Function In Horses Research Articles

Renal function in horses

Renal function in horses

Ultrasonographic measurement of diaphragm muscle activity for assessment of respiratory function in horses

Ultrasonographic imaging of the diaphragm is a non-invasive alternative for respiratory function evaluation in horses. This study aimed to measure diaphragm thickness, thickening (change in thickness with contraction) and thickening fraction in healthy adult horses during tidal breathing and forced vital capacity. Correlation between body weight (≤400 kg and >400 kg) and diaphragm thickness was investigated. To that purpose, 20 adult horses, weight 409±50 kg, height 1.47±0.05 m, and age 16±6 years were included in the study. Diaphragm thickness was measured at end-inspiration and end-expiration using B-mode and M-mode. The transducer was placed in the 10th, 11th and 12th intercostal spaces of both hemithoraces. Measurements obtained at end inspiration using M-mode during forced vital capacity were greater than for tidal breathing for diaphragm thickness (P=0.006), diaphragm thickening (P<0.001) and thickening fraction (P<0.001). The same was found for thickening (P<0.001) and thickening fraction (P<0.001). Diaphragm thickness at end-inspiration was greater in horses weighing >400kg than those ≤400kg at the inspiration (0.93±0.2 cm and 0.74±0 0.02 cm, P<0.001) and at the end of expiration (0.77±0.02 cm and 0.63±0, 02 cm, P<0.001). There was no difference in thickening fraction between horses weighing ≤400kg and >400kg (tidal breathing: 18±2 % and 16±2 %, P=0.609; forced vital capacity: 39±6 % and 31±5 %, P=0.301). Diaphragm assessment in horses is possible using both B-mode and M-mode. Breathing workload has a positive correlation between breathing workload and diaphragm contraction. Due to the relationship demonstrated between diaphragm thickness and weight, it is recommended that diaphragm thickening fraction is used to compare diaphragm measurements between horses.

Effects of soaked hay on lung function and airway inflammation in horses with severe asthma.

Reducing inhaled dust particles improves lung function in horses with severe asthma. Soaked hay is commonly used by owners, but its efficacy in improving lung function and inflammation has not been documented. To measure the effects of soaked hay and alfalfa pellets in horses with severe asthma. Ten adult horses with severe asthma from a research colony. Prospective controlled trial. Horses in clinical exacerbation were housed indoors and allocated to be fed either soaked hay (n = 5) or alfalfa pellets (n = 5) for 6 weeks. Soaked hay was immersed for 45 minutes and dried out hay was discarded between meals. Pulmonary function and clinical scores were measured before and after 2, 4, and 6 weeks. Tracheal mucus scores and bronchoalveolar lavages were performed before and after 6 weeks. Lung function was analyzed with a linear mixed model using log-transformed data. Lung resistance decreased from (median (range)) 2.47 (1.54-3.95) to 1.59 (0.52-2.10) cmH2 O/L/s in the pellets group and from 1.89 (1.2-3.54) to 0.61 (0.42-2.08) cmH2 O/L/s in the soaked hay group over the 6-week period for an average difference of 1.06 cmH2 O/L/s for pellets (95% confidence interval [95% CI]: 0.09-2.04, P = .03, not significant after correction) and 1.31 cmH2 O/L/s for soaked hay (95% CI: -0.23 to 2.85, P < .001, significant). Soaked hay can control airway obstruction in horses with severe asthma. The strict protocol for soaking and discarding dried-out hay in this study could however be considered too great of an inconvenience by owners.

PSVII-12 The Effect of Two Supplemental Vitamin E Dosing Strategies in Morgan Horses with Marginal/Deficient Concentrations of Serum Alpha-Tocopherol

