhesion formation may be lower than previously reported.

Electromyographic activity of the palatinus and palatopharyngeus muscles in exercising horses.

REASONS FOR PERFORMING STUDY: Determining the respiratory related activity of the palatinus and palatopharyngeus muscles in exercising horses is relevant because dysfunction of these muscles has been implicated in the pathogenesis of dorsal displacement of the soft palate. OBJECTIVE: To determine if the palatinus and palatopharyngeus muscles have respiratory activity that increases with intensity in exercising horses. METHODS: Electromyographic activity was measured in the palatinus and palatopharyngeus muscles using bipolar fine-wire electrodes while the horses completed an incremental exercise treadmill protocol. RESULTS: Both muscles displayed synchronous expiratory activity that increased significantly (P < 0.05) with exercise intensity. Phasic expiratory activity of the palatinus increased 390 +/- 98%, whereas phasic expiratory activity of the palatopharyngeus increased by 198 +/- 30% as the treadmill speed increased from 6 to 12 m/s. CONCLUSIONS: The palatinus and palatopharyngeus muscles may be important respiratory muscles, functioning to stabilise the position of the soft palate during intense exercise. CLINICAL RELEVANCE: The predominant expiratory activity of these muscles may be associated with specific muscle function related to exercise or distinct upper airway phenomena of an obligate nasal breather, such as the horse.

The effect of uterine torsion on mare and foal survival: a retrospective study, 1985--2005.

REASONS FOR PERFORMING STUDY: Anecdotal speculation suggests that prognosis for survival of mares and foals following correction of uterine torsion has improved over the past 30 years. OBJECTIVES: To determine statistically the outcome of uterine torsion according to duration of clinical signs, stage of gestation, parity, physical examination findings, method of correction, prognosis for survival and reproductive health of the mare, and prospects for the foal within the neonatal period. METHODS: This retrospective study combined cases from 4 equine referral hospitals. RESULTS: The stage of gestation at which uterine torsion occurred was a risk factor for survival of mare and foal. Overall mare survival was 53/63 (84%); when uterine torsion occurred at < 320 days gestation, 36/37 (97%) of mares survived compared to 17/26 (65%) survival rate when uterine torsion occurred at > or = 320 days gestation. Overall foal survival was 54% (29/54). When uterine torsion occurred at < 320 days gestation, 21/29 (72%) foals survived compared to 8/25 (32%) when uterine torsion occurred at > or = 320 days gestation. Thirty mares were discharged from the hospital carrying a viable fetus following uterine torsion correction and 25/30 (83%) of these mares delivered live foals that survived beyond the neonatal period. CONCLUSIONS: Prognosis for survival for mares and foals following uterine torsion is good and improves if torsion occurs < 320 days compared to > or = 320 days gestation. CLINICAL RELEVANCE: Gestational timing of uterine torsion should be considered when advising clients about the prognosis for survival of the mare and foal. The prognosis for a mare delivering a live foal is good if the mare is discharged from the hospital following uterine torsion correction with a viable fetus.