Physical characteristics, blood hormone concentrations, and plasma lipid concentrations in obese horses with insulin resistance

Effect of pregnancy on isolation efficiency and in vitro proliferation of equine peripheral-blood derived mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) have regenerative and immunomodulatory potential and may be used to treat injured tissues. Pregnancy has been associated with increased MSCs in the peripheral circulation in multiple species, but to date, there are no reports on this matter in horses. This study aimed to evaluate the effect of pregnancy on isolation efficiency and proliferation capacity of equine MSCs derived from the peripheral blood (PB) of mares. Venous blood samples were collected at the 11th month of gestation and 1 month after delivery from clinically healthy Arabian mares that presented normal pregnancies. Blood samples were processed for in vitro cellular culture and hormonal and metabolic profiles. MSCs were isolated and characterized by trilineage differentiation potential, immunophenotyping, analyzed by gene sequencing and proliferation assays. The isolation of peripheral blood mononuclear cells (PBMCs) of pregnant mares were associated with higher isolation efficiency and proliferative capacity of MSCs derived from peripheral blood (PB-MSCs) recovered pre-partum than those isolated post-partum. Although fetal gender, parity, 5α-reduced pregnanes, insulin, and cortisol were shown to affect cellular proliferation, individual factors and the small population studied must be considered. This study suggests that PB-MSCs from pregnant mares could be a valuable alternative source of MSCs for therapeutic purposes.

Prevalence of insulin dysregulation in the non-obese stock-type horse and relationship with morphometric neck measurements

Insulin dysregulation (ID), core to equine metabolic syndrome, may present without obesity. Testing for ID risk is commonly based on breed and obese phenotype but might be valuable for non-obese stock-type horses. This study aimed to determine the prevalence of ID in non-obese stock-type horses and evaluate if morphometric neck measurements (MNM) correlate with ID. Sixty-two, non-obese (BCS 5, range 2.5-6/9) stock-type horses were assessed for MNM: neck circumference at 25%, 50% (NC50), and 75% (NC75) length, and crest height. An oral sugar test (OST; 0.15 mL/kg BW corn syrup) was performed with blood taken pre- and 60 min post-OST for insulin (PREI, POSTI) and glucose (PREG, POSTG). Insulin dysregulation was defined as insulin concentration > 45 µIU/mL POSTI. Three of 62 horses were ID (4.8%; 95% CI 1.0%-13.5%). Horses with ID had greater PREG (121.0 ± 7.56 vs. 105.3 ± 1.72 mg/dL; LS means ± SEM; P = 0.04) and PREI (15.7 ± 2.63 vs. 10.5 ± 0.59 µIU/mL; P = 0.05) than normal responders. Mares had greater PREI than geldings (11.7 ± 0.76 vs. 9.4 ± 0.89 µIU/mL; P = 0.04). Stepwise regression indicated a weak relationship with crest height and POSTG (y = 51.27 + (0.88 x NC50); R2 = 0.09; P = 0.02). Post-glucose correlated with NC50 (r = 0.30; P = 0.04) and NC75 (r = 0.29; P = 0.03). This study showed 4.8% of non-obese horses had ID, warranting testing irrespective of phenotype, but only a weak association between MNM and POSTG was found.

Use of FreeStyle Libre for continuous glucose monitoring in adult horses

OBJECTIVES

To evaluate the feasibility of using the FreeStyle Libre (a continuous glucose monitoring system [CGMS]) for instantaneous continuous monitoring of interstitial glucose in adult horses and examine the applicability and accuracy of this system in horses submitted to combined glucose-insulin test (CGIT).

DESIGN

Laboratory measurements and continuous glucose monitoring system (CGMS) readings were analyzed using a 2 × 2 factorial statistical model with repeated measures over time. This analysis assessed the effects of the test (factor 1), group (factor 2), and their interactions (test × group, test × time, and group × time). Pearson's correlation analysis was applied to blood glucose values. Mean comparisons were conducted using the t-test, and agreement between techniques was assessed via the Bland-Altman method, with a 95% confidence interval.

SETTING

Field study on private horse farms in association with a veterinary school.

ANIMALS

Ten healthy stallions were assigned to one of two groups based on their body condition scores (BCS). Group 1 (G1, n = 5) consisted of nonobese horses with a BCS of 5 or 6, while Group 2 (G2, n = 5) consisted of obese horses with a BCS of 7 or higher.

INTERVENTIONS

A CGMS sensor was attached to the dorsolateral aspect of the proximal one third of each horse's neck. Laboratory blood glucose measurements and CGMS interstitial glucose readings were compared at different time points for up to 7 days after sensor fixation. Obese horses were also submitted to CGIT on Day 4.

MEASUREMENTS AND MAIN RESULTS

A comparative analysis of glucose measurements obtained in G1 and G2 horses using the CGMS and enzymatic methods revealed significant group × time interactions (P < 0.001) and time effects (P < 0.001). No interactions were detected between group (P = 0.45), test (P = 0.62), group and test (P = 0.28), or time and test (P = 0.92). In G1 and G2, tests were significantly correlated (r = 0.84 and P = 0.00) at all time points (T0-T5). Agreement between the glucose values obtained using different methods was excellent despite a small time delay in CGMS detection of rapid changes in blood glucose.

CONCLUSIONS

It was concluded that the CGMS can be used for indirect assessment of glycemic status (ie, based on interstitial glucose measurements) in nonobese and obese adult horses submitted to CGIT.

Obesity and obesity-associated metabolic disease conditions in Connemara ponies in Ireland

BACKGROUND

Equine obesity combined with insulin dysregulation (ID) is a major risk factor associated with laminitis. Some pony breeds appear to be at increased risk. However, little is known regarding the prevalence of obesity or hyperinsulinaemia as evidence of ID in Irish ponies.

OBJECTIVE

To investigate the prevalence of obesity and associated endocrine/metabolic disease conditions in Connemara ponies and to determine if hyperinsulinaemia in these ponies could be predicted by morphometric or metabolic markers.

STUDY DESIGN

Cross-sectional study.

METHODS

The study population included registered Connemara ponies recruited through public and veterinary social media posts. Ponies underwent a physical examination and information on their management and clinical history was obtained via owner questionnaire. The body condition score (BCS) was measured using the Henneke system; cresty neck score (CNS) and regionalised adiposity were also assessed. Hyperinsulinaemia was confirmed by measuring serum basal insulin concentration (BIC) or insulin concentration after an oral sugar test (OST). Blood glucose and triglyceride concentrations were measured. Characteristics of hyperinsulinaemic and insulin-sensitive ponies were compared by logistic regression.

RESULTS

Two hundred ponies were included; 59 ponies (29.5%) had a BCS ≥7, 58 (29.0%) had a CNS ≥2.5 and 135 (67.5%) had regionalised adiposity; 137 (68.5%) ponies had at least one of these abnormalities. Owner-reported history or clinical evidence of chronic laminitis was found in 92 ponies (46.0%). Hyperinsulinaemia was confirmed in 32 ponies (16.0%), including 23 of 91 (25.3%) detected by OST and 9 of 109 (8.3%) by BIC. Hypertriglyceridaemia was observed in 12 of 198 ponies (6.1%) ponies and hyperglycaemia in 11 of 197 ponies (5.6%) ponies. The odds of hyperinsulinaemia increased by a factor of 6.53 (95% confidence interval: 2.95, 15.21) when BCS was ≥7.

MAIN LIMITATIONS

The OST was not performed in all ponies.

CONCLUSIONS

Increased adiposity, laminitis and metabolic derangements are prevalent in this native Irish pony breed.

Equine Metabolic Syndrome: A Complex Disease Influenced by Multifactorial Genetic Factors

Equine metabolic syndrome (EMS) has become an important issue in modern veterinary medicine and is linked to the common, extremely painful, most-of-the-time performance-terminating hoof laminitis. The growing knowledge in the field of genetic background, inducing environmental factors, diagnosis, treatment and maintenance of affected equines led us to summarise the available information to be used not only for scientific purposes but for fieldwork. In horses, the clinical presentation of EMS includes: obesity or local fat deposition, bilateral lameness or hoof rings attributed to ongoing or previous (pasted) laminitis with the key feature of the occurrence of insulin dysregulation, disturbing the homeostasis within insulin, glucose and lipid metabolism. The management of EMS is based on dietary and fitness discipline; however, intensive research is ongoing in the field of regenerative medicine to develop modern and promising therapies.

