Development Of Laminitis Research Articles

Remediating Cambridge: Human and Horse Co-Relationality in a Culture of Mis-Re-Presentation

This case study aims to problematise concepts of equine and human co-relational agency in the context of ‘mis-re-presentations’ in the Australian media of harms experienced by the Anglo Arab stallion, Cambridge, following his development of laminitis and his consequent confinement at a leading national Equestrian centre. Autoethnographic narrative is used to retrospectively and selectively narrate the evolving relationship between Cambridge and his owners, farrier, and treating veterinarians within the dominant housing and veterinary practices and welfare paradigms in equestrian culture of 1990’s Australia. Structured author/owner autoethnographic vignettes are framed by newspaper and internet reportage to highlight a productive tension between the public mediation of the case, and what it means to be fully embodied in relationship with an equine companion agent within a particular, racialised, gendered, and biopoliticised location. Adopting a phenomenologically informed intersectional feminist ethics of care perspective, a counternarrative to the gendered, racialised and essentialising rights-based judgements about Cambridge’s illness and eventual death that dominated the popular media is provided. Crucially, the autoethnographic vignettes are chosen to capture the corporeal reciprocity and rapport of forces that produced a co-created agentivity that characterised the horse’s birth, training, and treatment. The embodied interspecies knowledge that informs the training and care of equines (and all animal species) is always historically situated within permeable, dynamic worlds of self and other that are fluid, contextual, and always in relation. It is suggested that the case of Cambridge illustrates how competing stakeholder investments in animal welfare can play out in the public mediation of particular cases in ways that exclude their historical and interspecies situatedness and serve to reinforce dominant ideologies governing human and animal relationships.

Effect of short-term dopamine reduction on insulin sensitivity and post-prandial insulin and glucose responses in Standardbred horses

The role of dopamine in the regulation of insulin secretion in horses is poorly understood and requires further investigation. Pituitary pars intermedia dysfunction (PPID) is associated with decreased activity of dopaminergic neurons which normally suppress peptide hormone secretion from the pituitary pars intermedia. A high proportion of horses with PPID also have insulin dysregulation (ID), characterised by post-prandial hyperinsulinaemia and/or tissue insulin resistance, which are risk factors for the development of laminitis. The aim of this study was to investigate the effects of alpha-methyl-para-tyrosine (AMPT), a tyrosine hydroxylase inhibitor that reduces dopamine production, on insulin sensitivity and the post-prandial insulin response to a glucose-containing meal. Six healthy Standardbred horses were enrolled in a placebo-controlled randomised crossover study, in which one dose of AMPT (40 mg/kg BW) or placebo was administered orally, prior to performing an in-feed oral glucose test (OGT) and a frequently sampled intravenous glucose tolerance test (FSIGTT). Dopamine reduction by AMPT was confirmed by an increase in plasma prolactin concentration and the lack of post-prandial increase in plasma dopamine concentration compared to placebo. Post-prandial insulin responses, both peak and AUCi, were increased after AMPT compared to placebo (P=0.048 and P=0.005, respectively), without affecting blood glucose concentrations. However, one dose of AMPT did not appear to affect tissue sensitivity as assessed by the FSIGTT. This study confirmed that dopamine plays a role in the regulation of insulin secretion in horses, as it does in other species, whereby the post-prandial release of dopamine into the circulation may inhibit pancreatic insulin secretion. Further studies are required to evaluate different dosing protocols for AMPT, and to further investigate the links between PPID, ID and laminitis risk in horses.

Methylated tirilazad may mitigate oligofructose-induced laminitis in horses.

