Johan Bröjer

Cardiac troponin I and the occurrence of cardiac arrhythmias in horses with experimentally induced endotoxaemia.

The aim of this study was to determine whether experimentally-induced endotoxaemia induced elevations in plasma cardiac troponin I (cTnI) concentrations in horses and how this might affect the incidence of cardiac arrhythmias. Eight Standardbred horses received an intravenous continuous rate infusion of endotoxin (total dose 500 ng/kg) for 6 h while being monitored using electrocardiography (ECG). Blood samples were collected before the start of the endotoxin infusion, every 60 min during the infusion, then 1, 2, 3, 8, 10 and 24 h post-infusion, and analysed for cTnI concentrations. One horse was excluded from the study owing to a high initial cTnI concentration. Endotoxin infusion induced an increase in cTnI concentrations in all horses, reaching mean peak concentration of 0.135±0.094 μg/L by 1 h post-infusion. The cTnI concentrations then decreased and were no longer significantly different from pre-infusion concentrations at 6, 10 and 24 h post-infusion. The number of ventricular events was generally low during the infusion period, but increased during the first 3 h post-infusion in 6/7 horses. In conclusion, elevated cTnI concentrations could be detected early after an endotoxaemic insult using an ultrasensitive cTnI assay, with peak cTnI concentrations preceding the occurrence of ventricular events on ECG.

Radiographic parameters for diagnosing sand colic in horses

BackgroundIngestion of sand can cause colic, diarrhoea and weight loss in horses, but these signs are unspecific and can have many other causes. The amount of sand that induces disease may vary between individuals. To avoid over-diagnosing, it is important to determine the amount of sand that can be found in horses without clinical signs of gastrointestinal disease. The aim of this study was to use previously suggested parameters for establishing a radiographic diagnosis of sand colic, and compare these findings between a sand colic group and a control group.MethodsAbdominal radiographs were obtained in 30 horses with a complaint unrelated to the gastrointestinal tract. In addition, archived abdominal radiographs of 37 clinical cases diagnosed with sand impaction were investigated. The size of the mineral opacity indicative of sand in the abdomen was measured and graded according to a previously published protocol based on height and length. Location, homogeneity, opacity and number of sand accumulations were also recorded.ResultsTwenty out of 30 control horses (66%) had one or more sand accumulations. In the present study; height, length and homogeneity of the accumulations were useful parameters for establishing a diagnosis of sand colic. Radiographically defined intestinal sand accumulation grades of up to 2 was a common finding in horses with no clinical signs from the gastrointestinal tract whereas most of the clinical cases had much larger grades, indicating larger sand accumulations.ConclusionFurther work to establish a reliable grading system for intestinal sand content is warranted, but a previously proposed grading system based on measurements of height and length may be an alternative for easy assessment of sand accumulations in the meantime. The present study indicates that a grade 1 – 2 sand accumulation in the intestine is a frequent finding in horses. When working up a case with clinical signs from the gastrointestinal tract, one or more accumulations of this grade should not be considered the cause until other possibilities have been ruled out.

Enilconazole treatment of horses with superficial Aspergillus spp. rhinitis.

BACKGROUND Mycotic rhinitis is an uncommon disease in horses with a wide range of clinical signs and treatment options based on case studies of a single or only a few individuals. Moreover, while dogs with mycotic rhinitis appear to respond well to treatment with topical enilconazole, this approach has yet to be reported in horses. OBJECTIVES The aim of this study was to describe the clinical findings, results of diagnostic investigations, treatment, and outcome in horses with mycotic rhinitis treated with topical enilconazole. ANIMALS Eight horses were included in the study. METHODS Medical records from 1995 to 2007 from an equine veterinary teaching hospital were reviewed to identify cases with a diagnosis of mycotic rhinitis. RESULTS Eleven cases were identified, of which 8 were treated with topical enilconazole. Seven of those 8 horses recovered and had normal appearance of the nasal passages on endoscopic examination. Fungal culture, where positive, yielded only Aspergillus spp. Treatment was readily performed and no adverse effects were noted in these horses. In 5 horses, long-term follow-up revealed complete recovery for an average of 5 years. CONCLUSIONS AND CLINICAL IMPORTANCE Mycotic rhinitis owing to Aspergillus spp. in horses can be effectively and safely treated with topical enilconazole.

Interday variation and effect of transportation on indirect blood pressure measurements, plasma endothelin-1 and serum cortisol in Standardbred and Icelandic horses.

