Evaluation of decoquinate, lasalocid, and monensin against experimentally induced sarcocystosis in calves

Effects of decoquinate, lasalocid, and monensin against experimentally induced sarcocystosis (Sarcocystis bovicanis) were evaluated in 12 calves, 3 of which were inoculated, nontreated controls. Three additional calves were noninoculated, nontreated controls. Drugs were administered in the feed (33 mg/kg of feed) of the treated calves (3 calves/group) for 87 days. Eight of the 12 inoculated calves died from acute sarcocystosis during the experiment (the 3 inoculated, nontreated controls, the 3 calves given decoquinate, and 2 of the 3 calves given lasalocid). Large numbers of sarcocysts were found in tissues from inoculated calves that survived in the experiment (1 of the 3 calves given lasalocid and the 3 calves given monensin). Although large numbers of sarcocysts developed in the muscles of monensin-treated calves, monensin may have an ameliorating effect on acute sarcocystosis.     

Vaccination against paratuberculosis of lambs already infected experimentally with Mycobacterium avium subspecies paratuberculosis

OBJECTIVE: To assess the protective value of a live-attenuated vaccine in sheep already exposed to Mycobacterium avium subsp paratuberculosis and to investigate the progression of a systemic immune response in experimentally infected sheep. STUDY DESIGN: Twenty-eight lambs, aged 1 to 1.5 months, were dosed via stomach tube with approximately 4.4 x 10(8) M a paratuberculosis organisms. Two weeks later, 14 of these 28 animals received subcutaneous injections of 1 mL of a live-attenuated vaccine. Thirteen additional lambs were neither dosed nor vaccinated (negative controls). Antigen-induced production of IFN-gamma in blood, and antibody concentrations in serum were sequentially monitored in vaccinated, unvaccinated and control animals for 1 year. Each sheep was examined for infection by an IS900-based PCR test on samples of ileum and ileocaecal lymph node and histological examination at the time of necropsy. RESULTS: Seven of 14 unvaccinated and two of 14 vaccinated sheep developed clinical paratuberculosis that was later confirmed by histological examination and/or the IS900-based PCR test. The granulomatous inflammation in the jejunal and ileal mucosa was less severe in vaccinated than in unvaccinated sheep. Acid-fast organisms were detected only in the unvaccinated group. The PCR assay on ileal samples gave positive reactions in two vaccinated and eight unvaccinated sheep. Both the antibody response and IFN-gamma response were detected earlier and were more substantial in vaccinated than in unvaccinated sheep. Furthermore, in experimentally infected but unvaccinated sheep, the IFN-gamma concentrations were higher in those animals without acid-fast organisms than in those with them. CONCLUSIONS: Vaccination of lambs with live-attenuated vaccine 2 weeks after oral inoculation with M a paratuberculosis stimulated the host response against the organism and led to a reduced mycobacterial burden. The diminished IFN-gamma responses in experimentally infected sheep with acid-fast organisms suggest a positive relationship between the magnitude of the systemic cell-mediated immune response and an animal's ability to control infection.     

Protective effect of glucan against experimentally induced staphylococcal mastitis in ewes

Glucan, an immunostimulant, was evaluated for its ability to modify a staphylococcal mammary challenge in ewes. Glucan was administered subcutaneously to ewes prior to lactation or during lactation, and all ewes, including a control group, were subsequently challenged intramammarily with Staphylococcus haemolyticus 40 days after the mean lambing date. The glucan treatment was shown to modify the staphylococcal mammary infection as the milk bacterial counts from all of the glucan-treated groups were significantly reduced compared to controls. For the glucan-treated groups, the highest mean somatic cell counts were recorded 1 day post-challenge, while for the control group, the mean cell count rose more gradually to peak by 3 days post-challenge. Glucan did not increase serum lysozyme levels or blood neutrophil bactericidal activity. However, there was a negative correlation between the bactericidal activity of blood neutrophils collected from the glucan-treated ewes prior to challenge and their mean milk bacterial counts post-challenge. Glucan was observed to stimulate ovine mammary macrophages in vitro, while the addition of zymosan or opsonised killed Staphylococcus aureus to macrophage cultures had no effect. These studies indicate that, in sheep, glucan can enhance some elements of the immune system against staphylococcal infections.     

Immunosuppression in deer mice with experimentally induced trypanosomiasis.