Laminitis is a serious health condition that can cause severe pain and lameness in horses. Due to lack of understanding of laminitis, treatments often fail to achieve the desired results. In recent years, we have begun to recognize that laminitis may involve a complex interaction between local and systemic inflammation. Dysbiosis of the gut microbiota has been linked in the development of systemic inflammation, and our previous findings suggest that the development of laminitis is closely linked to the production of harmful metabolites of the gut microbiota. In addition, it was found that localized lesions in the hoof, especially lamellar injuries, are the most direct cause of laminitis. Matrix metalloproteinases have been found to be strongly associated with the development of laminitis. Recent discovery has found that methylated tirilazad has a role in repairing laminar tissue in vitro. However, its efficacy in horses never has been studied. Therefore, we aimed to investigate the efficacy of methylated tirilazad (product name: PTP-102) in the prevention/treatment of oligofructose-induced laminitis. The results showed that oligofructose successfully induced laminitis in horses, resulting in detreated clinical signs. Blood indices (including inflammation-related indices and other related indices) were significantly increased. Observations of dissection and staining showed significant bleeding, swelling, and damage to hoof tissue. Analysis of the gut microbiota showed a significant decrease in abundance and diversity, and a significant increase in the relative abundance of specific bacteria. Following methylated tirilazad intervention, there were a significant improvement in clinical signs, blood markers and lamellar tissue damage. Additionally, methylated tirilazad positively influenced the gut microbiota structure by reducing the relative abundance of genera closely associated with the development of equine laminitis. This suggests that some of the therapeutic mechanism of methylated tirilazad may be linked to its effects on the gut microbiota. Notably, methylated tirilazad had better effect in the treatment group than the prophylactic group, indicating the post-diagnosis utility of methylated tirilazad for laminitis management.

Radiological measurements of the feet of normal Straight Egyptian Arabian horses in Qatar

The Arabian horse has been identified as carrying a risk locus for equine metabolic syndrome, predisposing this breed to development of laminitis. Radigraphy of the equine foot is widely considered the main diagnostic imaging technique for evaluation of the laminitic horse. Knowledge of ‘normal’ breed values allows assessment of the degree and severity of radiological changes associated with laminitis. The objective of this study was to investigate the normal values for radiological measurements of the feet of the Straight Egyptian Arabian horse in Qatar. The design was a clinical prospective study. Radiographs of the fore and hind feet of 10 clinically normal adult Straight Egyptian Arabian horses were taken. On the lateromedial views, 17 measurements were taken (13 distances and four angles). On the horizontal dorsopalmar/plantar views, two measurements were taken. On the dorsal 45 degree, proximo-palmarodistal oblique projections, four measurements were taken. Normal reference ranges were reported for radiological measurements of the feet of the Straight Egyptian Arabian horse. Several variables showed significant differences between fore and hind feet, including hoof angle, distal wall thickness, and two proximal inner layer measurements (p < 0.05). In addition, the Straight Egyptian Arabian horse was found to have a number of measurements which varied from previously published reports. The results reported within provide a useful reference for normal radiographic measurements of the Straight Egyptian Arabian horse with relevance for laminitis.

Focus on the epidemiology, pathophysiology, diagnosis, and management of insulin dysregulation in horses

Because there are various inter-related disorders of insulin metabolism that all may contribute to the final result of hyperinsulinaemia, the phrase "insulin dysregulation" has become the most acceptable term to use when describing equine metabolic syndrome (EMS). Insulin dysregulation is widespread in horses, and it appears to be more prevalent in physically sedentary horses. Laminitis and hyperinsulinaemia have been linked, as have other components of insulin dysregulation. Diagnosis of insulin dysregulation should be done in stages, beginning with basal testing, which includes baseline values of insulin and glucose, and concluding with dynamic tests, which detect tissue insulin resistance and hyperinsulinaemia. Dietary adjustments are the key to weight loss in the majority of EMS horses. To encourage weight loss, the horse should be given around 1.25% of its body weight every day. Exercise not only aids equid weight loss but also improves insulin sensitivity. The exercise should be tailored to the specific horse, taking into account its breed, fitness level, and owner's resources. When an obese horse is unable to exercise owing to laminitis or when obesity persists after extensive exercise and dietary management, levothyroxine sodium and metformin hydrochloride can be given to help accelerate weight loss and increase insulin sensitivity. Insulin dysregulation is a defining feature of equine metabolic syndrome and has garnered attention due to its direct link to laminitis. There is need for an in-depth understanding of ID in order to prevent the development of clinical laminitis. The current study discusses the epidemiology, pathophysiology, diagnosis, and management of insulin dysregulation in horses.

