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Laminitis is a common and painful condition of the equine foot and approximately 90% of cases are associated with insulin dysregulation (ID) that is a central feature of the common endocrine disorder equine metabolic syndrome (EMS) and occurs in a subset of animals with pituitary pars intermedia dysfunction. Additional features of EMS include obesity, altered circulating concentrations of adipokines (particularly adiponectin and leptin) and hypertriglyceridaemia. Obesity, ID, hypoadiponectinaemia, hyperleptinaemia and an altered plasma lipid profile are also features of human metabolic syndrome (HMS) alongside hyperglycaemia. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are a novel class of oral hypoglycaemic agents used in combination with lifestyle changes in the management of HMS. SGLT2 receptors are responsible for 90% of the renal glucose reabsorption that occurs in the proximal convoluted tubule. Thus, these drugs increase urinary glucose excretion by suppressing glucose reabsorption from the glomerular filtrate resulting in urinary calorie loss with consequent weight loss and improvements in ID, hyperglycemia, hypoadiponectinaemia and hyperleptinaemia. There are no licenced veterinary drugs available for treating ID and preventing insulin-associated laminitis in horses. Thus, the use of SGLT2i for the control of equine hyperinsulinaemia with the goal of improving recovery from associated active laminitis or preventing future laminitis has recently been advocated. There are a small number of published studies reporting the use of the SGLT2i canagliflozin, ertugliflozin and velagliflozin to aid the management of equine ID. However, the doses used are largely extrapolated from human studies with limited consideration of species-specific variations. In addition, there is limited evaluation of the fundamental differences between ID in horses and humans, particularly the fact that most horses with ID remain hyperinsulinaemic but normoglycaemic such that increased urinary loss of glucose may not explain the beneficial effects of these drugs. Further study of the potential deleterious effects of treatment-associated hypertriglyceridaemia is required together with the effect of SGLT2i therapy on circulating concentrations of adipokines in horses., (© 2024 The Author(s). Journal of Veterinary Pharmacology and Therapeutics published by John Wiley & Sons Ltd.)

Background: Pituitary pars intermedia dysfunction (PPID) is a prevalent, age-related chronic disorder in equids. Diagnosis of PPID can be challenging because of its broad spectrum of clinical presentations and disparate published diagnostic criteria, and there are limited available treatment options., Objectives: To develop evidence-based primary care guidelines for the diagnosis and treatment of equine PPID based on the available literature., Study Design: Evidence-based clinical guideline using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework., Methods: Research questions were proposed by a panel of veterinarians and developed into PICO or another structured format. VetSRev and Veterinary Evidence were searched for evidence summaries, and systematic searches of the NCBI PubMed and CAB Direct databases were conducted using keyword searches in July 2022 and updated in January 2023. The evidence was evaluated using the GRADE framework., Results and Recommendations: The research questions were categorised into four areas: (A) Case selection for diagnostic testing, pre-test probability and diagnostic test accuracy, (B) interpretation of test results, (C) pharmacological treatments and other treatment/management options and (D) monitoring treated cases. Relevant veterinary publications were identified and assessed using the GRADE criteria. The results were developed into recommendations: (A) Case selection for diagnostic testing and diagnostic test accuracy: (i) The prevalence of PPID in equids aged ≥15 years is between 21% and 27%; (ii) hypertrichosis or delayed/incomplete hair coat shedding provides a high index of clinical suspicion for PPID; (iii) the combination of clinical signs and age informs the index of clinical suspicion prior to diagnostic testing; (iv) estimated pre-test probability of PPID should be considered in interpretation of diagnostic test results; (v) pre-test probability of PPID is low in equids aged <10 years; (vi) both pre-test probability of disease and season of testing have strong influence on the ability to diagnose PPID using basal adrenocorticotropic hormone (ACTH) or ACTH after thyrotropin-releasing hormone (TRH) stimulation. The overall diagnostic accuracy of basal ACTH concentrations for diagnosing PPID ranged between 88% and 92% in the autumn and 70% and 86% in the non-autumn, depending on the pre-test probability. Based on a single study, the overall diagnostic accuracy of ACTH concentrations in response to TRH after 30 minutes for diagnosing PPID ranged between 92% and 98% in the autumn and 90% and 94% in the non-autumn, depending on the pre-test probability. Thus, it should be remembered that the risk of a false positive result increases in situations where there is a low pre-test probability, which could mean that treatment is initiated for PPID without checking for a more likely alternative diagnosis. This could compromise horse welfare due to the commencement of lifelong therapy and/or failing to identify and treat an alternative potentially life-threatening condition. (B) Interpretation of diagnostic tests: (i) There is a significant effect of breed on plasma ACTH concentration, particularly in the autumn with markedly higher ACTH concentrations in some but not all 'thrifty' breeds; (ii) basal and/or post-TRH ACTH concentrations may also be affected by latitude/location, diet/feeding, coat colour, critical illness and trailer transport; (iii) mild pain is unlikely to have a large effect on basal ACTH, but caution may be required for more severe pain; (iv) determining diagnostic thresholds that allow for all possible contributory factors is not practical; therefore, the use of equivocal ranges is supported; (v) dynamic insulin testing and TRH stimulation testing may be combined, but TRH stimulation testing should not immediately follow an oral sugar test; (vi) equids with PPID and hyperinsulinaemia appear to be at higher risk of laminitis, but ACTH is not an independent predictor of laminitis risk. (C) Pharmacologic treatments and other treatment/management options: (i) Pergolide improves most clinical signs associated with PPID in the majority of affected animals; (ii) Pergolide treatment lowers basal ACTH concentrations and improves the ACTH response to TRH in many animals, but measures of insulin dysregulation (ID) are not altered in most cases; (iii) chasteberry has no effect on ACTH concentrations and there is no benefit to adding chasteberry to pergolide therapy; (iv) combination of cyproheptadine with pergolide is not superior to pergolide alone; (v) there is no evidence that pergolide has adverse cardiac effects in horses; (vi) Pergolide does not affect insulin sensitivity. (D) Monitoring pergolide-treated cases: (i) Hormone assays provide a crude indication of pituitary control in response to pergolide therapy, however it is unknown whether monitoring of ACTH concentrations and titrating of pergolide doses accordingly is associated with improved endocrinological or clinical outcome; (ii) it is unknown whether monitoring the ACTH response to TRH or clinical signs is associated with an improved outcome; (iii) there is very weak evidence to suggest that increasing pergolide dose in autumn months may be beneficial; (iv) there is little advantage in waiting for more than a month to perform follow-up endocrine testing following initiation of pergolide therapy; there may be merit in performing repeat tests sooner; (v) timing of sampling in relation to pergolide dosing does not confound measurement of ACTH concentration; (vi) there is no evidence that making changes after interpretation of ACTH concentrations measured at certain times of the year is associated with improved outcomes; (vii) evidence is very limited, however, compliance with PPID treatment appears to be poor and it is unclear whether this influences clinical outcome; (viii) evidence is very limited, but horses with clinical signs of PPID are likely to shed more nematode eggs than horses without clinical signs of PPID; it is unclear whether this results in an increased risk of parasitic disease or whether there is a need for more frequent assessment of faecal worm egg counts., Main Limitations: Limited relevant publications in the veterinary scientific literature., Conclusions: These findings should be used to inform decision-making in equine primary care practice., (© 2023 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

