Blood-based assessment of oxidative stress, inflammation, endocrine and metabolic adaptations in eventing horses accounting for plasma volume shift after exercise.

BACKGROUND: After submaximal exercise, blood values of eventing horses show physiological reactions. OBJECTIVES: This prospective longitudinal study investigated blood parameters in 20 elite eventing horses before and after two-four-star cross-country rides. METHODS: Using a mixed model adjusting for plasma volume shift, we assessed exercise-dependent parameters and compared blood values with reference ranges for healthy horses at rest. RESULTS: Following exercise, cortisol, triiodothyronine (T3) and thyroxine (T4) showed short-term increases, and superoxide-dismutase showed a small short-term increase. Hepatic values showed short-term (haemoglobin [HGB], globulins) or sustained increases (bilirubin, glutamate dehydrogenase, alanine aminotransferase). Digestion-related parameters showed small short-term increases (α-amylase, triglycerides) or decreases (cholesterol, DGGR-lipase), apparent through plasma shift adjustment. Zinc decreased in the short term, and iron showed a delayed decrease. White blood cell count increased persistently after training, whereas serum amyloid A remained unchanged. CONCLUSIONS: Exercised eventing horses had consistently elevated HGB and cortisol levels 10 and 30 min after submaximal exercise, exceeding the reference ranges for healthy horses at rest. Exercise activates the hypothalamic-pituitary-adrenocortical and hypothalamic-pituitary-thyroid axes. Antioxidant activity was observed. Increased energy requirements led to the mobilization of energy reserves, and a sustained increase in liver enzymes indicated hepatocellular injury. Mild haemolysis suggested increased muscle metabolism, whereas signs of inflammation were subtle. Further research is needed to identify which horses deviate from mean values.

Influence of feeding and other factors on adrenocorticotropin concentration and thyrotropin-releasing hormone stimulation test in horses and ponies.

BACKGROUND: The basal (bACTH) and post-thyrotropin-releasing hormone stimulation concentration of adrenocorticotropin (pACTH) are recommended for diagnosis of pituitary pars intermedia dysfunction (PPID). Many factors influence bACTH (e.g., disease, age, month) and some affect the results only in autumn (e.g., breed, colour, sex). There are discrepancies about the impact of feeding on b/pACTH. OBJECTIVES: To determine whether feeding, month, age, breed, colour, sex and body condition score affect b/pACTH. STUDY DESIGN: Prospective crossover. METHODS: Sixty-one animals were divided into groups: healthy, PPID, treated-PPID. The b/pACTH was measured three times (1 mg protirelin; blood collection after 10 min; mid-November to mid-July) after different feedings: fasting, hay, hay + grain. Friedman's test was applied to evaluate the influence of feeding on b/pACTH and linear mixed model to evaluate impact of further factors. RESULTS: The b/pACTH was not significantly affected by feeding (p = 0.7/0.5). The bACTH was lowest in healthy (29.3 pg/mL, CI 9-49.5 pg/mL) and highest in PPID-group (58.9 pg/mL, CI 39.7-78.1 pg/mL). The pACTH was significantly lower in healthy (396.7 pg/mL, CI 283.2-510.1 pg/mL) compared to PPID (588.4 pg/mL, CI 480.7-696.2 pg/mL) and treated-PPID group (683.1 pg/mL, CI 585.9-780.4 pg/mL), highest in July (881.2 pg/mL, CI 626.3-1136.3 pg/mL) and higher in grey (723.5 pg/mL, CI 577.5-869.4 pg/mL) than other colours (338.7 pg/mL, CI 324.8-452.5 pg/mL). The size of effect for those variables was >0.5. MAIN LIMITATIONS: Small number of animals, subsequent bACTH measurements were significantly lower in each horse. CONCLUSIONS: There was no evidence that feeding influences the b/pACTH. There was evidence that pergolide affects the bACTH but it had little effect on pACTH. Further investigation of the impact of month and coat colour on b/pACTH is warranted to better interpret the results.

Antibiotic prophylaxis and hospitalization of horses subjected to median laparotomy: gut microbiota trajectories and abundance increase of Escherichia.