Abstract Vitamin E is an important antioxidant for normal neuromuscular function in horses. Dietary deficiencies are common in northern climates with seasonal access to pastures. Certain breeds, such as Morgan Horses, with predisposition to equine metabolic diseases, may exhibit deficiencies in vitamin E because of management systems imposed which restrict access to pasture. Few studies have compared strategies for initial supplementation to increase serum alpha-tocopherol in horses. The objective of this study was to compare two dosing strategies of d-alpha-tocopherol acetate to increase serum alpha-tocopherol in marginal/deficient horses. Eight Morgan horses (two geldings, six mares; mean BW = 460 kg) with marginal/deficient serum alpha-tocopherol (0.47-1.12 µg/mL) were enrolled in a randomized block design study. Blocks were balanced for age, sex, and pre-study vitamin E level and horses were assigned to one of two treatments: 1) HIGH - 10,000 IU liquid d-alpha-tocopherol acetate top-dressed on grain for 4 wk followed by 10 d step-down to 5,000 IU of powder d-alpha-tocopherol acetate through 16 wk; or MEDIUM – 5,000 IU of powder d-alpha-tocopherol acetate for 16 wk. Horses were housed in box stalls with daily turnout without access to grass. Horses were fed hay at 2% of BW and 0.45 kg of concentrate daily with vitamin E feed activity of 45.5 and 1378 IU/kg, respectively. HIGH and MEDIUM treatments were fed once daily with the AM feeding. To ensure horses consumed the powder d-alpha-tocopherol acetate, cookies made from alfalfa powder, gelatin and d-alpha-tocopherol acetate powder were created. Serum alpha-tocopherol was assessed pre-feeding every two weeks from 0 to 16 weeks. Before the step-down to 5,000 IU dose, horses receiving the HIGH dosage had greater concentrations of serum alpha-tocopherol (P &amp;lt; 0.01; Figure 1). All horses receiving the HIGH treatment attained serum alpha-tocopherol concentrations greater than 2.0 µg/mL after 2 weeks, while only one-half of horses receiving the MEDIUM dosage reached serum alpha-tocopherol concentrations greater than 2.0 µg/mL by 4 weeks. To attain and maintain normal concentrations of serum alpha-tocopherol, deficient horses should follow the HIGH supplementing strategy of d-alpha-tocopherol acetate.

Long-term outcome after colic surgery: retrospective study of 106 horses in the USA (2014-2021).

To determine long-term survival rate, defined as survival to 1 year after discharge from the hospital, and rate of return to prior athletic, breeding, or other function in horses undergoing colic surgery at the first presentation at one referral hospital in the Pacific northwest region of the United States. Records were reviewed for all horses that underwent colic surgery between October 2014 and October 2021. Owners of horses that survived to discharge were contacted to obtain follow-up information via internet-based questionnaire or telephone interview. The percentage of horses that survived to 1 year after discharge, rates of return to function, and complications occurring after hospital discharge were determined. The possible association of patient signalment, lesion type, and surgical procedures with long-term survival was examined with Chi-square and Fisher's exact tests. Overall satisfaction was indicated on a scale of 1 (unsatisfied) to 5 (very satisfied). Of 185 horses that underwent surgical intervention for colic and met the inclusion criteria, 134 horses recovered from anesthesia, with 106 of these recovered horses (79.1%) surviving to discharge. Of the 71 horses for which follow-up information was obtained, 61 horses survived to 1 year after discharge (long-term survival rate of 85.9%). There were no demographic, lesion type, or surgical procedure variables significantly associated with long-term survival. Prior to surgery, 59/71 horses (83.1%) were engaged in some type of athletic activity. After surgery, 44/61 horses (72.1%) were reported to be athletically active. Only one horse was reported to be retired from athletic activity as a direct result of a complication from surgery. Overall satisfaction with the decision to proceed with colic surgery was rated by all respondents as 4 or 5. The long-term survival for this sample of horses was similar to previously published reports of long-term survival after colic surgery. Horses that survived to hospital discharge were highly likely to remain alive and be athletically active 1 year later. There were no factors related to the signalment of the horse, the specific cause of colic, or the surgical procedures performed that were significantly associated with likelihood of survival.

The Effect of Inhaled Ciclesonide Treatment on Systemic Markers of Immune Function in Horses

