Evaluation of the pathology,pathogenesis and aetiology of auricular elephantiasis in slaughter pigs

Ears from slaughter pigs with auricular elephantiasis (n = 24) and the corresponding lymph nodes (lnn.) (n = 26) were grossly, histopathologically and microbiologically examined. Immunostaining for IgM, IgG, Cd3epsilon and bacterial antigens of Arcanobacterium pyogenes and Staphylococcus aureus was performed by indirect enzyme-based techniques. Ears were variably thickened depending on the sampled area (basis, centre and apex). However, at all locations the thickness, the length from basis to apex and the weigh of whole ears with elephantiasis were significantly increased (P < 0.01). The corresponding lnn., that is, ln. parotideus superficialis and profundus, had also increased significantly (P < 0.01) in volume. Histopathologically, lesions of the ears and the corresponding lnn. revealed changes characterized by diffuse fibrosis intermingled with multiple pyogranulomatous foci containing asteroid bodies. In the majority of lesions, four distinct zones due to different cellular infiltrates encircled the central core of the asteroid bodies. In several lesions, the pyogranulomatous foci were contained within the lymph vessels. Immunohistochemically, only the bacterial antigen of S. aureus was detected within the cytoplasm of the macrophages and/or in the asteroid bodies of the ears (41.5%) and in the regional lnn. (30.8%). An abundant number of IgM, IgG and CD3epsilon-positive cells were present in all the pyogranulomatous lesions, whereas a positive IgG-staining was observed only in a single asteroid body. Thus, porcine auricular elephantiasis is a chronic pyogranulomatous inflammation that is frequently positive for S. aureus and is lymphogenically spread. Therefore, the lesions of the ears with auricular elephantiasis and the corresponding lnn. should be termed auricular botryomycosis and botryomycotic lymphadenitis, respectively. Moreover, as the disease is observed frequently in slaughter pigs it must also be considered according to the welfare of the animals and in relation to post-mortem meat inspection.     

Bacteriologic and histologic studies of hepatic abscesses in cattle

Twenty-eight abscessed livers were collected from feedlot cattle at an abattoir; specimens were obtained from 49 abscesses for bacteriologic culture and for histologic examination. Cultural procedures included techniques to enumerate and isolate facultative and obligate anaerobic bacteria. Anaerobic bacteria were isolated from all 49 abscesses, whereas facultative bacteria were isolated from only 22. Mean bacterial counts for anaerobic and facultative bacteria were 3 X 10(8) and 8 X 10(8) bacteria/g of purulent material, respectively. Fusobacterium necrophorum, the only anaerobe isolated, was detected in 100% of the abscesses. Fusobacterium necrophorum biotype A was isolated from 57% of the abscesses (in pure culture from 75%), and F necrophorum biotype B was isolated from 47% of the abscesses (from 96% with mixed infections). Corynebacterium pyogenes was the predominant facultative bacterium isolated. Histologic changes in abscesses were qualitatively similar; abscesses were pyogranulomatous, with a necrotic center surrounded by zones of inflammatory tissue. However, the severity of lesions varied, depending on the F necrophorum biotype involved. Portal triad fibrosis and bile-duct proliferation were most severe in biotype A and mixed biotype B infections and less severe in abscesses from which biotype B was isolated in pure culture.     

Mammary development and milk production in the sow: Effects of udder massage, genotype and feeding in late gestation

The primary aim of the study was to investigate whether post-ejection udder massage 1–2 weeks pp (post partum) had an effect on the amount of mammary tissue and milk production in the domestic sow.

The nursing behaviour of 35 primiparous LYL or YLY sows and their litters was followed on days 7 and 14 pp. The milk production was measured by the weigh–suckle–weigh method of the whole litter on days 11 and 18 pp. After weaning on day 28 pp, the sows were slaughtered and the mammary tissue excised and weighed.

No significant correlations were found between the duration of post-ejection udder massage and the subsequent milk production. LYL sows had more mammary tissue (P < 0.05) and their piglets spent more time performing post-ejection udder massage compared to the YLY sows (P < 0.01). Individual variation was found in the proportion of time that the sows were lying on either their right or left side. The weight of the mammary tissue from the left side was positively affected by the amount of udder massage (pre- and post-ejection massage) that the sows had received while lying on the right side relative to the amount that she had received while lying on the left side on day 7 pp (P < 0.01).

