Therapeutic and prophylactic efficacy of imidocarb dipropionate on experimental Babesia ovis infection of lambs

The objective of this study was to evaluate the therapeutic and prophylactic efficacy of imidocarb dipropionate (IMDP) against babesiosis and to determine specific antibodies against Babesia ovis in experimentally infected lambs. Thirty-six 6-month-old splenectomized lambs were used. The lambs were randomly divided into six groups with six animals each, and were intravenously inoculated with 50 mL B. ovis-infected erythrocytes as follows: group I (therapy group) was treated with IMDP (1.2 mg/kg body weight) starting on the day of onset of clinical signs of babesiosis after the inoculation; group II (untreated control animals) was not treated with any therapeutic treatment after the inoculation; groups III, IV, V and VI (prophylaxis groups) were administered IMDP (2.4 mg/kg body weight) 1, 2, 3 and 4 weeks before the inoculation, respectively. The animals were housed in a tick-proof room with water and food ad libitum up to the 30th day post-inoculation (PI). The lambs were monitored from the first day PI by recording the manifestation of clinical disease, rectal temperature, and the degree of parasitaemia. All the lambs became infected with B. ovis, except five animals from group III, which were treated 1 week prior to experimental infection. Other animals showed signs of acute clinical babesiosis. The animals treated with IMDP (group I) were able to clear the parasite from the blood circulation after 48 h post-treatment. The recrudescence of B. ovis was observed in two lambs 7 days after treatment, and they were treated with the second similar dose of the drug. Six lambs (1, 1, 2 and 2 lambs in group III, IV, V and VI, respectively) from the prophylaxis groups died within 7-17 days after showing high parasitaemia and clinical symptoms of the disease. Regardless of the clinical symptoms, 83.30% and 66.66% of the lambs which were administered IMDP 1-2 and 3-4 weeks before, were determined to be protected against the virulent field strain of B. ovis.     

Bluetongue virus serotype 20 infection in pregnant Merino sheep

Eleven maiden Merino ewes, free of antibody to bluetongue virus serotype 20 (BTV-20) in agar gel immunodiffusion and serum neutralisation tests, were mated once with a ram. Ten ewes were inoculated with BTV-20 35 to 42 days after service, and one ewe was left as an uninoculated control. One of the inoculated ewes and the control ewe remained uninfected throughout the experiment. Eight of the remaining 9 ewes showed clinical signs ranging from mild to moderate, and the other showed no clinical signs of infection. BTV-20 viraemia was detected in ewes between days 3 and 11 post inoculation, and the serum antibody response was followed. The control ewe and 5 of the 9 infected ewes were pregnant when examined 90 to 97 days after service. Each of these animals produced a normal lamb. There was no evidence of abortion in the remaining 5 ewes, and no transplacental transfer of virus was detected in the lambs of the 5 infected ewes. At necropsy, 46 days after the birth of the last lamb, no gross or microscopic lesions were observed in either the ewes or lambs.     

Variation in the immuno-pathological responses of lambs after experimental infection with different strains of Mycobacterium avium subsp. paratuberculosis

Ruminant infection by Mycobacterium avium subsp. paratuberculosis (MAP) causes a granulomatous inflammatory response in the intestine and associated lymph nodes. Differences either in the affected organs or in the inflammatory infiltrate were observed between species and individuals. Such differences are usually attributed to variations in host immune responses or to inconsistent effects among different MAP strains. To evaluate if different MAP strains induce different immuno-pathological responses in lambs, 28 one-month-old individuals were divided into six groups and inoculated with different MAP strains. Groups 1 and 2 were inoculated with two bovine strains isolated in Argentina that showed different genetic patterns after BstEII-IS900-RFLP (hereafter strains E and A respectively). Group 3 was inoculated with a bovine strain isolated in Spain obtained after a previous step of culture (patterns C1). Group 4 was inoculated with a homogenate of intestinal mucosa of a clinical case affected by the same bovine strain as that of group 3. Group 5 was inoculated with an ovine strain that was directly purified from the intestinal mucosa of a clinical case, and group 6 was kept as control (i.e. no inoculation). Peripheral immune responses were assessed until 150 days post-infection (dpi), when lambs were humanely killed. Pathological studies were performed in tissues from the intestine and lymph nodes. Lesion types and inflammatory infiltrates were examined as indicators of pathogenicity. All the lambs infected with bovine MAP strains showed a common lesion pattern regardless of the strain type. Such pattern was characterized by focal lesions mainly in the mesenteric lymph nodes, the presence of fibrous tissue, and, occasionally, necrosis in the granulomas as well as the presence of numerous giant cells. Differences in lesion severity were observed among groups: lambs from groups 1 and 2 had the highest number of granulomas and the largest lymph node area affected. Lesions in animals from group 5 (infected with an ovine strain) were more severe and occurred mostly in the intestinal lymphoid tissue; necrosis, fibrosis or giant cells were never detected in this group. These results indicate that the MAP strain type induces different pathological responses in lambs.     