Light and electron microscopic examinations of deer mice (Peromyscus maniculatus) chronically infected with Trypanosoma equiperdum revealed hyperplasia of germinal center lymphocytes (germanocytes) in the lymph follicles of spleen and lymph nodes and infiltration of the splenic red pulp cords and nodal medullary cords with plasma cells. Proliferation and infiltration of plasma cells caused disruption of the B- and T-lymphocyte areas in these organs. Stimulation of splenic lymphocytes in vitro by phytohemagglutinin and concanavalin A revealed marked depression in T-lymphocyte response; stimulation with lipopolysaccharide and pokeweed mitogens showed depression of B-cell response. Deer mice infected with virulent trypanosomes had decreased immunologic response to injection of sheep red blood cells, whereas deer mice given radioattenuated trypanosomes had normal to enhanced immunologic response to injection of sheep red blood cells.     

The effect of monensin against swine dysentery

The use of monensin sodium against naturally transmitted swine dysentery was evaluated in 4-week-old piglets, with an average weight of 8 kg, over a period of 112 days. Three treatments were compared using between two and four pens per treatment and 12 pigs per pen. Monensin was administered via the feed, either immediately post weaning to four pens of pigs (T1), or after 12 days (T2, two pens). The T1 group received monensin at the rate of 100 ppm (days 0-56), 50 ppm (days 57-84) and 25 ppm until the end of the trial. In the other group monensin was given at 100 ppm (days 12-84) and at 50 ppm (days 85-112). Unmedicated feed was given to two pens (T3). The continuous administration of monensin from weaning was effective in the control or prevention of swine dysentery. A significant (P less than 0.05) improvement, in comparison with the other two groups, was observed in terms of mortality, diarrhoea score, average daily gain (ADG) and feed conversion ratio (FCR). There was a reduction in mortality, diarrhoea score/days and an improvement in growth performance parameters in pigs treated with monensin after the disease had been established, with ADG and FCR values significantly (P less than 0.05) different compared with the untreated controls.     

Prophylactic efficacy of buparvaquone in experimentally induced Theileria annulata infection in calves

The antitheilerial activity of buparvaquone (BW 720C) was evaluated in experimentally induced Theileria annulata infections in cross-bred male calves. T. annulata infections were induced by injecting a suspension of infected ground tick tissue suspension (GUTTS) equivalent to two ticks subcutaneously into each calf. Buparvaquone at a dose of 2.5 mg kg-1 body weight was given as a single injection (intramuscularly) on Day 0 (Group 1), Day 8 (Group 2) and Day 12 (Group 3) post-infection. The animals in Groups 4 and 5 were untreated and challenged controls, respectively. All of the recovered animals from Groups 1-4 were challenged with a lethal dose of T. annulata at 6 weeks post-infection. The immunized animals were resistant to the homologous challenge, which killed three of four control animals (Group 5); the controls showed typical antemortem and post-mortem lesions of theileriosis.     

Efficacy of monensin sodium for the reduction of fecal shedding of Mycobacterium avium subsp. paratuberculosis in infected dairy cattle

Reducing the quantity of Mycobacterium avium subsp. paratuberculosis (MAP) being shed by cows with Johne's disease should decrease the risk of spread of this disease to young stock. Previous work has suggested that monensin sodium decreases the pathologic lesions associated with Johne's disease, but the impact on shedding of viable MAP remains unknown. After serologic screening of 32 dairy herds in southwestern Ontario, 228 cows from 13 of these herds were enrolled into a randomized clinical trial. Fecal culture and PCR were used to identify 114 cows as potential fecal shedders, while another 114 cows were enrolled as ELISA negative, herd and parity matched controls. All cows were randomized to receive either a monensin controlled release capsule (CRC) or a placebo capsule. Serial fecal and blood samples were collected for fecal culture and serum ELISA testing over a 98-day period. On day 98 of the study, treatments were switched for all cows continuing in the trial. These remaining cows were followed for another 98 days with a similar sampling protocol. Mixed effect models were used to measure the impact of treatment on the number of colony forming units identified on fecal cultures over time. During the first 98 days of the study, cows treated with a monensin CRC were found to shed 3.4 cfu per tube less than placebo treated cows (P = 0.05). The serum ELISA S/P ratio was reduced by 1.39 units in cows given monensin (P = 0.06). However, treatment with monensin did not reduce the odds of testing positive on serology. Only the cows shedding MAP on day 0 were found to have a reduced odds of testing positive on fecal culture when treated with monensin (OR = 0.27; P = 0.03). Monensin sodium administered to infected animals at 335 mg/day marginally reduced fecal shedding of MAP in mature dairy cattle, but the biological significance of this reduction is unknown.     

