Effects of xylazine and acepromazine on bronchomotor tone of anaesthetised ponies

The effects of xylazine (an alpha 2-adrenoceptor agonist) and acepromazine (an alpha-adrenoceptor antagonist) on bronchomotor tone were investigated in seven anaesthetised, apnoeic ponies using a computer aided forced oscillation technique, which separates changes in bronchial calibre from changes in lung volume. Both agents produced bronchodilatation and a decrease in lung volume.     

Effects of endotoxemia on lung water and hemodynamics in conscious calves

The effects of endotoxemia on cardiovascular and pulmonary parameters were determined in conscious, 4- to 6-week-old calves. Escherichia coli endotoxin was infused continuously (4 micrograms/kg/hr, IV) for 5 hours. During endotoxemia, pulmonary vascular resistance and mean pulmonary artery pressure increased, and cardiac index, central plasma volume, and mean systemic arterial pressure decreased. Neutrophil, lymphocyte, and platelet counts also decreased. During the first hour of endotoxemia PaO2 decreased, and alveolar-arterial O2 gradient and shunt fraction increased. Lung extravascular thermal volume was increased from 2 to 5 hours. Postmortem extravascular lung water/extravascular dry weight ratio, bronchoalveolar lavage albumin, and poly morphonuclear cell content did not change. Microscopically, the septal capillaries of endotoxemic calves were dilated and engorged with erythrocytes, accompanied by focal accumulations of neutrophils. Intraalveolar edema and hemorrhage were not seen.     

Evaluation of isotonic sodium bicarbonate solution for alkalizing effects in conscious calves

After intravenous (i.v.) infusion of various volumes of 1.35%-isotonic sodium bicarbonate solution (ISB), acid-base equilibrium, blood pressure, plasma volume and biochemical parameters in healthy Holstein calves were studied. Four calves each were randomly assigned to the low-dose (LD; i.v. infusion of 5 ml/kg ISB), middle-dose (MD; i.v. infusion of 10 ml/kg ISB) and the high-dose groups (HD; i.v. infusion of 15 ml/kg ISB). Administration volumes of ISB in the LD, MD and HD groups were decided based on the first half volumes of 5, 10 and 15 mEq of base requirement by the acceptable equation. Systemic, pulmonary artery and central venous pressures, cardiac output and plasma osmotic pressure were not changed by ISB infusion and remained constant throughout the experiment for all groups. There was good correlation (r(2) = 0.950) between relative changes in base excess and infused volume of bicarbonate (y=2.491x). The coefficient of distribution for bicarbonate ions was calculated to be 0.401 (=1/2.491). Therefore, it is suggested that a value of 0.4 would be most appropriate when calculating the base requirements in calves. Therefore, the first half volumes of ISB correcting base deficits of 5, 10 and 15 mEq in calves were estimated to be 6, 12 and 18 ml/kg, respectively. On the basis of the findings in this study, ISB may be used to correct metabolic acidosis without altering the plasma osmotic pressure, hemodynamic status and respiratory function in the calves.     

脲酶抑制剂在单胃动物中的应用研究进展

脲酶抑制剂作为一类特殊的饲料添加剂在畜牧业生产中逐渐被人们认识。在畜牧业发达的国家脲酶抑制剂的应用已较为广泛,我国20世纪90年代开始脲酶抑制剂在畜牧方面的应用性研究,在反刍动物生产中研究较多,而在单胃动物生产中应用研究较少。本文综述脲酶抑制剂的种类、作用机理及其在单胃动物生产中的应用。1脲酶抑制剂的种类及作用机理1.1脲酶抑制剂的种类脲酶抑制剂是指能够直接或间接抑制脲酶活性的一类物质。有关脲酶抑制剂的研究大多数是在已发现的土壤脲酶抑制剂的基础上进行的,目前发现的脲酶抑制剂见表1(单安山等,2002)。脲酶抑制剂基…     