Introduction: Horse clinics are hotspots for the accumulation and spread of clinically relevant and zoonotic multidrug-resistant bacteria, including extended-spectrum ß-lactamase producing (ESBL) Enterobacterales. Although median laparotomy in cases of acute equine colic is a frequently performed surgical intervention, knowledge about the effects of peri-operative antibiotic prophylaxis (PAP) based on a combination of penicillin and gentamicin on the gut microbiota is limited. Methods: We collected fecal samples of horses from a non-hospitalized control group (CG) and from horses receiving either a pre-surgical single-shot (SSG) or a peri-operative 5-day (5DG) course of PAP. To assess differences between the two PAP regimens and the CG, all samples obtained at hospital admission (t0), on days three (t1) and 10 (t2) after surgery, were screened for ESBL-producing Enterobacterales and subjected to 16S rRNA V1-V2 gene sequencing. Results: We included 48 samples in the SSG (n = 16 horses), 45 in the 5DG (n = 15), and 20 in the CG (for t0 and t1, n = 10). Two samples of equine patients receiving antibiotic prophylaxis (6.5%) were positive for ESBL-producing Enterobacterales at t0, while this rate increased to 67% at t1 and decreased only slightly at t2 (61%). Shannon diversity index (SDI) was used to evaluate alpha-diversity changes, revealing there was no significant difference between horses suffering from acute colic (5DG, SDImean of 5.90, SSG, SDImean of 6.17) when compared to the CG (SDImean of 6.53) at t0. Alpha-diversity decreased significantly in both PAP groups at t1, while at t2 the onset of microbiome recovery was noticed. Although we did not identify a significant SDImean difference with respect to PAP duration, the community structure (beta-diversity) was considerably restricted in samples of the 5DG at t1, most likely due to the ongoing administration of antibiotics. An increased abundance of Enterobacteriaceae, especially Escherichia, was noted for both study groups at t1. Conclusion: Colic surgery and PAP drive the equine gut microbiome towards dysbiosis and reduced biodiversity that is accompanied by an increase of samples positive for ESBL-producing Enterobacterales. Further studies are needed to reveal important factors promoting the increase and residency of ESBL-producing Enterobacterales among hospitalized horses.

Serum and Urinary Matrix Metalloproteinase-9 Concentrations in Dehydrated Horses.

Matrix metalloproteinase-9 is increased in renal tissue in human kidney disease, but its role as a biomarker for kidney disease has not been fully evaluated yet. The aim of this study was to evaluate serum MMP-9 (sMMP-9) and urinary MMP-9 (uMMP-9) concentrations in dehydrated horses. Dehydrated horses were prospectively included. Blood and urinary samples were taken at admission, and after 12, 24, and 48 h (t0, t12, t24, t48), an anti-equine MMP-9 sandwich ELISA was used. Four healthy horses served as the controls. Serum creatinine, urea, symmetric dimethylarginine (SDMA), urine-specific gravity, urinary protein concentration, fractional sodium excretion, and urinary gamma-glutamyl transferase/creatinine ratio (uGGT/Cr) were measured. Statistical analysis included a repeated measures ANOVA and mixed linear regression model. Overall, 40 dehydrated horses were included (mild dehydration 13/40, moderate 16/40, severe 11/40). Acute kidney injury was found in 1/40 horses; 7/40 horses showed elevated serum creatinine, 11/40 horses elevated serum SDMA, and 5/28 elevated uGGT/Cr at presentation. In dehydrated horses, sMMP-9 concentrations were significantly higher on t0 (median: 589 ng/mL, range: 172-3597 ng/mL) compared to t12 (340 ng/mL, 132-1213 ng/mL), t24 (308 ng/mL, 162-1048 ng/mL), and t48 (258 ng/mL, 130-744 ng/mL). In healthy horses, sMMP-9 (239 ng/mL, 142-508 ng/mL) showed no differences over time or compared to patients. uMMP-9 and uMMP-9/creatinine did not differ over time or to the controls. No differences were found between dehydration groups. Urinary casts (p = 0.001; estimate = 135) and uGGT/Cr (p = 0.03; estimate = 6.5) correlated with sMMP-9. Serum urea was associated with uMMP-9/Cr (p = 0.01, estimate 0.9). In conclusion, sMMP-9 was elevated at arrival in dehydrated patients compared to later measurements. Correlations to uGGT/Cr and urinary casts need further evaluation.

Verification of documentation plausibility in equine passports-drug documentation for geldings in comparison to self-reported veterinarian drug usage for equine castrations in Germany.