头孢噻肟钠体外抗菌活性及对实验性感染鸡大肠杆菌病的药效学试验

头孢噻肟(cefotaxime)为第三代头孢菌素类抗菌药物,具有抗菌谱广、抗菌活性强等特点,已广泛用于医学临床治疗感染性疾病,并收到较好疗效[1,2]。我国已有将其用于兽医临床防治宠物及畜禽感染性疾病的报道,但尚缺乏试验数据。本试验测定了头孢噻肟钠对大肠杆菌、沙门氏菌、金黄色葡萄球菌、兽疫链球菌等4种兽医临床常见致病菌的体外抗菌活性,以及头孢噻肟钠与氧氟沙星联合用药时对上述4种病原菌的联合抑菌浓度(FIC)指数;通过对实验性感染雏鸡大肠杆菌病的治疗试验评价其疗效,为头孢噻肟钠在家禽疾病防治中的推广应用提供依据。1材料与方法1.…     

莫能霉素在反刍动物中的应用

莫能霉素是一种聚醚类抗生素，学名为莫能霉素钠(monensin sondium)，在饲料应用时又称为瘤胃素，是离子载体中最具代表性的一种。它在以下几方面对反当动物起作用：①抑制瘤胃革兰氏阳性菌的生长；⑧增加瘤胃丙酸产量和比例；⑨减少甲烷产生；④抑制乳酸的产生，提高瘤胃pH；⑥降低饲料蛋白在瘤胃的降解；⑧减少氨的产生，增加血中葡萄糖的含量。莫能霉素已在国外肉牛业和禽业中广泛应用，也作为治疗性药物用于防治奶牛酮病，是一种很有发展前景的饲料添加剂。     

Antibody complement-dependent bacteriolysis in experimentally induced pasteurellosis in mice

Affinity-purified bovine immunoglobulin isotypes were bacteriolytic for Pasteurella haemolytica biotype A, serotype 1 (PHA-1). This bacteriolysis was specific and complement-dependent. The IgM and IgG1 were the most active isotypes in the classic complement cascade. These isotypes also induced bacteriolysis through the alternative complement cascade. The comparative bacteriolytic activities of IgG1 and IgM were equal within each cascade; however, the bacteriolytic activities of IgG1 and IgM were lower in the alternative cascade than in the classical cascade. The IgG2 was more bacteriolytic than IgA in the classic and alternative complement pathways. Bovine immunoglobulins passively protected C57BL/6 mice from experimentally induced pasteurellosis. There were no major differences in the protection among hyperimmune sera, purified IgM, or purified IgG. Mice were protected from PHA-1 by approximately 1.9 micrograms of IgG and 1.2 or 0.1 micrograms of IgM. Elimination of murine complement with cobra venom factor 3 reduced PHA-1 clearance in passively immunized C57BL/6 mice. The protective effect of IgM mediated resistance was highly dependent on an intact complement system. The intact complement cascade was associated with enhanced clearance of PHA-1 from the liver. Although PHA-1 was susceptible to antibody complement-mediated bacteriolysis in vitro, the dependence on an intact complement cascade was not absolute in experimentally induced murine septicemic pasteurellosis.     

牛胚胎移植技术在中国内蒙古的研究和应用

1991－1996年，对6个品种138头供体母牛超排处理199次，共获得A、B级胚胎1148枚，平均每次每头获可用胚5．77枚；共移植受体1299头（包括鲜胚和冻胚），妊娠产犊593头，总移植妊娠率为45．7％。对牛的超数排卵技术进行了深入研究，对不同超排方法的超排效果、不同品种肉牛的超排反应及重复超排的效果进行了分析，获得了适于重复应用、效果稳定的超排方案，邓用FSH－PG法，FSH总剂量在4－6mg,5d 10次递减注射。同时，对受体牛饲养管理条件与受体诱导同期发情效果和移植妊娠率之间的关系进行了探讨，对经产牛和育成牛受本移植妊娠效果进行了比较，并对移植人员技术熟练程度对妊娠率的影响进行了分析，从而为大规模实施牛ET计划提供了受体牛选择依据。     

Susceptibility of Mycobacterium avium sbsp paratuberculosis to monensin sodium or tilmicosin phosphate in vitro and resulting infectivity in a murine model

