Pulmonary Thromboembolism in Dogs

Pulmonary thromboembolism (PTE) is an infrequently diagnosed complication of many systemic diseases including heartworm disease, glomerulopathy leading to the nephrotic syndrome, immune-mediated hemolytic anemia, hyperadrenocorticism, pancreatitis, neoplasia, and sepsis. Acute, unexplained dyspnea in a patient with minimal abnormalities on thoracic radiographs should prompt consideration of this diagnosis. Confirmation requires ventilation-perfusion radionuclide scanning or selective pulmonary angiography. Treatment includes cage rest, anticoagulant therapy with heparin and warfarin, correction of the underlying disorder, and supportive care. Clinicians should be prepared to treat hemorrhage associated with anticoagulant therapy. Recombinant tissue plasminogen activator may prove useful as a thrombolytic in the treatment of animals suffering massive PTE, but is, at present, expensive.     

缺氧、肺动脉高压、心脏功能与肉鸡腹水综合征的关系

为阐明缺氧、肺动脉高压、心脏功能与肉鸡腹水综合征 (ascites syndrome,AS)之间的关系 ,比较了正常肉鸡、亚临床腹水鸡和腹水鸡的右心室平均压 (m RVP)、平均肺动脉压 (m PAP)、心电图 导联 S波幅 (L ead S)、红细胞压积(HCT)、动脉血血氧饱和度 (Sa O2 )、心率 (HR)和右心肥大指数 (RV/ TV) ,并对这些指标进行相关分析和回归分析。结果表明 :在 AS的发展过程中 ,m RVP、m PAP、L ead S、HCT和 RV/ TV逐渐升高 ,HR和 Sa O2 逐渐下降 ;各指标相互之间的相关性都很高 (P<0 .0 0 1) ;HCT发生变化较其他指标早。此外 ,亚临床腹水鸡的左心室和体质量的比值 (L V/BW)及全心室和体质量的比值 (TV/ BW)最高 ,与腹水鸡的 L V/ BW值差异显著 (P<0 .0 5 ) ;正常鸡的 TV/ BW最低 ,与亚临床腹水鸡的差异显著 (P<0 .0 5 )。结果说明肺动脉压升高与机体慢性缺氧有关 ,且是造成右心肥大衰竭和 AS的原因 ;AS发展早期肉鸡心脏功能是代偿性增加的 ;m RVP、m PAP、L ead S、HCT和 Sa O2 可作为早期诊断、预测AS的指标。     

Echocardiographic changes induced by moderate to marked hypobaric hypoxia in dogs

Hypobaric (high-altitude) hypoxia is a physiologic cause of pulmonary hypertension, and alters left ventricular (LV) systolic and diastolic function. In the presence of tricuspid regurgitation, systolic pulmonary artery pressure can be measured noninvasively using the peak tricuspid regurgitation velocity and the Bernoulli equation. In the absence of measurable tricuspid regurgitation, severity of pulmonary hypertension may be estimated using two-dimensional, M-mode, and Doppler-derived parameters. To evaluate the usefulness of echocardiographic parameters for detecting mild-to-moderate pulmonary hypertension caused by moderate-to-marked hypoxia and to study the effect of high-altitude hypoxia on systolic and diastolic LV function in dogs, 19 Greenland dogs were examined at moderate altitude (2300 m) and high altitude (3500 m), and 10 Greenland control dogs were examined at 700-900 m. Evaluated parameters were pulmonary flow profile (shape, right ventricular acceleration time (RVAT), ejection time (RVET), RVAT/ET), peak mitral inflow velocities (LVE, LVA, LVE/A-ratio), LV % fractional shortening (FS), systolic time intervals (LVPEP, LVPEP/ET), and stroke volume index (SVI). Notching during deceleration was common in dogs at high altitude and in the control dogs, but not in dogs at moderate altitude. RVAT was shorter in dogs at high altitude compared with moderate altitude, but not compared with control dogs. Peak A-velocity was higher and E/A-ratio was lower in dogs at high altitude compared with moderate altitude and control dogs. FS was increased in dogs at high altitude compared with moderate altitude, and LVPEP and LVPEP/ET were shorter in the dogs at high altitude compared with moderate altitude and control dogs. In conclusion, significant differences in pulmonary flow profiles and systolic and diastolic parameters can be observed echocardiographically in dogs at different degrees of hypobaric hypoxia. However, overlap between the groups compromises their usefulness for diagnosing and estimating the degree of mild-to-moderate pulmonary hypertension in individual dogs.     

