Thymic hyperplasia causing right ventricular outflow tract compression following treatment for oesophageal rupture in an Arabian colt

True thymic hyperplasia has been reported sporadically in the human literature as an immunological rebound phenomenon following immunosuppressive treatment or disease. There are limited accounts in domestic species, mainly following vaccination, and thymic hyperplasia has not been a recognised condition in the horse to date. This report details a case of true thymic hyperplasia in a 10-week-old Arabian colt diagnosed by histopathology of core biopsy samples. The colt developed pulmonary stenosis caused by compression due to a space occupying lesion in the cranial mediastinum following a 3-month history of hospitalisation for treatment of traumatic oesophageal rupture with perioesophageal abscess formation. Diagnostic imaging of the cranial mediastinum was indicative of a thymic mass, and histopathology confirmed the mass was normal (hyperplastic) thymic tissue. The colt was treated with a tapering dose of corticosteroids, which led to involution of the hyperplastic tissue and resolution of pulmonary artery compression. Thymic hyperplasia may be an unrecognised sequela to chronic inflammation in horses and was only identified in this case when the size was sufficient to compress right cardiac outflow.     

An exploratory investigation of echocardiographic parameters and the effects of posture on cardiac structure and function in the Livingstone's fruit bat (Pteropus livingstonii)

There is growing evidence that dilated cardiomyopathy may be a major cause of death in captive Livingstone's fruit bats (Pteropus livingstonii). Therefore, the primary aim of this prospective, exploratory study was to examine whether a systematic cardiac ultrasound protocol is feasible in this critically endangered species and to report basic measures of cardiac structure and function from a cohort of apparently healthy bats. A secondary aim was to test the effect posture (dorsal recumbency vs. roosting) has upon cardiac function in this species. Transthoracic echocardiograms, including 2D, Doppler, and tissue Doppler measures of cardiac structure and function were completed as part of routine health examinations for bats at a single center (n = 19). Bats were then grouped by age and disease status and the mean and range data reported for each group. In healthy adult bats, with the exception of a reduction in heart rate (P ≤ 0.05), right atrial systolic area (P ≤ 0.05), and right ventricular velocity during atrial contraction, there were no significant changes in cardiac structure or function in response to the roosting position. However, in the bats presenting with dilated cardiomyopathy the current data suggest that left ventricular ejection fraction is improved while roosting. Further work is required to confirm our initial findings, generate diagnostic reference intervals, and explore the causes of dilated cardiomyopathy in this species.     

Aortic rupture causing cardiac tamponade in a 24‐day‐old Friesian colt with concurrent colonic Chlamydiosis and Balantidiasis

A 24‐day‐old Friesian colt died suddenly and a physical examination the morning the foal died showed no abnormalities and serum IgG levels >8.0 g/l. Necropsy examination revealed haemopericardium and a 2 cm transverse tear at the root of the aorta. The foal was also found to have Chlamydophila spp. in the epithelium and Balantidium coli on the mucosal surface of the large colon. An aortic rupture is a novel finding in a foal, colonic Chlamydiosis has not been previously reported in horses and Balantidium coli has not been reported in equids in North America.     

The cardiopulmonary effects of dobutamine and norepinephrine in isoflurane-anesthetized foals

OBJECTIVE: To evaluate the cardiovascular effects of norepinephrine (NE) and dobutamine (DB) in isoflurane-anesthetized foals. STUDY DESIGN: Prospective laboratory study. METHODS: Norepinephrine (0.05, 0.10, 0.20, and 0.40 microg kg(-1) minute(-1)) and dobutamine (2.5, 5.0, and 10 microg kg(-1) minute(-1)) were alternately administered to seven healthy, 1- to 2-week-old isoflurane-anesthetized foals. Arterial and pulmonary arterial blood pressure, right atrial pressure, pulmonary artery occlusion pressure, heart rate, body temperature, cardiac output, arterial and mixed venous blood pH, partial pressure of carbon dioxide, partial pressure of oxygen [arterial partial pressure of oxygen (PaO(2)) and mixed venous partial pressure of oxygen (PvO(2))], and packed cell volume were measured. Standard base excess, bicarbonate concentration, systemic and pulmonary vascular resistance, cardiac index (CI), stroke volume, left and right stroke work indices, oxygen delivery (DO(2)), consumption, and extraction were calculated. Results Norepinephrine infusion resulted in significant increases in arterial and pulmonary arterial pressure, systemic and pulmonary vascular resistance indices, and PaO(2); heart rate was decreased. Dobutamine infusion resulted in significant increases in heart rate, stroke volume index, CI, and arterial and pulmonary arterial blood pressure. Systemic and pulmonary vascular resistance indices were decreased while the ventricular stroke work indices increased. The PaO(2) decreased while DO(2) and oxygen consumption increased. Oxygen extraction decreased and PvO(2) increased. CONCLUSIONS AND CLINICAL RELEVANCE: Norepinephrine primarily augments arterial blood pressure while decreasing CI. Dobutamine primarily augments CI with only modest increases in arterial blood pressure. Both NE and DB could be useful in the hemodynamic management of anesthetized foals.     

