Age Of Horses Research Articles

Early Castration in Horses Does Not Impact Osteoarticular Metabolism

The castration of stallions is traditionally performed after puberty, at around the age of 2 years old. No studies have focused on the effects of early castration on osteoarticular metabolism. Thus, we aimed to compare early castration (3 days after birth) with traditional castration (18 months of age) in horses. Testosterone and estradiol levels were monitored from birth to 33 months in both groups. We quantified the levels of biomarkers of cartilage and bone anabolism (CPII and N-MID) and catabolism (CTX-I and CTX-II), as well as of osteoarthritis (HA and COMP) and inflammation (IL-6 and PGE2). We observed a lack of parallelism between testosterone and estradiol synthesis after birth and during puberty in both groups. The extra-gonadal synthesis of steroids was observed around the 28-month mark, regardless of the castration age. We found the expression of estrogen receptor (ESR1) in cartilage and bone, whereas androgen receptor (AR) expression appeared to be restricted to bone. Nevertheless, with respect to osteoarticular metabolism, steroid hormone deprivation resulting from early castration had no discernable impact on the levels of biomarkers related to bone and cartilage metabolism, nor on those associated with OA and inflammation. Consequently, our research demonstrated that early castration does not disrupt bone and cartilage homeostasis.

Epidemiology and pathogenicity of M. equirhinis in equine respiratory disorders

Mycoplasmas are pathogens involved in respiratory disorders of various animal hosts. In horses, Mycoplasma (M.) equirhinis is the species most frequently detected in clinical respiratory specimens, with a prevalence of 12–16%, but its clinical implication in equine respiratory disorders remains unclear. Here we screened 1948 clinical specimens for the presence of M. equirhinis. The samples were both tracheal washes (TW) and bronchoalveolar lavages (BAL) collected by veterinarians in France in day-to-day work between 2020 and 2022. The samples were associated with a standardized form that served to collect key general and clinical information, such as horse age, breed, and living environment. M. equirhinis was detected using a combination of culture and post-enrichment PCR. Other diagnostic data included virology and bacteriology as well as neutrophil counts, when available. Prevalence of M. equirhinis was examined as a function of a clinical score based on four significant clinical signs (nasal discharge, cough, dyspnoea, and hyperthermia). Multivariate logistic regression analysis was run to identify risk factors for the presence of M. equirhinis, and comparative prevalence analysis was used to test for association with other bacteria and viruses. TW and BAL were analysed independently, as we found that TW samples were associated with a higher prevalence of M. equirhinis. As prevalence remained steady whatever the clinical score, M. equirhinis cannot be considered a primary pathogen. M. equirhinis was more frequently isolated in thoroughbreds and trotters and in horses living exclusively stabled compared to other horses or other living environments. M. equirhinis was never detected in BAL specimens with a ‘normal’ neutrophil count, i.e. 5%, suggesting it could be associated with an inflammatory response, similar to that observed in equine asthma. Prevalence of M. equirhinis was shown to increase in the presence of other bacteria such as Streptococcus equi subsp. zooepidemicus (S. zoo) or viruses, and S. zoo load was higher in M. equirhinis-positive samples, suggesting a potential increase of clinical signs in the event of co-infection.

A preliminary investigation of the subcutaneous tissue reaction to a 3D printed polydioxanone device in horses

BackgroundA 3D printed self-locking device made of polydioxanone (PDO) was developed to facilitate a standardized ligation technique. The subcutaneous tissue reaction to the device was evaluated after implantation in ten horses of mixed age, sex and breed and compared to loops of poly(lactic-co-glycolic acid) (PLGA). In two of the horses, the implants were removed before closing the skin. The appearance of the implants and surrounding tissue was followed over time using ultrasonography. Implants were removed after 10 and 27 (± 1) days for histologic examination.ResultsOn macroscopic inspection at day 10, the PDO-device was fragmented and the surrounding tissue was oedematous. On ultrasonographic examination, the device was seen as a hyperechoic structure with strong acoustic shadowing that could be detected 4 months post-implantation, but not at 7 months. Histology revealed a transient granulomatous inflammation, i.e., a foreign body reaction, which surrounded both PDO and PLGA implants. The type and intensity of the inflammation varied between individuals and tissue category.ConclusionsThe 3D printed PDO-device caused a transient inflammatory reaction in the subcutaneous tissue and complete resorption occurred between 4 and 7 months. Considering the intended use as a ligation device the early fragmentation warrants further adjustments of both material and the 3D printing process before the device can be used in a clinical setting.