The use of dexamethasone to control equine asthma is a common and effective treatment. Although short-term systemic dexamethasone treatment has not been shown to induce systemic immunosuppression in the horse, the goal of this study was to determine whether inhaled ciclesonide, an FDA-approved drug for the treatment of equine asthma, exerts any systemic immunosuppressive effects when compared to dexamethasone-treated and untreated horses. Eighteen light, mixed breed horses, ranging in age from 3 to 8 years of age, were used for this study and randomly assigned to one of three treatment groups: (1) nontreated controls, (2) ciclesonide treatment, or (3) dexamethasone treatment. Blood was collected daily for steady-state messenger RNA (mRNA) analysis, as well as at Days 0, 5, 10, and 15 of treatment for in vitro stimulation with Concanavalin A (ConA). Messenger RNA relative quantities were determined using RT-qPCR for select genes. Two-way, repeated measures analysis of variance was used to analyze qPCR data and results considered significant at P < .05. There were significant decreases in the steady-state, whole-blood expression of granzyme B and interferon-γ due to dexamethasone treatment, when compared to the nontreated control group. Within ConA-stimulated samples, there remained a suppressive effect of dexamethasone treatment on granzyme B expression compared to nontreated control horses. Similar effects were not noted in the ciclesonide-treated horses. Significant effects of ciclesonide treatment on markers of immune function were not noted in this study, suggesting a low risk for immunosuppression with inhaled ciclesonide treatment.

Adequacy of equine thyroid function testing in mares

The gold standard for thyroid function in horses is a thyroid releasing hormone (TRH) response test. We hypothesized that published reference values for thyroxine (T4), triiodothyronine (T3) would apply to mares in an iodine deficient zone. Our objective was to evaluate basal thyroid hormone levels and TRH responses in twenty-seven healthy Quarter Horse type mares fed grass hay, oats, with free access to cobalt iodine salt blocks and mean ± SD age of 9.2 ± 4.4 years, and weight of 527 ± 65.1 kg. Four mares were 10 to 35 days pregnant. Physical examinations were within normal limits including palpation and ultrasound of the thyroid gland. TRH response tests were performed mornings from July to September. A basal jugular blood sample (0 h) was obtained, TRH (1 mg IV, Sigma) was administered, and additional samples obtained at 2 h for T3 and 4 h for T4. Definitions: Fold change (FC) post-TRH level / basal level; Euthyroid basal T4 (12.87-38.6 nmol/L) and T3 (0.41-1.1 nmol/L) within reference ranges of Animal Health Diagnostic Lab, Ithaca, NY and TRH T4 and T3 responses with a FC >2. The Post TRH FC reference ranges for T4 and T3 reported by Breuhaus (2018) were also evaluated (T4 FC 1.3-3.8; T3 FC 1.1-10). Serum was separated and stored at -20C. A single assay was performed to measure T3 and T4 using the Siemen's Immulite method (PDS, Saskatoon, SK). Data were evaluated using Shapiro Wilk, Kruskal Wallis and Spearman Rank Correlation at P < .05. Low basal levels were measured in three mares for T3 (11%), and two for T4 (7.4%). Ten mares had T3 levels with a FC<2 (37%), and two had FC<1.1 (7.4%). Regarding T4 twenty-two mares (81%) had a FC<2 and ten had a FC <1.3 (37%). The FC was below the reference range for both T3 and T4 in two mares. There were significant correlations between basal T3 and T4 (R=0.47 P=.012) and between T3 FC and T4 FC (R=0.64, P=.0001), and no effect of pregnancy. We concluded that basal T3 and T4 values were too variable to assess thyroid function, as mares with low basal values usually had a FC>2. Using FC >2 as an adequate TRH response is problematic as a FC<2 was identified in 37% of T3 and 81% of T4 mares. There were 7.4% and 37% of mares below the low end of the FC reference for T3 and T4 respectively. These low values may indicate that the mares were hypothyroid, which is often due to underlying iodine insufficiency. Iodine status and its relationship to the thyroid response to TRH should be further evaluated due to iodine's central role in equine health.

41 A preliminary investigation of candidate genes from a GWAS identified QTL for relative body size in the American Quarter Horse