In conclusion, the intensity of udder massage influenced the amount of mammary tissue at slaughter. The genotype of the sow affected the expression of nursing behaviour and milk production. No connection was found between post-ejection udder massage and the measures of milk production 1–2 weeks pp. Finally, feeding during the last half of gestation affected the nursing behaviour.     

High and low virulence Staphylococcus aureus strains in a rabbit skin infection model

In the present study, an in vivo rabbit skin infection model was developed to reproduce the lesions caused by high and low virulence Staphylococcus aureus strains from rabbits. "O"-shaped dermal skin lesions were induced on the shaved flanks of anaesthetised rabbits using a tattoo pin and pincers. The induced lesions on the flanks of four groups of 10 rabbits were then inoculated by topical application of 0.1 ml of 10(8)cfu S. aureus bacteria. One group was inoculated with a typical high virulence (HV) S. aureus strain from rabbits, one group received an atypical HV strain and two groups were inoculated with low virulence (LV) strains. Five animals were kept as negative controls. The development, appearance and size of abscesses were scored daily for a period of 2 weeks. The infection model showed reproducible results for the different S. aureus inoculation groups. Inoculation of the skin with the typical HV strain resulted in significantly larger abscesses than those caused by the LV strains. The atypical HV strain caused abscesses of a size intermediate to that obtained with the HV and LV strains. In rabbits infected with LV strains, most of the lesions had healed by day 14 post-inoculation. The devised infection model is able to reliably reproduce the virulence properties of HV and LV S. aureus strains.     

Pyogranulomatous myocarditis due to Staphylococcus aureus septicaemia in two harbour porpoises (Phocoena phocoena)

Staphylococcus aureus septicaemia was diagnosed in a dead, stranded harbour porpoise from the German Baltic Sea and in a live harbour porpoise by-caught in inner Danish waters and taken into captivity. Lesions included pyogranulomatous myocarditis, necrotising suppurative bronchopneumonia, pyelonephritis, osteomyelitis and leptomeningitis, and abscesses in lymph nodes and skeletal muscles. The captive animal had fibrinous suppurative epicarditis and pyogranulomatous myocarditis with abscesses. In both animals the organism was suspected to have entered through skin lesions or via the respiratory tract.     

Pathological and microbiological characterization of mastitis in dairy cows

Mastitis may be caused by a wide range of microorganisms able to induce distinct lesions in mammary tissues. This study aims to characterize the gross and microscopic features of mastitis in dairy cows and to correlate them with the pathogens involved. The udders of slaughtered dairy cows were inspected and milk samples from each mammary quarter or fragments of the parenchyma were sent for microbiological analysis, and tissue collected for histopathological evaluation. A total of 148 cows and 592 mammary quarters were collected. From these, 432 quarters (73%) had mastitis and in 160 (27%), no changes were observed. Mastitis was classified into seven patterns based on the histopathological findings, of which mixed, lymphoplasmacytic, and suppurative mastitides were the most prevalent with 35.9% (155/432), 27.1% (117/432), and 14.3% (62/432) of the cases, respectively. These patterns were associated with the same set of pathogens: Streptococcus spp., coagulase-negative Staphylococcus (CNS), Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, and Corynebacterium bovis. The pyogranulomatous pattern represented 7.2% (31/432) of the cases with distinct distribution based on the agent involved, mostly S. aureus and Nocardia sp. Abscedative mastitis accounted for 6.0% (26/432) of the cases; it was characterized by multiple abscesses in the parenchyma and was mainly caused by Trueperella pyogenes. Necrosuppurative mastitis represented 5.8% (25/432) of the cases which were characterized by severe parenchyma necrosis and were caused by bacteria such as CNS and Escherichia coli. The granulomatous pattern represented 3.7% (16/432) of the cases and was occasionally associated with Mycobacterium sp.

