Chlamydial infection and perinatal mortality in a swine herd

Chlamydia psittaci was believed responsible for an episode of high perinatal death loss in a swine herd in which 8.5 pigs per litter normally were weaned. In this episode, 18 sows produced 186 pigs, with 50 survivors. Chlamydia was found in tissue samples, and other bacterial or viral pathogens could not be identified. Chlamydia was diagnosed by isolation (ELISA), histologic examination using immunoperoxidase staining techniques, and electron microscopy. Previously, C psittaci has not been considered in the differential diagnosis of swine perinatal mortality.     

Brucella suis biovar 3 infection in a Kentucky swine herd

Sows from a large farrow-to-finish operation in western Kentucky had late-term abortions. Boars and breeding-age sows were tested serologically for brucellosis, and 83 of 125 were classified as reactors. No brucellae were isolated from the tissues of 6 unbred reactor sows, but Brucella suis biovar 3 was recovered from 5 aborted fetuses. Epidemiological studies failed to determine the source of the infection.     

An outbreak of Lawsonia intracellularis infection in a standardbred herd in Ontario

An outbreak of protein-losing enteropathy associated with Lawsonia intracelluaris infection was diagnosed in 6 standardbred foals from a farm in Ontario. Wildlife exposure may have been involved in the perpetuation of disease in this outbreak. The clinical presentation, treatment, outcomes, and pathological findings are described.     

Outbreak of abortion associated with Neospora caninum infection in a beef herd

Abortion outbreaks caused by infection with Neospora caninum in beef cattle have not been well documented. Neospora caninum infection was confirmed in 4 fetuses that were aborted by cattle in a 350-head beef herd; an additional 58 cattle aborted during the next 2.5 months. Overall, 44.4% (157/354) of the cattle in the herd did not become pregnant or experienced fetal loss during this period. Initially, 81.3% (282/347) of the herd was seropositive for antibodies to N caninum, and seropositive cows were 6.2 times as likely to not be pregnant as were seronegative cows. Other potential causes of abortion were not identified in this herd. Following the outbreak, few cattle in the herd or in a second exposed herd seroconverted, but high antibody titers persisted in most seropositive cattle through the end of the calving season. Evidence of cow-to-fetus transmission of the organism was detected in > 82% of seropositive cows.     

Water medication of a swine herd with amoxycillin

A swine herd, consisting of 201 swine, was treated with amoxycillin. Amoxycillin was administered in the water system for 5 days, at a mean dose of 23 mg/kg body weight per day. Twice a day the water consumption was monitored, and blood samples collected from 10 randomly selected pigs. The plasma concentration of amoxycillin was measured by use of high performance liquid chromatography (HPLC). Three days after initiating amoxycillin treatment, the plasma concentration reached a constant level, at which it varied between a maximum of 1.3 μg/mL and a minimum of 0.5 μg/mL. The plasma concentration was compared with a predicted curve based on pharmacokinetic variables obtained previously. The plasma concentrations were at the same level as the simulated ones. The minimum inhibitory concentration (MIC) values of the common respiratory pathogens Actinobacillus pleuropneumoniae and Pasteurella multocida are about 0.1 μg/mL. In pigs the distribution between bronchial mucosa and plasma ( AUC _mucosa/ AUC _plasma) is 0.3, which indicates a therapeutic plasma concentration of 0.3 μg/mL. Data from the present study indicates that water medication with amoxycillin is effective as follow-up treatment.     

Epidemiology of Pasteurella multocida in a farrow-to-finish swine herd.

Thirty-eight clinical isolates of Pasteurella multocida, recovered from a continuous flow, farrow-to-finish swine herd, were characterized by capsular serotyping and restriction endonuclease analysis (REA) in order to study the epidemiology of P. multocida pneumonia. Twenty-three of the 38 isolates obtained in the study belonged to serotype A. They displayed three REA patterns after digestion with HpaII, of which one designated A-3 represented 70% of the samples. The remaining 15 isolates were serotype D. Four different REA patterns were observed in the type D isolates. The REA type D-1 was most prevalent and accounted for 47% of the serotype D isolates. All serotype A isolates were nontoxigenic, whereas five (33%) of the serotype D isolates were toxigenic. Vertical transmission of P. multocida could not be demonstrated, and was probably not a major route of infection. The results of this study suggest that strains of P. multocida virulent for pigs exist and cause swine pneumonic pasteurellosis in continuous flow herds by horizontal transmission.     

Nonresponsive generalized bacterial infection associated with systemic lupus erythematosus in a Beauceron.