Pathogenicity of a modified-live pseudorabies vaccine virus in lambs

Subcutaneous injections of modified-live pseudorabies virus (PRV) vaccine into lambs caused clinical signs and death within 1 week after injection in 4 of 5 inoculated lambs. The clinical signs included depression, high fever, muscle fasciculations and convulsions, occasionally followed by death within 48 hours of the initial clinical signs. Histologic examinations and virus isolation procedures demonstrated PRV in the CNS of infected lambs. Sera from sick lambs remained negative for PRV antibodies. Two subsequent serial passages of the vaccine virus in lambs resulted in similar clinical signs and death in 6 of 10 inoculated lambs. Again, PRV was isolated from tissues of sick lambs, and the histopathologic findings were characteristic of the disease. Affected lambs remained seronegative to PRV, as did lambs that remained clinically normal after inoculation. There was no evidence of PRV transmission to uninoculated lambs and pigs housed with the infected lambs.     

Interaction of bovine respiratory syncytial virus and Pasteurella haemolytica in the ovine lung

The potential synergistic effect of bovine respiratory syncytial virus (RSV) and Pasteurella haemolytica in the production of pneumonia after aerosol/intranasal infection of conventionally reared lambs was evaluated. A mild clinical response was observed in lambs given virus and/or bacteria. Gross pulmonary lesions were seen in 3 of 6 lambs given RSV and then P haemolytica 3 or 6 days later, respectively (groups D and E), and in 1 lamb of 5 given virus and bacteria simultaneously (group G). Gross lesions were not seen in control sheep (group A), in lambs given virus or bacteria alone (groups B and C), or in lambs exposed to bacteria and then virus 3 days later (group F). Bovine RSV and P haemolytica were recovered from the lungs of 5 of 7 lambs with macroscopic lesions. Gross pulmonary lesions were cranioventral firm areas of red consolidation. Microscopically, the predominant lesion was a suppurative bronchopneumonia. Bovine RSV was recovered from the nasal cavity of 8 of 27 (30%) lambs given RSV during days 3 to 6 after viral inoculation, including 1 lamb in group B, 2 in groups D, E, and F, and 1 in group G. Pasteurella haemolytica was recovered from the nasal cavity of 9 of 28 (32%) inoculated lambs, including 2 lambs from groups C and E, 3 in group D, and 1 in groups F and G. Viral antigen, as determined by immunofluorescence, was concentrated mainly in individual cells in alveolar walls, some alveolar macrophages, and a few bronchiolar epithelial cells. In vitro alveolar macrophage assays indicated decreased numbers of Fc receptors on those macrophages collected from lambs given RSV 6 days before P haemolytica infection, as compared with that in the other groups. These cellular defects disappeared after 24 hours of culture. Seemingly, bovine RSV does facilitate P haemolytica pulmonary infection in conventional, immuno-competent lambs and provides evidence for decreased Fc receptors on alveolar macrophages.     

Suspected photosensitisation in lambs grazing birdsfoot trefoil (Lotus corniculatus)

Suspected photosensitisation occurred in three groups of lambs grazing birdsfoot trefoil (Lotus corniculatus c.v. Grasslands Goldie). In one group, sucking lambs aged about 10 weeks, grazing birdsfoot trefoil, developed skin lesions while lambs of a similar age and from the same flock grazing lucerne (Medicago sativa) or a mixed sward of both species showed no signs of photosensitisation. Affected lambs had lesions on their backs and ears. In a few animals the tips of the ears were shortened by 2-3 cm. In the affected lambs, serum liver enzymes (gamma-glutamyltransferase, glutamate dehydrogenase), bilirubin and serum Vitamin B12 levels were within the normal range. At necropsy, no significant pathological changes were detected in the liver and histological changes in the skin were consistent with primary photosensitisation. In the second group, three of 80 weaned lambs grazing the same birdsfoot trefoil at a restricted intake were affected in the same manner as the first group. In the third group, 15 animals from 28 sets of sucking twin lambs were also affected. In only two sets of twins were both lambs affected. None of the ewes grazing with the lambs in the first or third groups showed any clinical signs of photosensitisation.     