Management of the older horse

The increasing age of horses presented for veterinary care has been recognised over several decades. The increase in the percentage of horses older than 20 years of age has been attributed to improved nutrition, early recognition and management of conditions seen more frequently in the geriatric horse, and the increased willingness of owners to pursue veterinary care to maintain the comfort of their senior horses. Geriatric medicine is devoted to the management of conditions that have increasing age as a risk factor for their development. Conditions that are seen more frequently in older horses include pituitary pars intermedia dysfunction, chronic weight loss, obesity, osteoarthritis, laminitis, neoplasia and cardiovascular dysfunction. In addition, routine wellness care is essential for early recognition of age-related changes and prompt institution of appropriate care to maintain the comfort of the horse.

Insulin signaling in insulin-dysregulated Icelandic horses

The underlying molecular mechanisms leading to insulin dysregulation are poorly understood in horses. Therefore, this study aimed to determine if insulin dysregulation is associated with an altered basal expression and extent of phosphorylation of key proteins of the insulin signaling cascade in liver (LT), muscle (MT), and subcutaneous adipose tissue (AT) under basal and stimulated conditions. Twelve Icelandic horses were subjected (1) to an oral glucose (Gluc PO) challenge and (2) to an intravenous (Ins IV) insulin challenge in a crossover study. Biopsies of LT, MT, and AT were taken in vivo under basal conditions and after Gluc PO and Ins IV stimulation. Corresponding insulin levels were measured by an equine optimized ELISA (Mercodia AB, Uppsala). Insulin levels ≥ 110 µIU/mL at 120 min indicated that six horses were insulin dysregulated (HI), while six were not (NI). Gluc PO stimulation resulted in a more pronounced hyperinsulinemia and hyperglycemia in HI horses compared to NI horses. Western blot analysis of key proteins of the insulin signaling cascade revealed an enhanced phosphorylation of the insulin receptor (InsR) under Gluc PO (P = 0.001) and Ins IV stimulation (P = 0.017) within LT, but not in MT and AT. Phosphorylation of protein kinase B was enhanced under Gluc PO stimulation in all tissues and under Ins IV stimulation in MT and AT, while phosphorylation of adenosine monophosphate protein kinase α was reduced after glucose administration (P = 0.005) in all horses. Interestingly, HI horses had significantly higher amounts of phosphorylated mechanistic target of rapamycin (mTOR) in MT (P = 0.049), irrespective of any stimulation. In LT, the amount of phosphorylated mTOR decreased under Gluc PO conditions in HI horses, while an increase was observed in NI horses (P = 0.015). A major limitation was the inclusion of only Icelandic horses of advanced age since insulin dysregulation could be related to both the equine metabolic syndrome and/or pituitary pars intermedia dysfunction. In summary, insulin signaling appeared to be maintained in both HI and NI Icelandic horses, although post-receptor alterations were observed. Thus, ID might be an equine-specific metabolic condition, in which alterations of the mTOR signaling pathway may play a crucial role, as emphasized by higher mTOR phosphorylation in HI horses.

Influence of Horse Age on Carcass Tissue Composition and Horsemeat Quality: Exploring Nutritional and Health Benefits for Gourmets