Occurrence of equine metabolic syndrome, clinical manifestations, and associated risk factors in Nigeria

Insulin dysregulation (ID) is central to the pathophysiology of equine metabolic syndrome (EMS), putting the horse at risk of laminitis. There is a paucity of information on the status of EMS in Nigeria. This study aimed to determine the occurrence of EMS, clinical manifestations, and associated risk factors in Nigeria. A cross-sectional study was carried out. Selected horses underwent an insulin 2-step response test to ascertain insulin dysregulation; a physical examination was carried out to diagnose laminitis and obesity. Risk factors were assessed using a questionnaire. The overall prevalence of EMS was 43.10%. Breed and sex were significantly associated with EMS, but age was not. Horses diagnosed with laminitis showed two signs of laminitis, namely, divergent hoof rings and widened white lines. Risk factors significantly associated with the prevalence of EMS were as follows: being a West African Barb horse (60.00%), being a stallion (67.86%), being a leisure horse (67.86%), only walking horses during exercise (68.00%), exercising horses once every 5 months (82.76%), tethering horses to a stake in the ground (67.86%), obesity (92.86%), and abnormal neck crest (83.33%). The risk of ID remains higher in obese horses. However, some of the horses with ID were not obese, indicating that there are other possible underlying causes of EMS.

Effect of sirolimus on insulin dynamics in horses

BACKGROUND

Sirolimus, a mechanistic target of rapamycin inhibitor, suppresses insulin production in other species and has therapeutic potential for hyperinsulinemia in horses.

HYPOTHESIS/OBJECTIVE

Determine the pharmacokinetics (PKs) of sirolimus and evaluate its effect on insulin dynamics in healthy and insulin dysregulation (ID) horses.

ANIMALS

Eight Standardbred geldings.

METHODS

A PK study was performed followed by a placebo-controlled, randomized, crossover study. Blood sirolimus concentrations were measured by liquid chromatography-mass-spectrometry. PK indices were estimated by fitting a 2-compartment model using nonlinear least squares regression. An oral glucose test (OGT) was conducted before and 4, 24, 72, and 144 hours after administration of sirolimus or placebo. Effects of time, treatment and animal on blood glucose and insulin concentrations were analyzed using mixed-effects linear regression. Sirolimus was then administered to 4 horses with dexamethasone-induced ID and an OGT was performed at baseline, after ID induction and after 7 days of treatment.

RESULTS

Median (range) maximum sirolimus concentration was 277.0 (247.5-316.06) ng/mL at 5 (5-10) min and half-life was 3552 (3248-4767) min. Mean (range) oral bioavailability was 9.5 (6.8-12.4)%. Sirolimus had a significant effect on insulin concentration 24 hours after a single dose: median (interquartile range) insulin at 60 min (5.0 [3.7-7.0] μIU/mL) was 37 (-5 to 54)% less than placebo (8.7 [5.8-13.7] μIU/mL, P = .03); and at 120 min (10.2 [8.4-12.2] μIU/mL) was 28 (-15 to 53)% less than placebo (14.9 [8.4-24.8] μIU/mL, P = .02). There was minimal effect on glucose concentration. Insulin responses decreased toward baseline in ID horses after 7 days of treatment.

CONCLUSION AND CLINICAL IMPORTANCE

Sirolimus decreased the insulinemic response to glucose and warrants further investigation.

A one-health approach to identifying and mitigating the impact of endocrine disorders on human and equine athletes

Endocrinopathies affect multiple species in ever-increasing percentages of their populations, creating an opportunity to apply one-health approaches to determining creative preventative measures and therapies in athletes. Obesity and alterations in insulin and glucose dynamics are medical concerns that play a role in whole-body health and homeostasis in both horses and humans. The role and impact of endocrine disorders on the musculoskeletal, cardiovascular, and reproductive systems are of particular interest to the athlete. Elucidation of both physiologic and pathophysiologic mechanisms involved in disease processes, starting in utero, is important for development of prevention and treatment strategies for the health and well-being of all species. This review focuses on the unrecognized effects of endocrine disorders associated with the origins of metabolic disease; inflammation at the intersection of endocrine disease and related diseases in the musculoskeletal, cardiovascular, and reproductive systems; novel interventions; and diagnostics that are informed via multiomic and one-health approaches. Readers interested in further details on specific equine performance conditions associated with endocrine disease are invited to read the companion Currents in One Health by Manfredi et al, JAVMA, February 2023.

Particle Size Distribution of Plasma Lipoproteins in Donkeys from Death Valley Compared to a Sampling of Horses

Simple Summary

Donkeys, like horses, belong to the Equidae family. Though they share some physical attributes, much of their physiology is quite different from horses. Both horses and donkeys can develop clinical issues associated with obesity; insulin dysregulation; and altered lipid metabolism, often termed equine metabolic syndrome or donkey metabolic syndrome, respectively. Unlike large breed horses, however, donkeys, ponies, and miniature horses are more susceptible to developing dyslipidemias. This study aimed to use a novel Lipoprint^® assay to compare the lipid profiles of apparently healthy donkeys and large-breed horses to establish a baseline for future work that may lead to the use of this test methodology for the evaluation and monitoring of equids with endocrine disorders.

Abstract

The clinical evaluation of lipid metabolism in equids is often limited to the measurement of total cholesterol and triglyceride concentrations. This provides a limited picture of metabolic state and general health, given the continuous exchange of lipid species between various lipoproteins. Major lipoprotein classes in equids include high-density lipoprotein (HDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and chylomicrons (CM). Unlike large breed horses, donkeys are highly susceptible to hepatic lipidosis. Currently, serum triglyceride concentrations serve as a surrogate marker of hepatic lipid exportation. Both VLDL, indicative of hepatic exportation, and its metabolic end-product, LDL, are rich in triglycerides, and contribute to this value. Diagnostic assays that distinguish VLDL from LDL could be useful in better recognizing the hepatic pathology in donkeys. The compositional differences of lipoproteins across species limit the use of commercially available assays developed for the measurement of human lipoproteins in domestic animals. In this study, we evaluated a high-resolution polyacrylamide gel electrophoresis method (Lipoprint^®) for separating major lipoprotein classes and sub-fractionating LDL and HDL based on particle size in a large group of donkeys, and compared the pattern to a representative set of horses. Donkeys proved an HDL-rich species, with HDL accounting for the bulk of all lipoproteins (average 78.45%, SD 6.6%, range 92.2–55%). VLDL accounted for a large portion of the total (average 21.6%, SD 6.6%, range 37.1–7.8%), with minimal amounts of LDL detected. The horses tested had higher proportions of VLDL as compared to donkeys (31.7% and 21.6%, respectively p = 0.00008). The later finding draws into question the purported relationship between VLDL, high triglycerides, and hepatic lipidosis, given the incidence of the disease in donkeys is far higher than in horses.

Hepatic Enzyme Profile in Horses

For diagnostic purposes, liver enzymes are usually classified into hepatocellular and cholestatic. These two groups of equine liver-specific enzymes include sorbitol dehydrogenase (SDH), glutamate dehydrogenase (GLDH), γ-glutamyl transferase (GGT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP). SDH and GLDH mostly reflect hepatocellular injury and cholestasis, while GGT expresses high values in biliary necrosis or hyperplasia. Likewise, AST, LDH, and ALP also reflect hepatocellular and biliary disease, but these enzymes are not liver specific. From the clinical point of view of the course of liver or biliary disease, AST and ALP are indicative of chronic disease, whereas SDH, GGT, and GLDH indicate an acute course. The patterns of enzymatic changes at the blood level are associated with different types of liver pathologies (infectious, inflammatory, metabolic, toxic, etc.). Increases in hepatocellular versus biliary enzyme activities are indicative of a particular process. There are different ways to diagnose alterations at the hepatic level. These include the evaluation of abnormalities in the predominant pattern of hepatocellular versus cholestatic enzyme abnormalities, the mild, moderate, or marked (5−10-fold or >10-fold) increase in enzyme abnormality concerning the upper limit of the reference range, the evolution over time (increase or decrease) and the course of the abnormality (acute or chronic).

