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1.
Perineural nerve blocks are often used in equine practice, especially since the use of diagnostic and surgical procedures in the standing sedated horse have expanded over recent decades. The purpose of this review is to discuss the different perineural nerve blocks for the equine head. The review starts with the currently most used blind approaches as described in textbooks and scientific studies. In human medicine, the role of guided techniques, such as ultrasound guidance, advanced imaging guidance and nerve stimulator guided techniques, is very extensively described. These techniques are promising to use in equine medicine as well. The first studies that describe these techniques in equine cases are also discussed in this review, as well as the possibilities for neuromodulation in equine pain syndromes like equine trigeminus-mediated headshaking and the role of perineural nerve blocks in diagnosing this syndrome.  相似文献   

2.
Insulin dysregulation is the hallmark of equine metabolic syndrome and has received attention because of its direct association with laminitis. In the absence of an adequate treatment for laminitis, a focus on prophylaxis is needed, making early detection of individuals at risk of developing laminitis one of the main challenges in equine endocrinology. Recent studies have shown that insulin dysregulation goes beyond tissue insulin resistance and it is now demonstrated that the equine enteroinsular axis plays a major role in insulin secretion and equine hyperinsulinaemia. In this review, we discuss the different tests currently available to diagnose insulin dysregulation in horses: the ones investigating tissue insulin resistance and those investigating the enteroinsular axis, detailing their goals, practicalities and limitations. This review supports the contention that the diagnosis of equine insulin dysregulation should now be based on the investigation of both tissue insulin resistance and the equine enteroinsular axis. Regardless of the tests used many factors of variation, such as breed, diet, fasting state or season, have been identified and could potentially confound the results of a specific test. Therefore, careful interpretation of the results of a given test in each individual situation is required to optimise the detection of horses at risk of laminitis.  相似文献   

3.
Susceptibility to equine hyperlipaemia is increased by poor food intake. To assess the contribution of changes in insulin sensitivity, plasma glucose and cortisol responses to an intravenous insulin challenge (0·4 kg−1 bodyweight) were compared with those observed after saline administration in six donkeys fasted either overnight or for three days. Three days of fasting decreased both the rate of insulin-induced hypoglycemia and the maximal hypoglycemic response. A transitory increase in plasma cortisol which peaked within one to four hours of insulin administration was observed in three of the six overnight-fasted donkeys and in all of the three-day fasted donkeys; inter-animal variation appeared to exist in the responsiveness of the hypothalamic-pituitary-adrenocortical ( ) axis to stimulation by insulin-induced hypoglycemia. Fasting is likely to present a risk of equine hyperlipaemia, at least in part, by the reduction in tissue sensitivity to the glucoregulatory action of insulin.  相似文献   

4.
Abnormalities of insulin metabolism include hyperinsulinaemia and insulin resistance, and these problems are collectively referred to as insulin dysregulation in this review. Insulin dysregulation is a key component of equine metabolic syndrome: a collection of endocrine and metabolic abnormalities associated with the development of laminitis in horses, ponies and donkeys. Insulin dysregulation can also accompany prematurity and systemic illness in foals. Causes of insulin resistance are discussed, including pathological conditions of obesity, systemic inflammation and pituitary pars intermedia dysfunction, as well as the physiological responses to stress and pregnancy. Most of the discussion of insulin dysregulation to date has focused on insulin resistance, but there is increasing interest in hyperinsulinaemia itself and insulin responses to feeding. An oral sugar test or in‐feed oral glucose tolerance test can be performed to assess insulin responses to dietary carbohydrates, and these tests are now recommended for use in clinical practice. Incretin hormones are likely to play an important role in postprandial hyperinsulinaemia and are the subject of current research. Insulin resistance exacerbates hyperinsulinaemia, and insulin sensitivity can be measured by performing a combined glucose‐insulin test or i.v. insulin tolerance test. In both of these tests, exogenous insulin is administered and the rate of glucose uptake into tissues measured. Diagnosis and management of hyperinsulinaemia is recommended to reduce the risk of laminitis. The term insulin dysregulation is introduced here to refer collectively to excessive insulin responses to sugars, fasting hyperinsulinaemia and insulin resistance, which are all components of equine metabolic syndrome.  相似文献   