A practical approach to hyperinsulinaemia in horses with equine metabolic syndrome

SummaryLaminitis associated with hyperinsulinaemia is a significant cause of morbidity and mortality in horses with equine metabolic syndrome. The diagnosis and management of hyperinsulinaemia are therefore critical to prevent the development of laminitis. This review article aims to help primary care clinicians manage patients with hyperinsulinaemia by providing an overview of diagnostics, management strategies and new therapies that are available.

Shape and Size Variations of Distal Phalanges in Cattle.

Studies on the structure of the distal phalanx help explain the development of laminitis. Additionally, examining the structure of the distal phalanx from a taxonomic perspective also contributes to veterinary anatomy. In this study, we examined shape variation in the medial and lateral distal phalanx of both fore- and hindlimbs using the geometric morphometry method. We investigated whether the shape of the distal phalanx differed between phalanx positions and how much of the shape variation in this bone depends on size. For this purpose, distal phalanges from 20 Holstein cattle were used, and the bones were digitized in 3D. A draft containing 176 semi-landmarks was prepared for shape analysis, and this draft was applied to all samples using automated landmarking through point cloud alignment and correspondence analysis. A principal component analysis was performed to obtain general patterns of morphological variation. The centroid size (CS) was employed as an approximation of size. Although distal phalanx groups generally showed close variations, PC1 statistically separated the hindlimb lateral distal phalanx (HL) and the forelimb medial distal phalanx (FM) from each other in shape. While PC2 separated HL from other distal phalanx groups, PC3 separated fore- and hindlimb groups. The shape (Procrustes distance) of the hindlimb medial distal phalanx (HM) is markedly less variable than the other three phalanges. The smallest distal phalanx in size was HL. For both forelimb and hindlimb, the medial distal phalanges were larger than the lateral ones. Size (CS) was found to have an effect on PC1 and PC3. In this study, a reference model of the same breeds for distal phalanx was created. These results can provide useful information, especially in terms of veterinary anatomy, zooarchaeology, and paleontology.

Survival rates and factors associated with survival and laminitis of horses with acute diarrhoea admitted to referral institutions.

Clinicopathological findings and their association with the outcome and development of laminitis in horses with acute diarrhoea has not been investigated in a multicentre study across different geographic regions. Describe and compare clinicopathologic findings of diarrhoeic horses between different geographic regions, survival rates and factors associated with non-survival and laminitis. Multicentre retrospective case series. Information from horses with acute diarrhoea presenting to participating institutions between 2016 and 2020 was collected, and clinicopathological data were compared between surviving and non-surviving horses and horses that did and did not develop laminitis. Survival rates and seasonal and geographic differences were also investigated. One thousand four hundred thirty-eight horses from 26 participating institutions from 4 continents were included; 76% survived to discharge with no differences identified between geographic regions. The survival proportion of horses with SIRS and creatinine concentrations > 159 μmol/L was 55% (154/279) compared with 81% (358/437) for those with SIRS and creatinine concentrations < 159 μmol/L (p < 0.001). The survival proportion of horses with SIRS that had an L-lactate concentration > 2.8 mmol/L was 59% (175/298) compared with 81% (240/296) in horses with SIRS and L-lactate concentration < 2.8 mmol/L (p < 0.001). The proportion of horses that developed laminitis was lower in Europe (4%, 19/479) compared with North America (8%, 52/619), Australia (8%, 12/138) and Latin America (11%, 16/146) (p < 0.05). More horses developed laminitis in the summer (46%, 39/85) compared with winter (18%, 15/85), spring (18%, 15/85) and fall (19%, 16/85) (p < 0.01). Horses with laminitis had greater odds of non-survival than those without laminitis (OR: 3.73, 95% CI: 2.47-5.65). Not all variables were available for all horses due to the retrospective nature. Clinicopathological findings in horses with acute diarrhoea and their association with survival are similar across geographic regions. However, developing laminitis secondary to diarrhoea is less common in Europe. In addition, factors associated with non-survival were indicative of disease severity and subsequent cardiovascular compromise.