The aim of this study was to show the influence of the age of horses currently in use in Poland on the tissue composition of carcasses and the quality of horsemeat. To conduct a detailed dissection and analysis of horsemeat quality, 12 half carcasses of foals and young horses, 14 half carcasses of adult horses, and 14 half carcasses of older horses were selected. A highly significant difference was demonstrated between the linear measurements of the carcasses of foals and young horses compared with those of adult animals. A significantly higher dressing percentage was observed in foals compared with older horses (p ≤ 0.05). Compared with the carcasses from older horses, the foal carcasses provided a significantly higher amount of meat in class I (p ≤ 0.05). Meat obtained from foal carcasses, when compared with the raw material from other age groups of animals, was characterized by a higher number of points for individual qualitative characteristics in the sensory evaluation. The physicochemical properties of horsemeat were dependent on the age of the horses. Compared with the oldest horses, foal meat was characterized by the lowest ability to bind and retain water. The significantly highest content of protein and fat was found in the meat of adult horses compared with the meat of foals. The horsemeats consumed today, compared with those from the 1980s and 1990s, are characterized by a much lower degree of fat deposition in the carcasses, and a higher dressing percentage index and carcass meatiness. This may result in a greater popularization of horsemeat, both among processors of this raw material and the consumers themselves. This can be a very important advantage, pointing to new aspects of food quantity and quality, especially for gourmets of this type of product.

Prevalence and diversity of ascarid and strongylid nematodes in Australian Thoroughbred horses using next-generation sequencing and bioinformatic tools

The study presents the results of a cross-sectional survey to describe the epidemiology of ascarid and strongylid nematodes in horses, the impact of diverse climatic conditions on parasite diversity and the levels of faecal egg shedding in different age groups of managed Thoroughbred horses. Individual faecal samples (n = 1377) collected from 62 Thoroughbred farms across four climatic zones in Australia were analysed using the modified McMaster technique for faecal egg counts (FECs) and strongylid nematodes were identified utilising PCR-directed next-generation sequencing (NGS) of the second internal transcribed spacer of the nuclear ribosomal DNA (ITS-2). Across all age groups, the prevalence of ascarid and strongylid nematodes was 12% (95% confidence interval 10–14%) and 72% (70–74%), respectively. Based on strongylid FECs, yearlings had the highest prevalence (89%) followed by weanlings (83%), foals (79%), wet mares (61%), dry mares (59%) and stallions (54%). However, for Parascaris spp., foals had the highest prevalence (46%) followed by weanlings (32%) and yearlings (13%). The highest mean FECs for Parascaris spp. were observed in foals (418 eggs per gram [EPG] of faeces) while those for strongylids were in yearlings (1002 EPG). Of the adult horses (mares and stallions), 67% (489 of 729) and 11% (77 of 729) were low (i.e., ≤250 EPG) and moderate (i.e., 251–500 EPG) strongylid egg-shedders, respectively. Strongylid egg shedding varied across climatic zones, with the highest mean FECs in the summer rainfall (723 EPG) followed by non-seasonal rainfall (629 EPG), winter rainfall (613 EPG), and Mediterranean (606 EPG) rainfall zones. Twenty-three nematode species were detected using NGS, with Cylicostephanus longibursatus (28%), Cylicocyclus nassatus (23%) and Coronocyclus coronatus (23%), being the most abundant species. Three species of Strongylus (i.e., S. vulgaris, S. equinus and S. edentatus) were also detected. The nemabiome composition, species richness and relative abundance varied within horse age and between climatic zones. These empirical findings provide a comprehensive understanding of the prevalence of parasites within horse populations and the multifaceted factors that influence their occurrence, thereby allowing for the formulation of tailored strategies aimed at parasite control in domestic horses.

Does earthworm density change the quality of degraded volcanic soil?

Earthworms, as ecosystem engineers, are known to inoculate organic residues with microorganisms, consuming and processing mineral soil and its organic matter, which may lead to changes in soil quality. We conducted a field experiment, in randomized complete blocks, using soil mesocosms incubated with 4 different densities of earthworms: L1 = 100 earthworms m−2, L2 = 500 earthworms m−2, L3 = 1000 earthworms m−2, and C0 = control without earthworms. All earthworm populations consisted of epigeic, endogeic and anecic earthworms in a ratio of 2:3:3, respectively. The earthworms used were Lumbricus rubellus, Octolasium cyaneum, Aporrectodea calliginosa, and Lumbricus friendi. Physical (aggregate stability and structure heterogeneity), chemical (pH CaCl2, Mineral-N, Olsen-P, exchangeable K+, Ca+2, Mg+2, Na+ and Al) and biological indicators (microbial biomass) were assessed to evaluate the changes in soil quality. After applying an equivalent of 18 tons ha−1 of aged horse manure to each mesocosm, soils were sampled at two depths: 0–25 cm and 25–50 cm and on two occasions: prior to inoculating the soil with earthworms, T0, and 96 days after the soil was inoculated with earthworms, T1. Earthworms were found to increase soil mineral nitrogen (NO3 + NH4) and exchangeable calcium (Ca+2) and decrease exchangeable aluminum (Al+3) and soil microbial biomass (g C g−1). These results could imply that earthworms promote the mineralization of organic nitrogen, increase the cation content, and decrease the solubility of the principal toxic elements in soil (Al+3). Finally, the incorporation of earthworms at the 0–25 cm depth proved to increase the quality of the degraded soil, which was reflected in the chemical quality parameters.

