Cellular immunophenotyping of exfoliative dermatitis in canine leishmaniosis (Leishmania infantum).

Lymphocyte subsets, major histocompatibility complex (MHC)-II expressing cells and number of amastigotes in the epidermis and dermis were investigated immunohistochemically in 48 dogs with patent leishmaniosis, with or without exfoliative dermatitis (ED) to study the immunopathogenesis of this common cutaneous form of the disease. Skin biopsies were obtained and compared for ED sites (group A, n = 26), normal-appearing skin from the same animals (group B, n = 24), and leishmanial dogs not exhibiting ED (group C, n = 22), and normal controls (group D, n = 22). The CD3+, CD45RA+, CD4+, CD8+ (CD8a+), CD21+, and MHC-II+ cells and leishmania amastigotes were identified immunohistochemically and counted with the aid of an image analysis system. Pyogranulomatous to granulomatous dermatitis, expressed in various histopathological patterns, was noticed in all groups A and B and in half of group C dogs. In the epidermis, the low number of T-cells and their subsets did not differ significantly between groups A and B, but CD8+ outnumbered CD4+ lymphocytes in both groups. MHC-II+ expression on epidermal keratinocytes was intense in the skin with and without lesions from dogs with ED but not in group C dogs. CD3+, CD8+ and MHC-II+ cells were fewer in group C compared to group A and B dogs. In the dermis, CD3+ cells in group A animals were mainly represented by the CD8+. CD45RA+ and CD21+ cells were also seen in high numbers. MHC-II expression, potentially in lymphocytes, fibroblasts, dendritic cells, and macrophages was intense. The numbers of all cellular subpopulations in the dermis were significantly different between the groups, being highest in group A and lowest in group D. In sebaceous adenitis sites, CD4+ outnumbered CD8+ cells in contrast to the neighbouring dermis and the epidermis. The number of CD21+ and CD45RA+ cells was much lower in the inflamed sebaceous glands compared to the dermis. Finally, the number of amastigotes in the normal-appearing skin was significantly higher in the ED dogs (group B) than in those not exhibiting this cutaneous form of the disease (group C).

Equine infectious anemia in mules: virus isolation and pathogenicity studies.

There appears to be a lack of information concerning responses of mules to natural infection or experimental inoculation with equine infectious anemia virus (EIAV). In the present study EIAV was isolated from mules, for the first time, and its pathogenicity in naturally infected and experimentally inoculated animals was investigated. Two naturally infected (A and B) and three EIAV free mules (C, D and E) were used for this purpose. Mule A developed clinical signs, whereas mule B remained asymptomatic until the end of the study. Mules C and D were each inoculated with 10ml of blood from mule A and developed signs of the disease; they were euthanatized or died at day 22 and 25 post-inoculation, respectively. Mule E served as a negative control. The virus was isolated from the plasma samples of mules with clinical signs of the disease (A, C and D), but not from the asymptomatic mule B. Both proviral DNA and viral RNA were amplified from blood and tissues of the infected animals by nested polymerase chain reaction (nPCR). Antibodies were not detected in the two experimentally infected mules until their natural death or euthanasia. Clinicopathological and laboratory findings showed that, in mules, EIAV produced clinical signs similar to those observed in horses and ponies. Nested PCR proved to be a rapid, sensitive and specific diagnostic method for the detection of EIAV, regardless of the disease stage.

The effect of organic acids on the control of post-weaning oedema disease of piglets.

Oedema disease usually occurs after weaning and is due to infection with Enterotoxaemic Escherichia coli strains. A total of 240 weaned piglets were used in five groups during a 28-day period. One group (a negative control) was offered feed free of antimicrobials ad libitum, three groups were offered the same diet ad libitum supplemented with either 1.6 per cent lactic acid, 1.5 per cent citric acid or 50 p.p.m. of enrotloxacin (ENR/Baytril I.E.R. 2 5 per cent, Bayer), respectively. Finally, one group was offered the same diet but the amount offered was restricted during the first 12 days post-weaning. Groups receiving acid or ENR additions to the diet had lower mortality than the negative control group (P<0.05). The three groups on treated feed also showed significantly better growth performance and food conversion ratio than the control group (P<0.05). Both organic acids and medication with 50 p.p.m. of ENR for a 10-day period are useful in controlling and/or preventing post-weaning oedema disease.

