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Effect of enrofloxacin-Na against pathogens related to the respiratory and alimentary diseases in suckling and weanling piglets.

A field trial was conducted to evaluate effect of enrofloxacin-Na against pathogens related to the respiratory and alimentary diseases in eighty suckling piglets (6-7 days old) and eighty weanling piglets (5-6 weeks old). Respective twenty of the suckling and weanling piglets were assigned to each of 4 experimental groups; control (non-treated), clinical injection dose (CID), 2x clinical injection dose (2CID). and premix. A 0.05 ml (2.5 mg) of enrofloxacin-Na injection (5% solution, 1 ml) per kg body weight of piglets as CID was injected intramuscularly for 3 days and the clinical signs were observed for 9 days. The premix (150 ppm) of enrofloxacin-Na was administered with feed for 7 days ad libitum and the clinical signs were observed for 13 days. The enrofloxacin-Na-treated piglets showed a higher increase in body weight and a lower feed per gain than the control piglets. In addition, the treatment of enrofloxacin-Na, regardless of the route of administration, decreased the incidence rate of diarrhea in suckling piglets and respiratory symptoms in weanling piglets. The isolation index of E. coli and Cl. perfringens during the treatment periods was also lowered by the enrofloxacin-Na treatment in both suckling and weanling piglets. The antibiotics was also evaluated as safe locally and whole bodily as treated by injection or feeding. These results indicate that the newly developed antibiotics, enrofloxacin-Na, is very useful for the prevention and therapy of swine diseases in the pig industry.

Animals↗

Introduction to classical swine fever: virus, disease and control policy.

Classical swine fever virus is a spherical enveloped particle of about 40-60 nm in diameter with a single stranded RNA genome of about 12,300 bases with positive polarity, classified as a pestivirus within the family Flaviviridae. Natural hosts are domestic and wild pigs. The virus causes one of the most severe diseases in pigs world wide with grave economic consequences. The clinical picture of classical swine fever is variable, depending on the age of the affected animals and viral virulence. The virus is well characterised and reliable laboratory diagnostic procedures are available. In many parts of the world live attenuated vaccines are being used as a safe and efficient prophylactic tool. However, in EU Member States and several other countries vaccination is prohibited and CSF is controlled by a strict stamping out policy. In order to overcome the disadvantages of conventional vaccination inactivated marker vaccines have been developed that enable the distinction between vaccinated and infected animals. Whether these vaccines will be accepted as an additional tool in the framework of the stamping out policy is not yet decided.

Animals↗

Swine lymphoid and myeloid neoplasms in Italy.

In the decade 1973-1982, data from all the principal diagnostic centers in Italy reveals that swine lymphoid and myeloid neoplasms (LMN) have been observed only few times (78 cases). In a 25-year period (1950-1984) 48 cases were diagnosed in our Institute, among which all the known forms of LMN, including the most uncommon such as multiple myeloma (1) and myeloid forms (4) including 1 chloroma and 1 erythraemic neoplasm. The incidence remains low; 1.17% of the diseased swine sent for necropsy, with no significant increase during the years. In the same period the incidence of other neoplasms was 1.14%. Also the data from the abattoir of Bologna confirm a low incidence: in the last 2 years lymphoid neoplasms were observed only twice among 130,000 slaughtered pigs (15 cases per million). This incidence is therefore similar to that noticed in slaughterhouses in other European countries and in the U.S.A. As for the anatomohistopathological features, lymphosarcoma presents a constant autochthonous production of immature collagen fibrils, but the degree of this production has no significant relation with either the macroscopic type of lesions, nodular or infiltrating (diffuse), or the level of cellular differentiation. Diffusely haemorrhagic lesions were observed in a relatively high percentage (14%) of lymphosarcomas. The incidence of myeloid neoplasms is relatively high compared with that of lymphosarcomas: from 5% of Italian cases as a whole to 14% of the cases studied in our Institute. This confirms that the pig is second to the dog as a domestic animal showing most of these myeloid neoplasms.

Animals↗

The role of immunostimulation in the development of postweaning multisystemic wasting syndrome in pigs under field conditions.