Obesity-Related Metabolic Dysfunction in Dairy Cows and Horses: Comparison to Human Metabolic Syndrome

Obesity has become a serious health problem with frequent occurrence both in human and animal populations. It is estimated that it may affect over 85% of the human population and 70–80% of horses and cows by 2030. Fat cow syndrome (FCS) is a combination of metabolic, digestive, infectious, and reproductive disorders that affects obese periparturient dairy cows, and occurs most frequently in loose-housing systems, where periparturient and dry cows are fed and managed in one group disregarding the lactation stages. Equine metabolic syndrome (EMS) was named after human metabolic syndrome (MetS) and has insulin dysregulation as a central and consistent feature. It is often associated with obesity, although EMS may occur in a lean phenotype as well. Other inconsistent features of EMS are cardiovascular changes and adipose dysregulation. Laminitis is the main clinical consequence of EMS. MetS holds a 30-years old lead in research and represents a clustering of risk factors that comprise abdominal obesity, dyslipidemia, hypertension, and hyperglycemia (impaired fasting glucose or type 2 diabetes mellitus—T2DM), which are associated with doubled atherosclerotic cardiovascular disease risk, and a 5-fold increased risk for T2DM. The main aim of this review is to provide critical information for better understanding of the underlying mechanisms of obesity-related metabolic dysfunction in animals, especially in cows and horses, in comparison with MetS. Human medicine studies can offer suitable candidate mechanisms to fill the existing gap in the literature, which might be indispensable for owners to tackle FCS, EMS, and their consequences.

"Feeding the Foot": Nutritional Influences on Equine Hoof Health

Nutrition plays an important role in equine health, including that of the foot. Deficiencies and excesses of dietary components can affect the growth and function of the foot and have been associated with important podiatric diseases. The recognition, prevention, and treatment of specific notable nutritional diseases of the foot are discussed, as well as information regarding specific ingredients included in supplements meant to improve equine hoof quality. Ensuring provision of a balanced diet, maintaining horses in appropriate body condition, and seeking guidance from an equine nutritionist when creating dietary recommendations will prevent most equine foot disease related to nutrition.

Refeeding syndrome in a miniature donkey

OBJECTIVE

To describe refeeding syndrome in an equid without a history of recognized risk factors.

CASE SUMMARY

Refeeding syndrome with marked hypophosphatemia developed in an aged miniature donkey gelding during treatment of suspected enterocolitis. Hypophosphatemia (manifested clinically as ileus and neuromuscular weakness) developed despite a short (3 day) history of hyporexia, increased body condition (7/9), and adherence to nutritional recommendations for critically ill equids. Nutritional support included nasogastric enteral feeding with a commercial equine nutrition product claiming to provide 100% of the National Research Council's daily recommended protein, vitamin, and mineral requirements for equids. Hypophosphatemia developed despite this enteral supplementation and was ultimately corrected by intravenous administration of sodium phosphate solution.

NEW OR UNIQUE INFORMATION PROVIDED

This case report suggests that risk factors for refeeding syndrome in equids may be broader than previously recognized. Specifically, critically ill equids at risk for insulin dysregulation may have unique nutritional co-morbidities and requirements. This report highlights the need for both broader recognition of risk factors for refeeding syndrome, and revised best-practice nutritional guidelines and supplementation products to improve equine critical care.

A Multiomic Approach to Investigate the Effects of a Weight Loss Program on the Intestinal Health of Overweight Horses

Obesity is endemic in human populations in the western society, and with mounting evidence that the intestinal ecological environment plays a major role in its pathogenesis, identification of therapies based on intestinal microbiota modulation are gaining attention. Obesity in companion animals is also a common clinical problem. We set out using a multidimensional approach, to determine the effectiveness and safety of a weight loss program for horses incorporating diet restriction and exercise. In addition, we aimed to investigate the effect of this program on the overall intestinal health of overweight sedentary horses. The investigation comprised of a randomized, controlled, 6-week study of 14 overweight sedentary horses and ponies who were blocked for age, gender, and breed (controls n = 7, treatment n = 7). The treatment group were fed a restricted diet (1.4% of body weight dry matter intake) and the control group a maintenance diet (2% of body weight as dry matter intake) over the study period. The treatment group were subjected to a prescribed exercise regime, while the control group were exercised to mimic foraging conditions. Several clinical measurements were taken at the start and end of the study, including morphological parameters, ultrasound measurements of subcutaneous fat, and blood pressure. Fecal microbiota analysis was performed using 16S rRNA gene sequence analysis, and fecal metabolome was analyzed using NMR spectroscopy, on samples taken at weeks 1, 3, and 6 of the study. All horses completed the study period successfully. However, two of the treatment group had to have modified exercise regimes. The treatment group showed significant weight loss (p < 0.00001) and an associated decrease in waste circumference (p < 0.0001) when compared with the control group. The alpha-diversity of the fecal microbiota in the treatment group showed a significant increase from the start to the end of the study period (p < 0.05); however, there was no significant difference between groups at any sampling point. There were significant changes (p < 0.05) in the metabolome in both groups between the start and end of the study, but not between groups at any sampling point. Finally, the resting blood pressure of all horses was significantly lower by the end of the study.

Metabolic Profile Changes in Mangalarga Marchador Horses Subjected to A Hypercaloric Diet Evaluated by Proton NMR Spectroscopy

The incidence of equine metabolic syndrome, a condition that results in endocrinopathic laminitis, is increasing worldwide. Although it is well known that the development of this syndrome depends on imbalances in energy metabolism and genetic traits, its pathophysiology remains unclear. Hydrogen nuclear magnetic resonance (¹H NMR) is a powerful tool used to compare metabolic profiles and to discriminate metabolites in living beings. The aim was to apply this technology to detect blood biomarkers candidates in horses that were previously demonstrated to developed metabolic changes when subjected to induced obesity. Nine Mangalarga Marchador horses received a hypercaloric diet for 5 months and serum metabolomic analysis was performed before, during, and after the diet period. The ¹H NMR results were subjected to multivariate analysis and NMR analysis allowed to identify six compounds (alanine, threonine, choline, α-glucose, β-glucose, and creatinine), and observe the increasing choline level over the assessment period in four animals. A hypercaloric diet altered the metabolic profile of horses, with an individual bias in the time at which these changes occurred. This study is the first to describe metabolomic compounds in Mangalarga Marchador horses subjected to a hypercaloric diet rich in non-structural carbohydrates.

Nutritional Considerations When Dealing with an Obese Adult Equine

Equine obesity is common, reducing quality of life and requiring dietary energy restriction. Equine obesity is identified using subjective body condition scoring. Considerations are given for life stage and health status when managing obese equines. Every effort should be made to maximize feeding duration, and minimize time spent without feed while meeting all essential nutrient requirements. Limiting total daily dry matter intake to 2% of current bodyweight per day of a low caloric, forage-based diet may result in adequate body weight loss. Weight loss and weight management plans should be monitored for success and potential gastrointestinal, metabolic, and/or behavioral complications.

Effect of Breed and Finishing Diet on Growth Parameters and Carcass Quality Characteristics of Navarre Autochthonous Foals

Simple Summary

Nowadays, populations are more health conscious and pay more attention to the environmental impact of their food choices. In this context, horsemeat plays a significant role, since it is claimed as “dietetic” meat by researchers. In addition, equine meat production is arousing interest due to its relevant environmental potential. However, several factors have been shown to affect carcass and horsemeat quality. In this sense, our study evaluates the impact of breed (Jaca Navarra and Burguete) and type of finishing diet (conventional diet and silage with organic feed) on carcass traits from Navarre endangered foals. Moreover, considering the limited information about Jaca Navarra foals from a meat production perspective, this work represents a starting point to improve the handling of these equids. Data reported Burguete predominance in growth and in most carcass traits, confirming its remarkable aptitude as a meat producer. However, finishing diet showed to improve Jaca Navarra features. A conventional diet showed a positive effect on the majority of variables studied in comparison with the other diet. Thus, breed and the type of finishing diet demonstrated a crucial role in the improvement and optimization of the majority of productive and carcass traits of these endangered equids.

Abstract

This research was conducted to study the effect of breed, Jaca Navarra (JN) vs. Burguete (BU), and finishing diet, conventional concentrate—diet 1 vs. silage and organic feed diet 2—on growth parameters and carcass characteristics from forty-six foals. Parameters as live weight (LW), average daily gain (ADG), body condition score (BCS), and fat depots were monitoring. In addition, the carcass parameters assessed were: carcass weight (CW), conformation, degree of fatness, morphology, and pH. Moreover, hindquarters of the left-half carcasses were sectioned in the main commercial primal cuts of leg. Results showed a clear “breed effect” in favor of BU foals, recording the highest productive values and carcass traits compared with JN foals. On the other hand, finishing diet contributed to improving the productive and carcass features of JN foals. In particular, diet 1 showed to affect positively the features analyzed compared with diet 2. Nevertheless, the meat primal cuts resulted in being unaffected by the breed and diet effects (except for knuckle), obtaining similar values among the groups of animals.