5.
Hyperinsulinaemia is a commonly-observed characteristic of insulin resistance, and a reduction in insulin sensitivity is thought to be either a causative and/or symptomatic feature of equine hyperlipaemia. A positive correlation (r=0·545, P=0·0015) existed between plasma insulin and triglyceride concentrations determined in 31 donkeys with naturally occurring hyperlipidaemia/hyperlipaemia. Greater insulin values tended to occur in the animals with an overweight body score. Inter-animal variation in insulin concentrations, however, prevented the identification of any differences either within hypertriglyceridaemic donkeys (when classified by clinical condition, date of arrival to a sanctuary and eventual outcome after treatment) or between groups of normotriglyceridaemic (n=6) and experimentally fasted hypertriglyceridaemic (n=5) donkeys. Determination of basal plasma insulin concentrations may not provide an accurate assessment of underlying insulin sensitivity. Alternatively, hyperinsulinaemia may be evident only in animals with established insulin resistance.  相似文献   

6.
Antimicrobial stewardship involves the judicious use of antimicrobials balanced against the requirement to treat the presenting clinical condition. The same mandate and principles as discussed in human medicine and other veterinary disciplines are relevant to equine practice. This brief review will focus on available resources for equine practitioners, emerging perspectives on antimicrobial use and stewardship, and opportunities for more effective antimicrobial use in equine practice. There is a need for improved client education, availability of faster and more accurate techniques for identification and sensitivity testing of bacterial pathogens, and the development of novel agents.  相似文献   

7.
Determining circulating equine insulin concentrations is becoming increasingly important in equine clinical practice and research. Most available assays are optimized for human medicine, but there is strong equine cross-reactivity because of the highly conserved nature of insulin. To identify an accurate and reliable assay for equine insulin, 6 commercial immunoassays were evaluated for precision, accuracy, and specificity. Only 1 assay initially reached the requisite standard: Mercodia Equine Insulin Enzyme-linked Immunosorbent assay (ELISA). Plasma matrix interferences were identified when the provided assay buffer was used with the Siemens Count-a-Coat Insulin radioimmunoassay (RIA) but not when charcoal-stripped equine plasma was used as the diluent. This modified RIA and the Mercodia Equine Insulin ELISA were evaluated further by directly examining accuracy by comparing their results for 18 equine plasma samples with values obtained using liquid chromatography and high-resolution/high-accuracy mass spectrometry (LC-MS). Compared with LC-MS measurements, the modified Siemens Insulin RIA rendered a moderate Lin's concordance coefficient (ρc) of 0.41, whereas the Mercodia Equine Insulin ELISA rendered a very poor ρc of 0.06. This suggests that the Siemens Insulin RIA is appropriate to use for routine evaluations when LC-MS is not available.  相似文献   

8.
The equine head is an anatomically highly complex area affected by a range of disorders, making the diagnosis of head conditions challenging. Imaging techniques play a crucial role in the diagnostic work-up of head disorders. Tomographic imaging methods, such as computed tomography (CT) and magnetic resonance imaging (MRI) are particularly useful in avoiding problems associated with superimposition of multiple structures in this highly complex region. Both techniques are becoming more widely available in equine medicine. However, the choice between CT and MRI for imaging the equine head is not always straightforward. Each modality has advantages and disadvantages in terms of practicality, costs and diagnostic value for particular problems. The aim of this review is to describe the application of CT and MRI for imaging the equine head and to provide a practical guide for their use in different anatomical structures and clinical indications. This should allow the equine practitioner to make an informed decision on which modality to choose.  相似文献   