Equine tapeworm (Anoplocephala spp.) infection: evaluation of saliva- and serum-based antibody detection methods and risk factor analysis in Slovak horse populations

A lack of accurate information on the prevalence and distribution of Anoplocephala spp. infections on horse farms has led to insufficient attention to tapeworm control and increasing horse anoplocephaloses in Europe. Our study aimed to examine the occurrence of Anoplocephala spp. infection using coprological, serum- and saliva-based antibody detection methods and to analyze the risk factors associated with tapeworm infection in domestic horses in Slovakia. Fecal, serum, and saliva samples were collected from 427 horses from 31 farms in Slovakia. Additionally, a questionnaire study was conducted to collect information on tapeworm distribution on horse farms and analyze risk factors associated with infection. Fecal samples were examined by the mini-FLOTAC and the double centrifugation/combined sedimentation-flotation techniques. Serum and saliva samples were analyzed by ELISA to determine antibody levels against Anoplocephala spp. The effects of variables associated with an individual horse were tested for the positive result of the saliva ELISA test on Anoplocephala spp. Cestode eggs were detected in 1.99% of fecal samples (farm prevalence 12.90%), with no differences between the two coprological methods. Serum-based tapeworm ELISA results revealed that 39.39% of horses tested positive (farm prevalence 83.87%); while saliva-based tapeworm ELISA results revealed 56.95% positive horses (farm prevalence 96.77%). Binary logistic regression analysis revealed four meaningful predictors that significantly impacted the likelihood of detecting tapeworm infection in horses: horse age, pasture size, anthelmintic treatment scheme, and access to pasture. The influences of other variables associated with an individual horse were not significantly associated with detecting tapeworm infection.

Diagnosis of equine pituitary pars intermedia dysfunction

Equine pituitary pars intermedia dysfunction (PPID) is common in aged horses. The majority of horses respond well to treatment, but treatment is lifelong, meaning accurate diagnosis of PPID is important. Similar to any condition, there is no perfect laboratory test to diagnose PPID and accuracy is affected by the characteristics of the population in which the test is being evaluated. This review details the importance of consideration of clinical factors and diagnostic test accuracy. Basal adrenocorticotrophic hormone (ACTH) concentration is used most frequently in practice and has very good diagnostic accuracy when used in combination with clinical judgement and the correct application of diagnostic thresholds. The thyrotropin-releasing hormone stimulation test can be used in horses with equivocal test results following basal ACTH testing, or to evaluate subtle cases due to its improved accuracy.

Prevalence of Exercise-Induced Pulmonary Hemorrhage, Tracheal Mucus and Recurrent Laryngeal Neuropathy in Competitive Draft Pulling Horses.

Respiratory disease is common in the horse population and is often be associated with poor performance in equine athletes. Despite their outstanding strength and aerobic capacity, little regard is given to draft horses and the respiratory disorders they may encounter when performing athletic activity. For this reason, the objectives of this study were: (1) to determine the prevalence of exercise-induced pulmonary hemorrhage (EIPH), tracheal mucus (TM) and recurrent laryngeal hemiplegia (RLH) in a population of competitive draft pulling horses, and (2) to determine if there was an association between horse weight, height, age, amount pulled, or competition placing with EIPH, TM or RLH in draft pullers. Results of this study identified EIPH in 26% of the study population, RLH in 32% and TM in 82% of participating horses; however, no risk factors were identified for the development of these problems in draft pulling horses.