Artificial selection during domestication has influenced an array of morphological traits in the horse, many that are now important economic traits for the horse industry. Growth and skeletal phenotypes impact the desirability and function of horses in diverse disciplines and are often key characteristics in the development of breeds. Skeletal traits also impact functionality: benefitting horses for specialized work or predisposing them to musculoskeletal injury. To investigate variations in body size and shape, we utilized measurements taken at 2 years of age (+/− one week) from 91 American Quarter Horses bred and owned by the University of Florida. We summarized 32 body measures from each horse using a principal component analysis followed by a varimax rotation. Factor 1 summarizes 19.5% of the variation and describes overall body size, except for head measurements which are better captured in Factor 2. Factor 1 traits encompass body proportions, heavily loading on the measure's height at dock and croup. DNA was extracted from blood and hair through previously published methods and genotyped at GeneSeek Inc. (Lansing, MI) using the Affymetrix Axiom Equine HD 670k array. We recently reported results from a preliminary genome-wide association study with 311,085 high-quality SNPs (poly-high resolution, MAF >0.05)suggesting a quantitative trait locus for the Body Factor 1 trait on chromosome 6 (raw P = 1.356e-09, Bonferroni P = 4.51e-07) and defines a candidate region spanning 1.5Mb. The QTL is in a region unrelated to a previously characterized HMGA2 body height locus. The candidate region contains 5 protein-coding genes, influencing human height and skeletal traits including one associated with Noonan Syndrome- a disease impacting height and facial morphology, an interesting parallel to the phenotype observed in our population. None of the 16,860 variants found in the European Nucleotide Archive for our candidate region had a functional impacted on a protein coding region. Therefore, we sequenced 2 whole genomes from American Quarter Horses to discover variants specific to the haplotype bearing this new body size QTL. Using the 10x Chromium library prep with 150bp paired end reads on an Illumina HiSeq2500, the 2 genomes totaled 1.5 billion reads. Following alignment and variant calling using the LongRanger package (v2.2, 10x Genomics Inc.), we observed 4,703 SNPs in the candidate region. Future investigation aims to investigate additional loci relevant to body morphological variations and develop predictive phenotype models in the horse.

73 Comparison of fecal particle size of Thoroughbred broodmares and their yearlings

Fecal particle size (FPS) may be an indicator of chewing efficiency and digestive function in horses. The objective of this study was to evaluate the effect of horse age on FPS by comparing FPS measured by wet sieving analysis between 6 mares (12.8 ± 2.8 y) and their yearlings (1.18 ± 0.06 y). Both groups were housed on pasture with access to alfalfa hay and fed 2.73–3.64 kg/d of concentrate feed formulated for breeding and growing horses. Feces were collected by free catch, and divided into subsamples. One subsample was used for dry matter (DM) determination and the remaining samples were frozen until analysis. Before analysis, samples were thawed and duplicate aliquots containing 3.8 g of DM were soaked overnight in 200 mL of water. The amount of sample needed to contain 3.8 g of DM was calculated using the predetermined sample DM. Samples were washed over a set of 203.2 mm stainless steel sieves (VWR, Radnor, PA) with sieve openings of 4, 2, 1, 0.5, 0.25, 0.125 and 0.063 mm using a standardized water flow rate of 6 L/min for 5 min. Each sieve was rinsed clean into a beaker from which particles were filtered onto dried, pre-weighed filter paper for DM determination. Particles passing the smallest sieve were not collected but the amount was calculated by difference between total DM sieved and DM retained on all sieves.Weighted mean FPS and percent DM retained on each sieve as a percent of total DM sieved were analyzed using paired t-test procedure in SPSS V28. There was no difference in weighted mean FPS between mares (1.59 mm ± 0.09) and yearlings (1.47 mm ± 0.06) (P > 0.05). There was no difference in the percentage of DM retained on the 3 largest and 2 smallest sieves between mares and yearlings (P > 0.05). Compared with yearlings, there were trends for mares to have greater DM retained on sieves with diameter 0.5 mm (P = 0.096) and 0.25 mm (P = 0.08). Mean ± SE percent DM retained for mares and yearlings, respectively, was 9.6% ± 1.6 and 6.95% ± 1.2 (4 mm sieve), 12.70% ± 1.09 and 10.65% ± 1.08 (2 mm sieve), and 12.48% ± 0.89 and 12.19% ± 1.7 (1 mm sieve). Soluble DM calculated by difference as DM escaping the smallest sieve was greater in yearling samples compared with mare samples (37.02 vs 29.88%; P = 0.019). The small sample size of this study is a limitation but suggests there may be differences in fecal particle size distribution between mare and yearling pairs that warrant further investigation.

Does high-intensity laser therapy speed return to primary function in horses with suspensory ligament desmopathy?