Background: There is a high prevalence of obesity in ponies and pleasure horses. This may be associated with equine metabolic syndrome and an increased risk of laminitis. Body condition scoring (BCS) systems are widely used but are subjective and not very sensitive., Objectives: To derive a body condition index (BCI), based on objective morphometric measurements, that correlates with % body fat., Study Design: Retrospective cohort study., Methods: Morphometric measurements were obtained from 21 ponies and horses in obese and moderate body condition. Percentage body fat was determined using the deuterium dilution method and the BCI was derived to give the optimal correlation with body fat, applying appropriate weightings. The index was then validated by assessing inter-observer variation and correlation with % body fat in a separate population of Welsh ponies; and finally, the correlation between BCI and BCS was evaluated in larger populations from studies undertaken in Australia, the United Kingdom and the United States., Results: The BCI correlated well with adiposity in the ponies and horses, giving a Pearson r value of 0.74 (P < 0.001); however, it was found to slightly overestimate the % body fat in leaner animals and underestimate in more obese animals. In field studies, the correlation between BCI and BCS varied particularly in Shetlands and miniature ponies, presumably due to differences in body shape., Main Limitations: Further work may be required to adapt the BCI to a method that is more applicable for Shetlands and miniature ponies., Conclusions: This BCI was able to provide an index of adiposity which compared favourably with condition scoring in terms of accuracy of estimating adiposity; and was more consistent and repeatable when used by inexperienced assessors. Therefore, this may be a useful tool for assessing adiposity; and may be more sensitive than condition scoring for tracking weight gain or weight loss in individual animals., (© 2023 Mars Horsecare UK Ltd and The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