Diagnostic approaches, aetiological agents and their associations with short-term survival and laminitis in horses with acute diarrhoea admitted to referral institutions.

An international description of the diagnostic approaches used in different institutions to diagnose acute equine diarrhoea and the pathogens detected is lacking. To describe the diagnostic approach, aetiological agents, outcome, and development of laminitis for diarrhoeic horses worldwide. Multicentre retrospective case series. Information from horses with acute diarrhoea presenting to participating institutions between 2016 and 2020, including diagnostic approaches, pathogens detected and their associations with outcomes, were compared between institutions or geographic regions. One thousand four hundred and thirty-eight horses from 26 participating institutions from 4 continents were included. Overall, aetiological testing was limited (44% for Salmonella spp., 42% for Neorickettsia risticii [only North America], 40% for Clostridiodes difficile, and 29% for ECoV); however, 13% (81/633) of horses tested positive for Salmonella, 13% (35/262) for N. risticii, 9% (37/422) for ECoV, and 5% (27/578) for C. difficile. C. difficile positive cases had greater odds of non-survival than horses negative for C. difficile (OR: 2.69, 95%CI: 1.23-5.91). In addition, horses that were positive for N. risticii had greater odds of developing laminitis than negative horses (OR: 2.76, 95%CI: 1.12-6.81; p = 0.029). Due to the study's retrospective nature, there are missing data. This study highlighted limited diagnostic investigations in cases of acute equine diarrhoea. Detection rates of pathogens are similar to previous reports. Non-survival and development of laminitis are related to certain detected pathogens.

50 Water-soluble carbohydrate content in equine pasture: Impact of fertilization, season, and grass species

Horses spend a significant proportion of time grazing to meet their nutritional requirements. However, many domesticated horses now graze on energy-dense pastures designed to support production animals. Excessive consumption of these pastures that often contain significant quantities of water-soluble carbohydrates (WSC) has been linked to the development of pasture-associated laminitis. Although seasonal changes in pasture WSC content are well documented, the impact of fertilization or grass species composition are less defined. To evaluate the effect of season and fertilization on WSC concentrations, grassland plots were established at SRUC Aberdeen, UK. Six distinct cool-season seed mixtures (Table 1) were sown in triplicate plots (3m x 4m) and split in half to evaluate the effect of fertilizer treatment (285kg/ha of 21–8-11, annual application in March). Samples were collected on ice at set 6-to-8-week intervals (May–October) across 2 consecutive years. The Anthrone method was employed to estimate WSC content of lyophilised and milled samples, expressed as glucose and fructose equivalents [g/kg DM]. Independent t-test analysis (significance set at P < 0.05) revealed that fertilization had no overall effect on the WSC fraction for glucose (t(94) = 1.02, P = 0.99, 95% CI [-7.57, 23.51]) or fructose (t(94) = 1.28, P = 0.78, 95% CI [-4.69, 21.85]). Analysis of variance analysis demonstrated a significant effect of seed mixture (F = 2.56, P = 0.033 for glucose, F = 2.39, P = 0.044 for fructose) and season (glucose: F = 21.88, P = < 0.001, fructose:F = 21.09, P = < 0.001). WSC concentration was highest in samples collected in Spring, while the perennial rye grass mix (5) and a diverse herb mix (4) had the highest and lowest WSC contents across all samples, respectively. These preliminary results suggest that season and grass species composition have a greater effect on WSC concentrations in pasture than fertilizer treatment. Further studies are warranted to estimate the impact of fertilizer on other aspects of grass chemical composition that may have implications for managing pasture for grazing animals.

Systematic review of the association between intrasynovial corticosteroid use and laminitis—What is the evidence?