Changes in metabolic and physiological biomarkers in Mangalarga Marchador horses with induced obesity

This study aimed to characterize and correlate physiological and metabolic changes in horses fed a hypercaloric diet (HD). Nine mature horses with a mean initial body condition score of 2.9 ± 1 (scale, 1-9) were fed a high-calorie diet for 5 months. Fasting blood samples were collected before the study and biweekly for the duration of the project to determine the concentrations of cholesterol (CHOL), very low (VLDL), low (LDL) and high-density (HDL) lipoproteins, triglycerides, non-esterified fatty acids, and fructosamine. A low-dose oral glucose tolerance test (LGTT) was conducted before, 75 and 150 days after HD introduction. Mean arterial blood pressure was measured monthly. Following HD introduction, CHOL, LDL, HDL, and fructosamine blood concentrations increased (P < 0.001). These four variables were also positively and significantly correlated with the blood insulin response to LGTT. These findings confirm the occurrence of hypercholesterolemia concomitantly with insulin dysregulation development in horses exposed to HD.

Evaluation of the Accuracy of Horse Body Weight Estimation Methods

Simple Summary

Horse body weight estimation and monitoring of the weight variations are necessary to determine the amount of feed and feed additives for the proper functioning of the animal. Due to the cost and practical challenge of weighing horses on a large scale, several alternative methods for estimating the body weight of horses have been developed. One of them is to determine a horse’s body weight using a formula. The aim of the study was to evaluate established formulae for estimating horse body weight from data gathered using measurement tape. The investigation was conducted on a group of 299 adult horses of five breeds: ponies, Polish Noble Half Breed, Silesian Breed, Wielkopolski Breed and Thoroughbred. For each horse, body measurements were performed and the actual body weight of the horses was measured with an electronic scales. The horse’s body weight measurements were compared with the result of seven different formulae. It was found that the use of formulae for body weight estimation can be useful in determining feed dosages and additives, medicines, or deworming agents.

Abstract

Methods of estimating horse body weight using mathematical formulae have better accuracy than methods of reading body weight from measuring tape. The aim of the study was to evaluate established formulae for estimating horse body weight from data gathered using measurement tape. The research was conducted in a group of 299 adult horses and ponies of selected breeds: ponies (n = 58), Polish Noble Half Breed (n = 150), Silesian Breed (n = 23), Wielkopolski Breed (n = 52), and Thoroughbred (n = 16). Body measurements were performed on each horse using a measuring stick and tape. The actual body weight of the horses was measured with electronic scale. Statistical analysis was carried out separately for individual breeds of horses. In each of the research groups formulae were selected, the results of which were closest to the actual horse body weight readings. The use of formulae for body weight estimation can be useful in determining feed dosages and additives, medicines or deworming agents. Regular weight measurement is important for maintaining a healthy horse.

High or Low Body Fat Deposition in the Presence of a Normal Oral Sugar Test is Not Associated With Postthaw Semen Parameters in Stallions

This study compared the postthaw semen parameters of stallions with high and low body condition score (BCS) and evaluated associations between body morphometric parameters and postthaw semen parameters. Twenty stallions were split into Low BCS (BCS<7, n = 11) and High BCS (BCS ≥7, n = 9) groups, and underwent a complete morphometric analysis (e.g., neck scores and circumference, crest neck height, body weight, and height), and subcutaneous body fat thickness (SFT) at the tail head, withers, shoulders, and retroperitoneal space. A fasted oral sugar test (OST) was conducted on all stallions. One ejaculate from each stallion was frozen with a commercial egg yolk-based extender. Postthaw sperm motility parameters, plasma membrane integrity, mitochondrial membrane potential, hydrogen peroxide and intracellular superoxide production, and lipid peroxidation were analyzed for all stallions. The circumference at 25% and 50% of the neck's length were larger for High-BCS stallions (P < .05). There were no differences between groups for the neck crest height (P > .05). Stallions with High BCS had greater SFT at the tail head than stallions with Low BCS (P < .05); however, there were no differences between groups in the SFT at the shoulders and withers (P > .05). All stallions had resting blood glucose below the cutoff for equine metabolic syndrome. There were no differences between groups for resting glucose concentrations or for a peak at 30 or 60 minutes after initiation of the OST (P > .05). There were no differences in sperm parameters between groups (P > .05). Collectively, the findings of the present study suggest that High BCS or Low BCS in the presence of normal OST do not explain post-thaw semen parameters.

The influence of equine body weight gain on inflammatory cytokine expressions of adipose tissue in response to endotoxin challenge

Background

Human obesity is linked with systemic inflammation. However, it is still controversial if equines produce more inflammatory cytokines with increasing body weight and if the production of those show breed type specific patterns. The main objective of this study was to determine if diet induced obesity is associated with increased inflammatory signatures in adipose tissue of equines and if a breed predisposition exists between ponies and horses. Additionally, we aimed to identify adipose tissue depot differences in inflammatory cytokine expression. Nineteen healthy, non-overweight and metabolically healthy equines received a hypercaloric diet for 2 years. Body weight, body condition score and cresty neck score were assessed weekly throughout the study. At three time points, insulin sensitivity was determined by a combined glucose-insulin test. Adipose tissue samples were collected from two intra-abdominal and two subcutaneous depots under general anesthesia at each time point after an endotoxin trigger. In the adipose tissue samples levels of CD68 mRNA (a marker of macrophage infiltration) and pro-inflammatory cytokine mRNA (IL-1β, IL-6 and TNFα) were analyzed with RT-qPCR. As markers of lipid metabolism mRNA levels of lipoprotein lipase (LPL) and fatty acid binding protein 4 (FABP4) were determined with RT-qPCR.

Results

CD68 mRNA levels increased with body weight gain in several adipose tissue (AT) depots (Wilcoxon signed rank test with Bonferroni correction; retroperitoneal AT horses: P = 0.023, mesocolonial AT horses: P = 0.023, subcutaneous tail head AT ponies: P = 0.015). In both abdominal depots CD68 mRNA levels were higher than in subcutaneous adipose tissue depots (Kruskal–Wallis-ANOVA with Bonferroni correction: P < 0.05). No breed related differences were found. Pro-inflammatory cytokine mRNA IL-1β, IL-6 and TNFα levels were higher in subcutaneous depots compared to abdominal depots after body weight gain. IL-1β, IL-6 and TNFα mRNA levels of mesocolon adipose tissue were higher in obese horses compared to obese ponies (Mann–Whitney-U test; IL-1β: P = 0.006; IL-6: P = 0.003; TNFα: P = 0.049). In general, horses had higher FABP4 and LPL mRNA levels compared to ponies in neck AT and tail AT at all time points.

Conclusion

Our findings suggest an increased invasion of macrophages in intra-abdominal adipose tissue with increasing body weight gain in equines in combination with a low dose endotoxin stimulus. This might predispose equines to obesity related comorbidities. In obese horses mesocolon adipose tissue showed higher inflammatory cytokine expression compared to obese ponies. Additionally, subcutaneous adipose tissue expressed more pro-inflammatory cytokines compared to intra-abdominal adipose tissue. Horses had higher FABP4 and LPL mRNA levels in selected AT depots which may indicate a higher fat storage capacity than in ponies. The differences in lipid storage might be associated with a higher susceptibility to obesity-related comorbidities in ponies in comparison to horses.

Bee Pollen Supplementation to Aged Horses Influences Several Blood Parameters

In humans and animals, aging leads to a decrease in immune function and an increased susceptibility to infection. Decreased immunity and an increase in the incidence of infectious diseases are particularly notable during the autumn. Bee pollen supplementation improves immunity and antioxidant enzyme activity, as well as general performance. The aim of this study was to evaluate the effects of bee pollen supplementation during the autumn on blood parameters in aged horses. The study was performed on 16 warmblood horses aged 15-26 years. Half of this group received 60 g of bee pollen (soaked in water) daily for 30 days during the autumn season. Blood samples were taken from all horses before and after the supplementation period. Numerous hematological and plasma biochemical parameters including indicators of oxidative stress were determined. The data collected after the supplementation were compared with data collected before the experiment using one-way analysis of variance and paired Student's t-test. In the control group, there was a decline in the total number of red blood cells, hemoglobin, and hematocrit and an increase in some lipid parameters, urea, total plasma proteins, and sulfhydryl groups. Supplementation with bee pollen prevented the variation of these parameters, except for low-density lipoprotein cholesterol. We believe that bee pollen supplementation for aged horses during autumn has beneficial effects because it inhibited some of the adverse changes observed in the control horses during this season.