     

Locomotive disorders associated with sow mortality in Danish pig herds

Given the increase in sow mortality in Danish pig herds over the last 10 years, we have investigated the causes of spontaneous death and killing of sows, especially those due to locomotive disorders. A total of 265 culled sows (93 spontaneously dead sows and 172 killed sows) from 10 different herds were sent for complete necropsy, and grouped according to primary diagnoses. From 35 of these sows, tissue for histological evaluation and samples for bacteriological cultivation were also collected, and secondary diagnoses and body condition were recorded. The main causes for killing were related to the locomotive system (72%), arthritis (24%) and fractures (16%) being the most frequent lesions. The main causes of spontaneous death were related to the gastrointestinal system and spleen (45%) and the reproductive system (24%). Arthrosis was a secondary diagnosis in 88% of the killed sows and in 92.5% of the spontaneously dead sows. Arcanobacterium pyogenes was the main cause of arthritis. The killed sows had significantly lower body condition compared with spontaneously dead sows. The first two parities and the time around farrowing were associated with the highest mortality in both groups. Hopefully, these observations can guide breeding units attempting to monitor, control and reduce sow mortality.     

Subcutaneous Botryomycosis Due to Bibersteinia trehalosi in a Texas Longhorn Steer

A 3-year-old Texas Longhorn steer had a long history of progressive swelling of the soft tissues of the jaw and neck. At necropsy, multifocal to coalescing dermal and subcutaneous pyogranulomas were surrounded by fibrous tissue. Microscopically, the pyogranulomas contained aggregates of gram-negative coccobacilli surrounded by Splendore-Hoeppli material and were separated by bands of fibrovascular tissue (botryomycosis). Phylogenetic analysis of multilocus sequence-typing data revealed that the bacteria recovered in pure culture from swabs of submandibular tissue were most closely related to Bibersteinia [Pasteurella] trehalosi. The bacterial colonies were immunohistochemically reactive with a rabbit polyclonal anti-Pasteurella class C acid phosphatase antibody. Botryomycosis is a pyogranulomatous inflammation caused by a variety of nonbranching, nonfilamentous bacteria that elicit the formation of Splendore-Hoeppli material. This case of botryomycosis is unique for its association with Bibersteinia trehalosi.     

Subcutaneous atypical mycobacteriosis in captive tiger quolls (Dasyurus maculatus)

From July 1989 to October 1998, 9/37 (24%) adult captive tiger quolls (Dasyurus maculatus) were diagnosed with atypical mycobacterial infection involving the subcutis and skin. Females were more often affected than males (seven females, two males). Grossly, lesions presented as focal thickenings, plaques, and abscesses within the subcutis, often with fistulous tracts. The subcutis and skin overlying cervical and thoracic regions were the primary sites of infection. Cytology of subcutaneous impression smears from all nine affected tiger quolls revealed pyogranulomatous inflammation admixed with several acid-fast bacilli. Histologically, all tiger quolls had nodular to diffuse pyogranulomatous panniculitis and cellulitis. Small numbers of acid-fast bacilli were noted histologically in 7/9 (78%) animals. Skin cultures from seven tiger quolls were positive for one or more different Runyon group IV mycobacteria. The disease described in these tiger quolls is similar to subcutaneous atypical mycobacteriosis of humans and domestic animals.     

Prevalence of subclinical udder infections and individual somatic cell counts in three dairy goat herds during a full lactation

For dairy goats, both the determination of the somatic cell counts (SCC) and the interpretation of these values may be a problem. Several investigations have shown that SCC for goat's milk, even from not infected mammary halves, are often higher than for cows milk. In the three herds examined about 40% of mammary halves and 30% of the goats were infected. However large differences between the three herds could be observed. In most cases, infections were caused by coagulase negative staphylococci (CNS) or corynebacteria. The SCC of individual milk samples from goats without any udder infection hardly differed from those of goats with at least one udder half infected with CNS. In 20% and 30% of the cases the SCC was higher than 750'000 cells/ml, respectively. The relation between California Mastitis Test (CMT) reactions and udder infections was not very close. Over 20% of mammary halves infected with CNS showed negative CMT reactions. On the other hand, 25% of samples from mammary halves without a proven infection reacted positively. The large differences in individual cell counts on herd and animal level indicate that production and breeding systems might be important reasons for the higher SCC. As a consequence, the most common methods for or the control of udder health and udder infections (SCC, California Mastitis Test) are of limited value for goats. Since there was only a weak relation between milk quality properties and SCC, any arguments for the introduction of legal limits below 1 million cells per ml can hardly be found.     