9.
It is well known that skeletal scintigraphy is an imaging modality with high sensitivity but low specificity. Sites of IRU provide good evidence of increased bone turnover but not its specific cause. Results of lameness workups, blocks, and other imaging techniques are required to determine specific causes. Overinterpretation of causes of IRU is tempting, especially in assigning diagnoses to EIBR--adaptive or non-adaptive. Nevertheless, a quarter of a century's experience with equine skeletal scintigraphy has shown that certain patterns and locations can be fairly predictive of certain pathologic findings. It behooves the equine scintigrapher to know those patterns and how they are affected by the patient's age, breed, and occupation so that he or she can indicate how to best focus other diagnostic procedures toward a definitive diagnosis. Those who are conducting research involving equine skeletal scintigraphy are challenged to help sharpen that focus, especially in evaluating the significance of relatively mild IRUs. Equine clinicians who use scintigraphy in their lameness workups are especially challenged. Working in concert with nuclear medicine imagers, they are in the best position to garner, collate, and analyze the information that is needed to correlate IRUs and the clinical picture. As difficult as they are to design and conduct, such studies are most productive if done prospectively and are most rewarding for those who carry them through.  相似文献   

10.
Reasons for performing study: Type 2 diabetes mellitus (T2DM) is diagnosed rarely in equine practice although it may be under‐recognised. A greater awareness of the condition and therapeutic considerations would be to the benefit of such cases presenting in practice. More investigation into the pharmacological management of these cases is needed. Objectives: Three cases of diabetes mellitus were investigated using a specific test for insulin sensitivity and pancreatic β cell function in order to define accurately and characterise the existence of T2DM in all 3 subjects. Methods: The insulin‐modified frequently sampled i.v. glucose tolerance test was performed in each case and the data so obtained were subject to minimal model analysis of insulin‐glucose dynamics. Cases were then monitored following treatment using a combination of dietary modification, metformin, glibenclamide and pergolide. Results: Marked insulin resistance was identified in each case and, furthermore, severe pancreatic β cell dysfunction was present therefore classifying each case as end stage T2DM. Treatment was nevertheless associated with restoration of normoglycaemia in all cases. Conclusions: T2DM in horses may be more common than generally considered. In some cases individuals may respond to therapy aimed at restoring insulin sensitivity and pancreatic function. Drugs used in other species for the treatment of T2DM have not yet been adequately tested in horses. Potential relevance: T2DM should be considered as an important differential diagnosis in mature to elderly horses and ponies suffering from weight loss, polydipsia and polyuria. Clinicians should be encouraged to offer treatment and management advice when such cases are encountered.  相似文献   

11.
Multiple dynamic field tests are used for assessment of equine insulin resistance or altered insulin regulation. However, the relationship between markers of glucose homeostasis and insulin disposal obtained by different testing protocols is unknown. We hypothesized that two recently developed field tests for evaluation of equine insulin dysregulation, the insulin response to dexamethasone test (IRDT) and oral sugar test (OST), would yield comparable results to the hyperinsulinemic euglycemic clamp (HEC). Fifteen light breed horses with body condition scores (BCS) 3 of 9 to 8 of 9 were used in this study. Eight horses (BCS, 5 of 9 to 7 of 9) underwent an OST under two different housing conditions, pasture, and stall (experiment 1). These eight horses also underwent an HEC and IRDT over a 4-week period (experiment 2), and results were compared with the OST stall. Finally, eight horses (BCS, 3 of 9 to 8 of 9), including one horse from experiments 1 and 2, underwent an OST on pasture three times over a 14–16-week period during the summer and the fall (experiment 3). The HEC did not correlate with either the OST or IRDT. The OST was not different when performed in the pasture compared within a stall but did change significantly over time on pasture. These results suggest that in insulin-sensitive horses, the OST and IRDT results are not primarily determined by tissue insulin sensitivity in horses of varying BCS. Furthermore, OST results may vary depending on pasture composition or season.  相似文献   