Background: Serum insulin concentration at 60 min (InsulinT60) during an oral sugar test (OST) indicates future laminitis risk and insulin dysregulation (ID). Associations between InsulinT60 and physical and owner-reported variables may help clinicians select individuals for ID testing. Associations between InsulinT60 and other metabolic markers may help elucidate ID pathophysiology., Objectives: To describe associations between (A) season, physically-apparent and owner-reported factors and binary InsulinT60 interpretation (initial models) and (B) variables included in the initial models, other metabolic markers and continuous InsulinT60 (full models)., Study Design: Prospective longitudinal., Methods: Non-laminitic ponies were examined and OSTs (0.3 mL/kg Karo syrup) performed every 6 months (autumn and spring) for ≤4 years. Factors associated with InsulinT60 were determined using mixed-effects models with physical, owner-reported, season and serum/plasma markers as fixed effects and pony and premises identifiers as random effects. Autumn and spring data were analysed separately for full models., Results: One thousand seven hundred and sixty-three OSTs from 367 ponies were included. High-risk InsulinT60 (>153 μIU/mL) was independently associated with (odds ratio, 95% confidence interval [CI]): age (1.36, 1.16-1.60), body condition score (BCS) (2.38, 1.21-4.69), and bulging supraorbital fatpads (7.25, 2.1-24.98). However, the initial models provided little explanatory power (Nakagawa R 2  = 0.1-0.27). LoginsulinT60 was independently associated with (effect estimate, 95% CI): age (0.02, 0.01-0.04), Welsh/Welsh X breed (0.22, 0.05, 0.39), sex (gelding = -0.2, -0.34 to 0.06), BCS (0.16, 0.08-0.23), plasma adiponectin (-0.02, -0.02 to 0.01) and basal insulin (0.01, 0.01-0.01) in spring, and: age (0.03, 0.02-0.04), BCS (0.17, 0.08-0.26), bulging supraorbital fatpads (0.37, 0.2-0.54), turnout score (0.05, 0.02-0.09), plasma adiponectin (-0.01, -0.02 to 0.01), ACTH (per 10 pg/mL) (0.01, 0.00-0.01), triglycerides (0.28, 0.07-0.49) and InsulinT0 (0.01, 0.01-0.01) in autumn., Main Limitations: Only non-laminitic ponies in one region were included., Conclusions: Owner-reported and physically-apparent data were limited InsulinT60 predictors. InsulinT60 is a complex trait, independently associated with numerous variables, some with seasonal interactions., (© 2023 Mars Horsecare and The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

A chemiluminescent immunoassay is commonly employed to measure adrenocorticotrophic hormone (ACTH) concentrations to assist pituitary pars intermedia dysfunction diagnosis. In a previous study, seasonally-dependent assay cross-reactivity to endogenous equine corticotropin-like intermediate lobe peptide (CLIP, ACTH 18-39) was suspected. The present study aimed to demonstrate binding of endogenous equine CLIP to the capture antibody of the ACTH chemiluminescent immunoassay. Liquid chromatography - mass spectrometry (LCMS) methods were optimised to identify selected ions from synthetic human ACTH, α-melanocyte stimulating hormone (α-MSH, ACTH 1-17) and CLIP. Synthetic ACTH and CLIP bound to the capture antibody of the chemiluminescent ACTH assay, but α-MSH did not. Equine endogenous CLIP was detected by LCMS in pony plasma taken in the autumn and could be eluted from the capture antibody of the ACTH chemiluminescent immunoassay. Further research is required to enable quantification of CLIP. Equine CLIP may alter measured ACTH concentrations in vivo., (Copyright © 2023. Published by Elsevier Inc.)

Background: Quantifying risk factors for laminitis development requires improvement., Objectives: To identify the most useful physical examination, metabolic and management factors to predict laminitis development in client-owned, nonlaminitic ponies., Study Design: Prospective cohort study., Methods: Physical examination, metabolic and management data were collected from a pony cohort 6 monthly for up to 4 years. Ponies were monitored for the development of laminitis. Metabolic data included basal plasma concentrations of ACTH ([ACTH]), adiponectin ([adiponectin]), triglycerides and glucose. Serum insulin concentrations ([insulin]) were measured in the unfasted basal state ([insulin]T0) and 60 minutes ([insulin]T60) after administration of corn syrup (0.3ml/kg). Separate multivariable Cox proportional-hazards models were developed for physical, management/signalment and metabolic data and later combined into two final models. Low-, medium- and high-laminitis risk categories were defined based on basal or T60 [insulin]., Results: Overall, 374 ponies (age 5-32 years) and 891 pony-years were included in the main analysis. Laminitis incidence (95% confidence interval (CI)) was 4.8 (3.5-6.5) cases/100 pony-years. Laminitis development was associated with numerous univariable factors. Significant (P < .05) factors retained in the final multivariable models included [insulin]T0, [insulin]T60, [adiponectin] and divergent hoof growth. [ACTH] was not independently associated with laminitis. Based on [Insulin]T0, low- (<21.6 µIU/ml), medium- (21.6-45.2 µIU/ml) and high-risk (>45.2 µIU/ml) categories encompassed 70, 20 and 10% of the population and had estimated 4-year laminitis incidences (95%CI) of 6 (2-9)%, 22 (10-33)% and 69 (48-82)% respectively. Based on [Insulin]T60 the low- (<53.4 µIU/ml), medium- (53.4-153 µIU/ml) and high-risk (≥153 µIU/ml) categories comprised 60, 30 and 10% of the population and had estimated 4-year laminitis incidences (95%CI) of 3 (0-6)%, 20 (10-29)% and 73 (52-84)% respectively., Main Limitations: Results may not apply to different insulin assays, geographical regions, breeds or management types., Conclusions: [Insulin]T0 or [insulin]T60 best quantify the risk of future laminitis development in nonlaminitic ponies., (© 2022 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

