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A partial atrioventricular septal defect, represented as a large ostium primum atrial septal defect and common (bridging) atrioventricular valve leaflets with cleft septal leaflet of the mitral valve, was diagnosed incidentally in a nine-year-old warmblood gelding used for show jumping. Initial examination findings and a three-year follow-up are documented in this report. The horse was first presented for the evaluation of chronic coughing. A left-sided, grade 4/6 holosystolic (band-shaped) murmur was identified along with a similar right-sided, grade 3/6 heart murmur. Echocardiography revealed a 6.4 cm diameter communication in the ventral atrial septum, considered an ostium primum atrial septal defect, with bidirectional shunting. A hypertrophic septomarginal trabecula, a thickened tricuspid valve, a cleft septal leaflet of the mitral valve, moderate mitral and tricuspid regurgitation likely related to leaflet prolapse, mild aortic regurgitation, and signs of moderate right ventricular volume overload were found as well. Electrocardiography showed no arrhythmias neither at rest nor during treadmill exercise. The owner continued to use the horse for show jumping. No exercise intolerance or other signs of disease were noted. Follow-up examination was performed three years after initial presentation. Contrast echocardiography confirmed the presence of right-to-left shunting through the atrial septal defect. Compared with the initial examination, the left ventricular internal diameter on M-mode echocardiography had increased. Occasional ventricular premature depolarizations were noted on the resting and exercise electrocardiogram. This is the first description of a clinically asymptomatic partial atrioventricular septal defect in an adult sport horse.

Equine atypical myopathy (AM) is caused by hypoglycin A (HGA) and methylenecyclopropylglycine (MCPG) intoxication resulting from the ingestion of seeds or seedlings of some Acer tree species. Interestingly, not all horses pasturing in the same toxic environment develop signs of the disease. In other species, it has been shown that the intestinal microbiota has an impact on digestion, metabolism, immune stimulation and protection from disease. The objective of this study was to characterize and compare fecal microbiota of horses suffering from AM and healthy co-grazers. Furthermore, potential differences in fecal microbiota regarding the outcome of diseased animals were assessed. This prospective observational study included 59 horses with AM (29 survivors and 30 non-survivors) referred to three Belgian equine hospitals and 26 clinically healthy co-grazers simultaneously sharing contaminated pastures during spring and autumn outbreak periods. Fresh fecal samples (rectal or within 30min of defecation) were obtained from all horses and bacterial taxonomy profiling obtained by 16S amplicon sequencing was used to identify differentially distributed bacterial taxa between AM-affected horses and healthy co-grazers. Fecal microbial diversity and evenness were significantly (p &lt, 0.001) higher in AM-affected horses as compared with their non-affected co-grazers. The relative abundance of families Ruminococcaceae, Christensenellaceae and Akkermansiaceae were higher (p ≤ 0.001) whereas those of the Lachnospiraceae (p = 0.0053), Bacteroidales (p &lt, 0.0001) and Clostridiales (p = 0.0402) were lower in horses with AM, especially in those with a poor prognosis. While significant shifts were observed, it is still unclear whether they result from the disease or might be involved in the onset of disease pathogenesis.

Lawsonia intracellularis (LI) is an obligate intracellular gram-negative rod causing equine proliferative enteropathy (EPE). Occasional cases of EPE have been reported in foals living in Belgium, but the seroprevalence of equine LI in this country is unknown. The target population included clinically healthy adult horses, whose blood samples were collected and analyzed for specific IgG antibodies against LI using a blocking enzyme-linked immunosorbent assay test. The results were expressed as percentage of inhibition (PI). Samples that had a PI20% were judged as negative, those between 20 and 30% as inconclusive, and those30% were considered positive. A total of 356 blood samples were analyzed with 352 horses (98.8%) testing positive, 2 horses (0.6%) testing negative, and 2 horses (0.6%) showing inconclusive results. The large percentage of seropositive samples obtained in this study confirms a widespread exposure of Belgian horses to LI.

Objective To identify prognostic variables for adult equids and foals with tetanus. Design Multicenter retrospective study (2000–2014). Setting Twenty Western, Northern, and Central European university teaching hospitals and private referral centers. Animals One hundred fifty-five adult equids and 21 foals with tetanus. Interventions None. Measurements and Main Results Variables from history and clinical examination were statistically compared between survivors and nonsurvivors (adults: 49 survivors, 85 nonsurvivors; foals: 7 survivors, 10 nonsurvivors). Cases euthanized for financial reasons were excluded. Mortality rates in adults and foals were 68.4% and 66.7%, respectively. Variables associated with survival in adults included: standing, normal intestinal sounds and defecation, voluntarily drinking, eating soft or normal food, lower heart and respiratory rates, high base excess on admission, longer diagnosis time, treatment and hospitalization delay, and mild severity grade. Variables associated with death included: anorexia, dysphagia, dyspnea, low blood potassium concentration on admission, moderate and severe disease grading, development of dysphagia, dyspnea, recumbency and seizures during hospitalization, treatment with glycerol guaiacolate, intravenous fluids, and intravenous glucose solutions. Variables associated with survival in foals included standing on admission, voluntarily eating soft food and drinking, older age, and longer hospitalization delay. Outcome was not different between different tetanus antitoxin (TAT) dosages, although there was a trend of increasing survival rate with increasing TAT dosages. Cases with appropriate vaccination prior to development of tetanus were rare, but had improved outcome and shorter hospitalization. Conclusions Prognosis for equine tetanus is poor with similar outcome and prognostic factors in foals and adults. The prognostic assessment of cases with tetanus provides clinicians with new evidence-based information related to patient management. Several prognostic indicators relate to the ability to eat or drink, and more severe clinical signs relate to poor outcome. Increasing intravenous dosages of TAT has no significant effect on outcome, but the positive trend identified may support a recommendation for high intravenous TAT dosages. Further evaluation is warranted.

OBJECTIVE: To describe clinical data of hospitalized adult equids and foals with tetanus. DESIGN: Multicenter retrospective study (2000-2014). SETTING: Twenty Western, Northern, and Central European university teaching hospitals and private referral centers. ANIMALS: One hundred fifty-five adult equids (>6 months) and 21 foals (

This case report describes the approach to an unusual case of headshaking of 1-year duration paired with unilateral ear hypersensitivity in a 11-year-old Belgian Warmblood mare. After the exclusion of other potential causes, an aural endoscopy was performed under general anaesthesia revealing an ulcerative lesion in the external right ear canal. Biopsies of this area revealed signs of skin inflammation characterised by acanthosis, hyperkeratosis and epidermal oedema leading to a diagnosis of otitis externa. Interestingly, extensive fungal flora characterised by budding yeasts was present in the stratum corneum of each biopsy. Considering the literature debating the difference between physiological fungal colonisation versus pathogenic growth, the horse received topical antifungal and steroid treatment combined with an ear cleanser solution for 12 days with subsequent resolution of most presenting complaints. A mini-review of current knowledge and terminology in human and small animal veterinary medicine concerning external otitis and otomycosis has been included.