The 'positive list for equines' (Regulation (EC) No 1950/2006) was implemented in the European Union in 2006. The drugs listed are approved for use in slaughter equines under certain conditions, although those drugs are not approved for use in livestock and are not listed in Table 1 of the annex to Regulation (EU) No 37/2010. The usage of such drugs has to be documented in the equine passport and a withdrawal period of six months must be adhered to before the equine can be slaughtered for human consumption. Since the withdrawal period is long, correct documentation is particularly important. This study compared the results of two sub-studies. In sub-study 1, 116 veterinarians and nine equine clinics in Germany were surveyed about the methods and drugs used for castration of equine stallions. In sub-study 2, the documentational findings of 195 equine passports, belonging to 194 horses and one donkey, were analyzed. Regarding sub-study 1, the most commonly used method for castration was reported as 'laid down'. Drug combinations entailing at least one drug from the 'positive list' were used by 86.7% (91/105) of veterinarians castrating horse stallions 'laid down' and by 64.3% (36/56) of veterinarians utilizing this method on donkey stallions. Regarding sub-study 2, drug documentation was verified in the passports of 4.6% (9/195) of all equines and in just 12.0% (3/25) of those belonging to slaughter equine geldings. Anesthetics from the 'positive list' were documented in 4.0% (1/25) of equine passports belonging to slaughter geldings. Because of the high discrepancy of the drug combinations used by veterinarians and the documentation actually found in equine passports, we conclude that drug administration is very seldom documented in equine passports in Germany. This could result in drug residues in equine meat and poses a potential risk for consumers.

Blood-Based Markers for Skeletal and Cardiac Muscle Function in Eventing Horses before and after Cross-Country Rides and How They Are Influenced by Plasma Volume Shift.

Horses competing in cross-country tests are subjected to high physical demands. Within the scope of this prospective longitudinal study, blood values of 20 elite eventing horses were examined before and after two- to four-star cross-country rides. The aim was to find out whether blood-based markers for skeletal muscle and cardiac muscle function change after cross-country exercise. Parameters that provide information about fluid balance, muscle enzymes, metabolites and cardiac muscle-specific markers were investigated. We developed an approach to eliminate the concentration changes caused by reduced plasma volume. Parameters were measured pre, 10 and 30 min post exercise and the next morning and were evaluated using a mixed model. Thirty minutes after exercise, most parameter concentrations changed in an exercise-dependent manner. The next morning, most exercise-related markers recovered rapidly, while creatine kinase (CK) (26% increase; p = 0.008) and lactate dehydrogenase (LDH) (15% increase; p < 0.001) showed a declining but sustained increase. Cardiac troponin I (cTnI) increased above the reference range in 40 of the 55 rides (73%) and in 18 of 20 horses in the morning after exercise.

Seroprevalence of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum Infections in German Horses.

There are limited data on Lyme borreliosis (LB), a tick-borne disease caused by the Borrelia burgdorferi sensu lato complex, in horses. Seropositivity is not necessarily associated with clinical disease. Data on seropositivity against Borrelia burgdorferi and Anaplasma phagocytophilum in German horses are sparse. Therefore, serum samples from horses (n = 123) suspected of having Lyme borreliosis and clinically healthy horses (n = 113) from the same stables were tested for specific antibodies against Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum. The samples were screened for antibodies against Borrelia burgdorferi (ELISA and an IgG line immunoblot assay). Furthermore, the samples were examined for antibodies against B. burgdorferi and Anaplasma phagocytophilum with a validated rapid in-house test (SNAP® 4Dx Plus® ELISA). The clinical signs of suspect horses included lameness (n = 36), poor performance (n = 19), and apathy (n = 12). Twenty-three percent (n = 26) of suspect horses and 17% (n = 18) of clinically healthy horses were seropositive for having a Borrelia burgdorferi sensu lato infection (p = 0.371), showing that the detection of specific antibodies against B. burgdorferi alone is not sufficient for a diagnosis of equine LB. Anaplasma phagocytophilum seropositivity and seropositivity against both pathogens was 20%/6% in suspect horses and 16%/2% in the clinically healthy population, showing only minor differences (p = 0.108). Unspecific testing for antibodies against B. burgdorferi without clinical suspicion of Lyme borreliosis is not recommended since the clinical relevance of seropositivity against Borrelia burgdorferi sensu lato remains to be elucidated.