Minerals and Trace Elements Profile of Apparently Healthy Horses in Ibadan ‎Polo Club, Oyo State, Nigeria

Roles of trace elements and minerals in the overall performance, health and wellbeing of horses cannot be underestimated vis a viz deleterious effects on normal functioning of living organisms posed by prolonged exposure to toxic metals. We evaluated the levels of some minerals and trace elements and compared these parameters among different breed, age and gender. Forty-six apparently healthy horses in Ibadan Polo Club, Ibadan, Nigeria were used for this study. Minerals and trace elements analyses were performed using the inductively coupled plasma optical emission spectrometry (ICP-OES) (Varian Vista Pro®, Varian Medical Systems, Inc., California, USA) and inductively coupled plasma mass spectrometry (ICP-MS) (Varian 820 MS®, Varian Medical Systems, Inc., California, USA). Student’s T-test was applied to establish differences in the values of minerals and trace elements in relation to breed, gender, and age. The results revealed statistically significant differences in the levels of Magnesium (Mg), Iron (Fe), and Iodine (I) and in the level of Silicon (Si), Chromium (Cr), and Iridium (Ir) in minerals and trace elements respectively with significantly higher values in Sudanese compared to Cross-bred horses. Mg, Fe, I, Cr, and Ir values were significantly higher in Mares compared to Stallion. Fe, I, Si, Mo and Cr values were significantly higher in young horses than in adult horses. Conclusively, significant variations were observed in the minerals and trace elements values regarding breed, sex, and age of Horses in Nigeria. Regular supplements of minerals lick and trace elements are advised especially for Cross-bred, Stallion, and adult horses.

Age-Related Differences in Short-Term Transportation Stress Responses of Horses.

Transportation of horses on short journeys can lead to an increase in stress. There are known age-associated changes in immune and metabolic responses in horses; however, no research exists evaluating how age may influence these responses to transportation stress. Eleven mares within two age groups, aged (n=5, 22 ± 1 year) or young (n=6, 2 ± 1 year), were transported 1 hour and 20 minutes. Peripheral blood and saliva were collected before and after transportation at baseline (2 to 3 weeks prior to transportation), 24 hours pre-transport, 1 hour before loading, 15 minutes, 30 minutes, 1 to 3 hours, 24 hours and 8 days post-transport. Heart rates, rectal temperatures, under the tail temperatures, serum cortisol, plasma ACTH, serum insulin, salivary cortisol and salivary IL-6 were measured. Whole blood gene expression of the cytokines IL-1b, IL-2, IL-6, IL-10, IFNγ, and TNFα were determined through qPCR, and peripheral blood mononuclear cells were isolated, stimulated, and stained to determine IFNγ and TNFα production. Serum cortisol (P < .0001), salivary cortisol (P < .0001) and heart rate (P=.0002) increased in response to transportation with no age differences. Rectal (P=.03) and under the tail temperatures (P=.02) were increased in young versus aged horses. ACTH was higher in aged horses (P=.007) and post-transportation (P=.0001). Aged horses showed a greater increase in insulin compared with young horses (P < .0001). While age does not seem to impact cortisol responses to short-term transportation in horses, it did influence the post transportation insulin response to stress in aged horses.

The prevalence of equine odontoclastic tooth resorption and hypercementosis and the role of interincisal angulation in disease severity in a representative cohort of horses in Switzerland.

Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is an increasingly diagnosed degenerative dental disease in aged horses. The primary aim of this retrospective study was to determine the prevalence of EOTRH in horses admitted to the Equine Hospital, University of Zurich, for dental procedures from 2004 to 2017. A secondary goal was to measure and compare interincisal angles on two-dimensional radiographs of horses with EOTRH to determine whether the interincisal angle is associated with age and severity of the disease. Radiographs were assessed for the presence of lysis and/or hypercementosis, and the number and position of the teeth affected were determined. Each tooth was also evaluated using the modified classification system introduced by Rehrl et al. (2018), in which stage 0 indicates no radiographic abnormalities and stage 3 denotes severe abnormalities. The overall stage was defined by the tooth with the most severe lesions. The interincisal angle was determined in horses that had suitable radiographs. The medical records of 838 horses admitted for dental procedures were evaluated, and 85 (10,1 %) had clinical evidence of EOTRH. The mean interincisal angle was 136,06 ° in horses with mild to moderate EOTRH and 135,10 ° (SD = 11,90 °) in severely affected patients. In conclusion, the angle measurements on lateral radiographs were highly reproducible. However, the interincisal angle was not associated with age or the severity of EOTRH. The interincisal angle and the disease pattern were not correlated.