Equine atypical myopathy in Europe is a fatal rhabdomyolysis syndrome that results from the ingestion of hypoglycin A contained in seeds and seedlings of Acer pseudoplatanus (sycamore maple). Acylcarnitine concentrations in serum and muscle OXPHOS capacity were determined in 15 atypical myopathy cases. All but one acylcarnitine were out of reference range and mitochondrial respiratory capacity was severely decreased up to 49% as compared to 10 healthy controls. The hallmark of atypical myopathy thus consists of a severe alteration in the energy metabolism including a severe impairment in muscle mitochondrial respiration that could contribute to its high death rate.

Contagious respiratory infections are an important cause of respiratory disease in horses, resulting in impaired pulmonary function, poor performance and sometimes severe illness. Although bacterial infections are often suspected to be involved, viruses are frequently overlooked and are an underestimated cause of respiratory disease outbreaks in horses. In this study, nasal swabs of 103 horses with acute symptoms of respiratory disease were analyzed for the presence of 13 different respiratory pathogens. Gamma herpesviruses were the most commonly detected, with 60% of the samples being positive, followed by streptococcus equi subsp. zooepidemicus infection (30%). Rhinovirus B, streptococcus equi subsp. equi, adenovirus 1 and EHV-4 were more rarely detected. Further research is necessary to correctly interpret the importance of gamma herpesviruses in horses, for example by screening a healthy control population. National surveillance of respiratory viruses in horses by PCR analysis on nasal swabs might be a useful, earlywarning system for viral epidemics.

Summary Reasons for performing study Ingestion of sycamore seeds (Acer pseudoplatanus) is the likely source of hypoglycin A in atypical myopathy (AM) but ingestion of seedlings in spring might also contribute to intoxication. Objectives To test for hypoglycin A in seeds and seedlings collected on pastures where AM cases were reported and compare its concentration in serum of affected and healthy horses. Study design Field investigation of clinical cases. Methods Whenever present, samaras (the winged nuts that each contain one seed) and/or seedlings were collected from pastures of 8 AM cases and 5 unaffected horses from different premises. Two AM cases were each co-grazing with an apparently healthy horse. Acylcarnitines and hypoglycin A were quantified in blood samples of all horses involved in the study. Results Hypoglycin A was detected in serum of AM (5.47 ± 1.60 μmol/l) but not in healthy controls pasturing where A. pseudoplatanus trees were not present. However, hypoglycin A was detected at high concentrations (7.98 μmol/l) in serum of a clinically healthy horse grazing a pasture with seedlings and samaras and also in the 2 healthy horses co-grazing with AM cases (0.43 ± 0.59 μmol/l). Hypoglycin A was detected in all samples of seeds and spring seedlings of A. pseudoplatanus. Conclusions Atypical myopathy can be associated with the ingestion of sycamore samaras and also ingestion of seedlings. Hypoglycin A can be detected in the blood of horses with no detectable clinical signs at pasture in which there is A. pseudoplatanus. Determination of hypoglycin A concentration in blood is useful for screening for exposure in suspected cases of AM.

Background Hypoglycin A has been recently identified has the causal agent of atypical myopathy (AM) in horses. Its identification and quantification in equine’s biological fluids is thus a major concern to confirm maple poisoning and to provide insight into the poorly understood mechanism of hypoglycin A intoxication. Methods Quantification of hypoglycin A has been achieved with the aTRAQ kit for amino acid analysis of physiological fluids (AB Sciex). Acquisition method on mass spectrometer has been updated to record the hypoglycin A specific MRM transition. Results Outlined accuracy profiles demonstrated very reliable data. A good linearity was observed from 0.09 to 50 μmol/L and precision was very good with coefficient of variation below 8%. Fifty-five samples collected from 25 confirmed AM horses revealed significant hypoglycin A concentrations, while toxin was not found in serum of 8 control animals. Conclusions The described aTRAQ variant method has been analytically and clinically validated. The reliability of our approach is thus demonstrated into the workup of atypical myopathy.

International audience; Equine atypical myopathy (AM) is caused by hypoglycin A intoxication and is characterized by a high fatality rate. Predictive estimation of survival in AM horses is necessary to prevent unnecessary suffering of animals that are unlikely to survive and to focus supportive therapy on horses with a possible favourable prognosis of survival. We hypothesized that outcome may be predicted early in the course of disease based on the assumption that the acylcarnitine profile reflects the derangement of muscle energetics. We developed a statistical model to prognosticate the risk of death of diseased animals and found that estimation of outcome may be drawn from three acylcarnitines (C2, C10:2 and C18 -carnitines) with a high sensitivity and specificity. The calculation of the prognosis of survival makes it possible to distinguish the horses that will survive from those that will die despite severe signs of acute rhabdomyolysis in both groups.

Natriuretic peptides are cardiac biomarkers, routinely used for diagnosis, prognosis, and guidance for treatment in human and small animal cardiology. However, their diagnostic and prognostic value in horses has received little study. The aim of this study was to investigate the plasma atrial natriuretic concentration (ANPPl) in a large group of horses with various degrees of valvular regurgitation (VR) and congestive heart failure (CHF). Clinical examination and two-dimensional time-motion mode and Doppler echocardiography were performed on 91 horses admitted to the Equine Teaching Hospital of Liege University, with either no, mild, moderate, or severe VR and presenting various stages of CHF. Plasma atrial natriuretic concentration was measured using a commercially available human radioimmunoassay test. Mean values of body weight, age, ANPPl, and echocardiographic parameters were compared among horses with no, mild, moderate, and severe VR and among horses in different CHF stages. Correlation and linear regression of ANPPl with each echocardiographic parameter and with the percentage of dilation of each of cardiac chambers were assessed. Horses with severe or moderate VR had significantly higher ANPPl than those with mild or no VR. Plasma atrial natriuretic concentration was significantly higher in horses presenting CHF than those without CHF. Plasma atrial natriuretic concentration was significantly correlated with the left atrial diameter and its percentage of dilation. These results suggest a diagnostic value of ANPPl in horses with VR, especially with tricuspid or mitral insufficiency with dilation of the atria.

Objective To assess the prognostic value of echocardiographic parameters of left ventricular (LV) function in horses with systemic inflammatory response syndrome (SIRS). Design Prospective observational study. Setting Veterinary teaching hospital. Animals Forty-one horses admitted for colic with clinical evidence of SIRS. Interventions All horses underwent Doppler echocardiographic examination on admission. LV echocardiographic parameters, including pulsed-wave tissue Doppler imaging parameters, were compared between nonsurvivors (n = 29) and horses that survived to discharge (n = 12). Measurements and Main Results With comparable heart rate and LV preload estimate, LV stroke volume index, the velocity time integral, deceleration time, ejection time of Doppler aortic flow, and peak early diastolic myocardial velocity were lower in the nonsurviving than in the surviving horses, while pre-ejection period to ejection time ratio (PEP/ET) of Doppler aortic flow and the peak early diastolic filling velocity to peak early diastolic myocardial velocity ratio (E/Em) were higher (P < 0.05). A cut-off value of 0.26 for PEP/ET predicted mortality with 100% sensitivity and 42% specificity (area under the receiver operating characteristic curve: 0.71), whereas a cut-off value of 2.67 for E/Em predicted mortality with 100% sensitivity and 83% specificity (area under the receiver operating characteristic curve: 0.89). Conclusions Echocardiography may provide prognostic information in colic horses with clinical evidence of SIRS. Especially, PEP/ET and E/Em could be useful markers of systolic and diastolic dysfunction, respectively, to detect horses with a high risk of death requiring more intensive cardiovascular monitoring as it has been reported in human patients with septic shock.