We evaluated the effects of immunostimulation in the development of postweaning multisystemic wasting syndrome (PMWS) in 930 pigs 53 to 54 d old in a grower/finisher barn with a history of PMWS. The pigs were allocated to 5 treatment groups: 4 groups received a single intramuscular injection of RespiSure-ONE (a commercial Mycoplasma hyopneumoniae vaccine; n = 197), Emulsigen (an oil-based adjuvant; n = 172), Alhydrogel (an aluminum-hydroxide-based adjuvant; n = 172), or physiologic saline (n = 218); 1 group received no treatment (n = 171). Pigs affected by PMWS were found in all the groups. Antigen to Porcine circovirus type 2 (PCV-2) was detected by immunohistochemical testing within lesions of mesenteric lymph node, spleen, Peyer's patch, and lung of affected pigs. There was no significant difference in the incidence of PMWS among the groups. The findings indicate that immunostimulation did not influence the expression of PMWS in this study. Thus, routine vaccination against swine diseases may not significantly contribute to the occurrence of PMWS under field conditions.

Adjuvants, Immunologic↗

Potential animal health hazards of pork and pork products.

The animal health hazards associated with the importation of pork and pork products include four viral agents: foot and mouth disease, classical swine fever (hog cholera), African swine fever, and swine vesicular disease viruses. The safety of importing pork from a zone infected with one or more of these diseases can be adequately determined only through risk assessment. This also applies for the safety of importing pork products which have undergone some form of processing (fully cooked pork products are not counted here). For each disease, the agent (pH and temperature lability), target organs, agent survival in pork and pork products, and agent quantification are discussed. Agent quantification is an input of the risk assessment which measures the viral titres in waste pork and pork products in relation to the oral infective dose estimated for each disease. Two other viral diseases, transmissible gastroenteritis of pigs and porcine reproductive and respiratory syndrome, are presented to illustrate why these two diseases are not hazards when associated with pork and pork products.

African Swine Fever↗

Evaluation of the prevalence of sarcoptic mange in slaughtered fattening pigs in southeastern Spain.

In this study the prevalence of sarcoptic mange in fattening pigs in Murcia, southeastern Spain was investigated. Results showed that 37% of the 1318 slaughtered pigs examined were positive for Sarcoptes scabiei var. suis. Skin lesions potentially attributable to this mite were present in 92.80% of animals, but the parasite could be detected in only 38.60% of them. The condition of the ear (clean/dirty) was not a defining characteristic for the diagnosis of this swine disease. A sucrose flotation-concentration technique was more effective than direct microscopy in finding the mite in ear scrapings.

Animals↗

Laboratory investigation of PRRS virus infection in three swine herds.

Late in 1991, an enveloped RNA virus (now called porcine reproductive and respiratory syndrome [PRRS] virus) was identified as the etiologic agent for mystery swine disease. In 1992, laboratory procedures for the diagnosis of this disease evolved rapidly, and veterinary diagnosticians started applying these tests to field cases. This report is written from the perspective of veterinary laboratory diagnosticians and utilizes 3 case studies to define the advantages and disadvantages of the various available diagnostic laboratory PRRS test procedures in different clinical situations. The diagnostic procedures currently used in our laboratory for investigating PRRS are pathologic examination, serologic testing, fluorescent antibody (FA) testing, and virus isolation. Interstitial pneumonia, characterized by mononuclear cell infiltration of alveolar walls with normal airway epithelium, is a hallmark lesion for the disease, especially in neonatal pigs with respiratory distress. Interstitial pneumonia is not a specific lesion and must be coupled with other tests to verify PRRS virus infection. Demonstration of seroconversion is helpful, especially in sows that have experienced reproductive failure. The indirect FA test detects antibody sooner than the serum neutralization test and will likely become the serologic test of choice. The direct FA test on fresh tissue utilizes monoclonal antibody and is useful for investigating PRRS virus-associated pneumonia. Virus isolation utilizing swine alveolar macrophages has also been a useful diagnostic procedure. All of the above tests have been universally unrewarding when applied to aborted, mummified, or stillborn piglets.

Animals↗

Inactivation by gamma irradiation of animal viruses in simulated laboratory effluent.

Several animal viruses were treated with gamma radiation from a 60Co source under conditions which might be found in effluent from an animal disease laboratory. Swine vesicular disease virus, vesicular stomatitis virus, and blue-tongue virus were irradiated in tissues from experimentally infected animals. Pseudorabies virus, fowl plague virus, swine vesicular disease virus, and vesicular stomatitis virus were irradiated in liquid animal feces. All were tested in animals and in vitro. The D10 values, that is, the doses required to reduce infectivity by 1 log10, were not apparently different from those expected from predictions based on other data and theoretical considerations. The existence of the viruses in pieces of tissue or in liquid feces made no difference in the efficacy of the gamma radiation for inactivating them. Under the "worst case" conditions (most protective for virus) simulated in this study, no infectious agents would survive 4.0 Mrads.