12.
Chicken leptin: properties and actions   总被引：6，自引：0，他引：6  
Chicken leptin cDNA shows a high homology to mammalian homologous, with an expression localized in the liver and adipose tissue. It is noteworthy, that the hepatic expression is most likely associated with the primary role that this organ plays in lipogenic activity in avian species. As in mammals, chicken leptin expression is regulated by hormonal and nutritional status. This regulation is tissue-specific and with a high sensitivity in the liver compared to adipose tissue. The blood leptin levels are regulated by the nutritional state with high levels in the fed state compared to the fasted state. The recombinant chicken leptin markedly inhibits food intake as reported in mammals, suggesting the presence of an hypothalamic leptin receptor. The chicken leptin receptor has been identified and all functional motifs are highly conserved compared to mammalian homologous. Chicken leptin receptor is expressed in the hypothalamus but also in other tissues such as pancreas, where leptin inhibits insulin secretion and thus may have a key role in regulating nutrient utilization in this species.  相似文献   

13.
Reasons for performing study: Hyperinsulinaemia is detected in horses with insulin resistance (IR) and has previously been attributed to increased pancreatic insulin secretion. Connecting peptide (C‐peptide) can be measured to assess pancreatic function because it is secreted in equimolar amounts with insulin and does not undergo hepatic clearance. Hypothesis: A human double antibody radioimmunoassay (RIA) detects C‐peptide in equine serum and concentrations would reflect responses to different stimuli and conditions. Methods: A validation procedure was performed to assess the RIA. Six mature mares were selected and somatostatin administered i.v. as a primed continuous rate infusion, followed by 50 nmol human C‐peptide i.v. Insulin and C‐peptide concentrations were measured in horses (n = 6) undergoing an insulin‐modified frequently sampled i.v. glucose tolerance test, and in horses with insulin resistance (n = 10) or normal insulin sensitivity (n = 20). Results: A human RIA was validated for use with equine sera. Endogenous C‐peptide secretion was suppressed by somatostatin and median (range) clearance rate was 0.83 (0.15–1.61) ml/min/kg bwt. Mean ± s.d. C‐peptide‐to‐insulin ratio significantly (P = 0.004) decreased during the glucose tolerance test from 3.60 ± 1.95 prior to infusion to 1.03 ± 0.18 during the first 20 min following dextrose administration. Median C‐peptide and insulin concentrations were 1.5‐ and 9.5‐fold higher, respectively in horses with IR, compared with healthy horses. Conclusions: Endogenous C‐peptide secretion decreases in response to somatostatin and increases after dextrose infusion. Results suggest that relative insulin clearance decreases as pancreatic secretion increases in response to dextrose infusion. Hyperinsulinaemia in insulin resistant horses may be associated with both increased insulin secretion and decreased insulin clearance. Potential relevance: Both C‐peptide and insulin concentrations should be measured to assess pancreatic secretion and insulin clearance in horses.  相似文献   

14.
This study investigated the effects of cortisol and insulin, hormones that affect both glycaemic status and vascular function, on the in vitro contractility of isolated healthy equine small laminar veins. Small veins (150–500 μm) draining the digital laminae from healthy horses or ponies were investigated by wire myography. Concentration response curves were constructed for noradrenaline (NA), phenylephrine (PE), endothelin‐1 (ET‐1) and 5‐hydroxytryptamine (5‐HT) in the presence of either cortisol (10?6 m ) or insulin (1000 μIU/mL). Cortisol significantly increased the maximum contractility of laminar veins to the vasoconstrictors NA and 5‐HT but decreased the maximal contraction to ET‐1. Insulin decreased the contractility of vessels to PE and ET‐1. It is possible that short‐term cortisol excess could enhance venoconstrictor responses to 5‐HT and NA in laminar veins in vivo, thereby predisposing to laminitis. Additionally, a reduction in the ability of insulin to counteract alpha‐adrenoreceptor and ET‐1‐mediated contraction, likely to occur in subjects with insulin resistance, may further exacerbate venoconstriction in animals prone to laminitis. These mechanisms may also predispose horses with disorders such as equine Cushing's disease and equine metabolic syndrome to laminitis.  相似文献   