A case of concurrent canine systemic lupus erythematosus (SLE) and generalized bacterial infection in a six-year-old female Beauceron is reported. The dog presented with purulent nasal and ocular discharges, skin lesions (including seborrhea, hyperkeratotic areas, and papules as well as ecchymoses around the eyes, on both sides of the pinnae, and on the vulva), generalized lymph node enlargement, a mitral murmur, and lameness. Later, facial swelling, a retrobulbar abscess, and a cough also developed. Occurrence of a generalized bacterial infection was established by culture of group-C, beta-hemolytic Streptococcus from the throat, the mouth, a biopsy site (popliteal lymph node area), the retrobulbar abscess, and the lung. The diagnosis of SLE was based on the clinical signs and particularly on the occurrence of antinuclear antibody (ANA) and antidoublestranded-desoxyribonucleic acid (ds-DNA) antibody. Interestingly, the latter type of antibodies were also detected in two young female puppies whelped by this dog. Salient histological findings included an extreme cell depletion of the lymph nodes and spleen and severe pneumonitis and peribronchiolitis. The results of this case indicate that a definite diagnosis of canine SLE can, at times, be made on the basis of the presence of serum ANA and ds-DNA antibodies.     

Cutaneous papillomas associated with a herpesvirus-like infection in a herd of captive African elephants

Proliferative cutaneous lesions developed in a herd of captive African elephants (33 from an animal importer in Texas [group 1], and 63 young elephants collected in Zimbabwe [group 2]). Group-1 elephants were purchased 8 months before the arrival of the group-2 elephants. On arrival, 7 group-1 elephants had raised nodular fibrous growths, located predominantly on their trunks. Lesions were not observed in the group-2 elephants until approximately 3 months after they were acquired. Lesions on group-2 elephants began as small focal proliferative growths that regressed or that progressed into large nodular fibrous growths that were similar in appearance to those seen in the group-1 elephants. Lesions at various stages of development were biopsied and examined. Histologically, early lesions were inverted papillomas, with hyperplastic and hypertrophic epithelial cells containing amphoteric intranuclear inclusions in the lesion center. Older, large, nodular fibrous growths were ulcerated and were composed predominantly of a thickened dermis containing fibroblasts, collagen, and a mixed inflammatory cell infiltrate; inclusions were not observed in adjacent epidermal cells. Using a peroxidase-antiperoxidase technique, we did not detect group-specific papillomavirus antigens. Southern blot hybridization analysis of DNA from lesion specimens did not indicate papillomavirus-specific genomes. Electron-microscopically, inclusions consisted of aggregates of virus particles. The particles had electron-dense and electron-lucent cores and were 95 to 103 nm in diameter. Virions developed envelopes from nuclear membranes. Mature particles were seen within the cytoplasm and filled the intercellular spaces. On the basis of size, location, conformation, and envelopment, the particles most closely resembled those of herpesviruses.     

Abortion epidemic in a dairy herd associated with horizontally transmitted Neospora caninum infection

A dairy herd experienced an abortion epidemic during which 43 per cent of the cows at risk aborted. Neospora caninum infection was demonstrated in four of six fetuses suitable for examination and the group of at-risk cows that aborted had significantly higher N. caninum antibody concentrations than the at-risk cows that delivered a live calf at term (P<0.001). The antibody concentrations in the cow herd were significantly higher than in the youngstock (P<0.001), and the concentrations in the youngstock increased significantly (P<0.001) with age. When seven months to a year old, the calves born at term to the at-risk cows had significantly higher (P=0.007) antibody concentrations than age-matched calves born before the epidemic. At the time of the epidemic, there was a significant increase in the antibody levels of the herd that was not consistent with vertical infection alone, indicating that there appeared to have been a sudden large increase in the incidence of horizontal postnatal transmission of N. caninum to the cow herd, or to the surviving offspring of the at-risk cows, or to both of these groups.     

Environmental source of mycobacteriosis in a California swine herd.

Between July 1985 and April 1986, mycobacterial lymphadenitis was recorded in six of 2407 slaughter pigs from a commercial swine herd in which the majority of pigs were raised in confinement. Records showed that all six affected pigs had access to dirt-floored pens at least 81 days prior to slaughter. The mycobacteriosis lesion rate for pigs exposed to dirt pens was 9.4% while in nonexposed pigs the lesion rate was zero. The risk associated with movement of pigs from concrete floored pens to dirt pens was evaluated by a field trial. In the field trial, two litters (5 of 15 pigs) exposed to dirt pens at 12-24 days of age but none of nine nonexposed litters (39 pigs) developed lesions. Mycobacterium avium-complex bacteria were recovered from both exposed litters (9 of 15 pigs) but from none of nine nonexposed litters. Serovars of M. avium-complex isolated from trial pigs included 1, 4, 8, 9, the dual serovar 4/8, and an untypable serovar. Incense-cedar bark (Calocedrus decurrens) used as a flooring material in the pens was demonstrated to be a potential source of M. avium-complex serovar 9. The dual serovar 4/8 and an untypable M. avium-complex were isolated from the dirt-floored pens. No evidence of cross-transmission of M. avium-complex infection was detected. The sporadic pattern of mycobacteriosis observed in the herd probably resulted from infrequent exposure to a common environmental source.     