Carcass condemnation causes of growth retarded pigs at slaughter

Condemnation causes of growth retarded pigs were studied in a Spanish abattoir. A total of 513 carcasses out of 6017 (8.5%) were rejected during inspection. The main reasons for condemnation were abscesses, cachexia, catarrhal bronchopneumonia, vertebral osteomyelitis, arthritis, pleuritis, peritonitis and pleuropneumonia. Positive relationships were found between tail lesions and arthritis (OR=5.23) or vertebral osteomyelitis (OR=24.81), while no relationships were found between tail lesions and abscesses. Lower risks were observed among carcasses condemned for cachexia, and were as follows: abscesses (OR=0.18), arthritis (OR=0.32), vertebral osteomyelitis (OR=0.06). Arcanobacterium pyogenes, either alone or in combination with other agents, was the main bacterial species isolated from abscesses, osteomyelitis and arthritis (73.5% of lesions). Direct economical losses associated with condemnation were calculated to be 30,000 Euro.     

Udder shape and teat-end lesions as potential risk factors for high somatic cell counts and intra-mammary infections in dairy cows

The association of common bacterial pathogens in milk samples during calving with udder shape or the presence of 'teat-end' lesions was investigated in 240 dairy cows from two herds. Sixty-three of 120 cows (53%) in one herd (herd A) and 54/120 animals (45%) in a second herd (herd B) had normal-shaped udders. The remaining animals had udder shapes defined as follows: large pendulous (18% herd A, 26% herd B); large between hindquarter (10% herd A, 17% herd B); overall small (8% herd A, 5% herd B); or small but pendulous (11% herd A, 7% herd B). At calving teat-end lesions were present in 63% and 76% of the quarters of herd A and B animals, respectively. There was no herd effect on udder shape or teat-end lesions. Analysis of variance revealed that udder shape and teat-end lesions did not have a significant association with quarter somatic cell count. However there was some association between mammary infection and udder shape and teat-end lesions. Compared to other udder shapes, cows with large between hindquarter shape had significantly less Staphylococcus aureus and Streptococcus uberis infection (P<0.001). There was a similar albeit less significant negative association with Escherichia coli infection (P<0.01). Infection with Streptococcus agalactiae and Streptococcus dysgalactiae was more frequent in cows with large pendulous and overall small udder conformations. The results also suggest an association between intra-mammary infection at calving and the presence of hyperkeratotic teat-end lesions, given that S. aureus, coagulase-negative staphylococci, S. uberis, S. agalactiae and E. coli were cultured from significantly more quarters with such lesions than from quarters without lesions or with other types of lesion (P<0.001).     

Systemic blastomycosis in a horse.

Progressive multisystemic disease caused by Blastomyces dermatitidis was diagnosed in a 17-year-old Quarter horse broodmare. The mare had been treated unsuccessfully with antibiotics for mastitis 3 months postpartum. The disease progressed to exudative cutaneous lesions affecting the ventrum, pectoral region, and limbs accompanied by weight loss across several months. Yeast bodies were observed in swabs of the cutaneous exudate, suggesting a clinical diagnosis of blastomycosis. Following referral, pleural effusion, cavitated lung lesions, and hyperproteinemia were identified, and the mare was euthanized because of poor prognosis. Necropsy revealed extensive pyogranulomas in the mammary gland, skin, subcutaneous tissues, and lungs, accompanied by thrombi in major blood vessels of the lungs and hind limbs. Histologically, pyogranulomatous inflammation was evident in many tissues, and fungal organisms were seen in sections of mammary gland, skin, subcutis, pericardium, and lung. Blastomyces dermatitidis was cultured from mammary tissue, lungs, lymph node, and an inguinal abscess. Although blastomycosis is endemic in the area of origin of the mare in northwestern Wisconsin, the disease is extremely rare in horses and hence easily misdiagnosed. Unique features of this case included the extent of mammary gland involvement and the presence of thrombi in multiple sites.     

