Cardiovascular effects of vasopressors in halothane-anesthetized dogs before and after hemorrhage

Exogenously administered vasopressors (sympathomimetics) were evaluated in halothane-anesthetized dogs to determine the effects of these drugs on cardiovascular function before and after hemorrhage. Six dogs were anesthetized with thiamylal sodium (20 mg/kg of body weight) and halothane (1.25 minimal alveolar concentration) in 100% oxygen. After instrumentation, cardiac output, systemic arterial blood pressure (SAP), heart rate (HR), left ventricular pressure, pulmonary arterial pressure, and an index of cardiac contractility (dP/dT) were measured. Stroke volume, cardiac index (CI), stroke index (SI), rate-pressure product, and systemic vascular resistance (SVR) were calculated. Epinephrine (0.1, 0.3, and 0.5 micrograms/kg/min [low, medium, and high doses, respectively]) and dobutamine (1, 5, and 10 micrograms/kg/min [low, medium, and high doses, respectively]) were infused. Methoxamine was given in a bolus of 0.22 mg/kg, IV. All measurements were taken at 2.5 minutes after infusion, and were repeated after removal of 40% of the estimated blood volume. Dobutamine administered at the low dose before hemorrhage increased SAP and dP/dT. At the high and medium dose, dobutamine significantly increased CI, dP/dT, and SAP, with no significant change in HR or SVR. The medium dose of epinephrine was the most effective dose of epinephrine at increasing key variables (CI, SI, dP/dT). The response of CI and SI to this dose was not significantly different from the changes seen with high-dose administration of dobutamine. The dP/dT was significantly lower with epinephrine than with dobutamine, and SVR and HR were unchanged with epinephrine, except at the low dose, which decreased SVR.     

Footing and gait of pigs on different concrete surfaces

Because pigs frequently lose their footing and slip, it is important to understand slipping and its relation to different floor surfaces. An experiment was conducted to evaluate the gait and footing of young pigs walking on concrete floor surfaces having known friction characteristics and to determine critical skid resistance values in terms of the fitness of a concrete surface for flooring in pig quarters. Barrows were cinematographed with a high-speed 16-mm camera as they walked on various surfaces, and gait and footing were subsequently analyzed in motion studies. The six concrete floor test pads with different surface treatments (fine and coarse sand, fine and coarse broom, wood float and steel trowel) were evaluated for friction coefficient (skid resistance value) using a British pendulum tester both before and after pig tests. Leg angle, pastern angle and time variables were not related with average skid resistance value of the different floors. However, slip variables during a stride's stance phase per se were well related to surface-treatment differences in average skid resistance. Thus, the average skid resistance value generated by the British pendulum tester yielded one piece of objective information useful in assessing the fitness of concrete surfaces for floors in pig quarters. All the surfaces except the steel trowel surface had average skid resistance value of greater than 65 British pendulum number, and they all reduced a pig's chance of slipping relative to the steel trowel (less than 60 British pendulum number). The front leg was a more sensitive indicator than the rear of a floor's effect on the pig's gait and footing.     

Splenomegaly in Dogs

Splenomegaly confirmed by surgery or necropsy in 100 dogs was diagnosed histologically as benign neoplasia (n = 1), primary splenic malignancy (n = 59), neoplastic metastases (n = 6), and nonneoplastic disease (n = 34). Dogs with known systemic disease, such as lymphoma and mast cell tumor, that caused splenomegaly were not included in the study. Hemangiosarcoma was the most common splenic disease (43 cases). Overall mean age of the dogs was 10.7 years, the most common breed was German Shepherd dog, and 72 of the dogs weighed more than 21 kg. Dogs with anemia, nucleated red blood cells, abnormal red blood cell morphology, or splenic rupture had a significantly greater chance of having splenic neoplasia (P less than 0.002). A multivariable logistic regression analysis found that the presence of anemia and splenic rupture in dogs with splenomegaly was up to 69% accurate in predicting presence of splenic neoplasia. After splenectomy, the median survival time of dogs with splenic neoplasia was 13 weeks. For dogs with nonneoplastic splenomegaly it was at least 36 weeks.     

Cold resistance and environmental temperature preference in diarrheic piglets

Piglets aged 12 to 72 h in which diarrhea had been induced by enteric Escherichia coli infection or sucrose gavage were studied with respect to cold resistance and thermal-circulation index in a 90-min test in a 6 C environment (Exp. 1) and free-choice environmental-temperature preference during a 60-min test in a 24 to 44 C thermocline (Exp. 2). In Exp. 1, diarrhea lowered the piglet's ability to maintain body temperature during the cold test. Also, diarrheic piglets tended to have lower thermal circulation index values at the end of the cold test, indicative of a greater vasoconstrictive response to the cold environment. In Exp. 2, mean preferred environmental temperatures were 35.7, 34.9 and 34.5 C, respectively, for piglets in sham-control, E. coli-infected and sucrose-gavaged groups. For reason(s) still unknown, diarrheic piglets did not choose to locate themselves in a warmer niche than did normal piglets; in fact, they did the opposite. Results of the two experiments indicate that diarrheic neonatal piglets need even more attention and care in terms of the thermal environment than do healthy ones.     

Response of caeruloplasmin to Escherichia coli endotoxins and adrenal hormones in the domestic fowl

The injection of chickens with Escherichia coli endotoxins immediately produced a 50 per cent rise in plasma caeruloplasmin activity which was attributed to the release of the protein from liver cell. This was followed by a fall in activity, which was probably due to a fall in activity, which was probably due to a stabilising effect of adrenocortical hormones on the cell membranes, and then by a five-fold increase. The results of experiments with cycloheximide, adrenocorticotrophin, beta-methasone and reserpine indicated that the third phase of the response reflected increased synthesis in the liver which was partly induced by adrenal hormones. It increased with the dose and was not elicited by the particulate nature of the toxin preparation or by its lipid and polysaccharide components.     

Understanding community perceptions of aquaculture: lessons from Australia

Aquaculture is a growing and high-value industry that depends on access to and wise use of shared inland, coastal and marine resources. Varied stakeholders and communities are very interested in these public resources, and there has been conflict about how the aquaculture industry uses them. Prior to the research discussed in this article, there have been few large-scale studies of community perceptions of aquaculture. Our research drew upon an extensive literature review, stakeholder interviews and a survey mailed to the public in two regional case studies in Australia: the Eyre Peninsula in the state of South Australia and Port Phillip Bay in the state of Victoria. The data revealed some public support for aquaculture’s socioeconomic benefits and strong interest in minimizing the risk of its environmental impacts. There were mixed opinions about the trustworthiness of governments’ aquaculture decisions and actions. Some industry sectors attracted greater trust and lower perceived environmental risks. The importance and credibility of different information sources varied. There was strong support for improved dialogue among governments, the aquaculture industry and communities. Key differences between the regions included levels of awareness of and knowledge about aquaculture. Our research is consistent with literature on risk communication and perception that suggests that conflict and subsequent costs to industry and the community can be overcome or mitigated if government and industry understand, acknowledge and respond to community perceptions of the industry.