Adiposity and weight gain in Mangalarga Marchador horses subjected to hypercaloric diet

ABSTRACT: In recent years, several researchers have been studying obesity in national horse breeds; however, no studies demonstrating the dynamic of body and regional fat accumulation (adiposity) Mangalarga Marchador horses subjected to hypercaloric diets have been found. This study aimed to characterize the deposition of body and regional fat in horses with diet-induced weight gain. A total of nine Mangalarga Marchador adult horses with initial body condition score (BCS) of 2.9 ±1/9 (mean ±SD) were subjected to a hypercaloric, grain-rich diet for five months. Body weight and the following morphometric regional adiposity variables were analyzed: BCS, cresty neck scores (CNS), neck circumferences (NC) at 25, 50 and 75% of its length, and accumulation of subcutaneous adipose tissue at the base of the tail using ultrasonography (BTU). These data were collected at baseline and fortnightly after beginning the diet-induced weight gain until the end of the experiment. The effect of time on the variables was verified by analysis of variance (ANOVA) in randomized blocks or the Friedman’s test, and the means were compared by the Tukey’s test (p≤0.05). Exposure to hypercaloric diet promoted a mean weight gain of 27.45% (p<0.001). Significant values were observed for NC at 25 and 75% during the first 45 days of the experiment, and for NC at 50% during the first 30 days. BTU presented significant changes after 60 days, with an increase of 268% compared with the baseline value. These findings demonstrate the weight gain and the dynamic and magnitude of regional adiposity in Mangalarga Marchador horses subjected to hypercaloric diet.

Higher body mass index may increase the risk for the development of incisional complications in horses following emergency ventral midline celiotomy

BACKGROUND

Obesity is common in the equine population and it has been associated with increased surgical morbidity and mortality in humans. The effect of increased body mass index (BMI) on the incidence of surgical site infections has not been investigated in horses.

OBJECTIVES

To determine whether horses with increased body fat, as estimated by BMI, are more likely to develop post-operative complications, particularly incisional complications, following emergency ventral midline celiotomy.

STUDY DESIGN

Retrospective, multi-institutional clinical study.

METHODS

Medical records of horses >2 years old presenting with colic that underwent ventral midline celiotomy between January 2010 and September 2018 with follow-up of a minimum of 30 post-operative days were reviewed. Extracted data included signalment, operative details and outcome. BMI was calculated by dividing the patient's weight (kg) by the withers height squared (m² ).

RESULTS

In all, 287 horses fit inclusion criteria. Incisional complication prevalence was 23.7%. Horses with incisional complications had a higher BMI (median 203.6 kg/m² , IQR = 191.5-217.4) compared with those without (median 199.1 kg/m² , IQR = 184.7-210.2) (P = .03). Multi-variable analysis of the effects of age, sex, breed and presence of metabolic disease on the association between BMI and risk of incisional complications, identified a tendency towards increased risk with a higher BMI, but statistical significance decreased to P = .07. Breed had an association with BMI (P < .01), but not with incisional complication risk.

MAIN LIMITATIONS

BMI as an estimate of body fat has limitations. Retrospective studies with reliance on owners reporting data and complete medical records is imperfect. When the data were subjected to multi-variable analysis, the trend towards an increased incidence of incisional complications in horses with higher BMI persisted but it was not statistically significant.

CONCLUSION

Higher BMI may increase the risk for the development of incisional complications in horses following emergency ventral midline celiotomy.

Indicators of Horse Welfare: State-of-the-Art

Animal welfare is defined as a chronic state reflecting an individual's subjective perception of its situation. Because it is possible to be in a good welfare state and nevertheless experience acute fear or pain, and conversely, short-term positive emotions can be experienced during impaired welfare states, welfare as a chronic state has to be clearly distinguished from temporary states related to emotions, pain or stress. The evaluation of non-verbal individuals' welfare state, particularly in interspecific situations, is a real challenge that necessarily implies animal-based measures and requires multidisciplinary scientifically validated measures. In the last decade, studies investigating horses' welfare flourished together with new measures that were not always scientifically tested before being used. At a time were legal decisions are made on animal welfare, it is crucial to rely on reliable welfare indicators in order to prevent false evaluation. The aim of this review is to identify the scientifically tested and reliable indicators of horses' welfare (e.g., body lesions, apathy, aggressiveness, stereotypic behaviours) from signals of temporary states related to acute pain emotions or stress and from popular beliefs, in order to give the scientific community and the horse industry accurate evaluation tools.

Comparison of Two Diagnostic Methods to Detect Insulin Dysregulation in Horses Under Field Conditions

Straightforward testing procedures to enable the diagnosis of insulin dysregulation (ID) in horses that are suitable for use in daily veterinary practice are needed because of the risk that ID could result in laminitis. In our study (that included 90 horses), we compared the proportion of horses classified as ID-positive, ID-suspect, and ID-not diagnosed according to the basal insulin concentration (BIC) with the proportion of horses classified as ID-positive or ID-negative according to a practical and feasible version of an oral sugar test (OST). Furthermore, BIC, basal glucose concentration, and insulin and glucose concentration after OST were analyzed and compared. In the total study population, the OST detected significantly more ID-positive cases than the BIC, with cutoffs at equivalent specificities. Receiver operating characteristics analysis showed that at a lower cutoff, the sensitivity of the BIC could be increased, but at the cost of a significantly lower specificity. Taking this into account, we found diagnostic performance of the OST to be considerably better than the BIC and therefore considered it more recommendable for use as a screening test for ID in ambulatory practice. Furthermore, we investigated the relationship between body condition score and breed type with glucose and insulin concentration as determined after our version of the OST. For that purpose, the study group was subdivided into lean, moderate, and obese horses and "easy keeper breeds" versus "non-easy keeper breeds". Results supported the general assumption that obese horses and "easy keeper breeds" are more prone to the development of ID.

Influence of Metabolic Status and Diet on Early Pregnant Equine Histotroph Proteome: Preliminary Findings

Insulin resistance (IR) is characterized by an increase in biomarkers of systemic inflammation and susceptibility to laminitis in horses. Impacts on reproduction include a lengthened interovulatory period in horses. Dietary omega-3 (docosahexaenoic acid [DHA]) promotes anti-inflammatory processes, has been implicated in health benefits, and can reduce cytokine secretion. This preliminary study investigated the impact of IR as well as the influence of dietary supplementation (DHA) on the uterine fluid proteome in early pregnant horses. Mares were artificially inseminated; uterine fluid and embryos were collected on d 12.5 after ovulation. Uterine fluid was pooled for metabolic and diet categories (n = 8; n = 2 per metabolic and dietary status) and concentrated, and the proteome was analyzed using tandem mass spectrometry (iTRAQ). Five proteins met differential abundance criteria (±1.5-fold change, P < .05) in all comparisons (Control C, IS vs. C, IR; C, IS vs. DHA, IS; C, IR vs. DHA, IR). Serum amyloid A, afamin, and serotransferrin were upregulated in C, IR mares but downregulated in DHA, IR mares when compared to C, IS and C, IR, respectively. Quantitative PCR supported mass spectrometry results. The presence of serum amyloid A and serotransferrin in histotroph of IR mares potentially indicates an inflammatory response not seen in IS counterparts. These preliminary findings provide novel evidence on the potential impact of insulin resistance and DHA supplementation on the secreted equine uterine proteome during early pregnancy.