Impact of intramammary infections in dairy heifers on future udder health, milk production, and culling

Dairy heifers represent the future of a dairy herd, and are expected to freshen with a healthy and well-developed udder, capable of producing an optimal amount of high quality milk. A high proportion of heifers have infected mammary quarters at calving, with coagulase-negative staphylococci (CNS) being the most common cause. Staphylococcus aureus and environmental pathogens are also found. The aim of this paper is to summarize how intramammary infections during (late) gestation and early lactation impair the development of the mammary gland and negatively affect future udder health and milk production. Heifers calving with either subclinical or clinical mastitis are also at a higher risk to be culled in first lactation. The magnitude of the effect is most likely related to the virulence of the causative pathogen, the persistence of the infection when milk production has started, and the time of onset of infection. Histological changes in udder tissue from quarters infected with S. aureus are more pronounced than those in udder tissue from CNS-infected quarters. The longer the infections exist and the longer they persist into lactation, the larger the impact on heifers' future udder health and milk production will be. In general, CNS infections are cleared early in lactation and some studies show that CNS do not have a large impact on future milk production and udder health. Future research should elucidate to what extent pathogen-specific as well as host-related factors affect the persistence of IMI in early lactating heifers.     

Helenalin reduces Staphylococcus aureus infection in vitro and in vivo

Staphylococcus (S.) aureus is a major udder pathogen causing bovine mastitis. Some pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha), enhance extracellular and intracellular growth of S. aureus, indicating that the inflammatory process favors S. aureus infection. Helenalin is a sesquiterpene lactone with potent anti-inflammatory properties. This study was designed to evaluate the effects of helenalin on S. aureus infection. First, in vitro experiments were conducted. These studies revealed that proliferation of S. aureus in bovine mammary epithelial MAC-T cells treated in the presence or absence of TNF-alpha was markedly reduced in the presence of helenalin. Secondly, in vivo effects of helenalin were investigated. Lactating mice treated in the presence or absence of helenalin were challenged by the intramammary route with S. aureus and the bacteria in the mammary glands were counted 12 h after infection. Significantly less numbers of bacteria were recovered from the infected glands of helenalin-treated mice compared with untreated mice. Moreover, histological examination of mammary tissue from helenalin-treated mice that were challenged with S. aureus indicated that helenalin is able to significantly reduce leukocyte infiltration in the mammary gland following S. aureus inoculation. Our results show that helenalin reduces S. aureus intracellular growth and experimental S. aureus infection. We conclude that helenalin may be of potential interest in the treatment of S. aureus-induced mastitis in the bovine species.     

Prevalence of and carcass condemnation from maedi-visna,paratuberculosis and caseous lymphadenitis in culled sheep from Quebec,Canada

We determined the prevalence of lung and mammary gland lesions associated with maedi-visna (MV) infection, the prevalence of paratuberculosis (PTB), and the prevalence and lesions distribution of caseous lymphadenitis (CL) in culled sheep. Total of 451 ewes and 34 rams were selected randomly from two slaughterhouses in Quebec, Canada. MV serostatus was determined by recombinant ELISA test. PTB diagnosis was based on characteristic histological lesions in the terminal ileum, ileocecal lymph node and/or ileocecal valve and CL by gross detection of abscesses and isolation of Corynebacterium pseudotuberculosis. Seroprevalence of MV was 44% (95% CI: 40, 48). Seropositivity increased with age and was higher in ewes than in rams. The percentages of lung and mammary gland lesions in seropositive sheep were 14 and 40%, respectively, but mammary gland lesions lack specificity. The prevalence of PTB was 3% (95% CI: 2, 5). PTB increased with age and was lower among sheep with abscesses. The prevalence of CL was >/=21% (95% CI: 17, 24). The most-prevalent site of caseous lymphadenitis lesions was the thoracic cavity. The risk of carcass condemnation was significantly associated with region, body score and abscesses. Only the presence of abscesses was associated with an increase in trimming of carcasses.     

