Studies on equine prematurity 6: Guidelines for assessment of foal maturity

This paper describes criteria used to assess maturity of the newborn foal and their clinical application to field cases of prematurity and dysmaturity. Premature and mature foals may be clearly distinguished by their behavioural and physical characteristics. Measurement of haematological parameters (mean cell volume, total white cell and differential counts), pancreatic beta cell activity (plasma glucose and insulin levels), adrenocortical-medullary function (plasma cortisol, adrenocorticotrophic hormone and catecholamines) and the renin-angiotensin system (plasma renin substrate concentrations) were found useful in evaluating the status of the newborn foal. Confirmation of the initial diagnosis can be made by response to various challenge tests eg, glucose tolerance test, short acting synthetic adrenocorticotrophic hormone (ACTH1-24) and frusemide. In the present investigation a small number of individuals appeared to be intermediate in maturity to the other two groups, indicating that a third state of maturity may be identified. The clinical implications of this work suggest that cortisol replacement therapy and administration of long acting synthetic ACTH1-24 may be of benefit.     

Studies on equine prematurity 5: Histology of the adrenal cortex of the premature newborn foal

The histology of the adrenal cortex of prematurely induced newborn pony foals in relation to their ability to survive the neonatal period is described.     

Studies on equine prematurity 4: Effect of salt and water loss on the renin-angiotensin-aldosterone system in the newborn foal

Plasma renin substrate concentration was measured in 18, four-day-old pony foals after the administration of the natriuretic agent frusemide. Thirteen foals had been delivered spontaneously; labour had been induced in the remaining five mares. Plasma aldosterone concentration was measured in 12 of the spontaneously delivered foals. Renin substrate concentration had risen sharply within 15 mins (P<0.005) and peaked at 1 h. The response was consistently greater in the induced foals. Serum sodium concentration fell rapidly in the induced foals (P<0.002 by 60 mins) but was better maintained in the spontaneous group. Individual serum potassium concentrations varied widely and were higher in both the induced group and smaller (30 kg or less) spontaneous foals. Plasma renin substrate concentration was positively correlated with plasma potassium in both groups (P<0.05, P<0.001 respectively). Plasma aldosterone rose significantly within 30 mins (P<0.025) and did not stabilise during the experiment. Plasma aldosterone was significantly correlated with renin substrate concentration in both lighter (P<0.005) and heavier (P<0.05) spontaneously delivered foals. It is suggested that maturation of renal sodium and potassium handling occurs late in gestation in the foal and is in part related to body mass. ‘Premature’ delivery following induced labour is associated with a more rapid loss of sodium when challenged with frusemide, even though the response of the renin-angiotensin system may be exaggerated.     

Studies on equine prematurity 1: Methodology

This paper describes the general management of mares and foals during the perinatal period and the methodology used in a collaborative research project on equine prematurity. Sixteen mares with dated pregnancies delivered 45 foals over three breeding seasons (1981 to 1983). In the majority, parturition was induced with oxytocin and/or fluprostenol; the remainder were allowed to foal spontaneously. Pre-colostral milk analysis provided a means of assessing the pre-foaling status of the mare. All were observed and monitored before, during and after parturition and the sampling protocol for both mare and newborn foal is discussed in detail. The foals were assessed for their degree of maturity at birth using behavioural, haematological, acid-base status and other criteria; they were then assigned to groups for further study and tests.     

A survey of equine abortion and perinatal foal losses in Hungary during a three-year period (1998-2000)

Cases of equine abortion and perinatal foal losses were investigated in Hungary during a three-year period (1998-2000). Samples from aborted equine fetuses and newborn foals (total n = 96) were examined using bacteriological, virological, pathological, immunohistochemical (IHC), molecular biological and serological methods. The cause of abortion and perinatal foal loss was identified in 67/96 cases (70%); viral infection was found in 22 (23%), viral and bacterial coinfection in 1 (1%), bacterial infection in 23 (24%), protozoan infection in 1 (1%) and fungal infection in 2 cases (2%). Morphological lesions suggestive of infection were recorded in 2 (2%) and non-infectious causes in 16 cases (17%).     