PICO question In horses with a suspensory ligament branch injury, does high-intensity laser therapy (energy output greater than 500 mW) combined with conservative management, compared to conservative management alone, result in a faster return to primary function? Clinical bottom line Category research Treatment. Number and type of study deisgns reviewed The number and type of study designs that were critically appraised were two peer-reviewed studies: a non-randomised controlled clinical trial and a randomised controlled experimental study. Strength of evidence Weak. Outcomes reported The outcomes reported are summarised as follows: the two appraised studies report positive effects of high-intensity laser therapy (HILT) on equine tendon and ligament injuries as measured by pain to palpation, lameness, swelling and ultrasonographic and magnetic resonance imaging (MRI) evaluation of HILT-treated lesions. Conclusion In view of the strength of evidence and the outcomes from the studies the following conclusion is made: the two appraised studies provide only weak evidence to show that horses treated with high-intensity laser therapy (HILT) and conservative management return to primary function sooner than horses treated with conservative management alone. Issues of design, methodology, statistical analysis and reporting reduce the reliability and external validity of these studies. How to apply this evidence in practice The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources. Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.

Evaluation of the effect of glucocorticoid treatment on adrenocortical functions by monitoring endogenous hydrocortisone in horses.

Glucocorticoid preparations have anti-inflammatory effects, and are commonly used in the equine clinical setting; however, such treatments can cause a number of side effects. Adrenal insufficiency is an adverse effect induced by the suppression of adrenal function following drug administration. This study aimed to investigate the influence of two glucocorticoid preparations, dexamethasone and hydrocortisone, on adrenocortical function in horses. The usual doses of dexamethasone and hydrocortisone preparations in equine practice were administered intramuscularly to six horses, and peripheral blood was collected at different time points. Concentrations of dexamethasone and hydrocortisone in the plasma, before and after drug administration, were measured using liquid chromatography-tandem mass spectrometry. Considering circadian rhythms in endogenous hydrocortisone levels, hormone concentrations, before and after drug administration, were compared at the same time of the day. Plasma dexamethasone concentrations were below the limit of quantification at 72 hr post-administration. Plasma hydrocortisone concentrations were significantly lower from 1 to 72 hr after administration. After hydrocortisone preparation administration, plasma hydrocortisone levels were significantly higher until 9 hr, and significantly lower at 24 and 48 hr. The suppression rate of endogenous hydrocortisone ranged over 2.2-5.3% with dexamethasone treatment and 17.5-45.7% with hydrocortisone treatment. The study clearly indicated the effects of glucocorticoids on adrenocortical function in horses and provided basic knowledge about the selection and prescription of glucocorticoid preparations and setting the withdrawal times in equine clinical setting.

Kinematics of the axial segment of horses submitted to dynamic mobilization exercises

This study aimed to investigate the kinematic effects of dynamic mobilization exercises on the axial segment in horses. Twelve horses crossbreed were used, which were monitored before (day 0) and at the end of the experimental period (day 120), distributed in an entirely randomized design, totalizing six repetitions per treatment The treatments consisted of two experimental groups, one composed of horses not performing the dynamic mobilization exercises and the other composed of horses submitted to the mobilization program. The static kinematic variables were evaluated, by means of hemispherical markers such as depth (cm), angle (°), difference in depth and angle, for each vertebral level analyzed (T10, T13, T17, L1 and L3), as well as total range of motion for depth and angle, in which this parameter expressed the thoracolumbar motion in its entirety. The performance of dynamic mobilization produced a significant (P&lt;0.05) decrease in thoracolumbar depth and increase in thoracolumbar flexion angle, compared to the group that did not perform the functional exercises. A reduction in the total thoracolumbar depth of -6.28 cm (P&lt;0.0001) was observed in horses that underwent the exercises. The same response behavior was verified for angular measurement, in which there was an increase in the total ROM of the angle, reflecting thoracolumbar flexion, of 15.54°(P&lt;0.00001). It was concluded that dynamic mobilization exercises consistently produce flexion of the axial segment, becoming a potential tool to improve range of motion and thoracolumbar function in horses.

Investigating the Relationship Between Cardiac Function and Insulin Sensitivity in Horses: A Pilot Study.