SummaryAnecdotal information has linked the clinical administration of intrasynovial corticosteroids with the development of laminitis in horses. This systematic review aims to compile and evaluate the level of current evidence from published works investigating this issue. A systematic search in PubMed, CAB Direct and Web of Science databases was conducted in February 2022. Studies were included if designed as experimental in vivo in horses, case series, observational cohorts (retrospective or prospective—with/without control group) or randomised clinical trials. A total of 237 studies were generated from the systematic search and after applying inclusion criteria, four were selected: two were designed as retrospective cohort studies, one included a retrospective and a prospective investigation, and the last one was a case series. Studies usually had a high risk of bias, and some also presented weaknesses such as a lack of controls or insufficient information (corticosteroid dose and treatment/follow‐up period). Reported incidence of laminitis following corticosteroid intrasynovial application was low, similar to controls, when these were included. The small number of articles that fitted the inclusion criteria of this systematic review highlights the lack of high‐quality evidence to draw conclusions. Current scientific information, mainly at a high risk of bias, suggests that there is no association between intrasynovial corticosteroid injection and laminitis in horses without concurrent risk factors.

Fecal microbiota of horses with colitis and its association with laminitis and survival during hospitalization.

The association of microbiota with clinical outcomes and the taxa associated with colitis in horses remains generally unknown. Describe the fecal microbiota of horses with colitis and investigate the association of the fecal microbiota with the development of laminitis and survival. Thirty-six healthy and 55 colitis horses subdivided into laminitis (n=15) and non-laminitis (n=39, 1 horse with chronic laminitis was removed from this comparison) and survivors (n=27) and nonsurvivors (n=28). Unmatched case-control study. The Illumina MiSeq platform targeting the V4 region of the 16S ribosomal RNA gene was used to assess the microbiota. The community membership (Jaccard index) and structure (Yue and Clayton index) were different (analysis of molecular variance [AMOVA]; P < .001) between healthy and colitis horses. The linear discriminant analysis effect size (LEfSe; linear discriminant analysis [LDA] >3; P < .05) and random forest analyses found Enterobacteriaceae, Lactobacillus, Streptococcus, and Enterococcus enriched in colitis horses, whereas Treponema, Faecalibacterium, Ruminococcaceae, and Lachnospiraceae were enriched in healthy horses. The community membership and structure of colitis horses with or without laminitis was (AMOVA; P > .05). Enterobacteriaceae, Streptococcus, and Lactobacillus were enriched in horses with laminitis (LDA > 3; P < .05). The community membership (AMOVA; P=.008) of surviving and nonsurviving horses was different. Nonsurviving horses had an enrichment of Enterobacteriaceae, Pseudomonas, Streptococcus, and Enterococcus (LDA >3; P < .05). Differences in the microbiota of horses with colitis that survive or do not survive are minor and, similarly, the microbiota differences in horses with colitis that do or do not develop laminitis are minor.

Effect of a GLP-1 mimetic on the insulin response to oral sugar testing in horses

BackgroundInsulin dysregulation (ID) is the most important risk factor for the development of laminitis in horses and therapies to control it are needed.Hypothesis/objectivesTo assess the effects of a single dose of the synthetic GLP-1 analog exenatide on postprandial insulin dynamics. We hypothesized that exenatide would improve insulin sensitivity and lower postprandial blood insulin concentrations.Study designRandomized, crossover, experimental study.AnimalsSix horses (3 mares, 3 geldings; 2 with normal insulin regulation [NIR] and 4 with mild ID).MethodsHorses completed both study arms: subcutaneous administration of exenatide (or no treatment) 30 min before an oral sugar test (0.15 ml/kg of Karo Syrup). Blood samples obtained over 240 min were assayed for glucose, insulin, lactate, c-peptide and total GLP-1. The area under the curve (AUC) was calculated using the trapezoidal rule. Insulin sensitivity (SI) was estimated using a mathematical model.ResultsExenatide resulted in a postprandial decrease of 20% (effect size: 2673 µU·min/ml; 95% CI: 900 – 4446 µU·min/ml; P = 0.003) in AUC of plasma insulin (control; mean AUC insulin: 11,989 µU·min/ml; 95% CI: 9673 – 14,305 µU·min/ml, exenatide; mean AUC insulin: 9316 µU·min/ml; 95% CI: 7430 – 11,202 µU·min/ml). Exenatide resulted in an approximately threefold increase (effect size: 5.56 10–4· µU/ml−1·min−1; 95% CI: 0.95 – 10.1 10–4· µU/ml−1·min−1; P = 0.02) in estimated insulin sensitivity (control mean SI: 1.93 10–4· µU/ml−1·min−1; 95% CI: 0.005 – 3.86 10–4·µU/ml−1·min−1 vs. exenatide mean SI: 7.49 10–4· µU/ml−1·min−1; 95% CI: 3.46 – 11.52 10–4· µU/ml−1·min−1).ConclusionsThe decrease in insulin response to carbohydrates was due to an increase in whole-body insulin sensitivity. GLP-1 agonists may have therapeutic potential for ID in horses.