Background: Blood l-lactate concentrations are higher in people with developing or established diabetes mellitus and insulin resistance., Objectives: To investigate whether blood l-lactate concentrations are positively correlated with measures of insulin dysregulation (ID) or increased autumnal ACTH concentrations in ponies., Animals: Systemically healthy client-owned ponies (n = 101)., Methods: Prospective case-control study. Blood samples were obtained from 101 clinically healthy ponies. Breed, weight, height, and subjective and objective measures of body condition were recorded. Blood l-lactate, glucose, triglyceride, total adiponectin, and ACTH concentrations were measured and an oral sugar test (OST) was carried out. Correlations between blood l-lactate and variables of endocrine health were determined., Results: Using a seasonal cutoff point of ACTH concentrations ≥47 pg/mL, 55 ponies had increased autumnal ACTH concentrations and 45 did not. Using a basal insulin concentration of >50 μiU/mL, 42 ponies were diagnosed with ID and 58 were not. Using a 60 minutes after OST cutoff point of >45 μiU/mL, 57 ponies had ID and 37 did not. Blood l-lactate concentrations were significantly lower in obese (average body condition score ≥ 7/9) compared to nonobese ponies (0.6 mmol/L; range, 0.0-1.9 mmol/L vs 0.8 mmol/L; range, 0.3-2.7 mmol/L; P = .01). No other significant correlations were detected. No differences were detected between ponies with and without increased autumnal ACTH concentrations (0.7 mmol/L; range, 0.0-2.7 mmol/L vs 0.7 mmol/L; range, 0.3-1.8 mmol/L; P = .84) and with and without ID (0.7 mmol/L; range, 0.3-2.7 mmol/L vs 0.8 mmol/L; range, 0.0-1.6 mmol/L; P = .63)., Conclusions and Clinical Importance: Results do not support an effect of endocrine status on l-lactate concentrations in blood of ponies., (© 2021 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: The chemiluminescence (CL) and immunofluorescence (IF) assays yield different results for basal adrenocorticotropin hormone concentrations [ACTH] in pony plasma. It is unclear whether this difference also occurs in basal samples from horses or samples from ponies following thyrotropin-releasing hormone (TRH) stimulation., Objectives: To compare the results of [ACTH] analysis by CL and IF methods in basal samples from horses and pony samples following TRH stimulation., Study Design: Method comparison., Methods: Plasma [ACTH] was measured concurrently using CL and IF methods in 12 ponies (basal and post-TRH stimulation) in November and basal samples from horses (n = 45; November and May)., Results: CL and IF methods yielded different results (P < .01). The median difference (CL-IF) (95% CI) for ponies was 5.9 (0.1-7.5) pg/mL at baseline and 227.9 (61-1001) pg/mL post TRH; and horses 1.9 (1.1-5.4) pg/mL in November and 9.4 (8.2-11.5) pg/mL in May, at baseline. Correlation was good in ponies at baseline (R = 0.80, P = .003) but not post-TRH, and good in horses in November and May (R = 0.68 and 0.71, P < .001). Bland-Altman analysis demonstrated moderate bias and wide 95% limits of agreement (95% LOA) in ponies at baseline (bias 5.5 pg/mL; 95% LOA -9.9 to 20.9 pg/mL) and horses in May (bias 10.6 pg/mL; 95% LOA -9 to 30.3 pg/mL) and very large bias and wide 95% LOA in ponies post-TRH (bias 477 pg/mL; 95% LOA -633 to 1587 pg/mL). Using CL cut-offs of >29 and >110 pg/mL, agreement was moderate (ƙ = 0.67) and very good (ƙ = 0.82) for binary classification of PPID in ponies at baseline and post-TRH; and good (ƙ = 0.73) for horses in November, but poor (ƙ = 0.40) in May., Main Limitations: Limited numbers of horses with [ACTH] above threshold values., Conclusions: The assays yielded different absolute values, particularly in post-TRH samples from ponies, suggesting TRH stimulates secretion of cross-reacting peptides other than ACTH. Agreement for binary classification for PPID was moderate to good, except in basal samples from horses in May., (© 2020 EVJ Ltd.)