Pre-Ride Biomarkers and Endurance Horse Welfare: Analyzing the Impact of the Elimination of Superoxide Dismutase, δ-Aminolevulinic-Dehydratase, Thiobarbituric Acid Reactive Substances, Iron, and Serum Amyloid A Levels in Elite 160 km Endurance Rides.

High elimination rates and concerns for horse welfare are important issues in endurance riding. Improved understanding of the causes of elimination could increase completion rates in this sport. We have identified pre-ride laboratory risk factors that enable an assessment of potential elimination before the ride. A longitudinal cohort study was performed among 49 healthy horses competing in the 160 km endurance ride at the 2016 World Championship of Endurance Riding in Samorin/Slovakia. Blood samples were taken before the event. For statistical evaluation, horses were categorized into three groups: finishers, lame horses, and metabolically eliminated horses. Risk factors were calculated for each group using multinominal logistic regression. δ-Aminolevulinic-dehydratase (ALAD), thiobarbituric acid reactive substances (TBARSs), iron, and serum amyloid A (SAA) were measured and did not show an impact on the race outcome, but elevated pre-ride superoxide dismutase (SOD) was shown to have an effect on lameness elimination (p = 0.011). It might serve as an indicator for withdrawing horses at risk of later elimination before endurance rides, ultimately resulting in lower elimination rates and an increase in overall horse welfare.

Multilineage Differentiation Potential of Equine Adipose-Derived Stromal/Stem Cells from Different Sources.

The investigation of multipotent stem/stromal cells (MSCs) in vitro represents an important basis for translational studies in large animal models. The study's aim was to examine and compare clinically relevant in vitro properties of equine MSCs, which were isolated from abdominal (abd), retrobulbar (rb) and subcutaneous (sc) adipose tissue by collagenase digestion (ASCs-SVF) and an explant technique (ASCs-EXP). Firstly, we examined proliferation and trilineage differentiation and, secondly, the cardiomyogenic differentiation potential using activin A, bone morphogenetic protein-4 and Dickkopf-1. Fibroblast-like, plastic-adherent ASCs-SVF and ASCs-EXP were obtained from all sources. The proliferation and chondrogenic differentiation potential did not differ significantly between the isolation methods and localizations. However, abd-ASCs-EXP showed the highest adipogenic differentiation potential compared to rb- and sc-ASCs-EXP on day 7 and abd-ASCs-SVF a higher adipogenic potential compared to abd-ASCs-EXP on day 14. Osteogenic differentiation potential was comparable at day 14, but by day 21, abd-ASCs-EXP demonstrated a higher osteogenic potential compared to abd-ASCs-SVF and rb-ASCs-EXP. Cardiomyogenic differentiation could not be achieved. This study provides insight into the proliferation and multilineage differentiation potential of equine ASCs and is expected to provide a basis for future preclinical and clinical studies in horses.

Zinc Status of Horses and Ponies: Relevance of Health, Horse Type, Sex, Age, and Test Material.

Little is known about the animal- and diet-related factors that could interfere with the plasma zinc (Zn) concentrations of equines. Additionally, the adequacy of plasma to reflect changes in the Zn intake is unclear. In the first part of this study, the plasma Zn concentrations of hospitalized horses and ponies (n = 538) were measured and evaluated for the impact of the age, sex, horse type, and internal diseases of the animals. In the second part, the effects of increasing dietary Zn chloride hydroxide and Zn methionine supplementations were assessed on the plasma and mane hair Zn concentrations of healthy horses (n = 2) and ponies (n = 8). Part 1: The age, sex, and horse type did not influence the plasma Zn concentrations. No effect of internal diseases was observed, with the exception of higher plasma Zn concentrations in animals with metabolic disorders compared to the control group (p < 0.05). Part 2: Both Zn supplements dose-dependently increased the Zn concentrations in the mane hair (p = 0.003), but not in the plasma of the horses and ponies. In conclusion, the plasma Zn concentrations were widely unaffected by nutritional and non-nutritional factors in equines, while mane hair samples better reflected the dietary Zn supply.

A comparative survey of veterinarians, equine owners, and equine keepers regarding the knowledge and implementation of legal requirements in Germany for the use and documentation of veterinary medicines in equines intended for slaughter.