Predictors of laminitis development in a cohort of nonlaminitic ponies.

Quantifying risk factors for laminitis development requires improvement. To identify the most useful physical examination, metabolic and management factors to predict laminitis development in client-owned, nonlaminitic ponies. Prospective cohort study. Physical examination, metabolic and management data were collected from a pony cohort 6 monthly for up to 4years. 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 60minutes ([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]. Overall, 374 ponies (age 5-32years) 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 (>45.2µIU/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- (<53.4µIU/ml), medium- (53.4-153µIU/ml) and high-risk (≥153µIU/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. Results may not apply to different insulin assays, geographical regions, breeds or management types. [Insulin]T0 or [insulin]T60 best quantify the risk of future laminitis development in nonlaminitic ponies.

Changes in the levels of MMP-9, MMP-2, and their inhibitors in the serum of dairy cows with laminitis

Laminitis is regarded as an important underlying cause of lameness disorders, yet its specific pathogenesis remains unclear. Consistent histological changes in cows with laminitis consist in the degradation of the basement membrane (BM). The breakdown of BM is accomplished by numerous proteases, especially MMP-9 and MMP-2. This study recruited 45 cows according to veterinary diagnostic criteria and divided them into three groups: subclinical laminitis cows (SCL, n = 15), chronic laminitis cows (CL, n = 15), and healthy cows (CON, n = 15). After blood samples were collected from the jugular vein, the serum was separated and frozen at –80°C. The serum samples were analyzed by gelatin zymography and reverse zymography to evaluate the activities of MMP-9, MMP-2, TIMP-1, and TIMP-2. In the SCL group, the activity of MMP-9 significantly increased (P &lt;0.01) and the activity of TIMP-1 significantly decreased (P &lt;0.05), compared with those in the CON group, while the activities of MMP-2 and TIMP-2 were not significantly different. In the CL group, the activities of MMP-9 (P &lt;0.001) and MMP-2 (P &lt;0.05) significantly increased, and the activities of TIMP-1 (P &lt;0.01) and TIMP-2 (P &lt;0.05) significantly decreased compared with those in the CON group. This is the first study to report changes in the content of MMP-2 and MMP-9 and their inhibitors, TIMP-2 and TIMP-1, in the serum of dairy cows with laminitis. These results indicate that inadequate regulation of the activities of MMPs and TIMPs in serum may play a role in the development of laminitis in dairy cows.

Approaches to endocrinopathic laminitis in the field: Results of a survey of veterinary practitioners in North America

Endocrinopathic laminitis is the most common cause of laminitis in the field. Insulin has recently been implicated as a key factor in development of endocrinopathic laminitis; however, it is unclear whether diagnostic, and treatment approaches reflect insights derived from recent research. This study sought to evaluate North American veterinary practitioners’ approach to endocrinopathic laminitis in the field. Demographic information, approach to diagnosis, management, and prognosis of endocrinopathic laminitis, as well as factors influencing changes in approach to laminitis were collected. To compare regional differences in approach to laminitis, results were compared to a recently published study from the United Kingdom. Findings of the present study suggest that North American practitioners have changed their approach to laminitis to more readily incorporate diagnostic testing for endocrine disease.