Salmonellosis in calves

Despite the efforts of both physicians and veterinarians, the number of cases of salmonellosis per year has held steady or risen. The ability of the organism to live in many different animal species and under inhospitable environmental conditions is likely responsible for Salmonella's prevalence today. Diverse clinical signs occur in salmonellosis; they range from unthriftiness to explosive, necrotizing diarrheas with high mortality. Secondary complications of pneumonia, bone and joint infections, and meningoencephalitis can result from calfhood infections. Treatment of enteric salmonellosis is chiefly aimed at maintaining fluid, acid-base, and electrolyte balance. Bacteremic or septicemic calves also require systemic antibiotics. The control measures for salmonellosis are based on sanitation and management. Individual calf hutches or pens provide adequate isolation if sufficient spacing and good sanitation are maintained. The Salmonella vaccines presently available provide limited protection; however, live vaccines made from auxotrophic strains of Salmonella appear to be more efficacious.     

Anencephaly in calves

Anencephaly occurred in four calves and was characterized by cranioschisis, absence of the diencephalon with the cerebral hemispheres and rostral midbrain, various forms of eye defects, and relatively normal development of caudal brain stem, cerebellum and spinal cord. Amorphous dysplastic vestiges of the cerebral tissue protruded into the cranial defects. Morphologic features varied but were essentially similar. The cerebellum was absent in one case. Anencephaly in calves at least those we observed and defined in this study is localized defect confined to the brain, eye and skull. No spinal defect was observed in the calves.     

Lysozyme in calves

Relatively high lysozyme concentrations, depending on age, were recorded from intestinal content, spleen, liver, kidney, lung, lymph nodes, and mucosa of calves. Yet, only minor quantities of lysozyme were found in blood serum or plasma and in granulocytes. Physicochemical characterisation, precipitation, using polyclonal antisera, and crosswise neutralisation of lysis reaction were likely to suggest occurrence of immunological relationship reactions as well as differences between organ lysozymes, on the one hand, and intestinal lysozymes, on the other.     

Citrullinaemia in Friesian calves

Six Friesian calves from a pedigree herd died or were killed within 1 week of birth because of progressive central nervous disease in which the only consistent lesion was cerebral oedema. The cause was citrullinaemia, resulting from an autosomally inherited dysfunction of the urea cycle enzyme arginosuccinate synthetase. Citrullinaemia was diagnosed by demonstrating markedly elevated concentrations of citrulline in the blood of one calf and in the cerebral spinal fluid of another. One of two sires used in the herd was a heterozygous carrier of the disease. Heterozygocity was demonstrated using a polymerase chain reaction/restriction endonuclease test designed to detect the genetic mutation that causes citrullinaemia in cattle.     

Neomycin toxicosis in calves

Calves (n = 4) were given neomycin (2.25 or 4.5 mg/kg) twice daily IM and were compared with 2 calves given penicillin IM. The 2 hallmarks of aminoglycoside toxicosis, nephrotoxicosis and ototoxicosis, were seen with both dosages of parenterally administered neomycin. Nephrotoxicosis was confirmed by abnormal findings in urinalysis (granular casts, proteinuria, low specific gravity), renal biopsy results (tubular degeneration and necrosis), and increased 24-hour amounts of urinary enzymes (alanine aminopeptidase and gamma-glutamyltranspeptidase). Azotemia, decreased creatinine clearance, polyuria, and polydipsia also were documented in calves given neomycin. Clinically, deafness was suspected in 2 calves and was documented by electrical auditory-evoked response tests. Abnormalities in partial thromboplastin times and renal residues of neomycin were seen in all 4 calves that were given neomycin, but not in calves that were given penicillin.     

Enterotoxemia in neonatal calves

The incidence, bacterial characteristics, disease syndromes, diagnosis, treatment, and prevention of enterotoxemia of neonatal calves caused by Clostridium perfringens (Types A, B, C, D, and E) are reviewed.