The objective of this study was to compare the sedative and peripheral hemodynamic effects of acepromazine (ACP) and promethazine (PTZ) in the standing healthy horse. Nine healthy Warmblood horses randomly received either intravenous ACP at 0.1 mg/kg or PTZ at 0.1, 0.2, and 0.3 mg/kg. A sedation score based on clinical examination was recorded, and systolic arterial blood pressure was noninvasively evaluated using a Doppler flow detector at the tail, just before and every 15 minutes until 60 minutes after drug injection. Hemodynamics of the median artery of the left forelimb was studied using Doppler ultrasonography just before and 45 minutes after injection of the drug, which allowed calculation of surface (SURF), diameter (DIAM), and circumference (CIRC) of the vessel and peak systolic velocity (PSV), end diastolic velocity (EDV), mean velocity (MV), volumetric flow (VF), and resistivity index (RI) of the blood flow. Regardless of the dose used, PTZ had lesser sedative and hypotensive effects than ACP at 0.1 mg/kg and did not induce significant variations in SURF, DIAM, CIRC, PSV, EDV, MV, VF, and RI of the studied standing horses. Conversely, the vasodilatory properties of ACP were illustrated by a significant increase in SURF, DIAM, CIRC, PSV, EDV, MV, and VF and a significant reduction of the RI. Unlike ACP, PTZ did not induce alterations on the morphology of the Doppler waveform. PTZ appears to have less sedative and peripheral vasodilator effects than ACP, thus it could be safer than ACP in patients suffering from hypotension.

Introduction The aim of this study was to establish echocardiographic reference values for the equine species using allometric regression equations based on body weight (BW) and thoracic circumference (TC). Animals A total of 239 horses or ponies were studied, including 65 warmbloods, 33 Standardbreds, 41 Thoroughbreds, 32 Arabian horses, 28 draft horses, and 40 ponies aged from 1 day to 30 years, weighing from 18 to 890 kg, with no evidence of cardiac disease. Methods For each horse or pony, a two-dimensional and M-mode echocardiography was performed. Within each breed, the relationships between BW or TC and echocardiographic dimensions were examined using power regression equations. Predictions and their 95% prediction intervals were calculated for the echocardiographic measurements. Results Within each breed, all echocardiographic measurements showed a significant and positive relationship with a high coefficient of determination for the estimation of the regression equations using BW and TC as the main explanatory variables. Breed-specific power regression equations as well as the 95% prediction intervals were calculated for each echocardiographic measurement as a function of BW and TC. Conclusions In the future, the body size-corrected and breed-specific echocardiographic reference values calculated in the present study could be used to discriminate between normal and abnormal values in a given animal.

Objectives To assess the feasibility and repeatability of two-dimensional speckle tracking echocardiography for the evaluation of left ventricular function in healthy calves. Animals 12 Holstein calves, 62 ± 11.6 days old; 75.25 ± 5.4 Kg. Methods Observational study. Right parasternal short-axis views at papillary muscle level were recorded in standing calves and subsequently analyzed by two-dimensional speckle tracking for global and regional radial and circumferential strains and strain rates and radial displacement. Echocardiographic examinations were performed by 2 observers to evaluate intra- and interobserver repeatability and variability. Results Two-dimensional speckle tracking was feasible in all calves. Automated tracking was better in systole than in diastole. Repeatability of the technique was good in calves. Systolic radial strain and strain rate peak values showed little variability compared with systolic circumferential strain and strain rate and to all diastolic measurements. Variability of the interobserver measurements was greater than the intraobserver measurements. Conclusions Two-dimensional speckle tracking is feasible in calves. As in other species, evaluation of systolic radial left ventricular function is more reliable than circumferential and diastolic left ventricular function.

Summary Reasons for performing study: Improved understanding of the epidemiology of atypical myopathy (AM) will help to define the environmental factors that permit or support the causal agent(s) to exert toxicity. Objectives: This European survey of AM aimed to describe spatiotemporal distribution, survival, clinical signs, circumstances in which AM develops and its different expressions between countries and over time. Methods: The spatiotemporal distribution, history and clinical features of AM cases reported to the Atypical Myopathy Alert Group from 2006 to 2009 were described. Comparisons of data from the most severely affected countries and from the large outbreaks were made with Fisher's exact and Welch's tests with Bonferroni correction. Results: Of 600 suspected cases, 354 met the diagnostic criteria for confirmed or highly probable AM. The largest outbreaks occurred during the autumns of 2006 and 2009 in Belgium, France and Germany. For the first time, donkeys, zebras and old horses were affected, and clinical signs such as gastrointestinal impaction, diarrhoea, penile prolapse, buccal ulceration and renal dysfunction were observed. Affected horses spent >6 h/day on pastures that almost always contained or were surrounded by trees. The latency period was estimated at up to 4 days. Overall survival rate was 26%. Although differences between countries in affected breeds, body condition, horse management and pasture characteristics were recognised, the common presenting clinical signs and mortality were similar between countries. Conclusions and potential relevance: This study describes new data on case details, history and clinical course of AM that is of preventive, diagnostic and therapeutic value. However, the true impact of the findings of this study on the development of or severity of AM should be tested with case–control studies.

Reasons for performing study: Appropriate management of atypical myopathy (AM) requires the establishment of an accurate diagnosis and prognosis. Furthermore, preventive measures to avoid AM need to be refined. Objectives: The aims of the study were as follows: 1) to improve the diagnosis of AM; 2) to identify prognostic predictors; and 3) to refine recommended preventive measures based on indicators of risk factors. Methods: An exploratory analysis of cases in Europe between 2006 and 2009 reported to the Atypical Myopathy Alert Group was conducted. Based on clinical data, reported cases were allocated into 2 groups: confirmed or highly probable AM (AM group; further divided into survivors and nonsurvivors); and cases with a low probability of having AM or with another final diagnosis (non-AM group). Using Welch's test and odds ratios corrected for multiple comparisons, the AM vs. non-AM groups were compared to identify indicators for diagnosis and risk factors, and survivors vs. nonsurvivors in the AM group were compared to identify prognostic factors. Sensitivity, specificity and positive and negative predictive values were calculated for specific clinical signs related to final diagnosis and outcome. Results: From 600 reported cases, 354 AM cases (survival rate of 26%) and 69 non-AM cases were identified, while there were insufficient data to categorise the remainder. Variables valuable for diagnosing AM compared with similar diseases were as follows: presence of dead leaves and wood and/or trees on pastures; sloping pastures; full-time pasture access; no food supplementation; normal body condition; pigmenturia; normothermia; and congested mucous membranes. Nonsurvival was associated with recumbency, sweating, anorexia, dyspnoea, tachypnoea and/or tachycardia. Survival was associated with remaining standing most of the time, normothermia, normal mucous membranes, defaecation and vitamin and antioxidant therapy. Conclusions and potential relevance: This study refines the list of risk factors for AM. Clinical signs valuable for diagnosis and prognosis have been identified, enabling clinicians to improve management of AM cases.