Effect of oxytetracycline therapy on experimentally induced pneumonic pasteurellosis in lambs

Two groups of 10, specific pathogen free lambs were injected with a long acting oxytetracycline preparation at a dose rate of 20 mg/kg either 24 hours before or 24 hours after exposure to an aerosol of Pasteurella haemolytica. When compared with the response of similarly infected but untreated lambs, the effect of pretreatment was to postpone the appearance of clinical signs of pneumonia for four days and the deaths of five lambs for five to six days post infection, by which time seven untreated lambs had died. Treatment 24 hours after infection caused a rapid clinical recovery which persisted until six days after infection but two treated lambs died seven days after infection. Lung lesions in the group treated after infection were significantly less extensive than those in the untreated lambs.     

Inoculation of lambs with ovine adenovirus 5 (Mastadenovirus ovi 5) strain RTS-42

Twelve 1-week-old colostrum-deprived lambs inoculated with the RTS-42 strain of Mastadenovirus ovi 5 were killed and necropsied (2 lambs/day) on postinoculation days (PID) 2, 4, 6, 8, 12, and 21. Four noninoculated lambs were killed and necropsied (2/day) on PID 6 and 12. Virus was isolated from nasal secretions and feces on PID 1 to PID 6, from tracheal fluids and lung tissue of lambs necropsied on PID 2, 4, and 6, and from lung tissue from 1 lamb necropsied on PID 8. Virus was not recovered from liver, kidney, or small intestine of inoculated lambs or samples from noninoculated lambs. Serum antibody was first detected on PID 6 in the inoculated lambs. Noninoculated lambs remained seronegative. None of the lambs in the study developed clinical signs of infection although lesions were produced in the respiratory tract.     

Immune response of lambs to experimental infection with Orf virus

A group of six specific pathogen free (SPF) lambs were infected epidermally with Orf virus. Seven weeks later they were reinfected. For a period of 4 weeks after each inoculation they were observed clinically and blood was collected for analysis of virus specific antibody measured by ELISA and peripheral blood lymphocyte (PBL) proliferative response to various viral antigens. After the primary infection all animals showed clinical signs of Orf, namely vesicle formation which became pustular followed by scabbing; this steadily became heavier prior to shedding and the resolution of the infection by about 4 weeks. The severity of infection varied within the group. Little lymphoproliferative activity was recorded during the primary infection, although five/six test animals had positive lymphoproliferative responses to an sodium dodecyl sulphate (SDS) solubilised scab purified Orf virus preparation at some point between days 7 and 14 after inoculation. All animals seroconverted to Orf virus, lymphoproliferative activity always preceding specific antibody detection. Resolution of the secondary infection was very rapid. Vesicles were visible by day 2 after inoculation which became pustular followed by scab formation and resolution in the majority of animals by day 8. All animals showed a significant (greater than four-fold) rise in specific antibody titre following secondary inoculation. The proliferative activity of PBL's was much greater than that recorded for the primary infection although the magnitude of this response varied greatly between individuals.     

Role of thiamine status in sulphur induced polioencephalomalacia in sheep.

The effects of excess dietary sulphur were studied in sheep supplemented and unsupplemented with thiamine. The diets contained either 0.19 per cent sulphur (LS) or 0.63 per cent sulphur (HS) in combinations with 14 mg kg-1 thiamine (LB1) or 243 mg kg-1 thiamine (HB1). A total of 56 two-month-old lambs were used. Groups consisting of nine, nine, 22 and 16 lambs were fed LS-LB1, LS-HB1, HS-LB1 and HS-HB1 diets, respectively for 14 weeks. Out of 22 lambs fed the HS-LB1 diet, seven lambs developed neurological signs between the third and eighth week of the trial. Two of these lambs died, three that were in extremis were euthanased, and two recovered completely. All clinically affected animals had extensive malacic lesions in the cerebral cortex, midbrain and brainstem. None of the lambs from the LS groups or HS-HB1 group developed clinical signs. Several clinically normal lambs from the HS-LB1 group had necrotic lesions in their brains at gross and microscopic examination. Supplementation with dietary thiamine prevented development of clinical signs, but did not totally prevent development of microscopic brain lesions. Brain thiamine concentration, transketolase activity and thiamine pyrophosphate (TPP) effect were not different (P greater than 0.05) among groups. There was a strong effect (P less than 0.0001) of dietary thiamine supplementation on blood thiamine concentration and TPP effect. Blood thiamine concentration was higher whereas TPP effect was lower in the thiamine supplemented sheep. Blood and tissue thiamine concentrations in sheep exposed to high dietary sulphur did not indicate either systemic or local thiamine deficiency per se. Increased TPP effect in sheep fed the HS-LB1 diet indicated mild to moderate metabolic thiamine deficiency. Thiamine inadequacy may be an effect of an increased requirement for thiamine in animals exposed to excess dietary sulphur.     