Effects of Epinephrine, Detomidine, and Butorphanol on Assessments of Insulin Sensitivity in Mares

Sympathoadrenal stimulation may perturb results of endocrine tests performed on fractious horses. Sedation may be beneficial; however, perturbation of results may preclude useful information. Four experiments were designed to 1) determine the effects of epinephrine on insulin response to glucose (IR2G), 2) assess the effects of detomidine (DET), alone or combined with butorphanol (DET/BUT), on IR2G and glucose response to insulin (GR2I), and 3) assess the effects of BUT alone on IR2G. In Experiment 1, mares were administered saline or epinephrine (5 μg/kg BW) immediately before infusion of glucose (100 mg/kg BW). Glucose stimulated (P < .05) insulin release in controls at 5 minutes that persisted through 30 minutes; insulin was suppressed (P < .05) by epinephrine from 5 to 15 minutes, rising gradually through 30 minutes. Experiments 2 (IR2G) and 3 (GR2I) were conducted as triplicated 3 × 3 Latin squares with the following treatments: saline (SAL), DET, and DET/BUT (all administered at .01 mg/kg BW). Glucose stimulated (P < .05) insulin release that persisted through 30 minutes in SAL mares; DET and DET/BUT severely suppressed (P < .0001) the IR2G. Sedation did not affect resting glucose and had inconsistent effects on the GR2I when mares were treated with 50 mIU/kg BW recombinant human insulin. Butorphanol had no effect on IR2G. In conclusion, adrenergic agonists severely suppress the IR2G and cannot be used for sedation for this test. The use of DET did not alter the GR2I, and therefore may be useful for conducting this test in fractious horses.

Relação espacial entre o estojo córneo e a falange distal em éguas Campolina adultas com e sem obesidade

RESUMO A laminite endocrinopática tem acometido um número crescente de equinos com sinais de obesidade. Em um estudo recente com fêmeas jovens (até cinco anos) da raça Campolina, demonstraram-se indícios de alterações no dígito, ainda discretas, aparentemente associadas ao aumento da adiposidade. Com a hipótese de que essa associação é mais evidente em animais em faixa etária superior, o objetivo do presente estudo foi estudar éguas adultas (acima de cinco anos) da raça Campolina com e sem obesidade, avaliando-se radiograficamente a relação espacial entre estojo córneo e falange distal. Foram utilizadas 27 éguas entre seis e 14 anos de idade, sendo analisadas variáveis de adiposidade e medidas radiográficas dos cascos dos membros torácicos de equinos com escore corporal de 5 a 7/9 (grupo controle) e de 8 a 9 (grupo obeso). Foram feitas comparações entre os grupos e correlacionaram-se as variáveis de adiposidade com variáveis casco. A distância de afundamento da falange distal foi cerca de 20% superior nas éguas obesas (12,3±2,5 contra 10,2±2,2mm no grupo controle). Esse parâmetro também correlacionou (P<0,01) com vários parâmetros de adiposidade, com destaque para o escore de condição corporal (r=0,47) e a circunferência de pescoço a 75% (r=0,42). Os resultados corroboram estudos prévios que demonstraram associação entre obesidade e indícios de separação entre falange distal e estojo córneo em equinos de raças nacionais, comprovando, assim, a utilidade da avaliação radiográfica nesses animais. Em conclusão, éguas da raça Campolina com obesidade possuem alterações evidentes na relação espacial entre estojo córneo e falange distal, que se intensificam com o aumento da idade e da adiposidade.

Evaluation of combined testing to simultaneously diagnose pituitary pars intermedia dysfunction and insulin dysregulation in horses

Background

The thyrotropin‐releasing hormone (TRH) stimulation test and the 2‐step insulin sensitivity test are commonly used methods to diagnose, respectively, pituitary pars intermedia dysfunction (PPID) and insulin dysregulation (ID).

Objectives

To investigate the diagnostic value of combining the TRH stimulation test and the 2‐step insulin sensitivity test to diagnose PPID and ID simultaneously.

Animals

Twenty‐seven adult horses, 10 control horses without PPID or ID, 5 horses with PPID only, 5 horses with ID only, and 7 horses with PPID and ID.

Methods

Randomized prospective study. Horses underwent a TRH stimulation test alone, a 2‐step insulin sensitivity test alone, and combined testing with simultaneous TRH and insulin injection in the same syringe. Data were compared by 2‐way repeated measures analysis of variance and 2 1‐sided tests to demonstrate equivalence. Bland‐Altman plots were generated to visualize agreement between combined and independent testing.

Results

The effect of combined testing on plasma adrenocorticotropic hormone, blood glucose concentration, or percentage decrease in blood glucose concentration was not significantly different from the effect obtained with independent testing. One control horse appeared falsely positive for PPID, 2 PPID‐only horses appeared falsely positive for ID, and 1 PPID and ID horse appeared falsely negative for ID when tests were performed simultaneously. Bland‐Altman plots supported the agreement between combined and independent testing.

Conclusions and Clinical Importance

Combining the TRH stimulation test and the 2‐step insulin sensitivity test appears to be a useful diagnostic tool for equine practitioners in the field, allowing testing of a horse for both PPID and ID simultaneously.

Lipidograma e sensibilidade à insulina em éguas Mangalarga Marchador

RESUMO A dislipidemia é um achado comum, porém não determinante, na síndrome metabólica equina (SME). O objetivo do presente trabalho foi caracterizar a dislipidemia em animais obesos com risco de SME. Para isso, 18 éguas foram alocadas em grupos, de acordo com escore corporal (EC) de 1 a 9: no grupo ideal, animais com EC de 4,5 a 5,5 (n= 6), no grupo sobrepeso, com EC de 6 a 7 (n= 6) e no grupo obeso, animais com EC de 7,5 a 9 (n= 6). Coletaram-se amostras de sangue em jejum de concentrado para determinação de triglicerídeos, colesterol total, glicemia e concentração de insulina. Valores preditivos de sensibilidade à insulina (RISQI) e de secreção β-pancreática (MIRG) foram calculados. O grupo obeso apresentou níveis maiores em relação aos outros grupos de triglicerídeos (P=0,001) e acima do ideal em concentrações de colesterol (P=0,012). Não foi observada diferença nas concentrações plasmáticas de glicose (P=0,53), de insulina (P=0,10) ou de RISQI (P=0,46). Houve diferença entre os grupos nos valores de MIRG (P=0,048), tendo o grupo obeso obtido resultados maiores quando comparado com o grupo ideal. O aumento do EC foi associado ao aumento das concentrações plasmáticas de colesterol e triglicerídeos, o que caracteriza um estado de dislipidemia e de elevação da secreção das células β-pancreáticas.

Plasma Apelin Concentration in Exercised Horses: Preliminary Study

Physical effort is one of the key aspects of keeping horses in good condition. The condition of the animal is reflected by multiple blood parameters. The newly discovered cytokine-apelin can pose one of them, however, so far, has not been studied in the horse population. Apelin is produced by adipocytes and myocytes and plays an important role in the energy metabolism of the body through the influence, for example, on the process of adipogenesis and lipolysis. The aim of this study was to investigate if physical effort of various intensity affects the plasma concentration of apelin in horses. The study involved 20 purebred Arabian horses divided into two groups. The first group included 10 race horses, aged 3 years, and second group included 10 horses aged from 6 to 12 years, used in endurance rides. Blood samples were collected from each horse at rest and after exercise. The concentrations of apelin, lactic acid, cortisol, uric acid (UA), triacylglycerols, total plasma protein, and glucose were determined in plasma samples. Race training sessions induced significant decreases in plasma apelin concentrations (P < .05). In endurance horses, significant correlations were found only between exercise-induced changes of apelin and cortisol (r = 0.55) and apelin and UA (r = 0.67) concentrations. In conclusion, the concentration of apelin in equine plasma decreases in response to short-time exercise unlike endurance exercise. Blood plasma apelin concentration determined at rest is lower in long-time regularly trained horses than in the ones at the beginning of their training process.

Influence of Exercise, Age, Body weight, and Growth on the Development of Tarsal Osteoarthritis in Young Mangalarga Marchador Horses

In this study, the effect of early exercise, age, body weight (BW), and growth on the articular cartilage and subchondral bones of the tarsocrural joints was evaluated in 40 young Mangalarga Marchador horses allowed free choice exercise in pasture. Twenty of the horses had additional controlled exercise 3 days per week from a mean age of 30 ± 20 days until 36 months. The training program consisted of an increasing number of 15-minute gallop sprints in an oval paddock with a concrete floor covered by a thick layer of sand. BW, withers height (WH), and neck circumference were measured and body condition scores, cresty neck scores, and obesity index were rated. For each tarsus and foal, 5 standard radiographic projections were evaluated. All evaluations were performed at time point 1 (18 months of age) and time point 2 (36 months of age). Radiographic changes suggestive of tarsal osteoarthritis were observed in two male foals of the trained group at time point 2 (10% of 20). No horses from the untrained group developed OA. Training of the foals did not result in alterations of the morphometric parameters evaluated. However, significant differences were found between time point 1 and 2 in trained and untrained animals. At time point 2, the animals presented greater weights and WHs than at time point 1. We conclude that specific levels of physical activity during initial development do not increase the prevalence of osteoarthritic injury in Mangalarga Marchador foals.