In Europe, equines destined for human consumption (hereafter called slaughter equines) are subject to the same restrictions of usage of veterinary drugs as other food-producing animals, with amendments regulated in the so-called 'positive list', Regulation (EC) No. 1950/2006. Due to the complex legal requirements for drug administration in slaughter equines, it might be that specific knowledge regarding the legislation of slaughter equines may be insufficient among veterinarians, equine owners, and equine keepers. To study this assumption, three target group-specific surveys were conducted in 2021. Answers from 153 equine treating veterinarians, 170 equine owners, and 70 equine keepers were included in the analysis. In total 68.4% (91/133) of the participating veterinarians, the regulations of the 'positive list', Regulation (EC) No. 1950/2006, were 'rather complicated' to 'complicated'. Among the participating veterinarians, 38.4% (58/151) did not or could not answer correctly how to proceed if a slaughter equine is scheduled to receive phenylbutazone, usage of which is prohibited in all livestock by Regulation (EU) No. 37/2010. Simultaneously, 56.2% (86/153) of the participating veterinarians named phenylbutazone as the, or one of the, most often used non-steroidal anti-inflammatory drugs. Altogether, 41.2% (70/170) of participating equine owners and 42.9% (30/70) of equine keepers did not know under which circumstances an equine can legally be slaughtered for human consumption. In total, 34.3% (24/70) of the equine keepers classified their knowledge of national regulations for animal keepers regarding the documentation of drug usage in equines as 'poor' to 'nonexistent'. This lack of knowledge in all three surveyed groups, combined with the complex legal regulations regarding the usage and documentation of drugs in slaughter equines, could result in missing and false documentation, treatment of slaughter equines with prohibited substances and therefore pose a risk factor for drug residues in equine meat.

Effects of dietary zinc chloride hydroxide and zinc methionine on the immune system and blood profile of healthy adult horses and ponies.

The effects of dietary zinc on the immune function of equines have not been evaluated in detail so far. In the present study, eight healthy adult ponies and two healthy adult horses were fed a diet supplemented with either zinc chloride hydroxide or zinc methionine in six feeding periods of four weeks each (according to maintenance zinc requirement, 120 mg zinc/kg dry matter, and 240 mg zinc/kg dry matter, for both dietary zinc supplements, respectively). All animals received the six diets, with increasing amounts of zinc chloride hydroxide in the feeding periods 1-3, and with increasing amounts of zinc methionine in the feeding periods 4-6. At the end of each feeding period, blood samples were collected for a blood profile and the measurement of selected immune variables. Increasing dietary zinc chloride hydroxide doses increased the glutathione concentrations in the erythrocyte concentrate and the glutathione peroxidase activity in the erythrocyte lysate, decreased the numbers of total leukocytes and granulocytes in the blood, and also decreased the interleukin-2 concentrations in the plasma of the animals. The dietary supplementation of increasing doses of zinc methionine enhanced the mitogen-stimulated proliferative activity of peripheral blood mononuclear cells, and decreased the glutathione concentrations in the erythrocyte concentrate and the glutathione peroxidase activity in the plasma of the animals. The percentage of blood monocytes with oxidative burst after in vitro stimulation with E. coli decreased with increasing dietary zinc concentrations, independently of the zinc compound used. The blood profile demonstrated effects of the zinc supplements on the red blood cells and the bilirubin metabolism of the horses and ponies, which require further investigation. Overall, high doses of dietary zinc modulate the equine immune system, for the most part also depending on the zinc compound used.

Does colonization with MRSA, ESBL - producing Enterobacteriaceae, and/or Acinetobacter baumannii - increase the risk for postoperative surgical site infection?

OBJECTIVE: Evaluation of the role of indicator pathogens in equine surgical site infection (SSI) and other infection-promoting factors. STUDY DESIGN: Cross-sectional study. ANIMALS: Horses presenting with an open injury or surgical colic during 1.5 years. METHODS: A nasal swab and a faecal sample were collected from every patient upon admission. Furthermore, a wound swab was collected from wounds of injured horses. Details on the wounds and procedures were documented. Laparotomy incisions and injuries were monitored for signs suggesting infection. RESULTS: In total, 156 horses presented because of a surgical colic (n = 48) or open injuries (n = 108). Thirteen surgical colic patients and three injured horses did not survive beyond 24 h, and four injured horses were discharged from the clinic at the day of admission. SSIs occurred in 31 (30.7%) injured horses and 11 (31.4%) horses after laparotomy. Regarding injuries, general anaesthesia increased the risk of developing a WI compared to sedation. Indicator pathogens were cultured from 29/42 SSI. In total, 10/11 infected laparotomy incisions and 19/31 injuries with SSI tested positive for multidrug-resistant pathogens (MDRPs) . Indicator pathogens were not detected at admission in any of the horses that developed incisional SSIs after laparotomy but were detected in two of the injured horses that developed SSIs. CONCLUSION: MDRPs were identified in almost 70% of the SSI. Less than 5% of the affected animals were colonized with the same pathogen before admission, indicating that colonization with MDR pathogens is only one of the crucial factors for the development of SSI. CLINICAL SIGNIFICANCE: Colonization with MDRP seems not to predispose horses to MDR SSIs.

