Effect of constant rate infusion of detomidine with and without vatinoxan on blood glucose and insulin concentrations in horses.

OBJECTIVE: To assess the effects of an α2-adrenoceptor agonist (detomidine) constant rate infusion (CRI) with and without an α2-adrenoceptor antagonist (vatinoxan) CRI on blood insulin and glucose concentrations, heart rate, intestinal borborygmi, and sedation during and after infusion in horses. STUDY DESIGN: Randomized, blinded, crossover, experimental study. ANIMALS: A total of nine healthy, adult Finnhorse mares. METHODS: Horses were treated with an intravenous (IV) detomidine loading dose (0.01 mg kg-1), followed by CRI (0.015 mg kg-1 hour-1), and the same doses of detomidine combined with an IV vatinoxan loading dose (0.15 mg kg-1), followed by CRI (detomidine and vatinoxan; 0.05 mg kg-1 hour-1) with an 18 day washout period. Infusion time was 60 minutes and horses were monitored for 240 minutes after the infusion. Heart rate, borborygmi score and sedation were assessed, and blood glucose, insulin and triglyceride concentrations were measured. Data were analyzed using repeated measures ancova and Wilcoxon signed-rank tests. Values of p < 0.05 were considered statistically significant. RESULTS: Insulin concentration decreased during (median nadir 1.7, range 0.0-2.9 µIU mL-1 at 60 minutes, p < 0.0001) and increased after detomidine CRI (median 36.6, range 11.7-78.4 µIU mL-1 at 180 minutes, p = 0.0001) significantly compared with detomidine and vatinoxan CRI. A significant elevation of blood glucose (peak 11.5 ± 1.6 mmol L-1 at 60 minutes, p < 0.0001) was detected during detomidine CRI. Vatinoxan alleviated the insulin changes and abolished the significant increase in blood glucose. Vatinoxan alleviated the decrease in heart rate (p = 0.0001) during detomidine infusion. No significant differences were detected in sedation scores between treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Vatinoxan attenuated the negative adverse effects of detomidine CRI and thus is potentially beneficial when used in combination with an α2-adrenoceptor agonist CRI in horses.

Lipid species profiling of bronchoalveolar lavage fluid cells of horses housed on two different bedding materials.

The lipidome of equine BALF cells has not been described. The objectives of this prospective repeated-measures study were to explore the BALF cells' lipidome in horses and to identify lipids associated with progression or resolution of airway inflammation. BALF cells from 22 horses exposed to two bedding materials (Peat 1-Wood shavings [WS]-Peat 2) were studied by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The effects of bedding on lipid class and species compositions were tested with rmANOVA. Correlations between lipids and cell counts were examined. The BALF cells' lipidome showed bedding-related differences for molar percentage (mol%) of 60 species. Whole phosphatidylcholine (PC) class and its species PC 32:0 (main molecular species 16:0_16:0) had higher mol% after Peat 2 compared with WS. Phosphatidylinositol 38:4 (main molecular species 18:0_20:4) was higher after WS compared with both peat periods. BALF cell count correlated positively with mol% of the lipid classes phosphatidylserine, sphingomyelin, ceramide, hexosylceramide, and triacylglycerol but negatively with PC. BALF cell count correlated positively with phosphatidylinositol 38:4 mol%. In conclusion, equine BALF cells' lipid profiles explored with MS-based lipidomics indicated subclinical inflammatory changes after WS. Inflammatory reactions in the cellular lipid species composition were detected although cytological responses indicating inflammation were weak.

The effects of obesity and insulin dysregulation on mare reproduction, pregnancy, and foal health: a review.

Obesity is a growing welfare concern in modern equine populations and predisposes horses to disturbances in energy metabolism such as insulin dysregulation. However, equine metabolic syndrome has only been recognized in recent decades. Functioning energy metabolism is pivotal to normal body homeostasis and affects essentially all organ systems, including reproduction. Previous literature suggests that obesity has an effect not only on the reproductive processes in mares but also on offspring health, predisposing the offspring to later-onset orthopedic and metabolic problems. This review focuses on the effects of obesity, insulin dysregulation and hyperinsulinemia on the reproductive functions of mares and the implications on foal health before and after birth. The points of interest are the cyclicity and ovarian function, uterine environment, gestation, the postpartum period, and the newborn foal. The aim is to review the current state of knowledge, and identify outstanding questions that could stimulate future research. This topic is important not only from the equine industry and production perspective but is also relevant for the welfare of future populations and individuals.

Variation in insulin response to oral sugar test in a cohort of horses throughout the year and evaluation of risk factors for insulin dysregulation.