Novel lipoprotein density profiling in laminitic, obese, and healthy horses

Lipoproteins are water-miscible macromolecules enabling the transport of lipids in blood. In humans, altered proportions of lipoproteins are used to detect and classify metabolic diseases. Obesity and obesity-related comorbidities are common in horses. The pathophysiology of obesity is poorly understood and likely multifactorial. Development of new diagnostic tests to identify horses at risk of developing obesity to implement preventative measures is critical; however, a necessary first step to accomplish this goal is to improve our understanding of the pathophysiology of disease. Thus, the objective of this study was to characterize and compare lipoprotein profiles of horses with normal and excess body conditions, with and without laminitis using a novel method of continuous lipoprotein density profiling (CLPDP). Comparisons were made between 4 groups of horses: (1) laminitic, obese horses (n = 66); (2) laminitic, nonobese horses (n = 35); (3) nonlaminitic, obese horses (n = 41); and (4) nonlaminitic, nonobese horses (n = 95). Lipoprotein profiling, including evaluation of triglyceride-rich lipoprotein (TRL), low-density lipoproteins (LDLs), and high-density lipoproteins (HDLs) was performed using CLPDP, and all 4 groups were compared. A significant difference was observed among groups for the subfractions TRL, LDL1, LDL2, HDL2b, HDL2a, HDL3a, HDL3b, HDL3c, and total HDL. This is the first known description of CLPDP to characterize equine lipid profiles and holds promise as a useful method for lipid characterization of horses.

Effects of body weight gain on insulin and lipid metabolism in equines

The objective of this study was to illuminate the changes in serum NEFA concentrations during a combined glucose-insulin test (CGIT) and basal serum triacylglycerides (TGs) with increasing BW in Shetland ponies and warmblood horses. Therefore, basal blood samples were taken during fasting and a CGIT was performed in 19 healthy equines (10 Shetland ponies, 9 warmblood horses) (t0). After one (t1) and two (t2) year(s) of receiving 200% of their maintenance metabolizable energy requirement, procedures were repeated in the same equines. Sixteen of 19 equines had no signs of insulin dysregulation confirmed by CGIT. Basal plasma glucose concentrations increased in ponies (P = 0.001) when comparing t0 and t2, and basal serum insulin concentrations increased in ponies (P = 0.009) and horses (P = 0.024) from t0 to t2. Basal serum NEFA concentrations increased in ponies comparing t0 and t2 (P = 0.01). During CGIT, NEFA levels dropped until reaching a nadir and subsequently recovered until reaching basal concentrations. The minimum serum NEFA value did not change over time in ponies or horses. However, a strong correlation between basal serum NEFA concentrations and the percentage drop to minimum NEFA levels was found in ponies. Two of three equines (one horse and one pony) graded as insulin-dysregulated suffered from laminitis at t2. The serum NEFA concentrations of these animals had a delay in recovery of the minimum NEFA levels. Basal serum TG levels did not change with BW gain, and no breed differences were observed. In conclusion, serum NEFA concentrations are useful parameters during CGIT to detect insulin dysregulation in equines. Thus, further investigation should be focused on lipid metabolism during insulin dysregulation.

Are There Shared Mechanisms in the Pathophysiology of Different Clinical Forms of Laminitis and What Are the Implications for Prevention and Treatment?

Laminitis is a consequence of primary disease processes elsewhere in the body. The key pathophysiologic events are insulin dysregulation in endocrinopathic laminitis, ischemia in supporting limb laminitis, and inflammation in sepsis-related laminitis. These apparently disparate mechanisms converge to cause lamellar attachment failure through epithelial cell adhesion loss and stretch, possibly mediated by common growth factor signaling pathways. Tissue damage through mechanical distraction, inflammation, pain, and a proliferative epithelial healing response are features of acute laminitis regardless of the cause. Preventive and treatment strategies based on knowledge of these unique and common mechanistic events are likely to improve clinical outcomes.

Effects of Diet Versus Exercise on Morphometric Measurements, Blood Hormone Concentrations, and Oral Sugar Test Response in Obese Horses

Weight loss plans in horses typically use dietary restriction, but exercise may have additional benefits. This study aimed to compare the effects of a diet or exercise protocol resulting in comparable caloric restriction in obese horses. Ten obese horses were paired according to sex, age, and breed or breed type. One horse from each pair was randomly assigned to either diet (DIET)-intake restricted to approximately 85% of digestible energy requirements or exercise (EX)-exercised to expend approximately 15% of digestible energy requirements, resulting in 85% of requirements available, for 4 weeks. Body weight (BW), heart girth (HG), girth-to-height ratio (G:H), neck circumference (NC), neck circumference-to-height ratio (NC:H), belly girth (BG), body condition score (BCS), cresty neck score (CNS), serum insulin, plasma leptin, and plasma ghrelin concentrations were measured weekly. An oral sugar test was conducted on days 0 and 28 to measure insulin to glucose ratio (Ins:glc) and 60-minute insulin sensitivity index (ISI₆₀). Results were analyzed using repeated measures. A P ≤ .05 was considered significant, and .05 <P ≤ .10 was considered a tendency. Both groups showed similar decreases over time in BW, HG, G:H, BG, BCS, and CNS, but the EX group showed significantly greater losses in NC (and NC:H). The EX group showed significant improvements in (log) Ins:glc, as well as a tendency for improvements in (log) ISI₆₀ and plasma leptin concentrations, while the DIET group showed no change. Horses showed no changes in (log) plasma ghrelin with weight loss.

Associations between endocrine disrupting chemicals and equine metabolic syndrome phenotypes

Equine Metabolic Syndrome (EMS) is characterized by abnormalities in insulin regulation, increased adiposity and laminitis, and has several similarities to human metabolic syndrome. A large amount of environmental variability in the EMS phenotype is not explained by commonly measured factors (diet, exercise, and season), suggesting that other environmental factors play a role in EMS development. Endocrine disrupting chemicals (EDCs) are associated with metabolic syndrome and other endocrine abnormalities in humans. This led us to hypothesize that EDCs are detectable in horse plasma and play a role in the pathophysiology of EMS. EDCs acting through the aryl hydrocarbon and estrogen receptors, were measured in plasma of 301 horses from 32 farms. The median (range) TEQ (2,3,7,8-TCDD equivalent) and EEQ (17β-estradiol equivalent) were 19.29 pg/g (0.59-536.36) and 10.50 pg/ml (4.35-15000.00), respectively. TEQ was negatively associated with plasma fat extracted and batch analyzed. EEQ was positively associated with pregnancy and batch analyzed, and negatively associated with being male and superfund score ≤100 miles of the farm. Of particular interest, serum glucose and insulin, glucose and insulin post oral sugar challenge, and leptin concentrations were associated with EEQ, and serum triglyceride concentration was associated with TEQ. Overall, we demonstrated that EDCs are present in the plasma of horses and may explain some of the environmental variability in measured EMS phenotypes. This is the first example of EDCs being associated with clinical disease phenotype components in domestic animals.

Insulin Resistance as a Result of Body Condition Categorized as Thin, Moderate, and Obese in Domesticated U.S. Donkeys (Equus asinus)

Donkeys are often kept, especially in industrialized countries, as companion animals. Donkeys have greater digestive efficiency and tend to expend less energy than horses or ponies, which contributes to obesity in nonworking donkeys. Obesity in all equine species increases risk of chronic health conditions such as laminitis and insulin resistance. Previous studies in horses and ponies have documented obesity's potential effects on glucose-insulin dynamics with lower insulin sensitivity and higher insulin responses to glucose. However, limited studies on obesity and its health impacts in donkeys exist, so these effects on glucose-insulin dynamics have not been fully studied. Twenty-four donkeys were selected according to initial body condition score (BCS) and divided into three categories with eight donkeys in each: thin, moderate, and obese. A frequently sampled glucose-insulin tolerance test was performed with subsequent MINMOD analysis to determine the effects of BCS on glucose-insulin dynamics. Basal insulin was highest in obese donkeys when compared with moderate and thin donkeys (P = .02 and P = .01, respectively). There was an overall trend across groups for BCS to lower insulin sensitivity (P = .06). No other effect was found. Body condition score seems to affect donkeys in a similar manner to horses and ponies as higher BCS was associated with higher basal insulin and may lower insulin sensitivity. Higher basal insulin concentrations in obese donkeys could negatively influence health and contribute to serious, chronic conditions.