Association between incubation time and genotype in sheep experimentally inoculated with scrapie-positive brain homogenate

OBJECTIVE: To compare incubation time and clinical signs of scrapie in codon 136/171 alanine-valine/glutamine-glutamine (AVQQ) experimentally inoculated sheep with that in sheep with the more common 136/171 AAQQ genotype. ANIMALS: 60 Suffolk sheep. PROCEDURE: Twenty-seven 171 QQ ewes purchased from 2 private flocks were bred with a 171 QQ Suffolk ram before being inoculated with a 20% solution of scrapie-positive brain homogenate (5 mL, PO) from sheep containing genotypes 136/154/171 AA/arginine-arginine (RR)/QQ, AVRRQQ, and VVRRQQ that had died of scrapie. Ewes had 33 lambs, which were inoculated in the same manner on the day of birth. RESULTS: All 16 genotype 136/154/171 AVRRQQ sheep that died of scrapie were 9 to 11 months of age; clinical signs lasted 1 day to 3 weeks with no wasting and only mild pruritus. The first AARRQQ sheep died with typical clinical signs of scrapie 27 months after inoculation, and 14 were still alive 37 to 42 months after inoculation. The 136/171 AVQQ sheep had minimal accumulation of modified cellular protein (PrP(SC)) as determined by immunohistochemical (IHC) staining within affected cells; thus the severity of clinical signs and time of death were not associated with brain lesions or the amount of PrP(SC) in brain TISSUE OF 136/154/171 AVRRQQ sheep as determined by IHC staining. CONCLUSIONS AND CLINICAL RELEVANCE: The rapid incubation time may have been influenced by the codon 136 genotype, a new unreported valine (V)-dependent strain of scrapie similar to strain SSBP/1, or the inoculum may have contained a traditional strain and a V-dependent or SSBP/1-like strain of scrapie.     

Naturally occurring and experimental Stachys arvensis (staggerweed) toxicity in lambs in New Zealand

Stachys arvensis (staggerweed) is a common, widely distributed weed of cultivated and waste land with the potential to intoxicate sheep. Two naturally occurring outbreaks of suspected staggerweed toxicity in the lower North Island were investigated. Affected lambs had been recently moved onto staggerweed-contaminated Brassica spp. crops. In total, 150/1,200 (13%) lambs developed hindlimb paresis, a fine generalised muscular tremor, and hunched posture. When forced to move, many became recumbent. Most lambs recovered within 48 h of removal from staggerweed, although a few developed clinical signs again when transported 2–3 weeks later. Grossly, affected lambs had large amounts of staggerweed plant material and seeds within the rumen. Histopathology showed mild, multifocal degeneration of the white matter tracts of the central nervous system (CNS), most commonly in the ventral funiculi of the spinal cord, and acute, mild to moderate, multifocal degeneration of skeletal muscles. Creatine kinase (CK) activity in serum was mildly to markedly elevated in affected lambs. In a feeding trial, ten 10-month-old Romney lambs were randomly assigned to equal treatment and control groups. Treated lambs were drenched with a liquid extract of staggerweed once daily for 7 days. Three of five treated lambs developed mild exercise intolerance, and 1/5 displayed mild paresis of the hindlimbs, slightly crouched hindlimb stance, and shortened gait, on days 6 and 7. Histologically, 4/5 treated lambs had degeneration in white matter tracts of the CNS, indistinguishable from those seen in the lambs in the outbreak, and in 1/5 lambs there was scattered regeneration of skeletal muscle. CK activity in serum in treated lambs was not significantly higher than that in control lambs. None of the control lambs developed significant clinical signs, histological changes or increases in CK activity in serum. The clinical signs and lesions observed in both the outbreaks and feeding trial were similar to those previously described in studies in Australia, with the exception that myodegeneration was more prominent in the outbreaks in New Zealand. Further characterisation of the pathogenesis of staggerweed toxicity and its potential role as a food safety hazard will be facilitated through identification of the toxic principle(s).     