Background: Blood l-lactate and glucose concentrations were higher in ponies with gastrointestinal disease than in horses, possibly because of differences in body condition (BC)., Objectives: To investigate whether l-lactate and glucose concentrations correlate with BC and differ between healthy horses and ponies., Animals: Systemically healthy client-owned ponies (n = 101) and horses (n = 51)., Methods: Prospective observational study. Breed, weight, height, and subjective and objective measures of BC were recorded and l-lactate and glucose concentrations were measured. Correlations between l-lactate and glucose concentrations and BC were established. The association between l-lactate concentrations, equid type (pony or horse), BC, age, and glucose concentrations was investigated using a multivariable model., Results: Weak but significant (P = .001) negative correlations were detected between l-lactate concentration and average BC score (r = -0.29), heart girth:height ratio (r = -0.27), and age (r = -0.27). Glucose concentrations were significantly (P < .001) positively correlated with neck length:heart girth ratio (r = 0.37) and heart girth:height ratio (r = 0.31). l-lactate and glucose concentrations were weakly correlated (r = 0.15; P = .04). In the final multivariable model, age (-0.02 ± 0.006; P = .001) and heart girth:height ratio (-1.74 ± 0.53; P = .001) were significantly associated with the natural logarithm of l-lactate concentration (Lnl-Lactate). This represents a 2% decrease in l-lactate concentration per year increase in age and 10% decrease in l-lactate concentration per 0.06 unit increase in heart girth:height ratio., Conclusions and Clinical Importance: In healthy horses and ponies, age and BC significantly influence l-lactate concentrations., (© 2019 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Circulating adiponectin concentrations were lower in ponies with a history of endocrinopathic laminitis and in nonlaminitic ponies that subsequently developed laminitis. The assays used in these studies have been discontinued or are no longer valid., Objectives: (1) to determine the validity of immunoturbidimetric (IT) and enzyme linkedimmunosorbent (ELISA) assays for equine total and high molecular weight (HMW) [adiponectin] measurement and (2) to investigate the association between [adiponectin] measured using these assays and endocrinopathic laminitis., Study Design: Method validation and cohort study., Methods: Accuracy and precision of IT and ELISA assays for measuring total (TAC) and HMW (HMWAC) [adiponectin] were determined. Using the IT assay, the effects of anti-coagulant and storage temperature were assessed, TAC was measured in previously laminitic (PL) and never laminitic (NL) ponies (n = 6/group). Comparison with a previously validated radioimmunoassay was made in NL ponies (n = 223). Association between TAC and subsequent laminitis development in NL ponies was investigated using univariable logistic regression and ROC curve analysis., Results: The IT assay was precise and demonstrated good agreement with the previously validated radioimmunoassay. TAC was significantly (P<0.01) lower in PL (mean ± s.d. 8.9 ± 2.9 μg/mL) compared to NL (24.2 ± 11.8 μg/mL) ponies and in NL ponies that developed laminitis within 12 months (median 4.8 μg/mL; IQR 2.65-13.4 μg/mL) compared to those that remained nonlaminitic (19.9 μg/mL; 9.95-31.5 μg/mL). TAC was significantly (P = 0.01) associated with laminitis occurrence within 12 months. Use of the area under the ROC curve to distinguish animals that did and did not develop laminitis showed good accuracy (0.76). None of the ELISA methods validated satisfactorily., Main Limitations: Laminitis risk is based on data from ponies in one region., Conclusions: The IT method is suitable for measurement of equine TAC. TAC is lower in ponies with previous or future laminitis. The ELISA methods are not suitable for measurement of equine HMWAC or TAC., (© 2018 EVJ Ltd.)

Background: Analysis of plasma adrenocorticotropic hormone concentration [ACTH] aids diagnosis of pituitary pars intermedia dysfunction (PPID). Comparisons of the validated chemiluminescent-immunoassay (CI) and immunofluorescent (IF) assays are limited., Objectives: To compare the results of [ACTH] analysis by CI and IF methods of samples collected in autumn and spring and assess cross-reactivity., Study Design: Method comparison., Methods: Plasma from nonlaminitic ponies was analysed concurrently using the IF and CI methods in autumn and the following spring. Diagnostic thresholds for the IF method were derived using ROC curves and Youden indices to correspond with CI thresholds. Assay specificity was assessed using commercially available ACTH fragments and degradation products of endogenous ACTH., Results: CI and IF methods yielded different results (P<0.001); mean differences (CI-IF), (95% confidence intervals): Autumn (n=99) 38.6 (30.6-46.5) pg/ml, Spring (n=88) 5.1 (3.9-6.3) pg/ml. The association between CI and IF results differed in autumn and spring, consistent with seasonally dependent cross-reactivity or interference. Good (κ=0.66-0.74) agreement was obtained for binary interpretation in spring between IF and CI using thresholds of >24 and >29 pg/ml respectively and in autumn between IF and CI using thresholds of >27 and >47 pg/ml respectively or >33 and >77 pg/ml respectively. Of 88 ponies with both spring and autumn samples, 56 (64%) exceeded a published autumn CI threshold (>47 pg/ml), of which 39 (70%) were below the equivalent threshold (<29 pg/ml) the following spring without treatment. The CI assay showed apparent increases in [ACTH] following addition of CLIP (ACTH 18-39). Degradation of ACTH during storage affected the assays differently., Main Limitations: Limited numbers of PPID cases were included. Immunoreactivity of commercially available peptides may differ from their endogenous equivalents., Conclusions: The methods yielded different absolute values but the agreement for binary classification was good. An altered pituitary secretome in autumn that affects apparent [ACTH] values is likely. The Summary is available in Spanish - see Supporting information., (© 2017 EVJ Ltd.)