Isolation and partial characterisation of bacteria recovered from abscesses of normally slaughtered pigs

One hundred and one pig abscesses of different localisation were examined. Bacteria were re-covered from all abscesses. In 6’8 abscesses a mixed aerobic and anaerobic flora was found. In 22 abscesses solely aerobes and in 11 solely anaerobes were found. Gorynebaoterium pyogenes and Fuso-bacterium necrophorum were found in 61 and 45 abscesses, respectively. Hemagglutination litres of G. pyogenes strains were higher with pig erythrocytes than with sheep erythrocytes. Three of 4 isolates of Staphylococcus aureus produced enterotoxin type A.Key words: pig abscess, Corynebacterium pyogenes, Fuso-bacterium necrophorum, hemagglutination     

Teat lesions and their relationship to intramammary infections on small-scale dairy farms in Kiambu district in Kenya

Mammary gland quarters of 139 lactating dairy cows from small-scale dairy herds were examined visually and by palpation for teat lesions and by California mastitis test (CMT) and bacterial culture for subclinical mastitis. Teat lesions were observed in 97 teats. These included teat chaps (39.2%), teat papillomas (23.7%), teat erosions (22.7%), teat fistulae (5.1%), inverted teats (5.1%) and blocked teats (4.2%). According to the CMT, the prevalence of subclinical mastitis was 33.4% in all the mammary gland quarters, 71.0% in quarters with teat lesions and 24.5% in quarters without teat lesions. There was a significant (P < 0.01) association between teat lesions and the prevalence of subclinical mastitis. The mammary gland quarters with teat lesions were 7.2 times more likely to have a positive CMT (P < 0.01) and 5.6 times more likely to have bacterial organisms (P < 0.01) isolated from them than those without any teat lesions. The bacterial organisms most frequently isolated from the CMT-positive milk samples from both the mammary gland quarters with teat lesions and those without teat lesions were Staphylococcus aureus (50.0%), Streptococcus spp. (34.8%) and Arcanobacterium pyogenes (6.2%).     

Morphometric study of experimentally induced Staphylococcus bovis mastitis in the cow

Comparisons were made of bovine mammary tissue at 12 and 24 hours after 5,000 colony-forming units of Staphylococcus aureus 305 was injected into the mammary parenchyma with control tissue from the contralateral udder half. A mild form of staphylococcal mastitis was induced routinely. Generally, S aureus was found in udder tissue removed centrally from the site of injection. Varied degrees of tissue damage were found in infected quarters from alveolar epithelium without damage (similar to control) to extremely swollen epithelium which were typical of cells undergoing disruption. Infected tissues frequently displayed areas of swollen stroma and areas of diminished alveolar lumens. Cellular debris was often found in lumens, and neutrophils frequently filled the alveolar lumen in areas of greatest damage. Thus, a parenchymal injection of bacteria induced early forms of staphylococcal mastitis at the alveolar level.     

Genotyping of Staphylococcus aureus isolated from various sites on farms with dairy sheep using pulsed-field gel electrophoresis

We investigated the genetic diversity of 179 Staphylococcus aureus isolates recovered from various sites in 10 farms producing cheeses manufactured with raw ewe's milk. Isolates were collected from handcrafted cheeses, bulk tank milk, milk from half-udders, skin abscesses on the udder if present, hands and anterior nares of farmers, and air of the milking area. The isolates were typed using pulsed-field gel electrophoresis (PFGE) of DNA SmaI digests and compared to other isolates of S. aureus isolated in different hosts or in different locations. The results showed that nine farms were contaminated by S. aureus isolates with identical banding patterns (named OV) or by genetically related isolates (named OV'). These dominant banding patterns were found in a variable proportion of the samples from each farm (range: 11-100%). Most of the strains isolated from nasal carriage or strains isolated from other regions or from other animal species had different PFGE patterns to OV or OV', except for three strains. These results show that a single clone of S. aureus is widely distributed both in infected mammary glands and in cheese produced from raw milk. This study confirms that infected mammary glands are the main source of the contamination of dairy products in sheep.