Clinical and microbiologic findings in lambs inoculated with Pasteurella haemolytica after infection with ovine adenovirus type 6

Colostrum-deprived lambs (10 to 20 days old) were inoculated with either ovine adenovirus type 6 (OAV-6; n = 6), Pasteurella haemolytica type A1 (n = 6), or OAV-6 followed by P haemolytica 5 days later (n = 10). Another group (n = 3) served as sham-inoculated controls. Lambs inoculated with OAV-6 or P haemolytica developed mild and moderate respiratory tract disease of 6 and 3 days' duration, respectively. Lambs inoculated with virus and bacteria developed clinical signs of respiratory tract disease of greater intensity and duration (9 days) than with either agent alone. Within 3 hours of bacterial inoculation, all lambs that received P haemolytica were anorectic, listless, and febrile, and had hyperpnea and dyspnea. Ovine adenovirus type 6 was isolated from all virus-inoculated lambs. Although P haemolytica was not recovered from all bacteria-inoculated lambs, it was recovered for a longer period in the group that received both agents. Antibody to OAV-6 was detected in virus-inoculated lambs as early as day 6 after inoculation. The control lambs remained clinically normal and neither virus nor bacteria were recovered at necropsy.     

Chlorophacinone exposure causing an epizootic of acute fatal hemorrhage in lambs.

This report describes an epizootic of chlorophacinone toxicosis in lambs with severe acute hemorrhages. Eleven lambs, approximately 1-2 months of age, suddenly developed epistaxis, respiratory distress, and facial and cervical swelling. Affected animals died within 1-2 hours from the onset of clinical signs. Two lambs were available for complete postmortem examination. Gross lesions included mucosal and organ pallor, icterus, melena, and lung edema, as well as thymic, cervical muscle, and intra-articular hemorrhage. Histologically hepatocellular centrolobular necrosis was observed. The anticoagulant chlorophacinone was detected in the livers at 0.58 ppm and 0.50 ppm (wet weight), respectively. The source of exposure to chlorophacinone was old bait material placed between the wall studs of the building housing the ewes and lambs. The lambs were able to reach the bait through a hole in the plywood interior wall of the building.     

Experimental Corynebacterium pseudotuberculosis infection in lambs: kinetics of bacterial dissemination and inflammation

Infection and pyogranulomas induced by Corynebacterium pseudotuberculosis were experimentally reproduced in lambs. In two separate experiments, bacterial multiplication and dissemination were studied in 30 male lambs inoculated subcutaneously into the right ear with 1.1 or 1.5 X 10(8) viable C. pseudotuberculosis strain 19R. Infected lambs were necropsied at various times until the 28th day following inoculation. After a transient hyperthermia and a strong local inflammatory reaction, an abscess developed in the right ear from postinoculation day (PID) 6; it enlarged until PID 14 and stabilized thereafter and was associated with adenopathy of lymph nodes draining the head. Three acute phase indicators of inflammation were followed in 14 out of 30 lambs; plasma levels of copper and haptoglobin increased rapidly following inoculation whereas zinc levels decreased. The peaks were reached from PID 1 to 5, and thereafter the values came back slowly to the baseline. Antibodies against C. pseudotuberculosis exotoxin increased from PID 5 and reached a plateau on PID 21. Bacterial dissemination, assessed by the number of infected organs per lamb, was maximal on PID 16 and then stabilized until the end of the experiment. Lungs were infected in seven out of 18 lambs necropsied on PID 28. These results demonstrate a significant relationship between the clinical score of superficial lymph nodes or inoculation site and the infection level of these organs, and an early localization of pyogranulomatous lesions in regional lymph nodes. The subsequent development of the disease was related to the enlargement of these lesions and, in some animals, to a bacterial dissemination from primary sites of infection in the right prescapular lymph node and in the lung.     