15.
Little is known regarding nutrient requirements and feeding of geriatric horses, and more effort should be placed on this area of equine nutrition research. That which is known suggests that some geriatric horses may not have different requirements than other mature horses, whereas others affected by disease or poor dentition may have special nutritional needs. In general, rations for geriatric horses should be based on high-quality roughage supplemented with complementary minerals and vitamins. The need for additional energy aside from that provided by the forage can be supplied by adding energy concentrates, such as cereal grains or fat, to the ration. Processing techniques involving heat, such as pelleting and extruding, are advised when cereal grains are included in the ration so as to improve starch digestibility in the small intestine and avoid starch overload in the hindgut and it subsequent problem (ie, colic, laminitis). In addition, the environment in which geriatric horses are fed should be one that promotes ease of ration consumption and eliminates factors thar impair feed consumption, such as competition from other horses and the need to travel relatively long distances (eg, grazing marginal pastures). Finally, strict attention should be paid to the body condition of geriatric horses so as to evaluate adequacy of the ration and the general health of the horse.  相似文献   

16.
OBJECTIVE: To determine the effects of short-term IV administration of hydrocortisone or equine growth hormone (eGH) or long-term IM administration of eGH to horses on tissue sensitivity to exogenous insulin. ANIMALS: 5 Standardbreds and 4 Dutch Warmblood horses. PROCEDURE: The euglycemic-hyperinsulinemic clamp technique was used to examine sensitivity of peripheral tissues to exogenous insulin 24 hours after administration of a single dose of hydrocortisone (0.06 mg/kg), eGH (20 microg/kg), or saline (0.9% NaCl) solution and after long-term administration (11 to 15 days) of eGH to horses. The amounts of metabolized glucose (M) and plasma insulin concentration (I) were determined. RESULTS: Values for M and the M-to-I ratio were significantly higher 24 hours after administration of a single dose of hydrocortisone than after single-dose administration of eGH or saline solution. After long-term administration of eGH, basal I concentration was increased and the mean M-to-I ratio was 22% lower, compared with values for horses treated with saline solution. CONCLUSIONS AND CLINICAL RELEVANCE: Increases in M and the M-to-I ratio after a single dose of hydrocortisone imply that short-term hydrocortisone treatment increases glucose use by, and insulin sensitivity of, peripheral tissues. Assuming a single dose of hydrocortisone improves sensitivity of peripheral tissues to insulin, it may be an interesting candidate for use in reducing insulin resistance in peripheral tissues of horses with several disease states. In contrast, long-term administration of eGH decreased tissue sensitivity to exogenous insulin associated with hyperinsulinemia. Therefore, increased concentrations of growth hormone may contribute to insulin resistance in horses with various disease states.  相似文献   

17.
Reasons for performing study: Several conditions associated with laminitis in horses are also associated with insulin resistance, which represents the failure of glucose uptake via the insulin‐responsive glucose transport proteins in certain tissues. Glucose starvation is a possible mechanism of laminitis, but glucose uptake mechanisms in the hoof are not well understood. Objectives: To determine whether glucose uptake in equine lamellae is dependent on insulin, to characterise the glucose transport mechanism in lamellae from healthy horses and ponies, and to compare this with ponies with laminitis. Methods: Study 1 investigated the effects of insulin (300 µU/ml; acute and 24 h) and various concentrations of glucose up to 24 mmol/l, on 2‐deoxy‐D‐[2,6‐3H]glucose uptake in hoof lamellar explants in vitro. Study 2 measured the mRNA expression of GLUT1 and GLUT4 transport proteins by PCR analysis in coronary band and lamellar tissue from healthy horses and ponies, ponies with insulin‐induced laminitis, and ponies suffering from chronic laminitis as a result of equine Cushing's syndrome. Results: Glucose uptake was not affected by insulin. Furthermore, the relationship between glucose concentration and glucose uptake was consistent with an insulin‐independent glucose transport system. GLUT1 mRNA expression was strong in brain, coronary band and lamellar tissue, but was weak in skeletal muscle. Expression of GLUT4 mRNA was strong in skeletal muscle, but was either absent or barely detectable in coronary band and lamellar tissue. Conclusions: The results do not support a glucose deprivation model for laminitis, in which glucose uptake in the hoof is impaired by reduced insulin sensitivity. Hoof lamellae rely on a GLUT1‐mediated glucose transport system, and it is unlikely that GLUT4 proteins play a substantial role in this tissue. Potential relevance: Laminitis associated with insulin resistance is unlikely to be due to impaired glucose uptake and subsequent glucose deprivation in lamellae.  相似文献   