Effects of intravenous butorphanol on cardiopulmonary function in isoflurane-anesthetized alpacas

OBJECTIVE: To determine the effects of intravenous (IV) butorphanol on the cardiopulmonary system and on the bispectral index (BIS) in isoflurane-anesthetized alpacas. STUDY DESIGN: Randomized, blinded cross-over experimental trial. ANIMALS: Eight healthy, young (3 +/- 1 SD years) adult female alpacas weighing 64 +/- 9 SD kg. METHODS: Alpacas were anesthetized with isoflurane by mask followed by tracheal intubation and maintenance of anesthesia with isoflurane in oxygen and intermittent positive pressure ventilation. Animals were assigned to two treatments, butorphanol (0.1 mg kg(-1), IV) and saline (0.01 mL kg(-1), IV) in a randomized manner allowing a 2-week interval between treatments. Cardiovascular variables included systolic, diastolic, and mean arterial blood pressure, heart rate, pulmonary arterial pressure, pulmonary arterial occlusion pressure (PAOP), central venous pressure, cardiac output, and pulmonary temperature (TEMP). Cardiac index, systemic vascular resistance (SVR), and pulmonary vascular resistance (PVR) were calculated. Bispectral index was also measured. Arterial and mixed venous blood samples were collected for blood gas analysis. All variables were recorded at baseline (time 0) and at 5, 10, 15, 30, 45 and 60 minutes following injection and were analyzed by using repeated-measures ANOVA (p < 0.05). PAOP, PVR, and BIS were analyzed by paired t-tests. RESULTS: Butorphanol decreased SVR at all times when compared with the baseline, but no difference was detected between treatments. TEMP decreased with time in both treatments, but they were not different from each other. Other cardiovascular, BIS, and blood gas variables were not different between groups. CONCLUSION AND CLINICAL RELEVANCE: We conclude that butorphanol had minimal effects on the cardiovascular system of the alpacas, causing a mild decrease in SVR.     

肉鸡肺动脉高压综合征自然病例肺动脉压的动态变化

将自然发病的肺动脉高压综合征艾维茵商品代肉鸡按日龄分组,右心导管法测定平均肺动脉压(PAPm),根据腹水量确定各组内腹水程度,设无腹水的正常鸡作对照．并进行显著性比较。结果：(1)24、36日龄组发病鸡的PAPm均极显著高于同日龄的正常鸡,30日龄组发病鸡显著高于正常鸡,42日龄组发病鸡高于正常鸡(8．3％)但无显著性差异。(2)发病鸡的PAPm在30日龄时极显著高于24日龄;36日龄时显著高于30日龄;40日龄时低于36日龄(4．3％),但差异不显著。(3)发病鸡的PAPm与腹水量间呈极显著正相关。结果表明,PAPm在本病发生和发展过程中都起着重要作用,并且与本病致死率有一定联系。     

miR-210-5p对南极独角雪冰鱼心脏发育的作用机制研究

microRNA为短链非编码RNA,通过与靶基因3'UTR序列互补在转录后水平发挥作用。已有研究表明,microRNA在心脏发育过程中起着重要的调控作用。南极冰鱼因体内缺乏功能性血红细胞,其心脏出现了补偿性增生。前期的研究提示,独角雪冰鱼心脏中特异表达的microRNAs可能与冰鱼心脏的补偿性增生相关。本研究针对南极冰鱼心脏中高表达的miR-210-5p,运用斑马鱼显微注射、靶基因预测等手段研究了miR-210-5p对心脏发育的作用机制。结果表明:斑马鱼胚胎注射miR-210-5p后,出现心包膜水肿,心脏发育畸形等现象。qRT-PCR分析显示,过表达miR-210-5p的斑马鱼胚胎中,心脏发育相关的标志性基因bmp4、smad1、gata6以及tbx2b的表达水平下调。Western blotting分析发现,bmp/smad通路中的BMP2、BMP4、SMAD1、GATA6以及TBX2B的蛋白表达水平也显著下调。通过对tbx20基因3'UTR的靶基因生物信息学预测,以及对其进行GFP荧光表达分析,发现tbx20基因可能是miR-210-5p的一个靶基因。由此推测,miR-210-5p可能通过抑制tbx20基因的表达,并调控bmp/smad通路以抑制冰鱼心脏发育。