围产期酮病奶牛高糖现象的研究

在黑龙江省某集约化奶牛场随机选取产后14、21 d的69头奶牛,旨在调查产后酮病奶牛的高血糖现象。根据血浆β一羟丁酸(BHBA)浓度,将试验牛分成酮病组(K)和健康对照组(C)。在酮病组中将产后14d和21 d都发病的分为病程长组(LTK),否则分为病程短组(STK)。检测所有试验牛血浆中GLU,游离性脂肪酸(NEFA)、BHBA和肝功指标。结果显示,围产期高血糖现象主要集中在STK组中;LTK组BHBA极显著高于STK组和C组。LTK组和STK组NEFA极显著高于C组,而LTK组与STK组之间差异不显著。LTK组GIU显著低于C组和STK组,而STK组与C组之间无显著差异。结论是肝功正常的酮病奶牛病程短,血糖维持正常,具有高糖现象;反之,肝功异常的酮病奶牛病程长,血糖水平低于正常。因此,患病奶牛的病程长短与奶牛血糖的调节能力及肝脏的功能状况密切相关。     

Isolation of equine coital exanthema virus (equine herpesvirus 3) from the nostril of a foal

The virus causing equine coital exanthema (equine herpesvirus 3) was isolated from a lesion on the nostril of a 2-month-old foal. One week after the mare had returned from a stallion station, vesicular lesions developed on her vulva. They were diagnosed clinically as coital exanthema, and 5 days later a lesion developed on the nostril of her foal. This case is an example of horse-to-horse transmission of coital exanthema virus without coitus. A laboratory diagnosis is necessary to differentiate viruses that cause vesicular lesions about the oral and nasal cavities of horses.     

围产期患高发代谢病奶牛T_4、T_3、TSH、I含量动态变化的研究

试验以处于围产期的68头奶牛(以健康经产牛为对照组,患酮病、脂肪肝、胎衣不下牛为试验组)为研究对象,在奶牛产前第15,8,1天和产后第1,8,15,22天分别采集颈静脉血检测血清中甲状腺激素[四碘甲腺原氨酸(T4)和三碘甲腺原氨酸(T3)]、促甲状腺激素(TSH)、碘(I)的含量。结果表明:健康的经产牛围产期血清中T4、T3、TSH、I均呈现波浪式动态变化,最高值分别出现在产前第1天、产后第22天、产后第1天、产前第15天;TSH最低值出现在产前第15天,其他检测指标最低值出现在产后第1天。患酮病的奶牛和患脂肪肝的奶牛围产期处于缺碘状态,其产后甲状腺机能出现减退;患脂肪肝期间同时伴发甲状腺功能减退症;患胎衣不下的奶牛围产期碘含量低于正常值,其产犊前后伴发亚临床甲状腺功能减退症。数据统计结果显示:奶牛血清中T4与TSH、T3、I的相关系数分别为-0.749,0.535,0.691;T3与TSH、I的相关系数分别为-0.502,0.457。     

Changes in lymphocyte blastogenic response of mares during the perinatal period

A fluorometric assay was applied to evaluate blastogenesis of equine lymphocytes. Optimal culture conditions were as follows; concentrations of phytohaemagglutinin-P (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) were 1 microgram/ml, 40 micrograms/ml and 10 micrograms/ml, respectively, when 5 X 10(5) lymphocytes were incubated with culture medium containing 20% pooled horse serum (PHS) for 120 hours. The relative mean stimulation index of healthy non-pregnant mares were 5.107 +/- 0.323 (M +/- SE) with PHA, 4.019 +/- 0.183 with Con A and 3.610 +/- 0.131 with PWM. Sequentially the blastogenic responses of lymphocytes from twenty mares were observed during various stages of the perinatal period. Response decreased gradually before parturition was lowest at the time of parturition (PHA: 1.923 +/- 0.174, Con A: 1.698 +/- 0.206 and PWM: 1.706 +/- 0.177), and then increased gradually after parturition towards non-pregnant levels.     