BACKGROUND: The oral sugar test (OST) is commonly used to diagnose insulin dysregulation (ID) and equine metabolic syndrome; however, possible seasonal changes in OST results have not been evaluated. OBJECTIVE: To determine the possible variation in insulin response to OST throughout the year and risk factors associated with maximum insulin concentration (InsMax) and ID. STUDY DESIGN: Prospective, longitudinal cohort study. METHODS: The OST was performed on 29 Finnhorses every other month six times. Serum total adiponectin concentration and phenotypic variables related to obesity were also measured. Changes in InsMax, adiponectin, scale weight, body condition score, cresty neck score (CNS), and fasting glucose concentration were assessed. Risk factor analyses were performed on InsMax and ID status, and ID groups were compared with each other. RESULTS: Fourteen horses were categorised with non-ID each time and 15 as having ID at least once during the follow-up period. The ID status of 12 horses varied throughout the year, but neither the insulin variables measured during the OST nor adiponectin expressed significant seasonal variation. Increasing age and CNS, and decreasing adiponectin were observed as risk factors for a high InsMax after OST. The risk of ID was higher in horses with no exercise compared to horses with exercise (OR 7.6, 95% CI 1.2-49.3, P = .03). Horses with ID had lower serum adiponectin concentrations, longer neck circumference and larger height than horses in the non-ID group. MAIN LIMITATIONS: The environmental conditions (feeding, exercise) were not constant for all horses throughout the study and only one breed was used. CONCLUSIONS: Neither OST results nor adiponectin varies with season; however, there were a substantial number of horses with variable ID status throughout the year, in which repeated OSTs may be beneficial. Lack of exercise was a risk factor for ID.

Effects of Bedding Material on Equine Lower Airway Inflammation: A Crossover Study Comparing Peat and Wood Shavings.

Bedding materials affect stable air hygiene, and thus the development and exacerbation of equine asthma. There is limited knowledge concerning the effects of different types of bedding material on equine lower airway inflammation. The objective of our study was to investigate the effects of bedding materials on respiratory signs, tracheal mucus score, and lower airway cytology in healthy adult horses. The study design was a prospective controlled study, and the subjects were healthy adult riding school horses (n = 32) from a single stable. Wood shavings were compared to peat, which was used as a reference bedding material. Lower airway endoscopy and sampling (tracheal wash and bronchoalveolar lavage fluid) for cytological examination were performed after each 35-day bedding period. No difference between bedding periods was observed in the respiratory rate or tracheal mucus score. Tracheal wash neutrophil percentage with the wood shavings was higher compared to the previous (P = 0.040) or following (P = 0.0045) peat period. Bronchoalveolar lavage fluid neutrophil percentage with the wood shavings was higher compared to the following peat period (P < 0.001). We conclude that, between the two bedding materials used in this study, peat caused less neutrophilic lower airway inflammation in horses. The information gained from this study may assist veterinarians and horse owners in selecting bedding materials, especially for horses suffering from equine asthma.

Effects of Bedding Material on Equine Lower Airway Inflammation: A Comparison of Two Peat Beddings, Wood Pellet, and Straw Pellet.

The effects of bedding material on air quality are important amongst horses worldwide. Respiratory diseases, especially equine asthma, are highly prevalent with air hygiene playing a major role on the pathophysiology of these diseases. The objective of our study was to investigate the effects of four bedding materials on the respiratory signs, tracheal mucus score, and tracheal wash (TW) and bronchoalveolar lavage fluid (BALF) cytology in healthy adult horses. The study design was a prospective controlled cross-over study, and the subjects were healthy adult riding school horses (n = 32) from a single stable. Wood pellet, straw pellet, and loosely stored peat (Peat 3) were compared to peat packed in plastic-covered bales (Peat 2). Lower airway endoscopy and sampling (TW and BALF) for cytological examination were performed after each 35-day bedding period. The tracheal mucus scores (P = 0.014) and respiratory rate (P = 0.026) were higher during the straw pellet period compared to the Peat 2 period. The respiratory rate was lower during the wood pellet period compared to the Peat 2 period (P = 0.004). The TW neutrophil percentage during the straw pellet period was higher compared to the Peat 2 period (P = 0.0003). The BALF neutrophil percentage was higher during the straw pellet period (P = 0.005) and during the Peat 3 period compared to the Peat 2 period (P = 0.04). We conclude that baled peat (Peat 2) caused lower neutrophil percentages in the airway samples compared to straw pellet and loosely stored peat (Peat 3). No difference was observed between Peat 2 and wood pellet. The information gained from this study may assist veterinarians and horse owners in selecting appropriate bedding materials, especially for horses with equine asthma.