The use of echocardiography to study hemodynamic disturbances in colic horses has not been reported. The aim of this study was to noninvasively assess the effect of colic-related endotoxin shock on equine cardiac function. Fifty horses were admitted to the clinic on emergency for colic. A shock score from 1 to 4 was established for each horse on the basis of clinical evaluation, noninvasive systolic blood pressure, and blood tests. Left ventricular echocardiographic and Doppler parameters were compared between the four groups according to the shock score (1 = no or discrete signs of shock, n = 11; 2 = mild shock, n = 17; 3 = moderate shock, n = 12; 4 = severe shock, n = 10), using a multivariate analysis. Horses with a shock score of 1 were considered as controls. Significance was set at P

Summary Reasons for performing study: It is unknown whether or not exercise-induced cardiac fatigue (EICF), as demonstrated in human athletes performing long duration exercise, occurs in endurance horses. Objective: To examine the effects of a long distance endurance race on left ventricular systolic function in horses. Methods: Echocardiography was performed before, and after, a 2 or 3 star international endurance race (106–132 km) in 11 horses. Systolic (s) and diastolic (d) interventricular and left ventricular free wall thickness (IVS and LVFW, respectively), left ventricular, left atrial and aortic internal diameter (LVID, LA and Ao, respectively), fractional shortening (FS) and ejection fraction (EF) were measured by echocardiography. Heart rate (HR), peak flow velocity (Vmax), flow velocity integral (FVI), ejection time (ET), pre-ejection period (PEP), velocity of circumferential fibre shortening (Vcf), stroke volume (SV) and cardiac output (CO) were measured from aortic Doppler wave recordings. Results: After the race, LVIDd, Ao, LA, EF, FS, FVI, SV, ET and ET indexed for HR were significantly lower and IVSd, LVFWd, HR, PEP, PEP/ET and Vcf significantly higher as compared with prerace values. Pre- to post exercise changes in those parameters were not significantly correlated with changes in HR or in LVIDd. Conclusions: Results suggest that EICF, with a decrease in left ventricular systolic function, could occur post exercise in horses performing long duration endurance races. However, a multanecus effect of altered preload and heart rate on the studied variables cannot be discounted.

Background – Atypical myopathy is an acute, severe rhabdomyolysis occurring in grazing horses. In the beginning of October 2009, a new outbreak occurred in several European countries. Geographic, demographic and clinical data of the reported cases in the month October 2009 are described. Key Findings – The survival rate in this outbreak was 25%. The most frequently observed clinical signs were congested mucous membranes, dyspnea, tachycardia, depression, weakness, stiffness, recumbency, trembling, sweating, and myoglobinuria. Nonsurvivors were significantly more likely to be recumbent than survivors. Prognostic factors, symptomatic treatment, and preventive measures are discussed. Significance – Differences were encountered during the described outbreak of atypical myopathy in October 2009 compared with previous outbreaks reported. Equine practitioners should be aware that previous epidemiological studies have shown that after a high prevalence in the autumn, new cases are likely to occur in the following spring.

Background: Reports of doxycycline-induced toxicity are limited despite common use of this antibiotic to treat infectious respiratory disorders in calves. Objective: To describe previously unreported kidney lesions and diagnostic test results in doxycycline-overdosed calves and to compare these results with other findings reported previously. Animals: Thirty-two calves that presented with adverse effects after receiving high doses of doxycycline as a treatment for mild respiratory disorders. Method: Retrospective review of medical records. Results: Clinical examination identified mainly lethargy, dyspnea, cough, tongue paresia or paralysis associated with dysphagia and sialorrhea, tachycardia, tachypnea, and signs of myopathy. Blood analysis indicated increases in creatine kinase, lactate dehydrogenase, aspartate aminotransferase, and sorbitol dehydrogenase activities and increased serum creatinine and urea concentrations. ECG recordings and Doppler echocardiography examination identified ventricular premature beats and a decrease in left ventricular global and systolic function, respectively. Necropsy and histopathology disclosed necrosis of the myocardium, tongue, and some striated muscles, acute renal tubular necrosis, and fatty degeneration or congestion of the liver. Conclusions: Most of these findings corroborate previous observations made in doxycycline-overdosed calves, and further suggest myocardial and striated muscular toxicity as well as renal toxicity in doxycycline-overdosed calves.

The objective of this study was to compare the repeatability of echocardiographic measurements obtained from different echocardiographic modes and views in healthy adult equids of various sizes, breeds, and thorax shapes. Ten equids (body weight: 120–662 kg; age: 1–26 years) from various breeds, free of cardiac disease, were used in this study. Each animal was submitted to a standardized echocardiographic and Doppler protocol 3 times at 1 day interval. This protocol included the measurements of left and right ventricular, aortic, pulmonary, and left atrial parameters obtained from different views using the bidimensional (2D) or the motion (M) modes, and the measurement of several parameters of blood flow obtained from the pulsed wave Doppler mode. Repeatability of each measurement was estimated on the basis of the residual variance using a linear model and the coefficient of variation of repeated measurements. A two by two comparison of the repeatability of measurements performed in different views was performed using the residual variances in a variance ratio F test. Results showed that repeatability of echocardiographic or Doppler measurements in equids of various sizes, breeds, and thorax shapes are comparable to previously reported results in thoroughbred and standardbred horses. Left ventricular morphologic parameters showed a good repeatability in the classic M-mode right parasternal short axis view at the level of the chordae tendineae, but the 2D-mode right parasternal long axis four-chamber view appeared to offer an interesting alternative measurement. This latter view also allowed obtaining the most repeatable measurement of right ventricular internal diameter. The left atrial diameter was maximal and most repeatable in the 2D-mode left parasternal long axis four-chamber angled view, and the repeatability of the aortic diameter was best in the 2D-mode right parasternal long axis five-chamber view. Finally, aortic systolic time intervals were more repeatable when measured from the Doppler mode as compared with the M-mode. In conclusion, repeatability of echocardiographic measurements in horses could be optimized after the following protocol: (1) M-mode right parasternal short axis view at the level of chordae tendineae to measure left ventricular morphologic parameters, and 2D-mode right parasternal long axis four-chamber as an alternative view; (2) 2D-mode right parasternal long axis five-chambers to measure the aortic diameter; (3) 2D-mode left parasternal long axis four-chambers angled view to measure the left atrial diameter.