Studies of maternally-acquired antibodies in the foal to equine influenza A1 and A2, and equine rhinopneumonitis

Serum and colostrum were collected from 50 mares at parturition. Pre- and post-nursing serum samples were obtained from their foals. Bi-weekly serum samples were obtained from 25 of the foals for eight weeks. Hemagglutination-inhibiting (HAI) antibody titers to equine influenza viruses A₁ and A₂ (EIVA₁ and EIVA₂) and serum-neutralizing antibody titers to equine herpes virus 1 (EHV₁) were measured in serum and colostrum samples. IgG levels in serum and colostrum were determined.No antibody was detected in any foal's pre-nursing serum sample. Foal post-nursing antibody and IgG levels were equivalent to those measured in their dam's sera (EHVA₁ p=0.86; EHVA₂ p=0.54; EHV₁ p=0.91; IgG p=0.58). The half-life of maternally-acquired serum antibody in the foals was determined to be: EIVA₁=28.88 days (26.4 to 31.7 days); EIVA₂=29.1 days (26.7 to 32.1 days); EHV₁=31.0 days (28.1 to 34.8 days). Colostrum contained antibody and IgG at levels ranging from 2 to 8 times higher (4.3 average) than those detected in the mare's serum.     

Interleukin-1 receptor antagonist expression in the equine endometrium during the peri-implantation period

To identify factors involved in the establishment of pregnancy in the mare, endometrium was collected from day 13 (day 0 = day of ovulation) cyclic and day 13, 19, and 25 pregnant animals. From initial cDNA subtraction studies, interleukin-1 receptor antagonist (IL-1RN) mRNA was found as a candidate molecule expressed uniquely in the pregnant endometrium. Expression of IL-1RN mRNA was markedly increased in day 19 and 25 gravid endometrium. In situ hybridization analysis revealed that IL-1RN mRNA was localized to the glandular epithelium. Interleukin-1 receptor antagonist (IL-1RN) protein was found in the extracts of day 25 gravid endometrium and was immunochemically localized to the glandular epithelium/luminal cavity of the pregnant uterus. High concentrations of estradiol-17β (E₂) were detected in day 25 conceptuses. Concentrations of E₂ were higher in the gravid endometrial portion than in other endometrial regions. On the other hand, progesterone concentrations did not differ among endometrial samples analyzed. Furthermore, the expression of IL-1RN mRNA was up-regulated in endometrium culture samples treated with 10 ng/mL E₂ and 10 ng/mL progesterone. In the analysis of related gene expression, increased amounts of IL-1α and IL-6 mRNA were also found in the day 25 gravid endometrium; however, these expressions in endometrial culture samples were not up-regulated by the steroid treatment. These results indicate that expression of IL-1RN in the endometrium is likely regulated by E₂ and progesterone and suggest that IL-1RN regulates the degree of IL-1 signal transduction and thereby plays an important role in the establishment of equine pregnancy.     

反刍动物围产期能量负平衡的调控研究进展

在奶牛围产期,许多奶牛因能量负平衡(NEB)无法适应代谢、内分泌和生理的巨大变化,引发酮病和脂肪肝,影响奶牛产后恢复,造成严重的经济损失.奶牛分娩、产犊的应激性大,产奶量增长迅速,采食量降低,饲养中能量供应不足是此阶段存在的主要问题.为获得更高品质的肉制品以及更高的养殖收益,文章针对调控围产期NEB展开综述,以期为生产...     

微生态制剂对围产期牦牛瘤胃微生物及发酵功能的影响

试验旨在研究微生态制剂对围产期牦牛血液生化、瘤胃微生物区系和瘤胃发酵功能的影响。将20头牦牛,按照年龄、体重、胎次及生理状态相近的配对原则,分为对照组和处理组(微生态制剂),饲喂期42 d,在不同日龄收集血清和瘤胃液。结果表明,与对照组相比,微生态制剂可以降低血液中β-羟丁酸(BHBA)浓度和瘤胃液中乳酸浓度,增加瘤胃液中丙酸浓度;显著增加瘤胃液中反刍月形单胞菌和栖瘤胃普雷沃氏菌数量,降低黄色瘤胃球菌数量。研究表明,微生态制剂通过影响围产期牦牛瘤胃微生物,可以改善牦牛瘤胃发酵功能和产后代谢紊乱。     