Ovine white-liver disease (OWLD). Changes in blood chemistry

Changes in blood chemistry were examined in vitamin B12 deficient lambs which developed ovine white-liver disease (OWLD), and were compared with values of cobalt/B12 supplemented lambs on the same pastures, as well as clinically healthy, but sometimes B12 deficient, lambs on other pastures (H). In the OWLD group, signs of hepatic damage were seen concurrently with reduction in weight gain, or 1-3 weeks before, and comprised elevation of serum glutamate dehydrogenase (GLDH) and decrease of phospholipid and cholesterol. Drop of plasma glucose and elevation of gamma GT also came in the earlier phase of the disease. All other blood changes developed later, and were partly regarded as reflections of the inappetence or hepatic injury. The changes included a drop in packed cell volume (PCV) and mean corpuscular volume (MCV), elevation of serum iron, and reduction of total serum protein and urea. Generally Co/B12 supplementation prevented hepatic damage and normalized blood values. The clinically healthy H lambs also showed signs of hepatic damage, especially one year when they were B12 deficient, indicating that simple B12 deficiency causes a moderate liver damage as well. For diagnostic purposes, clinical pathology is recommended mainly on a flock basis.     

Epidermolysis bullosa in German black headed mutton sheep

In three flocks, 13 pure- and 1 crossbred German black headed mutton lambs were ascertained which had clinical signs of epidermolysis bullosa (EB). The three farmers reported of further 20 affected lambs with similar signs in their flocks in the past lambing seasons. The affected lambs were progeny of six rams and 17 ewes. Two rams and six ewes with affected offspring from two farms were used for a breeding trial. In the course of these experimental matings, 21 lambs were born, six of which were affected by EB. All lambs born in this trial underwent clinical and haematological examination and all the affected lambs had to be euthanised due to severe and progressing clinical symptoms. Clinical examinations in 20 affected lambs revealed shedding of claw horn, erosions and ulcers of skin and mucous membranes. Histopathology showed subepidermal splitting and blistering with intact basal keratinocytes. These findings together with the premature death of affected lambs within the first two months of life made a Herlitz type of junctional EB most likely. The results of the test matings demonstrated the genetic transmission and indicated an autosomal recessive mode of inheritance for this lethal condition.     

Properties of a respiratory syncytial virus isolated from a sheep with rhinitis

A virus isolated from a yearling cross-bred ewe was identified as respiratory syncytial virus (RSV) by indirect immunofluorescence and by virus neutralization with bovine RSV antisera. The virus caused a mild conjunctivitis in 3-month-old lambs when inoculated alone. Although clinical signs of pneumonia were not observed, there was gross and microscopic evidence of pulmonary inflammation in the lungs of lambs inoculated with either the sheep RSV isolate alone or in conjunction with Pasteurella haemolytica. Lung lesions in the dual infection were more severe, with approximately 10% of the total lung mass affected. Lavage fluids from lambs inoculated with virus and bacteria contained approximately 3 times more inflammatory cells than from control lambs or lambs inoculated with virus only. The sheep RSV isolate was classified as a mild respiratory pathogen in lambs of this age. Speculations on the potential importance of this virus in interspecies transmission to cattle and goats were discussed.     

Cross protection of mice and swine given live-organism vaccine against challenge exposure with strains of Erysipelothrix rhusiopathiae representing ten serovars

Mice and swine vaccinated (subcutaneous inoculation) with live acriflavine-fast attenuated Erysipelothrix rhusiopathiae, strain Koganei 65-0.15 (serovar 2), were challenge exposed with 10 strains of E rhusiopathiae pathogenic for swine; the latter strains comprised serovars 9 and 10 and other previously undetermined. Vaccinated mice did not die after they were challenge exposed (subcutaneous inoculation) with serovars 4, 6, 7, 8, 9, 10, 15, 16, or N, but vaccinated mice challenge exposed with strain 2553 (serovar 20) had 30% mortality. Nonvaccinated control mice died after they were challenge exposed with all serovars tested. One of 2 vaccinated swine challenge exposed (intradermal inoculation) with each of strains 911 (serovar 8), 2179 (serovar 10), or 2553 developed localized urticarial lesion at the site of intradermal inoculation. Vaccinated swine challenge exposed with serovars 4, 6, 7, 9, 15, 16, or N did not have clinical signs of acute swine erysipelas. Nonvaccinated control swine developed localized lesions at the site of intradermal challenge inoculation.