ECEIM consensus statement on equine metabolic syndrome

Equine metabolic syndrome (EMS) is a widely recognized collection of risk factors for endocrinopathic laminitis. The most important of these risk factors is insulin dysregulation (ID). Clinicians and horse owners must recognize the presence of these risk factors so that they can be targeted and controlled to reduce the risk of laminitis attacks. Diagnosis of EMS is based partly on the horse's history and clinical examination findings, and partly on laboratory testing. Several choices of test exist which examine different facets of ID and other related metabolic disturbances. EMS is controlled mainly by dietary strategies and exercise programs that aim to improve insulin regulation and decrease obesity where present. In some cases, pharmacologic aids might be useful. Management of an EMS case is a long‐term strategy requiring diligence and discipline by the horse's carer and support and guidance from their veterinarians.

Body condition and adrenal glucocorticoid activity affects metabolic marker and lipid profiles in captive female elephants in Thailand

Studies in western zoo elephants have found relationships between body condition and physiological function, and identified mitigating management strategies to optimize health and welfare. A similar methodological approach was used in this study, which evaluated a body condition score (BCS; 1 = thinnest, 5 = fattest) every other month and fecal glucocorticoid metabolite (FGM) concentrations twice monthly in 33 tourist camp elephants in Thailand for a 1-year period to assess seasonal variations, and determine how lipid profiles [total cholesterol (TC), low density lipoproteins (LDL), high density lipoproteins (HDL), triglycerides (TG)] and metabolic parameters [insulin, glucose, fructosamine, glucose to insulin ratio (G:I)] related to measures of body condition and adrenal function. The most prevalent BCS was 3-3.5 (60.6%), with 27.3% at BCS = 4 (overweight) and 12.1% at BCS = 4.5-5 (very overweight); no elephants had a BCS <2. BCSs were higher in rainy and winter seasons compared to summer, with FGM, TG, HDL, LDL, and insulin also higher in the rainy and/or winter seasons (p<0.05). By contrast, TC and glucose were lowest in the rainy season. FGM measures were negatively associated with two environmental factors: temperature and rainfall, but not humidity. Positive correlations were found between BCS and TC, LDL, and HDL, and between FGM and TC, HDL, glucose, and insulin (p<0.05), whereas BCS and FGM were both negatively associated with the G:I (p<0.05). However, there was no relationship between BCS and FGM among the camp elephants. Using BCS and FGM measures as outcome variables in separate regression models, this study found high BCS and elevated FGM concentrations were associated with altered lipid profiles and metabolic status in elephants. Furthermore, more work hours/day was associated with better body condition and health measures. Thus, being overweight and exposed to factors that increase adrenal activity could adversely affect health status, requiring alterations in management for some individuals, whereas exercise appears to have a protective effect.

Microbiome and Blood Analyte Differences Point to Community and Metabolic Signatures in Lean and Obese Horses

Due to modern management practices and the availability of energy dense feeds, obesity is a serious and increasingly common health problem for horses. Equine obesity is linked to insulin resistance and exacerbation of inflammatory issues such as osteoarthritis and laminitis. While the gut microbiome is thought to play a part in metabolic status in horses, bacterial communities associated with obesity have yet to be described. Here we report differences in metabolic factors in the blood of obese, normal and lean horses correlated with differences in gut microbiome composition. We report that obese horses had higher levels of leptin, triglycerides, glucose, and cortisol in their blood, and more diverse gut microbiome communities with higher relative abundance of Firmicutes, and lower numbers of Bacteroidetes and Actinobacteria. Network analyses of correlations between body condition, blood analytes, and microbial composition at the genus level revealed a more nuanced picture of microbe-host interactions, pointing to specific bacterial species and assemblages that may be signatures of obesity and leanness in the horse gut. In particular, bacteria groups positively associated with two blood analytes and obesity included Butyrivibrio spp., Prevotellaceae, Blautia spp., two members of Erysipelotrichaceae, and a Lachnospiraceae taxa. These results are an important first step in unraveling the metabolic differences between obese and lean horse gut communities, and designing targeted strategies for microbial intervention.

Use of principle component analysis to quantitatively score the equine metabolic syndrome phenotype in an Arabian horse population

Equine metabolic syndrome (EMS), like human metabolic syndrome, comprises a collection of clinical signs related to obesity, insulin dysregulation and susceptibility to secondary inflammatory disease. Although the secondary conditions resulting from EMS can be life-threatening, diagnosis is not straightforward and often complicated by the presence of other concurrent conditions like pituitary pars intermedia dysfunction (PPID). In order to better characterize EMS, we sought to describe the variation within, and correlations between, typical physical and endocrine parameters for EMS. Utilizing an unsupervised statistical approach, we evaluated a population of Arabian horses using a physical examination including body measurements, as well as blood plasma insulin, leptin, ACTH, glucose, and lipid values. We investigated the relationships among these variables using principle component analysis (PCA), hierarchical clustering, and linear regression. Owner-assigned assessments of body condition were one full score (on a nine-point scale) lower than scores assigned by researchers, indicating differing perception of healthy equine body weight. Rotated PCA defined two factor scores explaining a total of 46.3% of variation within the dataset. Hierarchical clustering using these two factors revealed three groups corresponding well to traditional diagnostic categories of "Healthy", "PPID-suspect", and "EMS-suspect" based on the characteristics of each group. Proxies estimating up to 93.4% of the composite "EMS-suspect" and "PPID-suspect" scores were created using a reduced set of commonly used diagnostic variables, to facilitate application of these quantitative scores to horses of the Arabian breed in the field. Use of breed-specific, comprehensive physical and endocrinological variables combined in a single quantitative score may improve detection of horses at-risk for developing EMS, particularly in those lacking severe clinical signs. Quantification of EMS without the use of predetermined reference ranges provides an advantageous approach for future studies utilizing genomic or metabolomics approaches to improve understanding of the etiology behind this troubling condition.

Evaluation of glucose and insulin response to haylage diets with different content of nonstructural carbohydrates in 2 breeds of horses

Information about the effect of nonstructural carbohydrates (NSCs) in forage on the postprandial glucose and insulin response in horses is scarce. This is of interest as postprandial hyperinsulinemia in horses is a risk factor for laminitis. In addition, insulin sensitivity (IS) differs between breeds. The aim was to evaluate the postprandial glucose and insulin response to haylage diets with different NSC content in horses of 2 different breeds and to evaluate the relationship between the postprandial insulin response and measures of IS derived from a frequently sampled intravenous glucose tolerance test (FSIGTT). Standardbreds (n = 9) and Icelandic horses (n = 9) with a mean body condition score of 5.5 ± 0.6 (scale 1-9) were studied. Horses were clinically healthy at the start of the study and had no history of endocrinopathic laminitis. The experiment was conducted as a replicate 3 × 3 Latin square, in which horses were fed haylage diets with low (4.2%), medium (13.6%), and high (18.2%) NSC content of dry matter. Blood sampling was performed before feeding and every 30 min until 300 min after feeding. An FSIGTT was also performed in all horses. The early (first 60 min) and the total (300 min) postprandial glucose and insulin response (area under the curve [AUC]) was higher after a meal of both medium and high NSC haylage in comparison with low NSC haylage when both breeds were combined (P ≤ 0.02). There was a main effect of breed for the early (P ≤ 0.004) but not for the total (P > 0.12) postprandial glucose and insulin response. The IS index was comparable between breeds (P = 0.75). The natural logarithm of the peak concentration, the AUC for the first 60 min and the total AUC for insulin, after a meal of medium and high NSC haylage, were moderately negatively correlated (P < 0.02; r = -0.55 to -0.72) with the natural logarithm of IS index from the FSIGTT. This relationship was not evident for haylage with low NSC content (P > 0.054). This study demonstrates that the postprandial insulin response is affected by both the NSC content of haylage and the horse's IS. However, the impact of IS was diminished when the NSC content in haylage was low (4.2% of dry matter).