This study was designed to determine the susceptibility in vitro and infectivity of 1 field isolate of Mycobacterium avium sbsp paratuberculosis after exposure to monensin sodium and tilmicosin phosphate. Minimum inhibitory concentrations (0.39 microg monensin sodium/mL; 1.60 microg tilmicosin phosphate/mL) were determined in quintuplicate. Organisms were then incubated with 3 different concentrations of each medication for 3 different lengths of time, then washed and resuspended in sterile physiologic saline and injected intraperitoneally into mice that were genetically susceptible to infection. Mice were euthanatized 50 d later and the number of hepatic granulomas was used as the indicator of infectivity. Neither time of incubation nor concentration of medication had any effect on the infectivity of the organisms. Monensin sodium significantly reduced the number of hepatic granulomas in genetically susceptible mice while tilmicosin phosphate did not. Antimycobacterial activity of monensin sodium suggests that the role of monensin in the control of bovine paratuberculosis should be evaluated further.     

One percent sodium carboxymethylcellulose prevents experimentally induced abdominal adhesions in horses

OBJECTIVE--To evaluate the efficacy of 1% sodium carboxymethylcellulose (SCMC) for prevention of experimentally induced abdominal adhesions in horses. STUDY DESIGN--Prospective, controlled, experimental study. ANIMAL POPULATION--Twelve healthy adult horses. METHODS--The effect of 1% SCMC on adhesion formation was evaluated in 12 healthy horses by using an established model of serosal trauma to induce intraabdominal adhesions. After ventral median celiotomy, 2 separate areas of the jejunum were abraded, and three 2-0 chromic gut sutures were placed in each abraded area. Jejunal resection and end-to-end anastomosis was performed at 2 sites distant to the abrasion sites. In treated horses (n = 6), 2 L of 1% SCMC was applied to the intestine before and after intestinal manipulation. In control horses (n = 6), 2 L of saline solution were applied to the intestine before and after surgical manipulation. All horses were euthanatized 10 days after surgery, and the abdominal cavity was evaluated for adhesion formation. The frequency of intraabdominal adhesions between groups was compared with a chi-square test. Statistical significance was set at P <.05. RESULTS--All control horses had intraabdominal adhesions. Fibrous adhesions were associated with both jejunal abrasion sites in 5 control horses. Fibrous adhesions were also associated with 1 or both jejunal anastomotic sites in 5 control horses. Only 1 treated horse developed adhesions at the jejunal abrasion sites, and no adhesions were present at the anastomotic sites in the treated horses. There were significantly fewer adhesions in the SCMC treatment group compared with the control group (P <.05). CONCLUSION--In this experimental model, application of 1% SCMC reduced the frequency of intraabdominal adhesions at areas of serosal abrasion and at jejunal anastomotic sites. CLINICAL RELEVANCE--In horses at an increased risk for developing intraabdominal adhesions after intestinal surgery, the use of 1% SCMC during celiotomy may decrease the frequency of adhesion formation.     

Efficacy of triclabendazole against experimentally induced Fascioloides magna infections in sheep

Efficacy of oral administration of 20 mg of triclabendazole/kg of body weight was evaluated against 12-week Fascioloides magna infections in 12 sheep, each inoculated orally with 250 viable metacercariae. From 6 sheep treated with triclabendazole, 1 immature F magna was recovered, whereas 116 F magna with a mean length of 19 +/- 6.5 mm were recovered from 6 untreated control sheep. Efficacy of triclabendazole was 99.14%. Signs of toxicosis or illness were not observed in the sheep.     

Activity of closantel against experimentally induced Fascioloides magna infection in sheep

The efficacy of closantel against experimentally induced Fascioloides magna infection in sheep was studied. In each of 3 experiments, closantel was administered 8 weeks after the sheep were given (oral inoculation) 100 metacercariae of F magna. In the 1st experiment, closantel was given orally to 5 groups of 6 sheep each at dosages of 0 (nontreated control), 5, 7.5, 10, and 15 mg/kg of body weight. In the 2nd and 3rd experiments, groups of 10 or 12 sheep were treated to confirm the efficacy of the previously determined optimal dosage of 15 mg/kg. An additional group of sheep (n = 10) was used in the 3rd experiment to evaluate the efficacy of closantel given IM at a dosage of 7.5 mg/kg. Closantel given orally at a dosage level of 15 mg/kg was highly effective (94.6% to 97.7%) in reducing F magna burdens. Also, pathologic scores associated with the F magna infection were reduced by 81.3% to 92.6% in sheep given this dosage of closantel. Efficacy of the IM administered dosage of 7.5 mg of drug/kg was equivalent to that of the 15 mg/kg oral dosage. Other than mild, transient lameness of the limbs which were injected with the drug (group 10), side effects were not observed.     