Background: It is recommended that the oral sugar test (OST) for insulin dysregulation (ID) be performed after an overnight fast, but fasting is impractical in ponies kept solely at pasture. There are few data on OST repeatability and reliability in ponies., Objectives: To report 1) whether OST results obtained in the morning after an overnight fast or without fasting in the afternoon (FASTING/FED) can be used interchangeably, 2) time of highest insulin concentration T max [insulin], repeatability and reliability of insulin response to the OST when FASTING or FED and 3) dichotomous agreement (ID/normal) within a small sample when FASTING or FED., Study Design: Method comparison study., Methods: Oral sugar tests were performed on four occasions in 10 adult native British ponies, twice FASTING and twice FED. Insulin concentrations were measured by radioimmunoassay at 0-120 min (T 0,30,60,75,90,120 ). Differences between FASTING and FED results were assessed using mixed effects models. Indices of repeatability and reliability were calculated; dichotomous agreement was reported using kappa statistics., Results: Serum [insulin] was significantly (P≤0.05) higher at T 60 -T 90 with prior fasting (estimated differences [95% confidence intervals]): T 60 : 23.5 μiu/ml (8.7-38.4 μiu/ml), T 75 : 27.1 μiu/ml (12.3-41.8 μiu/ml), T 90 : 15.1 (0.36-29.9 μiu/ml). Most frequently, T max [ins] occurred at T 30 . At any single time point, within-subject coefficients of variation were: FASTING: 40% and FED: 31%. The 95% limits for repeatability were FASTING: 29-340%, FED: 41-240%. Test reliabilities were FASTING: 0.70 and FED: 0.67. For dichotomous interpretation similar results (kappa = 0.7) were obtained using cut-offs of [Insulin] >60 μiu/ml at T 60 or T 90 for FASTING and [Insulin] >51 μiu/ml at T 30 or T 60 for FED samples., Main Limitations: Oral sugar tests were performed on a small number of animals on one pasture during one season (spring)., Conclusions: Clinicians should beware of interpreting changes in absolute OST results owing to poor repeatability. When stabling is unavailable, OSTs of ponies at pasture may yield similar dichotomous results without prior fasting., (© 2016 EVJ Ltd.)

Reasons for Performing Study: Survey data on equine tumours are sparse compared with other species and may have changed over time., Objectives: To describe the most frequently diagnosed equine tumours recorded by a diagnostic pathology laboratory over 29 years, to identify background factors associated with tumour type, and to identify any changes in the tumours diagnosed or the background of cases submitted during the study period., Study Design: Observational; cross-sectional analysis of records of a diagnostic pathology laboratory., Methods: The records of all neoplastic equine histology submissions to the University of Bristol (January 1982-December 2010) were accessed from a database, and a list of diagnoses compiled. The 6 most commonly diagnosed tumour types were analysed using logistic regression to identify background factors associated with tumour type. The overall population of equine tumour submissions and the relative frequency of diagnosis of the most common tumour types were compared between decades., Results: There were 964 cases included. The most frequently diagnosed tumours were: sarcoid (24% cases), squamous cell carcinoma (SCC) (19%), lymphoma (14%), melanoma (6%), gonadal stromal tumour (6%) and mast cell tumour (MCT) (4%). With sarcoid, Thoroughbred/Thoroughbred cross and gelding as reference categories: increasing age was significantly associated with the odds of each of the other tumour types, mares were at reduced risk of SCC, Arab/Arab cross had a higher risk of MCT, Cob/Cob cross had an increased risk of SCC and MCT, and ponies had an increased risk of melanoma. The mean age of submissions increased in each successive decade and the breed composition became broader. Sarcoids and lymphoma formed a smaller proportion of diagnoses in later decades., Conclusions: The types of tumours submitted to this laboratory have changed over the last 3 decades. Current data inform clinicians and researchers and further studies are warranted to follow trends., (© 2015 EVJ Ltd.)