Summary Reasons for performing study: Equine motor neuron disease (EMND) was diagnosed in 3 horses maintained on lush, grass-based pasture. This contrasted with North American studies which identified limited or no access to green herbage as an important risk factor for EMND. Hypothesis: Grazing horses that have an apparently adequate intake of pasture herbage to meet normal equine vitamin E requirements can develop EMND. Methods: Owners of 32 European horses diagnosed with EMND completed a questionnaire regarding intrinsic, managemental, nutritional and environmental factors that could potentially be risk factors for EMND, and also regarding clinical signs, treatments and case outcome. Plasma/serum vitamin E data for these horses were supplied by the veterinarians. No control population was studied. Results: Thirteen of 32 horses (termed the ‘grazing’ group) had part- or full-time access to grass-based pasture at the onset of EMND (median duration at pasture 12 h/day, range 3–24 h). Five of these horses were at pasture for at least 23.5 h/day at the onset of EMND, 2 of which were at pasture for at least 23.5 h/day throughout the year. Despite grazing, all these horses had a low vitamin E status. The remaining 19 horses resembled those cases reported from North America, in that they had no or limited access to pasture. Conclusions and potential relevance: A diagnosis of EMND should not be discounted on the basis that a horse has access, even full-time, to lush grass-based pasture. Inadequate vitamin E intake was probably not the sole cause of either the EMND or the low vitamin E status in the grazing horses; the latter was probably the result of abnormal bioavailability or excessive utilisation of vitamin E.

Summary This Case Report describes a periarticular abscess and a suppurative arthritis of the atlanto-occipital joint in an adult horse. The horse showed a painful swelling localised on the atlanto-occipital region and ataxia in all 4 limbs. During hospitalisation, the horse developed recumbency, dysphagia, facial paralysis and seizures. Ultrasonography of the atlanto-occipital region enabled a tentative diagnosis to be made, which was later confirmed at autopsy. Culture of the abscess revealed a Staphylococcus aureus. However, the horse had a history of recurrent fever, hypertrophy and abscessation of the submandibular lymph nodes, neck pain and dyspnoea for 2 months, which was suggestive of strangles.

Although echocardiography has greatly improved the diagnostic possibilities in equine medicine, determining the prognosis remains a difficult task. In humans, maximal cardiac power output (CPO) has been described as a powerful indicator of exercise capability and outcome in heart disease. The aim of the study is to describe the measurement of CPO by echocardiography and by thermodilution in healthy horses. Six healthy horses were studied. Cardiac output (CO) was measured by thermodilution and Doppler echocardiography at rest and during a pharmacologic stress test consisting of 35 μg/kg atropine followed by incremental steps 2, 4, 6, and 8 μg/kg/min of dobutamine infusion. Mean arterial pressure (MAP) was measured invasively by a catheter introduced into the transverse facial artery. CPO was calculated as the product of CO and MAP. Baseline CPO measured by thermodilution and by Doppler echocardiography was 10.7 ± 3.3 and 13.7 ± 4.5 watts, respectively. CPO increased significantly with pharmacologic stimulation and reached maximal CPO of 66.4 ± 3.6 and 60.4 ± 5.1 watts when measured by thermodilution and Doppler echocardiography, respectively. This study describes an estimation of CPO in horses. Further studies should demonstrate the usefulness of CPO as a predictive indicator in horses suffering from cardiac disease.

Background: Endocarditis is a rare heart condition with variable clinical expressions in equids. Risk factors for this disease are incompletely understood. Objective: Describe risk factors for endocarditis in equids. Animals: One hundred and fifty-three equids admitted to Liege University, 9 diagnosed with endocarditis and 144 free from endocarditis but admitted to the hospital with a differential diagnosis including this disease. Methods: Retrospective case-control study. Results: Equids with endocarditis were significantly younger (mean age = 4.84 ± 5.74 years) than control equids (mean age = 10.8 ± 7.73 years) (P= .01). No sex or breed predisposition was observed. Animals with hyperthermia (odds ratio [OR] = 24.4; confidence interval [CI] = 1.40–428), synovial distension (OR = 13.4; CI = 3.00–59.8), lameness (OR = 6.52; CI = 1.63–26.1), hyperglobulinemia (OR = 26.4; CI = 3.03–229), hypoalbuminemia (OR = 11.4; CI = 1.34–96.8), hyperfibrinogenemia (OR = 9.81; CI = 1.16–82.7), or leukocytosis (OR = 7.12; CI = 1.40–36.4) presented a significantly higher risk of having endocarditis than control horses. The presence of two of the clinical signs mentioned above significantly increased the probability of a diagnosis of endocarditis (P≤ .05). Conclusions and Clinical Importance: Age is associated with equine endocarditis. The diagnostic value of certain clinical signs and abnormalities in blood parameters in this disease are described.

Summary Atypical myopathy (AM) is a frequently fatal seasonal pasture myopathy that has emerged in several European Countries in recent years. Currently, the aetiology of AM is unknown but recent surveys of confirmed cases have led to new insights into the pathophysiology, prevention and management of the condition.

Background The equine faecal microbiota is very complex and remains largely unknown, while interspecies interactions have an important contribution to animal health. Clostridium difficile has been identified as an important cause of diarrhoea in horses. This study provides further information on the nature of the bacterial communities present in horses developing an episode of diarrhoea. The prevalence of C. difficile in hospitalised horses at the time of admission is also reported. Results Bacterial diversity of the gut microbiota in diarrhoea is lower than that in non-diarrhoeic horses in terms of species richness (p-value

Retropharyngeal infections in horses normally induce local painful swelling of the retropharyngeal area, which may lead to dyspnea, dysphagia, and systemic manifestations. Differential diagnosis of local painful swelling of the retropharyngeal area includes retropharyngeal lymph node infection, neoplasm, cellulitis, hematoma, guttural pouch empyema, parotiditis, and jugular thrombosis. Apart from Streptococcus equi ssp. equi , other bacteria are rarely reported as a cause of retropharyngeal abscesses. The reason for this might be a lack of specific sampling to identify the causative agent. This work deals with a case of retropharyngeal infection in an 11-year-old Standardbred stallion with acute depression, fever, tachycardia, asymmetric painful swelling in the throat area, ptyalism, and respiratory distress. Endoscopy, radiography, ultrasonography, blood analysis, and cytological examination of a puncture sample taken from the throat mass were consistent with a pyogenic to pyogranulomatous retropharyngeal inflammation. The clinical evolution was initially satisfactory in response to treatment with nonsteroidal anti-inflammatory drugs and antibiotics, but clinical signs relapsed twice, each time a few weeks after cessation of antibiotic therapy. The bacteriologic finding in this case was unusual and consisted of the isolation of a Pasteurella multocida strain that was obtained after the second relapse (ie, 79 days after initial admission), using a brain heart infusion (BHI) medium, and after two successive negative bacteriological cultures performed on day one of clinical signs and at the first relapse of clinical signs, respectively.