Comparative toxicology of monensin sodium in laboratory animals

The toxicology of monensin has been studied in several laboratory animal species. There was considerable species variation in acute oral LD50 values. The consistent signs of acute toxicity were: anorexia, hypoactivity, skeletal muscle weakness, ataxia, diarrhea, decreased weight gain and delayed deaths. The 3-mo study in rats fed diets containing 0, 50, 150 or 500 ppm monensin resulted in no effects at the lowest dose level, slight reduction of body weight gain in the middle-dose group and severe depression in body weight gain, skeletal and cardiac lesions, and deaths in the highest dose group. The 3-mo study in dogs given daily oral doses of 0, 5, 15 or 50 mg/kg monensin resulted in no effects at the lowest dose level. Dogs in the 15 and 50 mg/kg groups developed, during test wk 1 to 4, anorexia, weakness, ataxia, labored respiration, body weight loss, increased serum muscle enzyme values, severe skeletal muscle degeneration and necrosis with less severe heart lesions and deaths. Mice fed diets containing 0, 37.5, 75, 150 or 300 ppm monensin for 3 mo had reduced body weight gain in all test groups but no other physical signs. Serum creatine phosphokinase (CPK) values were increased in mice in the two highest dose groups and minimal heart lesions were found in the highest dose group. Dogs given daily oral doses of 0, 1.25, 2.5, 5 or 7.5 mg/kg monensin for 1 yr survived with no evidence of toxicity in the two lowest dose groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of sodium carboxymethylcellulose for prevention of experimentally induced abdominal adhesions in ponies

Twelve ponies were used to evaluate the reliability of an abdominal adhesion model and the efficacy of intraperitoneal infusion of sodium carboxymethylcellulose in preventing abdominal adhesions. A celiotomy was performed on each of the 12 ponies and the serosa of the distal portion of the jejunum was abraded with a dry gauze sponge at 5 locations. In addition to the serosal damage, a single 2-0 chromic gut suture was placed through the seromuscular layer of the jejunum in the center of the abraded area. After closure of the celiotomy, a 1% solution of sodium carboxymethylcellulose (7 ml/kg of body weight) was infused into the peritoneal cavity of 6 ponies. The other ponies served as untreated controls. All ponies were euthanatized 14 days after surgery. All ponies in the control group had abdominal adhesions at the time of necropsy. Four of the 6 ponies in the treatment group were free of adhesions. There was a significant (P less than 0.0001) difference in the total number of adhesions between the 2 groups.     

Accidental monensin sodium intoxication of feedlot cattle

Of 1,994 yearling and 2-year-old cattle in a winter feeding program, 117 died within 42 days of being fed toxic amounts of monensin sodium in a liquid protein supplement. Death losses commenced on the third day after ingestion of a toxic amount in the feed. Clinical signs in cattle that died in less than 9 days included anorexia, pica, diarrhea, depression, mild hindlimb ataxia, and dyspnea. Gross necropsy findings in cattle dying in the acute phase of the illness included hydrothorax, ascites, and pulmonary edema, as well as petechial hemorrhages, edema, and yellow streaking in skeletal and cardiac muscle. Cattle dying after 9 days had gray streaks in heart and skeletal muscle, generalized ventral edema, enlarged, firm, bluish discolored liver, and enlarged heart. Microscopic changes in cattle dying in the acute phase (less than 9 days) consisted of pulmonary edema, congestion, and hemorrhage. Cardiac and skeletal muscle had localized areas of edema, hemorrhage, and coagulative necrosis. In cattle dying after 9 days of illness, the changes included lymphocytic infiltration, sarcolemmal nuclear proliferation, and fibrosis in skeletal and cardiac muscle. Lungs contained increased alveolar macrophages and a few neutrophils. Centrilobular necrosis and mild fibrosis were found in the liver. Changes varied somewhat according to the area of heart or skeletal muscle that was affected. Active muscles, eg, those in the heart ventricles and diaphragm, were altered most severely. Intoxication appeared to be a result of sedimentation of monensin in the molasses carrier to give remarkable concentrations of the substance at the bottom of the holding tank.