Bluetongue virus↗

Localization of spirochetes with the structural characteristics of Treponema hyodysenteriae in the lesions of swine dysentery.

The large intestines of pigs with swine dysentery were examined by phase, light, and electron microscopy at intervals up to 11 days after oral inoculation with mucosal scrapings from infected pigs. Large spirochetes with the structural characteristics of Treponema hyodysenteriae were found only in infected pigs and were first observed in small numbers in the lumen of the large intestine 2 days after inoculation. Numerous large spirochetes were present on the luminal surface and in mucosal crypts as lesions developed. Degenerative changes were first observed in the apical portion of epithelial cells in close contact with large spirochetes. These large spirochetes were found intact in goblet cells and epithelial cells in the early stages of the disease and were numerous within degenerating epithelial cells as lesions became more advanced. Invasion beyond the lamina propria was not detected. These observations demonstrated the relationship between pathogenic large spirochetes and the mucosa of the large intestine in a specific disease, swine dysentery.

Animals↗

Immunisation against PCV2 structural protein by DNA vaccination of mice.

Porcine circovirus type 2 (PCV2) is the causative agent of an emerging swine disease, postweaning multisystemic wasting syndrome (PMWS). The disease affects primarily 5-12-weeks-old pigs which might suggest that infection with PCV2 occurs when the level of maternal antibodies have declined to sub-protective levels around weaning at 3-5-weeks of age. If immunoprophylaxis is to be effective, an immunisation method capable of breaking through maternal immunity must be employed. In this study, we have developed and investigated the potential of a DNA vaccination approach to be one such method. The gene encoding the capsid protein of PCV2 was cloned in a DNA vaccination plasmid and expression of capsid protein was demonstrated in vitro. Mice were gene gun vaccinated three timesand all mice responded serologically by raising antibodies against PCV2. The results suggest, that DNA based vaccination might offer opportunities for vaccination of piglets against PCV2.

Animals↗

Using slaughter inspections to evaluate sarcoptic mange infestation of finishing swine.

Sarcoptic mange is one of the common swine diseases worldwide. Although mange-free populations can be established with caesarean derived stock, by herd repopulation programmes or by eliminating mange with ivermectin, mange remains prevalent in many countries. Field and experimental studies indicate that hypersensitive mange is detrimental to performance of growing pigs. Typically, producers tolerate mange infestation in their herds and control measures are often haphazard. This tolerance to mange infestation is attributable to the covert nature of the losses (reduced growth rate and feed efficiency without mortality) and to the fact that clinical signs of hypersensitive mange (pruritus) are usually viewed as normal. Lack of tools to evaluate mange severity in pigs and to demonstrate its importance has hindered the efforts of veterinarians to control the disease. Traditionally, veterinarians have used slaughter inspections to assess respiratory diseases such as enzootic pneumonia and atrophic rhinitis. Much of the value of slaughter inspections is as a tool with which veterinarians can educate and motivate their clients to improve disease control measures. The potential for evaluating hypersensitive mange by inspecting slaughtered pigs for lesions of papular dermatitis was recognised some time ago, but quantitative evaluation of the reliability of this approach has been lacking. We have conducted several studies in Australia, the USA, Canada, Europe and Latin America to evaluate associations between Sarcoptes infestation and the severity of papular dermatitis at slaughter, using a simple ordinal scale for classifying carcasses. Our initial field and experimental data in Australia indicated the specificity of localised dermatitis to be in the order of 75-80%, but that the generalised dermatitis was highly specific (> 98%) for mange. Subsequent studies in the US Midwest yielded almost identical results, and indicated that the method may also have some utility for surveillance of mange-free herds. Results from other locations invariably have shown significant associations between dermatitis lesions and mange infestation. Relative to other methods such as skin scrapings and monitoring pruritus, this method is simple and relatively objective, and should be considered for routine inclusion in slaughter inspection protocols.

Abattoirs↗

Characterisation of PCV-2 isolates from Spain, Germany and France.

The new isolated circovirus variant PCV-2 is discussed to be the etiological agent of a new emerging swine disease with a variable morbidity and high lethality, postweaning multisystemic wasting syndrome (PMWS). PMWS has been diagnosed in North America and West Europe. Clinical signs include dyspnea, loss of weight, lymph node enlargement and lymphocyte depletion in lymphoid tissues. This report describes the characterisation of PCV-2 isolates from animals affected with PMWS from Germany, Spain and France. We could demonstrate the presence of circovirus by electron microscope, in situ hybridisation and PCR. PCR revealed incidence of PCV-2 in many tissues of one infected animal with the exception of heart and nervous system. The phylogenetic analysis of all PCV-2 isolates yet published in the database, showed relationship of isolates from Spain, Germany and France, with three sequences from Canada determined recently and two isolates from Taiwan, while other North American sequences display a separate cluster. PCR screening of randomly collected organ samples from German pigs not affected with PMWS, revealed a rate of infection with PCV-1 of 5% and with PCV-2 of 26.8%, while blood samples showed a lower incidence.