Association between the plasma concentration of melatonin and behavioral temperament in horses

Aggression in horses may engender serious accidents during riding and non-riding activities. Hence, predicting the temperament of horses is essential for selecting suitable horses and ensuring safety during activity. In certain animals, such as hamsters, plasma melatonin concentrations have been correlated with aggressive behavior. However, whether this relationship applies to horses remains unclear. To address this research gap, this study aimed to evaluate differences in the plasma melatonin concentrations among horses of different breeds, ages, and sexes and examine the correlation between plasma melatonin concentrations and the temperament of the horses, including docility, affinity, dominance, and trainability. Blood samples from 32 horses were collected from the Horse Industry Complex Center of Jeonju Kijeon College. The docility, affinity, dominance, and trainability of the horses were assessed by three professional trainers who were well-acquainted with the horses. Plasma melatonin concentrations were measured using an enzyme-linked immunosorbent assay. The consequent values were compared between the horses of different breeds, ages, and sexes using three-way analysis of variance and least significant difference post hoc test. Linear regression analysis was employed to identify the relationship between plasma melatonin concentrations and docility, affinity, dominance, and trainability. The results showed that the plasma melatonin concentrations significantly differed with breeds in Thoroughbred and cold-blooded horses. However, there were no differences in the plasma melatonin concentrations between the horse ages and sexes. Furthermore, plasma melatonin concentrations did not exhibit a significant correlation with the ranking of docility, affinity, dominance, and trainability.

Hierarchical Bayesian analysis of racehorse running ability and jockey skills

Abstract In this paper, we proposed a new method of evaluating horse ability and jockey skills in horse racing. In the proposed method, we aimed to estimate unobservable individual effects of horses and jockeys simultaneously with regression coefficients for explanatory variables such as horse age and racetrack conditions and other parameters in the regression model. The data used in this paper are records on 1800­m races (excluding steeplechases) held by the Japan Racing Association from 2016 to 2018, including 4063 horses and 143 jockeys. We applied the hierarchical Bayesian model to stably estimate such a large amount of individual effects. We used the Markov chain Monte Carlo (MCMC) method coupled with Ancillarity- Sufficiency Interweaving Strategy for Bayesian estimation of the model and choose the best model with Widely Applicable Information Criterion as a model selection criterion. As a result, we found a large difference in the ability among horses and jockeys. Additionally, we observed a strong relationship between the individual effects and the race records for both horses and jockeys.

Impact of oral Phytozen® EQ supplementation on plasma cortisol and behavior responses of young horses exposed to stressful stimuli.

Calming supplements are common in the equine industry. This study tested the hypothesis that Phytozen® EQ, a blend of citrus botanical oils, magnesium, and yeast would reduce startle response as well as reduce behavioral and physiological signs of stress in young (1.5-6 years of age) horses (n = 14) when tied in isolation and when trailered in isolation. During the 59-day (d) trial, horses were assigned to either the control (CON; n=7) or treatment (PZEN; n=7) group that received 56 g of Phytozen® EQ daily. Horses underwent a 10 min isolation test on d 30 and a 15 min individual trailering test on day 52 or 55. For both tests, blood samples were obtained pre, immediately after, and 1-hour (h) post for analysis of plasma cortisol concentrations, which were analyzed by repeated measures ANOVA. On d 59, horses underwent a startle test, for which time to travel 3 m and total distance traveled were recorded. These data were analyzed using a T-test. During trailering, PZEN horses tended to have lower overall geometric mean (lower, upper 95% confidence interval) cortisol concentrations than CON (81 [67, 98] vs. 61 [48, 78] ng/mL; P = 0.071). For the startle test, PZEN horses tended to have longer geometric mean times to travel 3 m than CON horses (1.35 [0.39, 4.70] vs. 0.26 [0.07, 0.91 seconds [s], P = 0.064). Other data points were not different between treatments (P > 0.1). It is possible that this dietary supplement could have beneficial calming effects on horses undergoing trailering or in novel situations.