The effect of organic acids on the control of porcine post-weaning diarrhoea.

Post-weaning diarrhoea syndrome (PWDS) of piglets is caused mainly by Enterotoxigenic Escherichia coli (ETEC) strains. Six organic acids were tested for their efficacy in the control of PWDS, using a total of 384 weaned piglets, in eight groups, during a 28-day period. One group (negative control) was offered a diet free of antimicrobials, one group (positive control) was offered the same diet medicated with 44 p.p.m. of lincomycin and 44 p.p.m. spectinomycin (Lincospectin 22 premix, Upjohn), and six groups were offered feed supplemented with either 1.0 per cent propionic acid, 1.6 per cent lactic acid, 1.2 per cent formic acid, 1.2 per cent malic acid, 1.5 per cent citric acid or 1.5 per cent fumaric acid. Groups were compared with regard to the appearance of clinical signs, mortality, weight gain and feed conversion. All groups supplemented with organic acids had reduced incidence and severity of diarrhoea, and performed significantly better than the negative control group (P<0.05). At the end of the trial, ETEC strains were detected in the control group not receiving antibiotics but not in the treated group. Organic acids and especially lactic acid are a useful tool in controlling PWDS.

Evaluation of ultrastructural changes associated with encephalomyocarditis virus in the myocardium of experimentally infected piglets.

OBJECTIVE: To evaluate the ultrastructural changes and localization of encephalomyocarditis virus (EMCV) and viral pathogenesis in the myocardium of experimentally infected piglets. ANIMALS: Eight 20-day-old piglets. PROCEDURE: Six piglets were inoculated oronasally with 5 ml (10(6) median tissue culture infective dose/ml) of EMCV suspension, and 2 were used as uninfected controls. Piglets were euthanatized or died between postinoculation days 1 and 3. Samples of heart tissue from all piglets were evaluated histologically, by virus isolation, and by use of immunohistochemistry and electron microscopy. RESULTS: All infected piglets had gross or microscopic lesions of interstitial myocarditis. immunohistochemically, EMCV antigen was detected in the cytoplasm of cardiac muscle cells, Purkinje fibers, and endothelial cells and in the nucleus of cardiac muscle cells and Purkinje fibers. Ultrastructural lesions were characterized by degeneration and necrosis of cardiac muscle cells and Purkinje fibers. Virus was present intracytoplasmically in cardiac muscle cells, Purkinje fibers, and endothelial cells of capillaries and intranuclearly in cardiac muscle cells. The cell membranes of the Purkinje fibers and endothelial cells had distinct protrusions that contained virus particles. In control piglets, no lesions were found, and no EMCV antigen was detected. CONCLUSIONS: Localization of EMCV intracytoplasmically or intranuclearly in various myocardial cells may well reflect the sites of viral proliferation. The presence of virus particles in cell membrane protrusions and in vacuoles within the lumen of capillaries indicates that virus is released not only by disintegration of the host cell but also via exocytosis.

Field study on the efficacy of two different vaccination schedules with HYORESP in a Mycoplasma hyopneumoniae-infected commercial pig unit.

A trial was carried out with HYORESP a Mycoplasma hyopneumoniae (M. hyo) vaccine in order to confirm the benefit of vaccination under field conditions in a commercial industrial farrow-to-finish unit, contaminated with M. hyo. Infection with M. hyo was confirmed through positive blood and colostrum samples [enzyme-linked immunosorbent assay (ELISA) test] combined with positive gross lesions of the lung at slaughter. Two different vaccination schedules were tested. Pigs were randomly allocated to three groups: control non-vaccinated group (n = 130, given a placebo injection at 3, 25 and 70 days of age); early vaccinated group (n = 128, given vaccination at 3 and 25 days of age and a placebo at 70 days of age); late vaccinated group (n = 132, given a placebo at 3 and 25 days of age and vaccination at 70 days of age). Both growth rate and feed conversion ratio were signifcantly (P < 0.05) improved in the vaccinated groups compared with the control group. The lung lesion score was also significantly (P < 0.05) improved in both vaccinated groups. In this trial, it was clearly demonstrated that vaccination is highly effective in improving performance in pig units infected with M. hyo. The improvement in the feed conversion ratio in the vaccinated groups was especially impressive: -0.411 (13% improvement) in the group vaccinated twice at 3 and 25 days of age; -0.162 (5% improvement) in the group vaccinated once at 70 days of age. Performances were better when two shots were given early in life compared with one shot later--probably due to an infection taking place rather early in life for most of the pigs. Moreover, a significant reduction in the cost of supportive (injectable) medication was noticed in vaccinated pigs. In conclusion, HYORESP proved to be a very efficacious tool to control M. hyo in infected herds with its remarkable flexibility that allows the vaccination schedule to be adapted to the specific field conditions.