Animals↗

Research on the presence of porcine enterovirus serotype 1 in north-eastern Italy.

The liquid-phase blocking sandwich ELISA, already developed for foot-and-mouth disease and swine vesicular disease serology, has been employed in pig sera for the antibody detection against porcine enterovirus serotype 1. ELISA-titers correlate positively with virus neutralization and their distribution show a high prevalence among the sampled pigs. The serological findings are confirmed by the isolation of a field strain of porcine enterovirus belonging to the serotype 1.

Animals↗

Experimental infection of Indonesia Taenia (Samosir strain) in domestic animals.

Three 58-day old Small-Ear-Miniature (SEM) pigs, six 36-day old Landrace-Small-Ear-Miniature (L-SEM) pigs, and two 5-day old Holstein calves were each fed 3000 or 30,000 Indonesia Taenia (Samosir strain) eggs and sacrificed 27-195 days after inoculation. A total of 4922 cysticerci were recovered only from the livers of the three SEM pigs (1977 cysticerci) and six L-SEM pigs (2945 cysticerci). The infection rate in pigs was 100%. Cysticerci recovery rates of SEM and L-SEM pigs were 22.0% and 1.6%, respectively. Calves were not susceptible to Indonesia Taenia. More cysticerci were found in the liver parenchyma (L-SEM, 66.4%; SEM, 76.2%) than on the liver surface (L-SEM, 33.6%; SEM, 23.8%) of the infected animals. Most (99.86%) of the cysticerci recovered from the livers of L-SEM pigs were degenerated or calcified but 77.9% of those in the livers of SEM pigs were mature and only 22.1% were degenerated or calcified. Measurements of length, width, diameters of protoscolex, rostellum, and sucker and hooklet pattern indicated that Indonesia Taenia is very similar to Taiwan Taenia and very different from Taenia saginata and Taenia solium. The present findings indicate that Indonesia Taenia and Taiwan Taenia may be the same new species.

Animals↗

Herd factors affecting the selection and success of intervention strategies in the program for eradication of pseudorabies (Aujeszky's disease) virus from Illinois swine farms.

The program for eradication of pseudorabies virus (PrV) from swine herds in Illinois was evaluated with respect to compliance with Livestock Conservation Institute (LCI) guidelines for selection of intervention strategies and for the effectiveness of these interventions under different herd conditions. The sample consisted of 395 swine operations quarantined between 1988 and 1994. These herds were followed until the end of 1996. The association of herd characteristics (number of sows, sow PrV seroprevalence, type of housing, number of PrV-seropositive farms within 1.5 mi) at the time of quarantine with the producer's selection of an initial intervention strategy (vaccination, offspring segregation, test-and-removal, depopulation-and-repopulation) was analyzed using logistic multiple regression. The interaction of herd characteristics with intervention strategies to affect the duration of quarantine was analyzed using multivariable Cox regression. Factors favoring selection of vaccination were increased herd size, higher sow PrV seroprevalence, and more PrV-seropositive farms within 1.5 mi. Offspring segregation was preferred when sow PrV seroprevalence was higher, and test-and-removal was preferred when seroprevalence was lower. Depopulation-and-repopulation was more likely in outdoor operations. Except for depopulation-and-repopulation, selection of an intervention strategy was in accordance with LCI guidelines. Vaccination and offspring segregation were associated with longer times under quarantine, and test-and-removal and depopulation-and-repopulation with shorter times. Test-and-removal was more effective in reducing the duration of quarantine when sow PrV seroprevalence was low. Vaccination increased the duration of quarantine less when sow PrV seroprevalence was high. Vaccination increased the duration of quarantine more when there were one or more PrV-seropositive farms within 1.5 mi than when there were no PrV-seropositive farms within 1.5 mi. It is apparent that herd characteristics affect the duration of quarantine and therefore need to be taken into account in the selection of a PrV-intervention strategy.

Animal Husbandry↗

Right aortic arch in a lamb and two pigs.

The necropsy findings of right aortic arch in a lamb, a mini-pig foetus and a mini-pig are described, and the pathogenesis of the vascular pattern found in these animals is discussed.

Animals↗