Metabolic syndrome in humans is commonly associated with cardiovascular dysfunction, including atrial fibrillation and left ventricular diastolic dysfunction. Although many differences exist between human and equine metabolic syndrome, both of these conditions share some degree of insulin resistance. The aims of this pilot study were to investigate the relationship between insulin sensitivity and cardiac function. Seven horses (five mares, two geldings, aged 17.2 ± 4.2 years, weight 524 ± 73 kg) underwent insulin-modified frequently sampled intravenous glucose tolerance testing to determine insulin sensitivity (mean 2.21 ± 0.03 × 10−4 L/min/mU). Standard echocardiograms were performed on each horse, including two-dimensional, M-mode, and pulse-wave tissue Doppler imaging. Pearson and Spearman correlation analyses were used to determine the association of insulin sensitivity with echocardiographic measures of cardiac function in 5 horses. Insulin sensitivity was found to be significantly correlated with peak myocardial velocity during late diastole (r = 0.89, P = 0.0419), ratio between peak myocardial velocity in early and late diastole (r = −0.92, P = 0.0263), isovolumetric relaxation time (r = −0.97, P = 0.0072), and isovolumetric contraction time (ρ = −0.90, P = 0.0374). These preliminary data suggest that decreased insulin sensitivity is correlated with alterations in both systolic and diastolic function, as measured with tissue Doppler imaging (TDI). Due to the small sample size of this study, the relationship between insulin sensitivity and myocardial function in horses requires further investigation.

Supplemental Nicotinic Acid Elevates NAD+ Precursors in the Follicular Fluid of Mares.

Simple SummaryMiscarriage and embryonic death have been associated with a deficiency in NAD+ resulting from a lack of dietary niacin in women and mice. Mares often suffer from high rates of early embryonic loss, but the dietary requirement of niacin in pregnant mares remains unknown. The aim of this study was to determine the effect of supplementing nicotinic acid, a form of niacin often supplemented in horse diets, on the elevation of other NAD+ precursors in the blood and follicular fluid of mares. We orally administered nicotinic acid to mares over consecutive days and collected blood and follicular fluid at the end of the feeding period. The results show that multiple examined NAD+ precursors were elevated in the follicular fluid of mares at the end of the feeding period, which we propose will aid in reducing early embryonic loss in the mare by promoting good quality oocytes.A deficiency in NAD+ has previously been linked with increased occurrences of congenital abnormalities and embryonic death in humans and mice. Early embryonic death is a major factor involved in pregnancy loss in mares, and very little is known regarding the NAD+ requirements for optimum reproductive function in horses. The aim of this study was to determine the effect of supplementing the diet of mares with nicotinic acid (NA) on the composition of NAD+ metabolites in the blood and follicular fluid. Vehicle alone or NA (3 g per os) were administered to seven mares over a minimum of 3 consecutive days during the follicular phase of the oestrous cycle. Blood samples were collected immediately prior to supplemental feeding and follicular fluid aspiration. Follicular fluid was collected from the dominant follicle through transvaginal ultrasound-guided aspiration. Blood and follicular fluid samples were processed and analysed by mass spectrometry. The concentration of nicotinamide mononucleotide (NMN) in the follicular fluid of NA-fed mares was 4-fold greater than that in the corresponding plasma and 10-fold greater than that in the follicular fluid of vehicle-fed mares. The concentrations of NA, nicotinamide (NAM) and nicotinuric acid (NUR) tended to be greater in the follicular fluid of NA-supplemented mares than in the corresponding plasma. The results show that NA supplementation increased the bioavailability of NAD+ precursors in the follicular fluid of the dominant follicle, which is proposed to better promote the maturation of good quality oocytes, especially in older mares.

Effects of equine SALSA on neutrophil phagocytosis and macrophage cytokine production.