Quantitative changes of lung tissue components during perinatal period in rats

Quantitative changes of lung tissue components (air spaces lined by PAS-positive and PAS-negative epithelium, blood vessels and interstitium) were investigated in developing rats from fetal day 18 through neonatal day 1. The volume of the left lung increased significantly from fetal day 18 through neonatal day 1. The percentage and volume of the air spaces increased strikingly between fetal days 20 and 21. However, the percentage of the air spaces lined by PAS-positive epithelium decreased significantly from fetal days 20 to 21, and that of the spaces lined by PAS-negative epithelium increased between the two days. The proliferating cell nuclear antigen (PCNA)-positive cells were rich in the interstitium and epithelium of the air spaces on fetal days 18 and 19. The percentage of the interstitium decreased significantly from fetal day 18 through neonatal day 1, showing remarkable decrease between fetal days 20 and 21. From fetal day 20 onward, the PCNA-positive cells decreased in number and located in the epithelium of the conducting air ways and interstitium. Based upon these findings, the present study suggests that the period from fetal days 20 to 21 is a critical time for the development of fetal lung: the period before fetal day 20 is that for proliferation and the period after fetal day 21, functional differentiation of the lung.     

马属动物气喘病研究

马属动物气喘病是役用马、骡、驴发生的一类以气喘为主要临床症状的呼吸器官疾病 ,一般称为气喘病或喘证。本病为世界性分布 ,我国对此病的研究报道也较多 ,甘肃、云南、内蒙古、西藏等省区均有发生。青海省 70年代就有该病发生 ,主要发生于海拔相对较低的农业区的役用马属动物 ,但引起的死亡率较低 ,造成的直接经济损失也不大 ,因此多年一直未有研究。但近年来 ,马属动物气喘病在青海省贵德县流行严重 ,1 996年 2～ 5月 ,马、骡气喘病占门诊马属动物病例的 78% ,为此笔者于 1 991年～ 1 996年先后对青海马属动物气喘病的发病情况及治疗作了…     

Effects of dietary yeast culture supplementation during the conditioning period on equine exercise physiology

Two groups of previously unconditioned young adult horses participated in 6 weeks of gradually increasing exercise on an inclined plane treadmill while receiving a cornoats-hay diet with or without a commercially available dietary yeast culture preparation. Forced treadmill exercise at a workload of 11.98 j/kg/m, equivalent to a workrate of 18.34 j/sec/kg and an estimated ground speed of 5.36 m/sec, began at 5 minutes per day (2.75 Mjoules/500 kg body-weight) and was increased by 5 minutes per week to a maximum of 35 minutes per day (19.25 Mjoules/500 kg) after 6 weeks. Treadmill exercise increased venous plasma lactate concentrations in direct proportion to the duration of an exercise bout, but the increases tended to be smaller after a given amount of work as the horses became conditioned. At the end of 35 minutes of exercise, plasma lactate concentrations averaged 30.08 mg/dl in the supplemented horses and 41.29 mg/dl in the unsupplemented horses (p<.01). Plasma glucose concentrations decreased significantly and triglyceride concentrations increased significantly in both groups as exercise duration exceed 10 minutes. Changes in plasma glucose concentrations were not significantly affected by yeast culture supplementation, while the supplemented horses exhibited somewhat slower rates of increased plasma triglyceride concentrations. During the 35-minute exercise bouts, significantly lower heart rates were recorded in the supplemented horses during the first 5 and the final 10 minutes of the workouts (p<.01), suggesting an enhanced state of athletic fitness. The digestible energy required for work (Mcal/500 kg bodyweight) was calculated to be 0.454 (Mcal/Mjoule) (Mjoules of work/500 kg bodyweight) + 0.024 Mcal/500 kg bodyweight (r²=0.95), with an efficiency of converting dietary DE to work of 53% for both groups of horses. Although the exercise challenges to these horses were not severe, these results suggest that dietary yeast culture supplementation of horses entering into conditioning programs may well enhance athletic training.