Systolic Time Intervals and Their Derivatives for Evaluation of Cardiac Function

Systolic time intervals provide a noninvasive indication of global left ventricular performance, are relatively sensitive, and are easily obtained from an M-mode echocardiogram. This paper defines systolic time intervals (preejection period, left ventricular ejection time, and total electromechanical systole) and their derivatives (preejection period/left ventricular ejection time and velocity of circumferential fiber shortening). Their utility and weaknesses, as well as the effects of heart rate, loading conditions, cardiac contractility, and drug therapies on systolic time intervals are discussed. Normal values for systolic time intervals for the dog and cat are provided.     

Pharmacokinetics, penetration into cerebrospinal fluid, and hematologic effects after multiple oral administrations of pyrimethamine to horses.

Pharmacokinetics, CSF penetration, and hematologic effects of oral administration of pyrimethamine were studied after multiple dosing. Pyrimethamine (1 mg/kg of body weight) was administered orally once a day for 10 days to 5 adult horses, and blood samples were collected frequently after the first, fifth, and tenth doses. The CSF samples were obtained by cisternal puncture 4 to 6 hours after administration of the first, third, seventh, and tenth doses. Pyrimethamine concentration in plasma and CSF was quantified by gas chromatography, and plasma concentration-time data were analyzed, using a pharmacokinetic computer program. Repeated daily dosing resulted in accumulation of pyrimethamine in plasma, with steady state being achieved within 5 days, when the mean peak plasma concentration was more than twice that measured after the first dose. Pyrimethamine concentration in CSF was 25 to 50% of corresponding plasma concentration and did not appear to accumulate with successive administration of doses. Blood samples collected during and after the dosing regimen were submitted for hematologic analysis; neutrophil numbers decreased slightly, but remained within normal range for adult horses.     

Intrapericardial Cysts in the Dog

Intrapericardial cysts were identified as the cause of impaired cardiac filling in six young dogs. Pneumo-pericardiography and two-dimensional echocardiography showed the cysts in 2 of 2 dogs and in 4 of 4 dogs, respectively. One dog, which was also infected with heartworms, died before surgical excision of the cyst could be performed. In the remaining dogs, surgical excision of the cysts and subtotal pericar-diectomy was successfully accomplished. Histologic examination of the excised tissue from one dog suggested that it was a pericardial coelomic cyst. The gross and histologic characteristics of the cysts removed from the other five dogs resembled those of acquired cystic hematomas. The etiopathogenesis of these cysts was uncertain, but all cysts were connected to a fatty pedicle of tissue. In one dog, a stalk of tissue was observed to enter the pericardium through a small peritoneopericardial diaphragmatic hernia. In four dogs, the stalk of tissue was adhered to the apex of the parietal pericardium. These observations suggested that intrapericardial cysts, in some dogs, develop in association with, and possibly as a result of, congenital herniation and entrapment of omentum or a portion of the falciform ligament into the pericardial sac. (Journal of Veterinary Internal Medicine 1993; 7:364–369. Copyright © 1993 by the American College of Veterinary Internal Medicine.)     

Experimental production of fatal mucosal disease in cattle

Three outbreaks of mucosal disease were investigated. Careful examination of 47 cattle that were persistently viraemic with bovine virus diarrhoea virus (BVDV) revealed no clinical disease, no or low levels of BVDV antibody and only non-cytopathic virus in their blood. The four animals with mucosal disease all showed clinical disease and both cytopathic and non-cytopathic virus in their blood. Following post mortem examination, there were particularly high levels of cytopathic virus in gut tissue. A hypothesis for the induction of mucosal disease is suggested. It states that animals become persistently infected with non-cytopathic virus following in utero infection and when, in post natal life, they become superinfected with a cytopathic virus, then mucosal disease ensues. The experimental reproduction of mucosal disease in support of this hypothesis is described.     

Cardiopulmonary effects of medetomidine in sheep and in ponies

Medetomidine was administered intravenously to six sheep at 5, 10 and 20 μg kg⁻¹ and to one horse and four ponies at 5 and 10 μg kg⁻¹. In both species medetomidine resulted in significant decreases in heart rate and cardiac output and, initially, in an increase in arterial blood pressure. In the ponies this increase in blood pressure was followed by a significant and prolonged decrease, but in the sheep the secondary decrease in blood pressure was not statistically significant. In the sheep, the three doses of medetomidine resulted in profound and significant decreases in arterial oxygen tensions, which were significantly dose related, but in the ponies the arterial blood oxygen tensions were not significantly decreased. In both species medetomidine caused a small but significant increase in arterial blood carbon dioxide tensions.     

Using the Tools of the Information Age to Enhance Research and Management of the Southern Pine Beetle

The Southern Pine Beetle (SPB) is a major pest in southern U.S.A., Mexico, and Central America. Enormous resources in terms of funding, personnel, and effort have been allocated for research and development of pest management tools for this pest over the past century. Access to information from journal articles, reports, fact sheets, etc. does require some effort and is often incomplete and difficult to obtain. The emergence of the Internet now allows rapid access to information from diverse sources. We have created a comprehensive website entitled, 'The Southern Pine Beetle Internet Control Center' (SPBICC) (www.spbicc.vt.edu). The goal of the site is to provide all available resources on SPB to anyone with access to the Internet. It is also designed to increase communication among researchers and professionals to help advance the management of this pest. The site is interactive, which permits constant updating without contacting a webmaster. Attributes of the site include background information in the form of fact sheets, reviews, and government handbooks; an interactive diagnostic identification key for SPB and other bark beetles; a searchable expertise directory; a calendar of SPB-related events; a discussion forum; an online SPB spot growth predictive model; a searchable bibliographic database; a webcrawler designed to search for SPB-related websites, and more. Web-based tools were developed to integrate relational databases as the functional base of this site. The dynamic nature of the SPBICC makes it a powerful tool and a model for development of websites for other major agricultural or forest pests.