BackgroundSystemic hypertension is a prominent feature in humans with metabolic syndrome (MS) and this is partly caused by an enhanced endothelin-1 (ET-1) mediated vasoconstriction. There are indications that systemic hypertension might be a feature in equine metabolic syndrome (EMS) but if ET-1 is involved in the development of hypertension in horses is not known. Increased levels of cortisol have also been found in humans with MS but there are no reports of this in horses. Before blood pressure, plasma ET-1 and serum cortisol can be evaluated in horses with EMS, it is necessary to investigate the interday variation of these parameters on clinically healthy horses. The aims of the present study were therefore to evaluate the interday variation and influence of transportation on systemic blood pressure, plasma ET-1 and serum cortisol in healthy Standardbred and Icelandic horses, and to detect potential breed differences.MethodsNine horses of each breed were included in the study. Blood pressure was measured and blood samples were collected between 6 and 9 am on two separate days. Eight of the horses (four of each breed) were transported to a new stable were they stayed overnight. The next morning, the sampling procedure was repeated.ResultsThe interday variation was higher for plasma ET-1 (37%) than for indirect pressure measurements (8-21%) and serum cortisol (18%). There were no differences in systemic blood pressure between the two breeds. The Icelandic horses had significantly lower serum cortisol and significantly higher plasma ET-1 concentrations compared to the Standardbred horses. Plasma ET-1 was significantly elevated after transportation, but systemic blood pressure and serum cortisol did not differ from the values obtained in the home environment.ConclusionsIndirect blood pressure, plasma ET-1 and serum cortisol are of interest as markers for cardiovascular dysfunction in horses with EMS. The elevated plasma ET-1 concentrations recorded after transportation was likely caused by a stress response. This needs to be considered when evaluating plasma ET-1 in horses after transportation. The differences detected in plasma ET-1 and serum cortisol between the two breeds might be related to differences in genetic setup, training status as well as management conditions.

Tachypnea and Antipyresis in Febrile Horses after Sedation with α2-Agonists

BACKGROUND Signs of tachypnea after sedation of febrile horses with alpha2-agonists have been noted previously but have not been further investigated. OBJECTIVES To examine the effects of xylazine and detomidine on respiratory rate and rectal temperature in febrile horses and to investigate if either drug would be less likely than the other to cause changes in these variables. ANIMALS Nine febrile horses and 9 healthy horses were included in the study. METHODS Horses were randomly assigned to sedation with xylazine 0.5 mg/kg or detomidine 0.01 mg/kg. Heart rate and respiratory rate were recorded before sedation and at 1, 3, and 5 minutes after injection. Hourly measurements of rectal temperature were performed starting before sedation. RESULTS All febrile horses experienced an episode of tachypnea and antipyresis after sedation. Rectal temperature in the febrile group was significantly lower at 1, 2, and 3 hours after sedation. In several measurements, the decrease was >1 degrees C. Respiratory rate in the febrile group was significantly increased after sedation. All febrile horses were breathing>40 breaths/min and 3 horses>100 breaths/min 5 minutes after sedation. No differences were noted between the 2 treatments. No significant changes in respiratory rate or temperature were noted in the reference group. CONCLUSIONS AND CLINICAL IMPORTANCE Febrile horses can become tachypneic after sedation with detomidine or xylazine. The antipyretic properties of alpha2-agonists need consideration when evaluating patients that have been sedated several hours before examination.

Effect of repeated oral administration of glucose and leucine immediately after exercise on plasma insulin concentration and glycogen synthesis in horses

OBJECTIVE To determine whether repeated oral administration of glucose and leucine during the period immediately after intense exercise would increase the release of insulin and thereby enhance glycogen synthesis in horses. ANIMALS 12 Standardbred horses. PROCEDURES In a crossover study design, after glycogen-depleting exercise, horses received oral boluses of glucose (1 g/kg at 0, 2, and 4 hours) and leucine (0.1 g/kg at 0 and 4 hours) or boluses of water (10 mL/kg at 0, 2, and 4 hours; control treatment). Blood samples for determination of glucose, insulin, and leucine concentrations were collected prior to and during a 6-hour period immediately after exercise. Biopsy specimens of a gluteus muscle were obtained before and immediately after exercise and at 3, 6, and 24 hours after exercise for measurement of glycogen concentration. RESULTS When glucose and leucine were administered to the horses, plasma insulin concentration was significantly higher during the 6 hours immediately after exercise than it was when water was administered to the horses. Serum glucose concentration during the 4 hours immediately after exercise was significantly higher when glucose and leucine were administered than the serum glucose concentration when water was administered. Muscle glycogen concentrations did not differ between the 2 treatments during the 24 hours after exercise. CONCLUSIONS AND CLINICAL RELEVANCE Synthesis of muscle glycogen after intense intermittent exercise was not enhanced by oral boluses of glucose and leucine after exercise despite pronounced increases in plasma insulin and serum glucose concentrations.