Markers for internal neoplasia in the horse.

The diagnosis of internal neoplasia in horses is challenging. Increased production of hormones physiologic for adult animals (e.g., adrenocorticotropin, norepinephrine, and erythropoietin) or typical for the foetal phase (alpha-fetoprotein, anti-Müllerian hormone, and parathyroid-hormone-related protein) might aid in tumour diagnostics. Thymidine kinase-1 and alkaline phosphatase are examples of intracellular enzymes, whose activity in the blood may increase in some neoplasia cases. Furthermore, inappropriate production of abnormal monoclonal or autologous antibodies can accompany lymphoma and multiple myeloma. Many of those tumour markers lead to clinical or laboratory changes, called paraneoplastic syndromes, such as hypercalcaemia and erythrocytosis. The interpretation of the results of the tumour marker measurements in horses is complicated due to many factors affecting the markers' concentration or activity (e.g., young age, pregnancy, and inflammation) and other diseases triggering the same changes. Moreover, the presence of paraneoplastic syndromes is inconsistent, which leads to low sensitivity of those substances as tumour markers. In conclusion, screening for neoplasia in horses is not recommended. The measurement of tumour markers should be performed only in risk groups with suspicious clinical or laboratory findings, and the results should be interpreted with caution. It is advisable to add inflammatory markers to the tumour profile or repeat the measurements.

Tongue ties do not widen the upper airways in racehorses.

BACKGROUND: There is contradictory evidence on the potential benefits of tongue ties on upper airway function and their efficacy in inhibiting intermittent dorsal displacement of the soft palate (DDSP) in racehorses. OBJECTIVES: To test the hypothesis that tongue ties increase the pharyngeal diameter and decrease the occurrence of dynamic airway obstruction in racehorses. STUDY DESIGN: Prospective, crossover blinded clinical study. METHODS: Data of 22 Thoroughbred and 8 Standardbred racehorses examined using overground endoscopy under full-intensity exercise on training racetracks with and without fixation of the tongue by use of tongue ties were analysed. Equivalent exercise intensity was ensured by measuring heart rate (bpm), speed (GPS) and venous lactate. Pharyngeal diameter was expressed as pharyngeal-epiglottis (PE) ratios and laryngeal abduction accordingly as laryngeal-median-ratios. Data were analysed using multivariable repeated-measurements ANOVA. RESULTS: The PE ratio increased significantly from 1.11 ± 0.19 to 1.28 ± 0.30 in all horses between rest and full-intensity exercise (p < 0.01). Multi-variable analysis revealed that this effect decreased significantly by the application of tongue ties (1.15 ± 0.27, p < 0.01). Tongue ties did not influence maximum laryngeal width (p = 0.09) and area (p = 0.2) significantly. DDSP was found in 4 of 30 examinations with tongue tie and in 1 of 30 examinations without tongue tie. MAIN LIMITATIONS: The study population was not randomly chosen and was heterogeneous. Few horses had a respiratory noise and the prevalence of upper respiratory tract disorders was too low for statistical comparison of the rate of DDSP with and without tongue ties. CONCLUSIONS: A positive effect of tongue ties on pharyngeal or laryngeal diameters was not found in this study. Therefore, the results of this study do not support the use of tongue ties to enhance upper airway function.

Plasma Amino Acid Concentration in Obese Horses with/without Insulin Dysregulation and Laminitis.