Immunohistochemical detection of encephalomyocarditis virus (EMCV) antigen in the heart of experimentally infected piglets.

Seven 40-day-old piglets were inoculated with encephalomyocarditis virus (EMCV) strain 424/90, isolated from an outbreak of the myocardial form of the disease in Greece. Two non-infected animals were used as controls. Of the seven inoculated piglets, five died suddenly on day 1.5, 2 (two piglets), 2.5 or 4 post-inoculation (p.i. ). The remaining two and the control piglets were killed on day 8 p. i. EMCV antigen was detected immunohistochemically in endothelial cells of capillaries from 1.5 to 2.5 days p.i. only, but was found in cardiac muscle cells, Purkinje fibres and macrophages on all occasions up to day 8 p.i. In endothelial cells and macrophages, EMCV antigen was detected intracytoplasmically, but in cardiac muscle cells and Purkinje fibres it was observed intracytoplasmically or intranuclearly, or both. The frequent presence of EMCV antigen in Purkinje fibres suggests an explanation for the sudden death of the piglets.

The effect of probiotic LSP 122 on the control of post-weaning diarrhoea syndrome of piglets.

Post-weaning diarrhoea syndrome (PWDS) of piglets is caused mainly by enterotoxigenic Escherichia coli (ETEC) strains. A new in-feed probiotic, LSP 122 (Alpharma), containing viable spores of Bacillus licheniformis was tested for its efficacy to control PWDS in piglets in a low health-status farm, using four groups with a total of 256 weaned piglets for a 28-day period. One group (negative control) was offered antimicrobial-free and probiotics-free fed, one group was offered feed supplemented with 10(6)viable spores of Bacillus toyoi (Toyocerin(R)) per gram of feed and two groups were offered feed supplemented with 10(6)and 10(7)viable spores of B. licheniformis per gram of feed, respectively, and were compared with regard to the appearance of clinical signs, mortality, weight gain and feed conversion. The results showed that all groups supplemented with probiotics exhibited a reduced incidence and severity of diarrhoea. Mortality in all probiotic supplemented pigs was significantly lower compared with the negative control group (P<0.05). The evaluation of the weight gain data, as well as feed conversion ratio, indicated that the three treated groups performed remarkably better than the negative control group (P<0.05) and the group receiving the high inclusion of LSP 122 performed better than the two other groups receiving probiotics (P<0.05). No ETEC strains were detected on day 22 in the high inclusion of LSP 122 and Toyocerin groups as compared with the untreated control. It was concluded that the high dosage schedule of LSP 122, providing 10(7)viable spores of B. licheniformis per g of feed, is a very useful agent for the control of PWDS due to ETEC.

A comparative study of the pathogenic properties and transmissibility of a Greek and a Belgian encephalomyocarditis virus (EMCV) for piglets.

Thirteen susceptible piglets, aged 40 days, were divided into two groups and were experimentally infected either with a Greek (myocardial) or a Belgian (reproductive) encephalomyocarditis virus (EMCV) strain (total dose 5 x 10(6) TCID50, intramuscularly and intranasally). Six piglets were placed in the same rooms, 24 h later, as contact controls. The following criteria were studied: ante mortem: clinical signs, serum cardiac isoenzyme activities (CK-MB and LD-1), viraemia, nasal and faecal virus excretion and serological response. Post mortem (after death or euthanasia): gross lesions, virus isolation from tissues, RT-PCR, as well as histopathological and immunohistochemical findings. The Greek strain was more pathogenic, producing mortality, with high cardiac isoenzyme activities and pronounced macroscopic myocardium lesions. The Belgian strain was able to induce mild heart lesions, as detected only by cardiac isoenzyme activity and histopathologically. All contact pigs were infected, within the first 1-2 days of their introduction, that coincided with the period of viral excretion by the experimentally infected pigs (up to the 3rd day post infection). Disease was mild, with no mortality.