扎鲁司特对低温诱发的肉鸡肺动脉高压的影响

将60只雄性艾维茵商品代肉鸡常规育雏，17日龄随机分为3组：常温对照组(常温组)、低温模型组(低温组)和低温扎鲁司特组(扎鲁司特组)。各组于处理后14d(31日龄)和21d(38日龄)分别用右心导管法及直接导管法测定扎鲁司特对肺动脉压(PAP)和股动脉压(FAP)的影响，同时测定红细胞压积(PCV)和腹水心脏指数(AHI)。结果：(1)在低温环境的早期，扎鲁司特使肉鸡肺动脉收缩压和舒张压均升高，后期仅使舒张压升高；(2)扎鲁司特使PCV升高，增加了血液黏性阻力；(3)扎鲁司特使AHI升高，促进右心肥大；(4)扎鲁司特对股动脉压无显著性影响。可见扎鲁司特促进了肉鸡肺动脉高压综合征的发生发展。     

高盐负荷诱发肉鸡肺动脉高压-腹水综合征

为探讨肺动脉高压在高盐负荷所致肉鸡腹水综合征发生发展的作用。将160只AA商品代肉仔鸡常规饲养至7日龄,随机分成对照组和试验组(饮水中添加0.30%氯化钠),分别于处理后1、2、3、4、5、6周,每组随机抽取8只鸡,利用右心导管法测定平均肺动脉压(mPAP),用温氏法检测红细胞压积(PCV),同时测定腹水心脏指数(AHI),统计腹水发生率。结果表明:(1)高盐负荷诱发肉鸡肺动脉高压,高盐处理1周试验组肉鸡肺动脉压升高为2.91±0.29kPa,显著高于对照组2.18±0.40kPa(P<0.05);并在整个处理期间持续升高,均显著(P<0.05)或极显著(P<0.01)地高于对照组;(2)高盐负荷诱发肉鸡AS,整个试验期间试验组的累计腹水发生率(16.3%)极显著高于对照组(2.5%)(P<0.01);(3)自分组后1周试验组的红细胞压积显著(P<0.05)或极显著(P<0.01)高于对照组,且与mPAP极显著相关(15～50日龄,r=0.612,P<0.01);(4)高盐负荷诱发肉鸡右心肥大,处理后2周试验组的AHI显著增高(P<0.05),与mPAP显著相关;并在整个处理期间相关程度逐渐密切(22日龄,r=0.532,P<0.05;50日龄,r=0.756,P<0.01)。这些结果说明肺动脉高压是高盐负荷所致肉鸡AS的中心环节,并且与右心肥大密切相关。     

环境低温和T3致肉鸡腹水、肺动脉高压和肺微细动脉肌型化

21 0羽 AA商品肉鸡随机分为 A、B、C 3个组 ,常规饲养。 1 4日龄后 A组鸡正常对照 ,而 B、C组鸡舍温按每日1～ 2℃由 2 5℃逐步降至 1 2℃ ,同时 C组在日粮中按 1 .5 mg/ kg的剂量添加甲状腺素 T3以诱发肉鸡腹水综合征 ( as-cites syndrom e,AS)。结果表明 :低温和 T3能显著增加 AS发病率、红细胞压积 ( PCV)值、右心室与全心室重量比( RV/ TV)、平均肺动脉压 ( m PAP)和厚壁末梢血管百分率 ( TWPV % ) ( P<0 .0 1 )。从而揭示了环境低温和 T3诱发的AS患鸡已发生了肺动脉高压和肺微细血管肌型化     

钙信号转导与缺氧诱发肉鸡肺动脉平滑肌细胞癌基因c-fos、c-myc表达的关系

利用细胞免疫组化、原位杂交技术研究钙信号与缺氧诱发肺动脉平滑肌细胞(PASMC)癌基因c-fos、c-myc表达的关系。结果显示,钙通道拮抗剂verapamil(V)、nifedipine(N)、Cyclosporin A(C)显著抑制缺氧引起的c-fos和c-mycmRNA的表达(其中c-fosmRNA:缺氧组198.1±32.8,缺氧 V组161.6±24.1,缺氧 N组173.7±35.8,缺氧 C组159.0±32.8,P<0.01;c-mycmRNA:缺氧组187.1±22.4,缺氧 V组150.5±22.6,缺氧 N组155.1±25.4,缺氧 C组148.9±29.7,P<0.01)。同时显著抑制缺氧引起的c-fos和c-myc蛋白的表达(其中c-fos蛋白:缺氧组225.9±37.0,缺氧 V组162.3±33.6,缺氧 N组157.4±28.9,缺氧 C组151.6±37.3,P<0.01;c-myc蛋白:缺氧组228.8±33.4,缺氧 V组170.2±26.7,缺氧 N组170.7±28.5,缺氧 C组179.1±29.2,P<0.01)。verapamil和nifedipine能够显著抑制缺氧引起的癌基因表达,表明钙信号转导参与了缺氧引起PASMC癌基因的表达过程。Cyclosporin A可显著抑制缺氧引起的癌基因的转录表达,表明钙信号转导系统中的Ca2 /CaM-CaN转导通路在PASMC增殖过程中具有重要作用。PASMC增殖是肉鸡腹水综合征的主要特征,钙信号转导激活引起PASMC增殖的c-fos和c-myc的转录表达,表明钙信号转导可能与肉鸡腹水综合征的发生发展密切相关。     

低温诱发肉鸡肺动脉高压中肺血管重塑的作用

采用低温处理肉仔鸡的方法,通过测定肺动脉压、肺小动脉中膜厚度占外径百分比及中膜面积与血管总面积比的变化,探讨肉鸡肺动脉高压的发生机制.结果表明:肺血管重塑在低温诱发肉鸡的肺动脉高压发生发展中起重要作用.