Laminitic horses commonly suffer from an endocrine disease such as equine metabolic syndrome. Hyperinsulinemia is considered a key factor in the pathogenesis of laminitis. Since insulin also affects protein turnover in the body, the resting plasma amino acid concentrations of obese horses that were presented for a combined glucose insulin test (CGIT) were determined. In total, 25 obese horses and two lean horses with recurrent laminitis underwent a CGIT. Of these, five were not insulin dysregulated (obese), 14 were insulin dysregulated (ID), and eight were insulin-dysregulated and laminitic (IDL). Significant differences in the resting concentrations between obese and insulin dysregulated and laminitic (citrulline p = 0.038, obese: 73.001 ± 12.661 nmol/mL, IDL: 49.194 ± 15.486 nmol/mL; GABA p = 0.02, obese: 28.234 ± 3.885 nmol/mL, IDL: 16.697 ± 1.679 nmol/mL; methionine p = 0.018, obese: 28.691 ± 5.913 nmol/mL, IDL: 20.143 ± 3.09 nmol/mL) as well as between insulin dysregulated individuals with and without laminitis (GABA p < 0.001, ID: 28.169 ± 6.739 nmol/mL) regarding three amino acids were determined. This may be an interesting approach, especially for diagnostic testing and possibly also for the feed supplements of horses at risk of developing laminitis. However, further research, including a higher number of cases, is required.

Plasma Amino Acids in Horses Suffering from Pituitary Pars Intermedia Dysfunction.

Pituitary pars intermedia dysfunction is one of the most common diseases of aged horses and ponies. In Parkinson's disease, which is, similar to PPID, a disease that involves oxidative damage to dopaminergic pathways but with different clinical signs, alterations to the serum amino acid profile have been reported. To examine changes in the plasma amino acid profile in horses with PPID, EDTA plasma of horses that were presented for various reasons that required laboratory examinations of blood anticoagulated with EDTA was collected. With this plasma, the basal ACTH concentration as well as the amino acid profile was determined. Horses were considered PPID patients if the ACTH concentration was ≥ 100 pg/mL, i.e., they would be considered affected at any time. Horses were defined as non-PPID (nPPID) patients if the ACTH concentration was below 30 pg/mL. Horses receiving pergolide with ACTH ≤ 30 pg/mL were allocated to the group PPIDrr (PPID, ACTH in reference range) and horses receiving pergolide with ACTH ≥ 100 pg/mL to the group PPIDarr (PPID, ACTH above reference range). In total, 93 horses were examined, including 88 horses at the clinic and 5 horses at a private practice. Of these, 53 horses fulfilled the inclusion criteria (ACTH ≤ 30 pg/mL or ACTH ≥ 100 pg/mL). A total of 25 horses were diagnosed as nPPID, 20 as PPID, 5 as PPIDrr, and 3 as PPIDarr. Arginine was significantly higher in PPIDrr than in PPID and nPPID, asparagine was significantly higher in PPID, PPIDrr, and PPIDarr than in nPPID, citrulline was significantly higher in PPIDrr than in nPPID and PPID, cysteine was significantly lower in PPIDrr than in PPID, nPPID, and PPIDarr, and glutamine was significantly higher in PPID and PPIDarr than in nPPID. Especially, asparagine, citrulline, and glutamine may be potential diagnostic markers and may offer interesting approaches for research regarding amino supplementation in PPID.

Detection of Anaplasma phagocytophilum in horses from Germany by molecular and serological testing (2008-2021).

BACKGROUND: Equine granulocytic anaplasmosis (EGA) is a tick-borne disease caused by Anaplasma (A.) phagocytophilum. In Germany, this pathogen is transmitted primarily by Ixodes ricinus. There is limited knowledge about its prevalence in horses in Germany. The aim of this retrospective study was to analyze the results of serological and molecular testing for A. phagocytophilum in horses which were done in a commercial laboratory in Germany over fourteen years. Additionally, risk factors were evaluated, and hematological abnormalities were addressed in horses with positive PCR results. METHODS: This retrospective study examined results of direct (Polymerase chain reaction [PCR]) and indirect (immunofluorescence antibody test [IFAT]) detection methods for A. phagocytophilum in horses on samples provided by German veterinarians and processed by the commercial laboratory LABOKLIN from 2008 to 2021. In horses with positive test results, a Complete Blood Count (CBC) and Serum Amyloid A (SAA) were also analyzed where possible. RESULTS: In total, 1217/4834 horses tested positive (PCR: 190/1246 horses, 15.2%; IFAT: 1036/3849 horses, 26.9%). Seasonality and location, as classified by federal state, had a statistically significant impact on PCR results (P < 0.001 for both). In horses with positive PCR results, hematological abnormalities were detected in 112/118 horses (95%), with thrombocytopenia (86%) and anemia (52%) representing the most common findings. The remaining 6/118 horses (5%) showed no hematological abnormalities on CBC. SAA was measured in 35 horses with positive PCR results, which exclusively showed marked elevation. CONCLUSIONS: The seasonality of A. phagocytophilum infections confirmed by PCR testing was consistent with known peaks in vector activity in Germany. The high rate of horses with positive PCR results when compared to dogs and cats may be due to a lack of ectoparasite prophylaxis. Infections with A. phagocytophilum should be considered as a differential diagnosis in horses with cytopenia on CBC and SAA elevation, especially in the summer and after any possible tick exposure.