Persistence of encephalomyocarditis virus (EMCV) infection in piglets.

Six piglets that had survived experimental infection with encephalomyocarditis virus (EMCV) were treated with dexamethasone for a period of 5 days. The virus had not been detected in excretions of putative carriers for a period of 13-20 days before the treatment. All piglets showed a rise in cardiac isoenzyme (CK-MB) activity, from the first day of treatment, suggesting myocardial damage. Antibody titres against EMCV remained stable or slightly decreased during treatment. EMCV was isolated from blood, nasal and faecal samples from all piglets on days 2 and 3 after initiation of treatment and from various tissues of three piglets. Four contact piglets, that were housed together with the dexamethasone-treated piglets, became infected, indicating that EMCV was shed by treated piglets. It is suggested that recovered pigs may play an important role in the dissemination of EMCV.

The efficacy of enrofloxacin in-feed medication, by applying different programmes for the control of post weaning diarrhoea syndrome of piglets.

Post weaning diarrhoea syndrome (PWDS) in piglets is caused mainly by enterotoxigenic Escherichia (E.) coli (ETEC) strains. Six different in-feed usage programmes of enrofloxacin (ENR/Baytril; I.E.R. 2.5%) were tested for their efficacy on the control of post weaning colibacillosis in piglets, using seven groups with totally 336 weaned piglets for a 28 day period. One group (negative control) was offered feed free of antimicrobials, three groups were offered feed medicated with 50 ppm of ENR starting on weaning day for 5, 7 and 10 days respectively, three groups were offered feed medicated with 50 ppm of ENR starting 7 days post weaning for 5, 7 and 10 days respectively, and were compared with regard to the appearance of clinical signs, mortality, weight gain and feed conversion. The results showed that all ENR treatments reduced the incidence and severity of diarrhoea. Mortality was similar in all ENR treatments, but in the groups where the ENR was added for 10 days immediately after weaning and/or 7 days post weaning for 7 and 10 days respectively was lower compared to the negative control group (P < 0.05). The evaluation of the weight gain data, as well as feed conversion ratio indicated that the six treated groups performed remarkably better than the control group (P < 0.05). No ETEC were detected on days 21 and 28 in all ENR groups contrary to the untreated control. It was concluded that a strategic medication initiated 7 days post weaning with 50 ppm of ENR and only for 7 and 10 days period of time is a useful tool in controlling PWDS due to ETEC.

The efficacy of enrofloxacin in-feed medication by applying different programmes for the control of post weaning oedema disease in weaned piglets.

Oedema disease (OD) usually occurs after weaning and is due to infection with (ETEEC) enterotoxaemic Escherichia (E.) coli. This study further examines the efficacy of three different in-feed usage programmes of enrofloxacin (ENR/Baytril I.E.R. 2.5%), on the control of post weaning OD in piglets. The recommended in-feed dosage of ENR for this clinical indication, i.e. 50 p.p.m., was used. Five groups with a total of 240 weaned piglets for 28 days period were used in this trial. One group (negative control) was offered feed free of antimicrobials, one group was offered feed as that of the negative control group except that the feed consumption was restricted for the first 12 days post weaning, and three groups were offered feed ad libitum medicated with 50 p.p.m. of ENR starting 7 days after weaning for 5, 7 and 10 days, respectively, and were compared with regard to their performance. Mortality was lower compared to the negative control group in all ENR treatments (P < 0.05). The evaluation of the growth performance data, as well as feed conversion ratio, indicated that the three treated groups performed remarkably better than the control group (P < 0.05). It was concluded that a strategic medication initiated 7 days post weaning with 50 p.p.m. of ENR and usually for a 10 day period is useful in controlling and/or preventing post weaning OD due to ETEEC.