Reasons for Performing Study: Acorn toxicity has been anecdotally reported to cause fatal colitis and colic in horses but reports in the scientific literature are sparse., Objectives: This study reports the diagnosis, treatment, prognosis and outcome of 9 cases with suspected acorn toxicity admitted to 2 referral hospitals., Study Design: Retrospective case series., Methods: Case records from 2004 to 2013 were reviewed. Horses were included in the study if they met 3 of 4 criteria: exposure to acorns; clinical and laboratory data suggesting alimentary or renal dysfunction; acorn husks in the faeces or gastrointestinal tract; and necropsy and histopathological findings consistent with acorn toxicity. Data collected included case history, clinical presentation, clinicopathological data, ultrasonographic findings, case progression, and necropsy and histopathological findings., Results: Nine horses met the inclusion criteria. Five cases presenting with haemorrhagic diarrhoea deteriorated rapidly and were subjected to euthanasia or died. Four cases showed signs of colic with gas distension, displacement of the large colon and diarrhoea. Three of these (33%) survived with medical management, the fourth was subjected to euthanasia. Post mortem examination of 6 cases demonstrated submucosal oedema of the large intestine and caecum (n = 6), acute tubular nephrosis (n = 6), diffuse necrohaemorrhagic and ulcerative typhlocolitis and enteritis (n = 4), and small intestinal oedema (n = 3)., Conclusions: Acorn ingestion may be associated with typhylocolitis leading to diarrhoea, colic and acute renal tubular nephrosis. Recovery is possible in mildly affected cases; more severe cases show hypovolaemia, intractable pain, renal dysfunction and cardiovascular failure, and often succumb to the disease process. Disease is only seen in a small proportion of the population exposed to acorns and there seems to be an increased occurrence in certain years. Further investigation into factors predisposing to disease is required, but limiting exposure to acorns in the autumn seems prudent., (© 2014 EVJ Ltd.)

Reasons for Performing Study: Ex vivo evidence suggests that cyclo-oxygenase (COX) 2-preferential inhibitor nonsteroidal anti-inflammatory drugs (NSAIDs), such as meloxicam, have a less detrimental effect on intestinal healing than flunixin meglumine (FM). Whether this translates to a beneficial effect in horses with naturally occurring strangulating small intestinal (SSI) lesions is unknown., Objectives: To compare the clinical outcome of horses with naturally occurring SSI lesions treated with meloxicam or FM., Study Design: Randomised prospective study., Methods: Cases presenting to the Royal Veterinary College Equine Referral Hospital and Bell Equine Veterinary Clinic during 2010 and 2011 in which an SSI lesion was identified at exploratory laparotomy were eligible for inclusion. Horses received either 1.1 mg/kg bwt FM or 0.6 mg/kg bwt meloxicam i.v. q. 12 h. Clinical outcomes and clinical and laboratory parameters associated with endotoxaemia were compared between groups., Results: Sixty cases were enrolled, 32 horses received FM and 28 received meloxicam. There was no difference in signalment, physical examination or surgical factors between groups. The overall survival to discharge was 81%; there was no difference in survival (P = 0.14) or incidence of post operative ileus (P = 0.25) between groups. There was no significant difference between the plasma lipopolysaccharide (LPS) concentrations at 0 h (P = 0.18) or 48 h (P = 0.60); however, there was a significant difference between neutrophil count at 48 h (P<0.05) and at 96 h (P<0.01) with significantly greater cell numbers in horses receiving meloxicam compared with FM. Blinded pain score evaluation showed that more horses receiving meloxicam showed gross signs of pain than those treated with FM (P = 0.04)., Conclusions: Nonsteroidal anti-inflammatory drug choice did not affect major clinical outcomes in horses with SSI lesions but had some effects on signs of pain. This study provides no evidence to recommend one NSAID treatment above another based on survival or the incidence of ileus; however, evaluation of a larger number of cases is required., (© 2013 EVJ Ltd.)

Reasons for Performing Study: Plasma fructosamine concentration ([fructosamine]) is believed to reflect medium term, average blood glucose concentration and in a previous study was higher in horses with active laminitis than in normal horses. Pituitary pars intermedia dysfunction (PPID) is associated with hyperglycaemia and laminitis., Objectives: To test the hypotheses that: [fructosamine] is higher in PPID cases than normal animals; furthermore, that within cases of PPID [fructosamine] is higher in those with active laminitis than nonlaminitic cases and in cases that have been affected by active laminitis in the preceding year than those that have not., Study Design: Observational, case-control/cross-sectional study., Methods: [Fructosamine] was measured in cases of PPID (n = 46) and normal animals (n = 139). A normal range was calculated; values were compared between the 2 groups and within the PPID group, between cases with and without active laminitis and between cases that had and had not been affected by active laminitis in the preceding year., Results: In normal animals mean [fructosamine] was 248.7 μmol/l; the normal range (mean ± 2 s.d.) was 195.5-301.9 μmol/l. Plasma [fructosamine] was not higher in PPID cases than in normal animals. In PPID cases, [fructosamine] was significantly (P = 0.006) higher in cases with active laminitis (mean ± s.d. 261.2 ± 39.2 μmol/l) compared with those without active laminitis (234.5 ± 32.9 μmol/), but [fructosamine] was not higher in cases that had been affected by active laminitis in the preceding year than those that had not., Conclusions: In horses affected by PPID, [fructosamine] is higher in cases with active laminitis than in cases without active laminitis., Potential Relevance: Clinical use of [fructosamine] is limited due to overlap with the normal range. Further studies into glucose and protein metabolism in cases of PPID are warranted., (© 2013 EVJ Ltd.)