Salivary scavenger and agglutinin (SALSA) is a secreted protein with various immunomodulatory roles. In humans, the protein agglutinates and inactivates microorganisms, and inhibits the release of pro-inflammatory cytokines. Saliva, which is rich in SALSA, accelerates bacterial phagocytosis, but SALSA’s contribution is unclear. In horses, the functions of SALSA in inflammation remain undetermined, so they were investigated through phagocytosis and cytokine assays. Equine SALSA was purified from duodenal tissue, which contains abundant SALSA. To assess phagocytosis, fluorescently-labelled bacteria were incubated with 20, 10, 5, or 2.5 μg/mL of SALSA or phosphate buffered saline (PBS), and then incubated at 37°C or on ice with whole blood from seven healthy horses. Fluorescence was measured by gating on neutrophils using a flow cytometer, and compared between groups. To assess effects on cytokine production, alveolar macrophages were isolated from bronchoalveolar lavage fluid of five healthy horses and cultured in serum-free media for 24 hours with different concentrations of SALSA plus 1 μg/mL lipopolysaccharide (LPS), only LPS, or only media. Cytokines were measured in supernatant using an equine-specific multiplex bead immunoassay. There was significantly greater phagocytosis in samples incubated at 37°C compared to incubation on ice. Samples incubated with 20 μg/mL of SALSA at 37°C had less phagocytosis compared to samples with 10 or 2.5 μg/mL SALSA, or PBS. Alveolar macrophages incubated with SALSA plus LPS released significantly less CXC motif chemokine ligand 1, interleukin-8, interleukin-10, and tumor necrosis factor α, and more granulocyte colony stimulating factor (G-CSF), compared to macrophages incubated with LPS alone. These findings indicate anti-inflammatory effects, which may be due to interference with toll-like receptor 4 recognition of LPS or downstream signaling. Increase in G-CSF following incubation with SALSA suggests a novel mechanism for immunoregulation of alveolar macrophages by SALSA, addressing a knowledge gap regarding its functions in horses.

A portable fan-based device for evaluating lung function in horses by the forced oscillation technique

Objective. The assessment of lung mechanics in horses is nowadays based on invasive methods that may require sedation. The forced oscillation technique (FOT) allows the non-invasive assessment of respiratory mechanics during spontaneous breathing, but current devices are complex, cumbersome, expensive, and difficult to be applied in horses. Approach. We developed a portable FOT device based on a novel approach in which the pressure waveforms are generated by a servo-controlled ducted fan. This new approach allows the design of devices that are more sturdy, compact, and portable compared to already existing approaches. The prototype includes 1) a small microcontroller-based electronic board for controlling the fan and measuring flow and pressure and 2) an optimized data processing algorithm. Main results. This device provides a maximum error of 0.06 cmH2O·s/L and 0.15 cmH2O·s/L in measuring respiratory resistance and reactance during in-vitro validation. A pilot study was also performed on three healthy horses and three horses with severe equine asthma (SEA) and it demonstrated good tolerability and feasibility of the new device. Total respiratory system resistance (R rs) and reactance (X rs) significantly differed (p < 0.05) between groups. At 5 Hz, R rs was 0.66 ± 0.02 cmH2O·s/L and 0.94 ± 0.07 cmH2O·s/L in healthy and in SEA, respectively. X rs 0.38 ± 0.02 cmH2O·s/L and −0.27 ± 0.05 cmH2O·s/L. Significance. This novel approach for applying FOT allowed the development of a small, affordable, and portable device for the non-invasive evaluation of respiratory mechanics in spontaneously breathing horses, providing a useful new tool for improving veterinary respiratory medicine. Moreover, our results provide supporting evidence of the value of this novel approach for developing portable FOT devices also for applications in humans.

β-Hydroxy β-methylbutyrate supplementation to adult Thoroughbred geldings increases type IIA fiber content in the gluteus medius.

Consumption of β-hydroxy β-methylbutyrate (HMB) alters muscle composition and metabolism leading to strength and agility improvements in human athletes. To determine if HMB affects athletic performance and muscle function in horses, Thoroughbred geldings were fed a control (CON; n = 5) or HMB (n = 6) supplement for 6 wk prior to completing a standardized exercise test (SET). Gluteus medius (GM) muscle biopsies were obtained before the SET for fiber typing. Heart rate, biceps femoris (BF) and semitendinosus (ST) surface electromyograms (EMG), and fore and hind limbs metacarpophalangeal joint angles were captured at the gallop of the SET. Results demonstrate that HMB supplementation increased (P < 0.05) the percentage of type IIA and IIA/X muscle fibers in the GM with a corresponding decrease (P < 0.05) in type IIX fibers. The percentage of type I fibers was unaffected by diet. Supplementation with HMB did not result in any measurable effects on performance or biomechanical properties by comparison to CON. Supplementation with HMB resulted in an increase (P < 0.05) in ST median frequency at speeds of 10 m/s and greater. Increasing treadmill speed resulted in an increase (P < 0.05) in stride length and the maximal proximal forelimb fetlock angle, and a decrease (P < 0.05) in stance phase time of the gait cycle. Integrated EMG (iEMG) increased (P < 0.05) with increasing treadmill speeds for both the BF and ST with the BF exhibiting greater (P < 0.05) iEMG values than the ST. In summary, HMB increased the percentage of type IIA GM fibers, which did not translate into improved performance.