Summary Reasons for performing study: Stress echocardiography could be a useful diagnostic test in horses suspected to suffer from exercise-induced myocardial dysfunction as a cause of exercise intolerance. Objective: To evaluate the effect of treadmill exercise and pharmacological stress test on left ventricular echocardiographic parameters. Methods: Echocardiography was performed in 2 groups of 5 healthy horses, either immediately after a near-maximal treadmill exercise (Group EXE) or during a pharmacological challenge (Group DOB) consisting of 35 ug/kg atropine, followed by incremental dobutamine infusion rates of 2–6 ug/kg bwt/min for 5 min duration each, which led to a cumulative dobutamine dose of 100 ug/kg. Left ventricular M-mode parameters were compared at rest and at heart rates of 80, 100, 110, 120 130, and 140 beats/min, within each group. Results: In 2 horses of Group EXE, echocardiographic measurements were impossible at 140 and 130 beats/min, as their heart rates dropped too fast in the immediate post exercise period. In the remaining 3 horses image quality was not always satisfactory at heart rates of 130 and 140 beats/min. Systolic left ventricular parameters and fractional shortening measured at 130 and 140 beats/min were significantly different from values obtained at lower heart rates. Horses in Group DOB reached expected heart rates of 80 and 100 beats/min, after the administration of atropine and during a dobutamine infusion rate of 2 ug/kg bwt/min, respectively. Heart rates targets of 110, 120, 130, and 140 beats/min were reached at mean (± s.d.) dobutamine infusion rates of 2.8 ± 0.4, 3.2 ± 0.4, 4.0 ± 0.7, 5 ± 0.7 ug/kg bwt/min, respectively. Systolic left ventricular parameters and fractional shortening at heart rates of 110, 120, 130, and 140 beats/min, were significantly different from values obtained at lower heart rates. Conclusion: The pharmacological stress test induced changes in ventricular dimensions at heart rates of 80 to 140 beats/min. Using this test, high quality images can easily be obtained at heart rates of 140 beats/min. Conversely, in post exercise echocardiography, obtaining good quality images at heart rates of 130 and 140 beats/min is difficult, which limits use of the technique in routine clinical settings. Potential relevance: Further studies should demonstrate the potential of pharmacological stress test as a diagnostic tool in horses suffering from exercise-induced myocardial dysfunction.

The aim of this study was to investigate the effect of combined atropine low-dose dobutamine stress test on left ventricular parameters in adult warmblood horses, to establish a potential protocol for pharmacological stress echocardiography. Seven healthy untrained warmblood horses aged 9 to 22 years were used. Heart rate (HR) and left ventricular B- and M-mode dimensions were recorded at baseline and during stress testing with 35 microg/kg atropine IV followed by incremental dobutamine infusion of 2 to 6 microg/kg/min. HR increased significantly (P.05) during the pharmacological challenge, and a maximal HR of 156.6 +/- 12.5 bpm was reached at maximal dobutamine infusion rate. Systolic and diastolic interventricular septum thickness, systolic and diastolic left ventricular free wall thickness, and fractional shortening increased significantly and reached a maximum at the highest infusion rate (mean +/- SD: 4.51 +/- 0.27 versus 5.65 +/- 0.31 cm, 2.89 +/- 0.19 versus 3.78 +/- 0.10 cm, 3.72 +/- 0.34 versus 4.77 +/- 0.18 cm, 2.44 +/- 0.28 versus 3.11 +/- 0.34 cm, 34.98 +/- 3.82 versus 50.56 +/- 3.42%, respectively). Systolic and diastolic left ventricular internal diameter decreased significantly during dobutamine infusion. Left ventricular external and internal area were significantly lower at a dobutamine infusion rate of 2 microg/kg/min but no further decrease was observed during the subsequent steps. Systolic and diastolic myocardial area was significantly lower after the administration of dobutamine but not significantly different during dobutamine infusion, when compared to baseline values. This pharmacological stress test induced significant changes in left ventricular echocardiographic parameters in adult warmblood horses. Additional research should evaluate the value of this stress test in horses suffering from cardiac disease.

Summary The increasing number of publications in the field of equine stress echocardiography demonstrates the growing interest in this area. Stress echocardiography consists of B- and/or M-mode echocardiography under active or passive stimulation of the heart, where the pre-stimulation images are compared to those obtained during or immediately after stimulation. In human medicine, stress echocardiography is mainly used as a routine tool in diagnosis and prognosis of coronary artery disease, but also in the evaluation of hypertrophied and dilated cardiomyopathy and valvular diseases. In horses, the principal indications include the detection of exercised-induced myocardial insufficiency and refining the prognosis of low- and mid-grade valvular diseases. The two major cardiac stressors that can be used in horses are (1) physical exercise, which has the major disadvantage of a rapid decline in heart rate in the immediate post-exercise period and (2) pharmacological stimulation, which ideally consists of dobutamine infusion in combination of a parasympatholytic drug, in order to overcome the strong dobutamine-induced baroreceptor reflex in horses. Most stress echocardiographic studies performed in horses demonstrated a significant decrease of left ventricular length, diameter, area and volume in response to stimulation. Other studies also revealed a stimulation-induced increase in the interventricular septum, left ventricular free wall thickness, and left ventricular fractional shortening. Some of these changes seemed to be more pronounced during pharmacological stimulation than after exercise. One study described the application of a semi-quantitative wall motion scoring system in horses. Exercise as well as pharmacological stress echocardiography enhances the diagnostic possibilities in equine medicine, because it increases the chance to detect a problem that is not present at rest. Furthermore, this technique could help to investigate the relationship between valvular insufficiencies and ventricular dysfunction.

Summary Bone responds to exercise with changes in bone (re-)modelling, which might be monitored non-invasively with biochemical bone markers. The aim of this study was to evaluate the influence of exercise on serum osteocalcin and serum carboxy-terminal cross-linked telopeptide of type I collagen generated by matrix metalloproteinases (CTX-MMP) concentration in young racehorses. Seventy-one 2 to 4-year-old Thoroughbreds were included in this prospective infield study. Blood sampling was performed six times (i.e. six sampling cycles) during a 9-month period. Serum samples were analysed with commercial osteocalcin and CTX-MMP radioimmunoassays. Two-year-old racehorses had higher serum osteocalcin and CTX-MMP values than 3-year-old horses. Gender and training amplitude did not significantly influence serum osteocalcin and CTX-MMP values. Two-year-old horses showed an increase in osteocalcin values between cycles 2 and 3 and an increase in serum CTX-MMP values between cycles 1 and 2. Serum osteocalcin and CTX-MMP concentrations decreased between cycles 4 and 5, and 5 and 6. Three-year-old horses showed an increase in serum osteocalcin levels between cycles 3 and 4 and an increase in serum CTX-MMP concentrations between cycles 1 and 2, and 3 and 4. Serum osteocalcin levels decreased between cycles 5 and 6, whereas serum CTX-MMP levels decreased between cycles 4 and 5, and 5 and 6. Two- and three-year-old horses showed a decreased osteocalcin/CTX-MMP ratio between cycles 1 and 2. Moreover, 2-year-old horses showed an increase in the osteocalcin/CTX-MMP ratio between cycles 2 and 3. Sore shin formation did not significantly influence serum osteocalcin and CTX-MMP values. Serum osteocalcin and CTX-MMP are promising bone markers for monitoring exercise induced changes in equine bone metabolism.