18.
Nutritional supplements are widely used in the equine industry with the aim of improving horse health, sports or reproductive performances. Over the years, a number of studies have focused on investigating the effects of several dietary compounds on the quality and preservation of stallion semen. This paper reviews the literature available on the use of nutritional supplementation for the improvement of reproductive performance and semen quality in equine species, critically appraising the benefits and negative effects of several compounds found in complementary feeds such as PUFAs from different sources, vitamins and antioxidants, carnitine and botanical extracts. Different nutraceuticals have been highlighted to improve stallion fertility by providing optimal levels of antioxidants, with the most promising results obtained by the combination of PUFAs and antioxidants that resulted to be essential for the maintenance of normal reproductive functions and the reduction of cryodamage in cooled and frozen equine semen.  相似文献   

19.
The equine colon is the primary site of fibre digestion and water absorption. It is therefore not surprising that colitis and associated colonic dysfunction can result in severe nutritional derangements, which can be exacerbated by reduced feed intake in affected horses. Dietary management of colitis is important for optimum recovery. In broad terms, it should prioritise provision of nutrients to horses that otherwise have reduced appetites. In some forms, such as right dorsal colitis, as well as those with chronicity, nutritional recommendations include restricting or eliminating long‐stem roughage from the diet and feeding a complete pelleted diet. Voluntary enteral nutrition is preferred, but horses that are not ingesting enough to meet the minimum recommended requirements as outlined, should be fed via nasogastric tube (if tolerated – no reflux, no ileus and no colic present; faecal output present). Parenteral nutrition may be necessary in some cases, as some colitis cases do not tolerate enteral feeding for reasons such as colic, intestinal dysmotility or abdominal distension. Timing and constitution of nutritional intervention is vital and should be tailored to the individual patient to prevent further complications of the disease process.  相似文献   

20.
Equine nutrition plays a critical role in equine health. The veterinarian is an expected major source of equine nutrition information, yet little evidence exists to evaluate this assumed role, particularly from the veterinarian’s perspective. The aim of this study was to investigate the knowledge and confidence levels and practices and perceptions regarding equine nutrition by surveying equine clinicians in Georgia, USA. A sample representative of a cross-section of equine veterinarians participated in the survey: response rate was 20%. Veterinarians reported that although their level of equine nutrition knowledge had improved since graduation, their confidence levels varied when giving nutritional advice on a number of prevalent nutritional-related conditions. Their confidence level in giving nutritional advice on colic was the highest and on hyperkalemic periodic paralysis the lowest. The majority of veterinarians had not taken any recent equine nutrition continuing education, mainly owing to lack of courses available; however, the majority expressed an interest in taking future courses, particularly if offered online. Although the veterinary profession was considered to be an important source of equine nutrition information, almost one-quarter of veterinarians offered no equine nutrition counseling to their clients. More than two-thirds of veterinarians reported having no access to a referral equine nutrition service, but would be likely to use one if it were available. The results of this survey reveal equine nutrition perceptions and practices from an equine clinician perspective. Several areas of concern are highlighted, questioning the quality, responsibility, and provision of equine nutrition in Georgia, USA, and are suggestive of a far more wide-reaching problem, requiring further research.  相似文献   

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