Role of acute respiratory diseases in pathogenesis of distal limb infections in cattle

According to current concepts, ruminal and metabolic acidosis occur due to feeding cattle mainly with preserved acidic feeds such as silage and haylage. However, errors in feeding are not the only etiological factor leading to acidosis. In some cases, metabolic acidosis in cattle can develop along with respiratory infection caused by viral and bacterial agents. The main pathological processes resulting from acute respiratory diseases of cattle are bronchitises, tracheites and pneumonias. When the respiratory tract is affected in cattle, hypoxia occurs, causing intoxication and, thus, leading to ruminal acidosis. As a result, vasoactive substances (bacterial endotoxins, histamine, lactate) enter the bloodstream, the vascular endothelium is damaged due to the simultaneous expansion of arterioles and compression of venules, blood fluid is perfused from the vessels into the surrounding tissues, the blood flow in the microcirculatory bed is disrupted. An important role in the disturbance of blood circulation in small blood vessels is played by circulating immune complexes representing the «antigen-antibody» complex. Low molecular weight circulating immune complexes settle in various organs and tissues of the body, lead to inflammation and damage the normal tissue structure. Most frequently, immune complexes affect the endothelium of blood vessels, renal glomeruli and joints. Distal limb vessels are primarily affected in cattle, leading to disturbance of skin trophism of the limbs and hooves, development of laminitis, while the hoof horn is weakly keratinized and cannot resist aggressive mechanical and chemical environmental factors. Damaged hooves are the gateway of infection for the agents of necrobacteriosis (Fusobacterium necrophorum), staphylococcosis (Staphylococcus spp.), streptococcosis (Streptococcus spp.) and other pathogens. In addition, favorable conditions evolve for the development of mixed infection due to reduction in the overall organism resistance, which is observed for both respiratory and distal limb infections.

Risk factors for laminitis and nonsurvival in acute colitis: Retrospective study of 85 hospitalized horses (2011-2019).

BackgroundAcute colitis is a serious cause of morbidity and death in horses. Recent studies have compared clinical features of coronavirus and salmonellosis, but no study has compared clinical features of enteric salmonellosis, coronavirus, and neorickettsiosis.Hypothesis/ObjectivesTo identify risk factors for laminitis and nonsurvival to discharge in horses with enteric salmonellosis, coronavirus, or neorickettsiosis.AnimalsEighty‐five horses hospitalized for acute colitis from 2011 to 2019.MethodsRetrospective case series. Medical record review (2011‐2019) of adult (≥2 years) horses with colitis. Primary outcomes were laminitis and survival to discharge. Multivariable logistic regression was performed to assess association between variables and the development of laminitis. Stepwise Cox regression was performed to assess association between variables and survival.ResultsSeventeen of 85 (20%) horses developed laminitis during hospitalization. Neorickettsiosis cases (11/26, 42%) were more likely to develop laminitis than coronavirus (0/16, 0%) cases (odds ratio [OR] 24.48; 95% confidence interval [CI]: 1.33‐451.74, P = .03). There was no significant difference in laminitis between salmonellosis and neorickettsiosis cases (OR 0.27; 95% CI: 0.07‐1.07, P = .06). Admission heart rate (OR 1.08; 95% CI: 1.02‐1.15, P = .01), total solids (OR 0.17; 95% CI: 0.06‐0.54, P = .003), band neutrophils (OR 1248.47; 95% CI: 6.62‐235 540, P = .008), and bicarbonate concentration (OR 0.68; 95% CI: 0.5‐0.92, P = .01) were predictive of development of laminitis during hospitalization. Sixty‐three of 85 (74%) horses survived to discharge: 16/16 (100%) coronavirus cases, 17/26 (65%) neorickettsiosis cases, 14/20 (70%) salmonellosis cases, and 16/23 (70%) unknown cases. Packed cell volume (hazard ratio [HR] 1.17; 95% CI: 1.09‐1.26, P < .001), L‐lactate concentration (HR 1.33; 95% CI: 1.14‐1.55, P < .001), and development of laminitis (HR 7.07; 95% CI: 1.67‐29.95, P = .008) were retained in the final multivariable model for prediction of nonsurvival to discharge.Conclusion and Clinical ImportanceNonsurvival and laminitis rates were high, likely related to the presence of neorickettsiosis in the region.