The purpose of this retrospective study was to further identify in the equine species the clinical signs and blood parameters that could be useful to identify a hepatic disease and act as predictors of the outcome in animals suffering from an acute hepatic insufficiency. The study included 31 equids that were hospitalized at the University of Liege and that suffered from a hepatic (group 1, 17 cases of hepatitis; group 2, 11 cases of hyperlipemia) or post-hepatic (group 3, 3 cases of cholelithiasis) disease. Frequency of the clinical signs and values of selected blood parameters on admission were compared statistically between surviving and non-surviving animals. The most frequently presented clinical signs were depression, decreased appetite or anorexia, fever, tachycardia, polypnea, icterus, and congested mucous membranes. Frequency of the clinical signs and blood parameter values were not statistically different in surviving and non-surviving animals, with the exception of gamma-glutamyl transferase (GGT) and alkaline phosphatase (ALP), which were significantly higher in animals with fatal outcome, with a cutoff value of 224 and 820 IU/L, respectively. These data could help the clinician identify a hepatic disease in equids and evaluate the prognosis in equids with a hepatic insufficiency.

The purpose of this study was to validate an equine-specific osteocalcin (OC) radioimmunoassay (RIA) for use in donkeys and to establish age-related changes in serum OC concentrations in healthy donkeys. Serial dilutions of donkey serum showed parallelism with standard curves obtained with the equine-specific OC RIA. There was a tight linear regression between donkey serum OC values obtained with the equine specific OC RIA and a commercially available bovine-specific OC RIA. Serum OC levels of 27 healthy donkeys, analysed with the equine-specific OC RIA, showed a tight negative logarithmic regression with age. Least square means and standard error of serum OC values were 67 +/- 10 microg/l in 0.6-4-year-old donkeys (group 1), 32 +/- 9 microg/l in 5-9-year-old donkeys (group 2) and 15 +/- 11 microg/l in > 9-year-old donkeys (group 3). Serum OC values were significantly (p < 0.01) higher in group 1 than in groups 2 and 3. The equine-specific OC RIA may be a useful and practical tool to assess bone metabolism and skeletal diseases in donkeys.

Objective—To evaluate a human assay for quantification of carboxy-terminal cross-linking telopeptide of type I collagen (CTX-I), assess the influence of age on plasma CTX-I concentration, investigate the relationship between plasma CTX-I and serum osteocalcin concentrations, and determine whether concentrations of plasma CTX-I or serum osteocalcin fluctuate in circadian manner in horses. Horses—75 clinically normal horses. Procedure—Cross-reactivity between equine serum CTX-I and CTX-I antibodies in an automated electrochemiluminescent sandwich antibody assay (ECLIA) was evaluated via a specificity test (ie, dilution test) and recovery calculation. Serum osteocalcin concentration was measured with an equine-specific osteocalcin radioimmunoassay. To analyze diurnal variations in plasma CTX-I and serum osteocalcin concentrations, blood samples were obtained hourly during a 24-hour period. Results—Results of the dilution test indicated good correlation ( r > 0.99) between expected serum CTX-I concentrations and measured serum CTX-I concentrations. The calculated CTX-I recovery was 97.6% to 109.9%. Plasma CTX-I and serum osteocalcin concentrations were correlated. Plasma CTX-I concentration was inversely correlated with age of the horse. No significant circadian variations in plasma CTX-I and serum osteocalcin concentrations were detected. Conclusions and Clinical Relevance—Results suggest that the fully automated CTX-I ECLIA can be used for evaluation of plasma and serum samples from horses and may be a useful tool to monitor bone metabolism changes. Horses in this study did not have notable diurnal fluctuations in serum osteocalcin and plasma CTX-I concentrations. ( Am J Vet Res 2004;65:104–109)

The purpose of this longitudinal in-field study was to evaluate the influence of exercise, age, and gender on superficial cortical bone of the third metacarpal bone (MC III) in young Thoroughbreds by measuring speed of sound (SOS) values with an axial transmission technique (Omnisense, Sunlight Ltd, Israel). Both MC III of 75 racehorses, 2 to 4 years old, were monitored with SOS measurements in 5- to 7-week intervals during a 9- month physical exercise period. Medical data and training programs (slow gallop, canter, and high-speed work) of each horse were recorded. SOS measurements began before 2-year-old horses started high-speed training. SOS values of the dorsal aspect of MC III were significantly lower in comparison with values obtained at the lateral and the medial aspect of MC III, and SOS values were inversely correlated with measurement cycles. Significant limb-associated differences in dorsal MC III SOS values were observed at measurement cycles 2, 3, and 4. SOS values obtained at the lateral and medial aspect of MC III increased with age. SOS values obtained at the dorsal aspect of MC III, decreased with age. Mares had significantly higher SOS values at the dorsal aspect of MC III, when compared with corresponding values in stallions. In 2-year-old Thoroughbreds SOS values of the dorsal MC III were significantly different between cycles 1 and 2, between cycles 3 and 4, and between cycles 4 and 5. Three-year-old horses showed significant differences between SOS values of the dorsal MC III obtained at cycles 3 and 4. Training intensities did not significantly influence SOS values. The results indicate that young exercising Thoroughbred racehorses have age-, gender-, and measurement-cycle-dependent variations in SOS values of MC III, which probably reflect adaptive variations in superficial cortical bone properties of MC III.

Objective—To evaluate the usefulness of multisite quantitative ultrasonography for noninvasive assessment of bone in horses.Sample Population—12 healthy horses and both forelimbs from 8 clinically normal horses.Procedure—For in vivo measurements, various regions of interest (ROI) were examined on the third metacarpal bone, radius, and tibia. Precision error for speed of sound (SOS) measurements was obtained by measuring each ROI of 4 horses 10 times with probe repositioning. Additionally, 3 operators measured each aspect of the third metacarpal bone of 6 horses 5 times each. For ex vivo measurements, third metacarpal bones were examined at 9 ROI, and SOS measurements were performed before and after soft tissue removal. One ROI of a single forelimb was subjected to 96 ex vivo measurements with 3 different contact media.Results—The lateral aspect of the third metacarpal bone had significantly higher SOS values than the dorsal and medial aspect of the third metacarpal bone. No difference was obtained between SOS values of the lateral and medial aspect of the radius. The tibia had significantly higher SOS values than the lateral aspect of the radius and the dorsal and medial aspect of the third metacarpal bone. Intraoperator coefficients of variation ranged from 0.62 to 3.15%, and interoperator coefficients of variation ranged from 0.78 to 2.70%. Values of SOS were highest when silicone oil was used as the contact medium.Conclusions and Clinical Relevance—Speed of sound measurements obtained by quantitative ultrasonography in axial transmission mode can be used to precisely measure superficial cortical bone properties of third metacarpal bone, radius, and tibia in horses. (Am J Vet Res2002;63:1464–1469)

Clostridium difficile has been identified as a significant agent of diarrhoea and enterocolitis in both foals and adult horses. Hospitalization, antibiotic therapy or changes in diet may contribute to the development of C. difficile infection. Horses admitted to a care unit are therefore at greater risk of being colonized. The aim of this study was to investigate the carriage of C. difficile in hospitalized horses and the possible influence of some risk factors in colonization. During a seven-month period, faecal samples and data relating the clinical history of horses admitted to a veterinary teaching hospital were collected. C. difficile isolates were characterized through toxin profiles, cytotoxicity activity, PCR-ribotyping, antimicrobial resistance and multilocus sequence typing (MLST). Ten isolates were obtained with a total of seven different PCR-ribotypes, including PCR-ribotype 014. Five of them were identified as toxinogenic. A high resistance to gentamicin, clindamycin and ceftiofur was found. MLST revealed four different sequencing types (ST), which included ST11, ST26, ST2 and ST15, and phylogenetic analysis showed that most of the isolates clustered in the same lineage. Clinical history suggests that horses frequently harbour toxigenic and non-toxigenic C. difficile and that in most cases they are colonized regardless of the reason for hospitalization; the development of diarrhoea is more unusual.