Prevalence and hematological criteria of piroplasmosis in horses of different ages, sex, and breed in Accra Metropolis, Ghana

Prevalence and hematological criteria of piroplasmosis in horses of different ages, sex, and breed in Accra Metropolis, Ghana

Equine synovial sepsis laboratory submissions yield a low rate of positive bacterial culture and a high prevalence of antimicrobial resistance.

To investigate (1) variables associated with the likelihood of obtaining a positive culture, (2) commonly isolated microorganisms, and (3) antimicrobial resistance patterns of isolates from horses with presumptive synovial sepsis. Synovial fluid, synovium, and bone samples from equine cases with presumptive synovial sepsis submitted to the Cornell University Animal Health Diagnostic Center from 2000 to 2020 for microbial culture and antimicrobial sensitivity testing. Univariable and multivariable analyses were performed to determine the effect of variables on the likelihood of positive culture. Frequency distributions for isolated organisms and antimicrobial resistance were generated. Multidrug resistance patterns and associations were assessed with association rule mining. The positive culture rate for all samples was 37.4%, while the positive culture rate among samples confirmed to be septic by a combination of clinical pathological variables and case details was 43%. Blood culture vial submissions were 1.7 times more likely to yield a positive culture compared to samples submitted in a serum tube. Structure sampled, tissue submitted, and horse age were associated with a positive culture. Staphylococcus spp (23.7%), Streptococcus spp (22.4%), and Enterococcus spp (9.67%) were commonly isolated. Multidrug resistance prevalence decreased from 92% (2000 to 2009) to 76% (2010 to 2020) of gram-negative isolates and 60% (2000 to 2009) to 52% (2010 to 2020) of gram-positive isolates. The positive culture rate from synovial fluid submissions with traditional sampling and culture methods remains low and may be optimized by submitting samples in blood culture vials. Overall, antimicrobial resistance was frequently observed but did not increase from the first to second decade for most genera.

Expression of genes with biomarker potential identified in skin from DSLD-affected horses increases with age.

Degenerative Suspensory Ligament Desmitis (DSLD) negatively impacts connective tissues in horses, which often leads to progressive chronic pain and lameness. DSLD has been shown to be a systemic disorder that affects multiple body systems, including tendons, sclerae, and the aorta. Currently, the diagnosis is confirmed by post mortem histological examination of a tendon or suspensory ligament. Histology reveals inappropriate accumulations of proteoglycans in the tendons and other tissues in DSLD-affected horses. Unfortunately, there is no reliable method to diagnose DSLD in living horses. Recently, bone morphogenetic protein 2 (BMP2) was identified in active DSLD lesions. In addition, recent data from RNA sequencing (RNA-seq) showed overexpression of numerous genes, among them BMP2, FOS and genes for keratins in DSLD skin biopsies-derived RNA. We hypothesized that some of these genes can be used as biomarkers for diagnosis of DSLD in a panel. Overexpression of some of them was verified in quantitative real time PCR. Immunohistochemistry and RNAscope in-situ hybridization (ISH) assays were used to determine the level of overexpression of specific genes in skin biopsies from control and DSLD-affected horses. The RNAscope ISH assay has shown to be more reliable and more specific that immunohistochemistry. ISH confirmed a significant increase in KRT83 and BMP-2 in hair follicles in DSLD cases, as well as abnormally high expression of FOS in the epidermis, especially in aging horses. Because statistically relevant specificity and sensitivity was documented only for FOS and BMP2, but not KRT83 we recommend the use of FOS and BMP2 panel to diagnose DSLD. We conclude that a panel of two markers from the studied group (BMP2 and FOS) can serve as an additional diagnostic tool for DSLD in living horses, especially in older animals. Further studies are necessary to confirm if this biomarker panel could be used as a prospective tool to identify DSLD in horses as they age.