[Opinion among veterinarians on equine Lyme disease - results of a questionnaire study]. / Tierärztliches Meinungsbild zur Equinen Lyme-Borreliose ­ Ergebnisse einer Fragebogenstudie.

AIM: Recording equine veterinarians opinion on equine Lyme disease. MATERIAL AND METHODS: A survey was conducted to get a general impression of the opinion of German equine vets on the topic of equine Lyme Borreliosis. The main focus of this questionnaire study was set on the diagnostic and therapeutic approach of the horse vets. RESULTS: Overall almost half of the veterinarians (48 %) detected only rarely or never serological antibodies against Bb , 47 %found occasionally and 5 % frequently Borrelia antibodies within their clientel.Concerning the existence of clinical LB in horses, 51 % of the veterinarians reported clinical cases, 43 % thought it might be possible but have not seen cases themselves and 6 % categorically ruled out the existence.On average, further diagnostic measures for LB diseases were initiated 15 ± 9 times per year and 1.4 ± 1.0 cases of equine LB diseases were diagnosed per year. In the majority of 68 % of the cases, the veterinarians chose serological tests as diagnostic measures, followed by a combination of serological tests and Antigen detection tests (27 %) and only 5 % of the veterinarians were using Antigen detection tests exclusively. Blood and skin biopsies were submitted most frequently for direct Antigendetection. The treatment of horses with positive laboratory results indicating Lyme disease and clinical symptoms assessed as suitable was carried out by 93 % of the veterinarians with antibiotics and 7% with homeopathy. Doxycycline (68 %) was used most frequently. The antibiotic treatment was applied over a period of 3 (31 %) to 4 (63 %) weeks.Regarding the question of a possible vaccination, 39 % of veterinarians do not offer vaccination against Lyme borreliosis, 20 % have not yet used it, but do not categorically reject it, and 41 % regularly carry out vaccinations against Lyme borreliosis. CONCLUSION AND CLINICAL RELEVANCE: The opinion on the clinical relevance of Equine Lyme Borreliosis among german equine veterinarians vary considerably. Uniform diagnostic guidelines and, possibly, recommendations for therapy would serve to counteract the existing uncertainty concerning this disease within the equine veterinary community.

Comparison of Sources and Methods for the Isolation of Equine Adipose Tissue-Derived Stromal/Stem Cells and Preliminary Results on Their Reaction to Incubation with 5-Azacytidine.

Physiological particularities of the equine heart justify the development of an in vitro model suitable for investigations of the species-specific equine cardiac electrophysiology. Adipose tissue-derived stromal/stem cells (ASCs) could be a promising starting point from which to develop such a cardiomyocyte (CM)-like cell model. Therefore, we compared abdominal, retrobulbar, and subcutaneous adipose tissue as sources for the isolation of ASCs applying two isolation methods: the collagenase digestion and direct explant culture. Abdominal adipose tissue was most suitable for the isolation of ASCs and both isolation methods resulted in comparable yields of CD45-/CD34-negative cells expressing the mesenchymal stem cell markers CD29, CD44, and CD90, as well as pluripotency markers, as determined by flow cytometry and real-time quantitative PCR. However, exposure of equine ASCs to 5-azacytidine (5-AZA), reportedly inducing CM differentiation from rats, rabbits, and human ASCs, was not successful in our study. More precisely, neither the early differentiation markers GATA4 and NKX2-5, nor the late CM differentiation markers TNNI3, MYH6, and MYH7 were upregulated in equine ASCs exposed to 10 µM 5-AZA for 48 h. Hence, further work focusing on the optimal conditions for CM differentiation of equine stem cells derived from adipose tissue, as well as possibly from other origins, are needed.