The cardiovascular response to 5-hydroxytryptamine (5-HT) challenge has been previously described in cattle. Abrupt bradycardia, followed by tachycardia, triphasic systemic blood pressure response, and pulmonary hypertension were the major changes elicited by 5-HT. The purpose of the present study was to determine whether the cardiovascular response to 5-HT in calves was attributable to 5-HT2receptors. A specific 5-HT2antagonist (metrenperone, 0.05mg/kg) was administered intramuscular to six unsedated Friesian calves 30min before the animals were given a 5-min intravenous 5-HT infusion. Mean systemic arterial (SAP), mean pulmonary arterial (PAP), pulmonary capillary wedge (PW) pressures were obtained by means of fluid-filled catheters, and cardiac output (CO) was measured by the thermodilution technique. Heart rate, stroke volume, systemic (SVR) and pulmonary (PVR) vascular resistances were calculated. Administration of 5-HT after metrenperone induced a short-lasting period of severe bradycardia followed by tachycardia and increased CO. The systemic blood pressure response was exclusively hypotensive and associated with a decrease in SVR. Conversely, PAP, PW, and PVR were not modified by 5-HT administration. The results establish that 5-HT induced systemic as well as pulmonary hypertension is mediated through the activation of type-2 serotonergic or a-adrenergic receptors, or both. In contrast, neither apnoea, bradycardia and hypotension, nor the positive chronotropic effect induced by 5-HT in cattle are mediated through such receptors.

Summary The effects of an acute non-isocapnic hypoxia on ventilation and pulmonary mechanics were investigated in 6 healthy unsedated Holstein-Friesian (HF) calves and in 7 double-muscled calves of the Belgian White and Blue (BWB) breed known to develop more severe hypoxemia during exercise and respiratory diseases. Data were collected at 1 min intervals throughout the following protocol: breathing air (FIO2 = 21%), then breathing hypoxic gas mixture (FIO2 = 10%) for 5 min, and, finally, breathing air again for 5 min of recovery. Arterial blood was sampled at rest and at the 4th min of hypoxia for blood gas analysis. In HF and BWB calves, hypoxia induced a significant increase in tidal and minute volume, but did not change respiratory rate, dynamic lung compliance and total pulmonary resistance. However, with regard to their ventilation during normoxia at rest, BWB calves showed a comparatively greater rise in ventilation than HF calves during the first 4 min of hypoxia. On the contrary, by the 5th minute of hypoxia, ventilation of BWB calves declined to the normoxic level while HF calves largely sustained hyperventilation. This hypoxic ventilatory depression in BWB calves could be explained by the proportionately greater initial increase in ventilation. It was concluded that BWB calves supported this hypoxic challenge less easily than HF calves.

The effects of norepinephrine (NOR) infusion on hemodynamic alterations induced with sedative doses of acepromazine (ACP) were evaluated. Infusion of NOR at 1 μg/kg body weight (BW)/minute for 15 min was administered to 5 standing horses 45 min (T45) after intravenous injection of ACP at 0.1 mg/kg BW. Systolic arterial blood pressure (SAP) and hemodynamic parameters were evaluated on the median artery. Parameters were evaluated every 5 min from 45 to 65 min (T65) at 75 (T75), 90 (T90), and 105 (T105) minutes after ACP administration, and the vessel’s surface (SURF), diameter (DIAM), circumference (CIRC), peak systolic velocity (PSV), end diastolic velocity (EDV), mean velocity (MV), volumetric flow (VF) and resistivity index (RI) of the flow were calculated. Acepromazine induced hypotension and vasodilation with a significant rise in SURF, DIAM, CIRC, PSV, EDV, MV, and VF and a reduction in RI and SAP, which were significantly counteracted from T50 to T60 for EDV, VF, MV and RI, and to T65 for SAP, from T50 to T90 for CIRC and SURF and to T60 for DIAM. These findings demonstrate that a 1 μg/kg BW/minute NOR infusion can reverse ACP’s vasodilatory effects, restoring hemodynamic parameters and blood pressure in horses.

Background Risk factors for cardiac diseases in horses have not been explored in a large population of animals. Objectives To describe risk factors for various cardiac diseases in a hospital-based population of horses. Animals Files of 3,434 horses admitted at the Internal Medicine Department of the Liege Equine Teaching Hospital between 1994 and 2011 were reviewed and of those, 284 were categorized as having moderate-to-severe cardiac disease. Methods Observational study. After calculating prevalence for each cardiac disease, we tested whether breed (chi-square test) or sex, age, body weight (BW), and other cardiac diseases (logistic regressions) were risk factors (p

To assess the prognostic value of echocardiographic parameters of left ventricular (LV) function in horses with systemic inflammatory response syndrome (SIRS).Prospective observational study.Veterinary teaching hospital.Forty-one horses admitted for colic with clinical evidence of SIRS.All horses underwent Doppler echocardiographic examination on admission. LV echocardiographic parameters, including pulsed-wave tissue Doppler imaging parameters, were compared between nonsurvivors (n = 29) and horses that survived to discharge (n = 12).With comparable heart rate and LV preload estimate, LV stroke volume index, the velocity time integral, deceleration time, ejection time of Doppler aortic flow, and peak early diastolic myocardial velocity were lower in the nonsurviving than in the surviving horses, while pre-ejection period to ejection time ratio (PEP/ET) of Doppler aortic flow and the peak early diastolic filling velocity to peak early diastolic myocardial velocity ratio (E/Em) were higher (P0.05). A cut-off value of 0.26 for PEP/ET predicted mortality with 100% sensitivity and 42% specificity (area under the receiver operating characteristic curve: 0.71), whereas a cut-off value of 2.67 for E/Em predicted mortality with 100% sensitivity and 83% specificity (area under the receiver operating characteristic curve: 0.89).Echocardiography may provide prognostic information in colic horses with clinical evidence of SIRS. Especially, PEP/ET and E/Em could be useful markers of systolic and diastolic dysfunction, respectively, to detect horses with a high risk of death requiring more intensive cardiovascular monitoring as it has been reported in human patients with septic shock.