Insulin dysregulation in a population of Finnhorses and associated phenotypic markers of obesity.

BACKGROUND: Obesity and insulin dysregulation (ID) predispose horses to laminitis. Determination of management practices or phenotypic markers associated with ID may benefit animal welfare. OBJECTIVES: Determine ID status of a population of Finnhorses using an oral sugar test (OST) and compare phenotypes and management factors between ID and non-ID Finnhorses. ANIMALS: One hundred twenty-eight purebred Finnhorses ≥3 years of age. METHODS: Owners were recruited using an online questionnaire regarding signalment, history, feeding, and exercise of their horses. Selected contributing stables within a predefined area were visited. Phenotypic markers of obesity and the weight of each horse were recorded. After fasting overnight, horses received 0.45 mL/kg corn syrup PO. Serum samples before and at 60 and 90 minutes after syrup administration were analyzed for insulin by chemiluminescent assay. Horses met ID criteria if insulin concentrations were ≥33 µIU/mL at T0, ≥66 µIU/mL at T60 or T90 or some combination thereof. Associations between phenotypic markers, feeding and exercise variables, and ID were examined using mixed effects logistic regression modeling. RESULTS: Several phenotypic markers of obesity were significant on univariable analysis but in the final multivariable model, only obesity (body condition score ≥8) was associated with ID (P = .04). Over half of the horses (60% [95% confidence interval (CI), 51%-68%]) were considered overweight or obese whereas 16% (95% CI, 10%-23%) were classified as having ID. CONCLUSIONS AND CLINICAL IMPORTANCE: Because obesity is associated with ID in cold-blooded type horses, objective monitoring of phenotypic markers by owners may be beneficial for health outcomes.

Long-term follow-up on recovery, return to use and sporting activity: a retrospective study of 236 operated colic horses in Finland (2006-2012).

BACKGROUND: Surgical treatment of colic is expensive and complications may occur. Information on the prognosis and the use of the horse after surgery for colic is important for surgeons and owners. Current literature on return to athletic function after celiotomy is limited. The present study reviewed surgical cases of the Veterinary Teaching Hospital, Helsinki, Finland for 2006-2012. The aim was to follow the population of horses of different breeds for surgical findings, postsurgical complications, long-term recovery and prognosis. The findings and their influence on survival, return to previous or intended use and performance were assessed. RESULTS: Most of the operated horses (82.6%; 195/236) recovered from anesthesia and 74.9% (146/195) were discharged. The total follow-up time was 8 years and 10 months and the median survival time 79.2 months. Age of the horse, location of the abdominal lesion (small vs. large intestine), incidence of postoperative colic, surgical site infection, incisional hernia or convalescence time after surgery, did not significantly affect the probability of performing in the previous or intended discipline after the surgery. A majority of the discharged horses (83.7%) was able to perform in the previous or intended discipline and 78.5% regained their former or higher level of performance. Operated horses had 0.18 colic episodes per horse-year during the long-term follow-up. The incidence of colic was 20.0% within the first year after surgery. Horses operated for large intestinal colic were 3.3-fold more prone to suffer postoperative colic than horses operated for small intestinal colic. The majority of the owners (96.3%) were satisfied with the veterinary care and nearly all (98.5%) evaluated the recovery after the colic surgery to be satisfactory or above. CONCLUSIONS: If the horse survives to discharge, prognosis for long-term survival and return to previous level of sporting activity and performance was good after colic surgery in a population of horses of different breeds. None of the factors studied were found to decrease the probability of performing in the same or intended discipline after surgery. The majority of horses were able to return to their previous activity and perform satisfactorily for several years after surgery.

Serum insulin concentration in horses: Effect of storage and handling.

Serum insulin concentration is commonly measured during investigation of suspected endocrinopathic disease in horses, but immediate analysis is frequently unavailable. The aim of this study was to examine the effect of storing samples at room temperature for 72 h as serum and as whole blood, compared to immediate separation and freezing. Samples from 14 horses were evaluated. Correlation was excellent for all comparisons (≥0.992). Bland-Altman plots revealed a negative bias (mean difference 2.16 µIU/mL) in samples stored as whole blood compared to serum, but this difference was not considered clinically significant. At two commonly used diagnostic cut-offs, there was no effect of storage on result. This study indicates that storage at room temperature for 72 h, either as serum or whole blood, has minimal effect on measured serum insulin concentration in horses.

Relationships among Body Condition, Insulin Resistance and Subcutaneous Adipose Tissue Gene Expression during the Grazing Season in Mares.