Evaluation of the airway mechanics of modified toggle laryngoplasty constructs using a vacuum chamber airflow model.

To evaluate the airway mechanics of modified toggle LP constructs in an airflow chamber model and compare these to the airway mechanics of standard LP constructs. Ex-vivo experimental study. Fifty-one equine cadaveric larynges. Bilateral LP constructs were performed using a modified toggle (n=23) or a standard (n=21) LP technique. Constructs were tested in an airflow model before and after cyclic loading which was designed to mimic postoperative swallowing. The cross-sectional area (CSA), peak translaryngeal airflow (L/s), and impedance (cmH2 0/L/s) were determined and compared between LP constructs before and after cycling. The mean CSA of the rima glottidis of the modified toggle LP constructs was 15.2 ± 2.6cm2 before and 14.7 ± 2.6cm2 after cyclic loading, and the mean CSA of the rima glottidis of the standard LP constructs was 16.4 ± 2.9cm2 before and 15.7 ± 2.8cm2 after cyclic loading. The modified toggle LP constructs had similar peak translaryngeal impedance before and after cyclic loading (p=.13); however, the standard LP constructs had higher peak translaryngeal impedance after cyclic loading (p=.02). The modified toggle and standard LP constructs had comparable airway mechanics in an ex-vivo model. Further investigation is warranted to determine the extent to which the modified toggle LP technique restores normal airway function in horses with RLN.

Is inhaled immunotherapy more effective than environmental management when treating equine asthma?

PICO question&#x0D; In horses with severe equine asthma syndrome, is inhaled immunotherapy compared to environmental reduction of allergen exposure more effective in disease modification?&#x0D; &#x0D; Clinical bottom line&#x0D; Category of research question&#x0D; Treatment&#x0D; The number and type of study designs reviewed&#x0D; 12 papers were critically reviewed. Nine clinical trials; one crossover study; one split-plot design study; and one cross-sectional study&#x0D; Strength of evidence&#x0D; Low&#x0D; Outcomes reported&#x0D; Four studies found inhaled immunotherapy to improve the clinical signs associated with equine asthma and the lung function of horses with asthma. Three papers found environmental modification by improved lung function and the clinical signs associated with equine asthma but two studies provide moderate evidence that environmental management alone is insufficient to permanently cure asthma&#x0D; Conclusion&#x0D; There is a low level of evidence to support the use of inhaled immunotherapy as a treatment for equine asthma&#x0D; &#x0D; How to apply this evidence in practice&#x0D; The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources.&#x0D; Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.&#x0D; &#x0D;

Effects of a nutraceutical supplement on gastrointestinal health in racing standardbreds.

Feed additives that accelerate gastrointestinal transit time may help support normal gastrointestinal function in horses at risk for impaction colic. Previous research has demonstrated significant stimulatory effect of a hemp-based nutraceutical product (Gs Formula; GF) on contractility of gastric smooth muscle and gastrin production in vitro. To quantify effects of GF on indicators of GIT transit time and tight junction proteins. Randomized placebo-controlled cross-over study. Eight Standardbreds were administered 200 plastic beads by nasogastric tube before (baseline; BL) and after receiving a diet containing GF (CON: 0g/day, LO: 160g/day or HI: 480g/day) for 28days. Total manure collection occurred every 2hours for 72hours after bead administration. Outcome measures included GIT transit time, faecal dry matter (DM), water intake, and complete biochemistry and haematology screens. There was no effect of GF on GIT transit time. Faecal output was significantly lower in LO and HI horses than CON horses after 28days on the supplement. HI horses have significantly lower rouleaux formation and lower faecal DM on Day 28 compared with BL. GF also produced changes in electrolytes associated with pH balance, which may indicate a role for GF as an alkalinizing compound in exercising horses. Clinical pathology results support the safety of GF up to 480g/day for 28days with no adverse effects being observed in haematology or biochemistry results. Future studies on GF should focus on evaluating effect of GF on gastrointestinal transit in horses with naturally or experimentally delayed gastrointestinal motility, and its effect on exercise performance and onset of fatigue. GF may help support normal gastrointestinal function in horses at risk for impaction colic by reducing faecal DM and rouleaux formation.