Repeated post-exercise administration with a mixture of leucine and glucose alters the plasma amino acid profile in Standardbred trotters

BackgroundThe branched chain amino acid leucine is a potent stimulator of insulin secretion. Used in combination with glucose it can increase the insulin response and the post exercise re-synthesis of glycogen in man. Decreased plasma amino acid concentrations have been reported after intravenous or per oral administration of leucine in man as well as after a single per oral dose in horses. In man, a negative correlation between the insulin response and the concentrations of isoleucine, valine and methionine have been shown but results from horses are lacking. This study aims to determine the effect of repeated per oral administration with a mixture of glucose and leucine on the free amino acid profile and the insulin response in horses after glycogen-depleting exercise.MethodsIn a crossover design, after a glycogen depleting exercise, twelve Standardbred trotters received either repeated oral boluses of glucose, 1 g/kg body weight (BW) at 0, 2 and 4 h with addition of leucine 0.1 g/kg BW at 0 and 4 h (GLU+LEU), or repeated boluses of water at 0, 2 and 4 h (CON). Blood samples for analysis of glucose, insulin and amino acid concentrations were collected prior to exercise and over a 6 h post-exercise period. A mixed model approach was used for the statistical analyses.ResultsPlasma leucine, isoleucine, valine, tyrosine and phenylalanine concentrations increased after exercise. Post-exercise serum glucose and plasma insulin response were significantly higher in the GLU+LEU treatment compared to the CON treatment. Plasma leucine concentrations increased after supplementation. During the post-exercise period isoleucine, valine and methionine concentrations decreased in both treatments but were significantly lower in the GLU+LEU treatment. There was no correlation between the insulin response and the response in plasma leucine, isoleucine, valine and methionine.ConclusionsRepeated post-exercise administration with a mixture of leucine and glucose caused a marked insulin response and altered the plasma amino acid profile in horses in a similar manner as described in man. However, the decreases seen in plasma amino acids in horses seem to be related more to an effect of leucine and not to the insulin response as seen in man.

Effects of diet-induced weight gain and turnout to pasture on insulin sensitivity in moderately insulin resistant horses

OBJECTIVE To quantify insulin sensitivity and monitor glucose, insulin, and lipid concentrations in a group of moderately insulin-resistant horses during induction of obesity by use of a forage diet supplemented with fat and during subsequent turnout to pasture. ANIMALS 9 adult Standardbred mares (11 to 20 years old). PROCEDURES Weight gain of horses was induced during 22 weeks by use of a forage diet supplemented with fat fed in gradually increasing amounts, followed by feeding of that fat-supplemented diet at 2.5 times the daily maintenance requirements. Horses were then turned out to pasture. Insulin sensitivity was measured with the euglycemic hyperinsulinemic clamp method before and after weight gain and after 4 weeks at pasture. Body weight, body condition score, and cresty neck score as well as fasting and postprandial concentrations of plasma insulin, plasma glucose, serum triglyceride, and serum nonesterified fatty acids were measured during the study. RESULTS Body weight typically increased by 10%, and body condition score (scale, 1 to 9) increased by > 1.5 from the start to the end of the weight-gain period. There was no difference in insulin sensitivity or metabolic clearance rate of insulin during the weight-gain period. Four weeks at pasture generally improved insulin sensitivity and metabolic clearance rate of insulin by 54% and 32%, respectively, but there was no change in body weight or body condition score. CONCLUSIONS AND CLINICAL RELEVANCE Findings indicated that dietary composition played a more important role than did short-term weight gain on alterations in insulin sensitivity of horses.

Relationship Between β-cell Response and Insulin Sensitivity in Horses based on the Oral Sugar Test and the Euglycemic Hyperinsulinemic Clamp

Background A hyperbolic relationship between β‐cell response and insulin sensitivity (IS) has been described in several species including rodents, dogs, and humans. This relationship has not been elucidated in the horse. Hypothesis/Objectives To determine whether the hyperbolic relationship between β‐cell response and IS exists in horses by using indices of β‐cell response from the oral sugar test (OST) and IS measurements from the euglycemic hyperinsulinemic clamp (EHC). A second aim was to compare how well IS estimates from the OST and EHC correlate. Animals Forty‐nine horses with different degrees of insulin regulation (normal‐to‐severe insulin dysregulation). Methods Cross‐sectional study. Horses were examined with an OST and an EHC. Results Decreased IS was associated with increased β‐cell response in the horses. Nine of 12 comparisons between indices of β‐cell response and IS measures fulfilled the criteria for a hyperbolic relationship. Indices of IS calculated from the OST correlated highly with the insulin‐dependent glucose disposal rate (M) and the insulin‐dependent glucose disposal rate per unit of insulin (M/I) determined from the EHC (r = 0.81–0.87). Conclusions and Clinical Importance A hyperbolic relationship between β‐cell response and IS exists in horses, which suggest that horses with insulin dysregulation respond not only with postprandial hyperinsulinemia but are also insulin resistant. The OST is primarily a test for β‐cell response rather than a test for IS, but calculated indices of IS from the OST may be useful to estimate IS in horses, especially when the horse is insulin resistant.

Comparison between the euglycemic-hyperinsulinemic clamp and the use of proxies for determination of insulin sensitivity in horses.

Background Accurate quantification of insulin resistance is important for diagnosing and determining the efficacy of treatment in patients with equine metabolic syndrome (EMS). The euglycemic-hyperinsulinemic clamp (EHC) is a goldstandard method for measuring insulin sensitivity (IS) but the complexity of the technique limits its use in research. The use of proxies based on fasting values offers an attractive alternative.