Obesity and insulin resistance have been shown to be risk factors for laminitis in horses. The objective of the study was to determine the effect of changes in body condition during the grazing season on insulin resistance and the expression of genes associated with obesity and insulin resistance in subcutaneous adipose tissue (SAT). Sixteen Finnhorse mares were grazing either on cultivated high-yielding pasture (CG) or semi-natural grassland (NG) from the end of May to the beginning of September. Body measurements, intravenous glucose tolerance test (IVGTT), and neck and tailhead SAT gene expressions were measured in May and September. At the end of grazing, CG had higher median body condition score (7 vs. 5.4, interquartile range 0.25 vs. 0.43; P=0.05) and body weight (618 kg vs. 572 kg ± 10.21 (mean ± SEM); P=0.02), and larger waist circumference (P=0.03) than NG. Neck fat thickness was not different between treatments. However, tailhead fat thickness was smaller in CG compared to NG in May (P=0.04), but this difference disappeared in September. Greater basal and peak insulin concentrations, and faster glucose clearance rate (P=0.03) during IVGTT were observed in CG compared to NG in September. A greater decrease in plasma non-esterified fatty acids during IVGTT (P<0.05) was noticed in CG compared to NG after grazing. There was down-regulation of insulin receptor, retinol binding protein 4, leptin, and monocyte chemoattractant protein-1, and up-regulation of adiponectin (ADIPOQ), adiponectin receptor 1 and stearoyl-CoA desaturase (SCD) gene expressions in SAT of both groups during the grazing season (P<0.05). Positive correlations were observed between ADIPOQ and its receptors and between SCD and ADIPOQ in SAT (P<0.01). In conclusion, grazing on CG had a moderate effect on responses during IVGTT, but did not trigger insulin resistance. Significant temporal differences in gene expression profiles were observed during the grazing season.

Morphological and cellular changes in secondary epidermal laminae of horses with insulin-induced laminitis.

OBJECTIVE: To determine cellular changes associated with secondary epidermal laminae (SEL) in forefeet and hind feet of ponies with insulin-induced laminitis. ANIMALS: 8 ponies. PROCEDURES: Laminitis was induced in 4 ponies by IV administration of insulin and glucose; 4 control ponies received saline (0.9% NaCl) solution IV. Laminar tissue samples obtained from the dorsal aspects of the hooves were histologically evaluated. Primary epidermal lamina (PEL) length and width and SEL length, width, and angle were determined. Numbers of epidermal cell nuclei per micrometer and per total length of SEL and numbers of apoptotic and proliferative cells in axial, middle, and abaxial laminar regions were determined. RESULTS: SEL in treatment group ponies were significantly longer, were significantly narrower, and had a smaller angle relative to PEL in all laminar regions versus control ponies. In treatment group ponies, the number of epidermal cell nuclei per SEL was typically higher and the number of cells per micrometer of SEL was lower in laminar regions, apoptotic cell numbers were higher in abaxial and middle regions in forefeet and hind feet, and proliferating cell numbers were higher in axial laminar regions in forefeet and all laminar regions in hind feet, versus control ponies. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated SEL elongation, narrowing, and alteration in orientation developed in all feet of ponies with insulin-induced laminitis. This was primarily attributable to cell stretching that developed at the same time as an accelerated cell death-proliferation cycle; differences in cell cycle responses among laminar regions between forefeet and hind feet may have been attributable to differences in load bearing.

Probiotic properties of Lactobacillus isolates originating from porcine intestine and feces.

In this study, a total of 94 lactic acid bacterial (LAB) isolates of porcine small intestinal and fecal origin were screened for their probiotic properties. The aim was to evaluate whether their isolation site and putative species identity play a role in these characteristics and whether either of these can be used as a predictive factor for the probiotic potential of bacterial isolates. The isolates were preliminarily identified by partial 16S rRNA gene sequencing and characterized in vitro for their pH and bile tolerance, adhesion capacity towards porcine enterocytes isolated from five intestinal sites and for antimicrobial activity towards five indicator pathogens. The interdependence of these characteristics was statistically evaluated. The isolates tolerated low pH and bile well. Adherence to the enterocytes of different origins did not correlate with the strain isolation site. In general, higher adherence was observed to colon cells in comparison to the small intestinal enterocytes. Culture filtrates of the isolates caused a decrease of up to three orders of magnitude in the intestinal pathogen cell numbers. The inhibition was mostly due to lactic and other organic acids. The predominating phylotypes identified were Lactobacillus reuteri and Lactobacillus salivarius, of which the former generally had the best adhesion capacity, whereas the latter appeared to be the best inhibitor. Based on the results, several strains of the pig Lactobacillus isolates tested may function as promising candidates for use in probiotic products. However, it was not possible to use the isolation site or the species identity of the isolates as reliable preliminary screening factors.