Reasons for Performing Study: Gastric impaction in the horse is poorly described in the veterinary literature., Objectives: To review the clinical and pathological features of gastric impaction., Methods: The clinical details of horses presenting with colic over a 7-year period and cases in which gastric impaction was considered to determine the outcome were reviewed. Clinical and clinicopathological data were recorded., Results: Twelve cases of gastric impaction were recorded (1.4% of 857 horses hospitalised for colic). Diagnosis was achieved by ultrasonographic examination, gastroscopy, exploratory celiotomy and/or post mortem examination. Five out of 12 horses were successfully treated, 5/12 were subjected to euthanasia (3 at celiotomy and 2 due to recurrence of impaction) and 2/12 died. Three out of 12 horses had spontaneous gastric rupture despite attempted treatment (one was subjected to euthanasia at celiotomy and 2 died). Post mortem examination (7 horses) revealed gross muscular thickening of the stomach wall in 6/7 horses. Histological examination revealed focal fibrosis of the stomach wall in 4/6 and focal myositis in 1/6 horses. CONCLUSIONS AND PRACTICAL SIGNIFICANCE: Gastric impaction is a rare cause of colic and affected horses can present with acute, chronic or recurrent colic in the presence or absence of other gastrointestinal disease. Spontaneous gastric rupture may occur. A proportion of affected horses have gross thickening of the muscular layers of the stomach wall.

Reasons for Performing Study: The use of plasma fructosamine concentration ([fructosamine]) as a marker of abnormal glucose homeostasis in laminitic horses has not been investigated., Hypothesis: Plasma fructosamine concentration may be higher amongst laminitic horses than normal horses; this might relate to underlying insulin resistance., Objectives: 1) To compare [fructosamine] between laminitic and normal horses. 2) To investigate associations between [fructosamine] at presentation in laminitic horses with a) single sample markers of insulin resistance and b) outcome., Methods: Plasma fructosamine concentration, fasting serum insulin concentration (insulin) and fasting plasma glucose concentration (glucose) were measured in 30 horses that presented with laminitis. Clinical details and follow-up data were recorded. Plasma fructosamine concentration was also measured in 19 nonlaminitic control horses., Results: Laminitic horses had significantly higher mean [fructosamine] than normal horses (P<0.001). Thirteen of 30 laminitic horses had fasting hyperinsulinaemia, 2/30 had fasting hyperglycaemia. Statistically significant univariable correlations were identified between [fructosamine] and [glucose], [insulin] and the proxies RISQI and MIRG. Trends for association between [fructosamine] and negative outcome did not reach statistical significance., Conclusions and Potential Relevance: Increased mean [fructosamine] in laminitic horses may represent abnormal glycaemic control and [fructosamine] may become a clinically useful marker., (© 2011 EVJ Ltd.)

Thirty horses with no external signs of strangles were tested for exposure to Streptococcus equi subspecies equi (S equi) using a new, commercially available serological test. The horses were also tested for persistent carriage of S equi by endoscopy of the guttural pouches and PCR analysis of lavage samples. The owners were questioned about the recent medical history of the horses. Serology suggested that four horses had been recently exposed to S equi. None of the horses had a known history of strangles but three of the four seropositive horses had recently shown non-specific signs of respiratory disease. One asymptomatic horse was positive for S equi by PCR, but none had both guttural pouch abnormalities and a positive PCR result. Ten additional horses known to have strangles were all seropositive by the serological test.

Two major stresses that threaten rock-inhabiting microbial communities are desiccation and freezing; both result in a loss of liquid water in the cells. The mechanisms necessary to tolerate these extremes may be similar, but are not well understood. In both cases extracellular polysaccharides (EPS) seem to play an important role. This study examines whether the EPS released by a rock-inhabiting phototroph can have a protective effect on other members of similar and neighboring microbial communities. This interaction was modeled by adding EPS isolated from the cryptoendolithic cyanobacterium Nostoc sp. to cells of the cryptoendolithic green alga Chlorella sp. and to cells of the epilithic cyanobacterium Chroococcidiopsis sp. The cells were then subjected to desiccation and freezing and the survival rates were determined by vital staining, using membrane integrity as a measure of viability. The results clearly demonstrate the importance of exogenous EPS in the desiccation tolerance of both species, while mixed results were found for the freezing trials.