Plasma amino acid concentrations during experimental hyperinsulinemia in 2 laminitis models

BackgroundEndocrinopathic laminitis develops in association with insulin dysregulation, but the role of insulin in the pathogenesis remains unclear. Hyperinsulinemia can cause hypoaminoacidemia, which is associated with integumentary lesions in other species and therefore warrants investigation as a potential mechanism in laminitis.ObjectiveEvaluate plasma amino acid concentrations in the euglycemic‐hyperinsulinemic clamp (EHC) and prolonged glucose infusion (PGI) laminitis models.AnimalsSixteen Standardbred horses.MethodsProspective experimental study. Plasma amino acid concentrations were measured in samples collected every 6 hours from horses that underwent a 48‐hour EHC (n = 8) or 66‐hour PGI (n = 8) after a 24‐ or 6‐hour baseline period in EHC and PGI groups, respectively.ResultsFifteen of the 20 measured amino acid concentrations decreased over time in both EHC and PGI horses (P < 0.001). The median percentage change from baseline for these amino acids was: histidine (EHC: 41.5%; PGI: 43.9%), glutamine (EHC: 51.8%; PGI: 35.3%), arginine (EHC: 51.4%; PGI: 41%), glutamic acid (EHC: 52.4%; PGI: 31.7%), threonine (EHC: 62.8%; PGI: 25.2%), alanine (EHC: 48.9%; PGI: 19.5%), proline (EHC: 56.2%; PGI: 30.3%), cystine (EHC: 34.9%; PGI: 31.2%), lysine (EHC: 46.4%; PGI: 27.8%), tyrosine (EHC: 27.5%; PGI: 16.9%), methionine (EHC: 69.3%; PGI: 50.8%), valine (EHC: 50.8%; PGI: 34.4%), isoleucine (EHC: 60.8%; PGI: 38.7%), leucine (EHC: 48.2%; PGI: 36.6%), and phenylalanine (EHC: 16.6%; PGI: 12.1%).Conclusions and Clinical ImportanceHypoaminoacidemia develops in EHC and PGI laminitis models. The role of hypoaminoacidemia in the development of hyperinsulinemia‐associated laminitis warrants further investigation.

Metabolic profile distinguishes laminitis-susceptible and -resistant ponies before and after feeding a high sugar diet

BackgroundInsulin dysregulation (ID) is a key risk factor for equine endocrinopathic laminitis, but in many cases ID can only be assessed accurately using dynamic tests. The identification of other biomarkers could provide an alternative or adjunct diagnostic method, to allow early intervention before laminitis develops. The present study characterised the metabolome of ponies with varying degrees of ID using basal and postprandial plasma samples obtained during a previous study, which examined the predictive power of blood insulin levels for the development of laminitis, in ponies fed a high-sugar diet. Samples from 10 pre-laminitic (PL – subsequently developed laminitis) and 10 non-laminitic (NL – did not develop laminitis) ponies were used in a targeted metabolomic assay. Differential concentration and pathway analysis were performed using linear models and global tests.ResultsSignificant changes in the concentration of six glycerophospholipids (adj. P ≤ 0.024) and a global enrichment of the glucose-alanine cycle (adj. P = 0.048) were found to characterise the response of PL ponies to the high-sugar diet. In contrast, the metabolites showed no significant association with the presence or absence of pituitary pars intermedia dysfunction in all ponies.ConclusionsThe present results suggest that ID and laminitis risk are associated with alterations in the glycerophospholipid and glucose metabolism, which may help understand and explain some molecular processes causing or resulting from these conditions. The prognostic value of the identified biomarkers for laminitis remains to be investigated in further metabolomic trials in horses and ponies.