Neospora caninum infection associated with stillbirths in captive antelopes (Tragelaphus imberbis)

Neosporosis was diagnosed in full-term stillborn twin calves of captive antelopes (Tragelaphus imberbis) in a German zoo. In both calves a multifocal non-suppurative encephalitis was present and infection with Neospora (N.) caninum was confirmed by foetal serology and PCR. N. caninum-DNA was detected in brain, heart, lung, liver and spleen of a third full-term stillborn calf. Histopathological lesions were absent in this calf and antibodies against N. caninum were not detected in pleural fluid. Immunohistochemistry failed to demonstrate N. caninum antigen in all three calves.     

Diagnostic characterization of a feral swine herd enzootically infected with Brucella.

Eighty feral swine were trapped from a herd that had been documented to be seropositive for Brucella and which had been used for Brucella abortus RB51 vaccine trials on a 7,100-hectare tract of land in South Carolina. The animals were euthanized and complete necropsies were performed. Samples were taken for histopathology, Brucella culture, and Brucella serology. Brucella was cultured from 62 (77.5%) animals. Brucella suis was isolated from 55 animals (68.8%), and all isolates were biovar 1. Brucella abortus was isolated from 28 animals (35.0%), and isolates included field strain biovar 1 (21 animals; 26.3%), vaccine strain Brucella abortus S19 (8 animals, 10.0%), and vaccine strain Brucella abortus RB51 (6 animals, 7.5%). Males were significantly more likely to be culture positive than females (92.9% vs. 60.6%). Thirty-nine animals (48.8%) were seropositive. Males also had a significantly higher seropositivity rate than females (61.9% vs. 34.2%). The relative sensitivity rates were significantly higher for the standard tube test (44.6%) and fluorescence polarization assay (42.6%) than the card agglutination test (13.1%). Lesions consistent with Brucella infection were commonly found in the animals surveyed and included inflammatory lesions of the lymph nodes, liver, kidney, and male reproductive organs, which ranged from lymphoplasmacytic to pyogranulomatous with necrosis. This is the first report of an apparent enzootic Brucella abortus infection in a feral swine herd suggesting that feral swine may serve as a reservoir of infection for Brucella abortus as well as Brucella suis for domestic livestock.     

Reproductive consequences of an X-autosome translocation in a swine herd.

A survey was conducted on the chromosome makeup and breeding data of pigs housed at the Arkell Research Station, University of Guelph, to determine the reproductive impact of a reciprocal translocation previously identified as t(Xp+;14q-). Blood samples were cultured and chromosome spreads were examined to identify carriers in the herd. Gonadal features of carrier boars and piglets and their age-matched normal counterparts were studied, and the reproductive history of carrier sows, including the number of breedings required for conception, mean litter size, prevalence of still births and malformations, and sex distribution among the piglets, was compared with that of normal (noncarrier) sows. Our observations on testicular histology confirmed that X-autosome translocation-carrier boars are sterile, and the analysis of reproductive data showed that the most striking effects of t(Xp+;14q-) on sows are the 50% increase in the number of breedings required for conception and the over 25% reduction in litter size compared with that of normal sows. The reproductive impact of this and similar translocations on the herd and on the swine industry in general is discussed.     

Lightning injury in an outdoor swine herd.

Three pigs, weighing 63 kg-70 kg each, from a group of 8 pigs in an outdoor pen that was struck by lightning were necropsied. All 3 pigs presented with hind limb paralysis. The only lesions identified were multiple fractures of the last (seventh) lumbar vertebral body and first sacral vertebral segment, with dorsal displacement of the sacrum and transection of the distal spinal cord and spinal nerves. Hemorrhages extended from the fracture sites into muscles immediately surrounding the lumbosacral junction and retroperitoneally into the pelvic cavity. These hemorrhages were not clearly visible until the pelvic region was dissected. Lesions commonly found in human lightning-strike victims were not present in these pigs. Because vertebral fractures may be the only lesions and may be grossly subtle in heavily muscled pigs, careful pelvic and vertebral dissection is recommended in cases of suspected lightning strike and electrocution.