Multifocal Granulomatous Hepatitis Caused by Actinobacillus pleuropneumoniae Serotype 2 in Slaughter Pigs: APP occurs in all pigs of all ages characterized by necrotizing, hemorrhagic bronchopneumonia and serofibrinous pleuritis. Other rare manifestations of APP are meningitis, osteomyelitis, arthritis, endocarditis, otits media and granulomatous hepatitis. The granulomas have asteroid bodies formation (Bodies with splendore hoeppli material)

Detection by In-situ Hybridization of Pasteurella multocida Toxin (toxA) Gene in the Lungs of Naturally Infected Pigs – PMT (ToxA gene product) produced by P multocida Types A and D are associated with pulmonary abscessation.  PMT causes increased vascular permeability and is toxic to neutrophils.

Histopathological Distinction and Evaluation of Biliary and Peribiliary Cysts in Pig Liver. J. Comp. Path. 2008, Vol. 139, 202e207.  Most intrahepatic cysts are derived from bile ducts (biliary cysts), but are usually not clinically significant.  Peribiliary cysts are derived from the peribiliary glands located in fibrous tissue of large portal areas and can cause local compression and circulatory disturbance

Capillary Haemangiomas of the Scrotum and Testicle in Boars. J. Comp. Path. 2008, Vol. 139, 177e186. Scrotal hemangiomas occur frequently, but testicular hemangiomas are rare, and they rarely occur together.  The authors suggest an inherited basis since all pigs in the study group were related and of a large white breed.  The authors suggest a UV component to the development of scrotal tumors.

Vascular-associated Lymphoid Tissue in Swine (Sus scrofa). Vol 58, No 2 April 2008. mononuclear cells were noted in the intima and occasionally the inner portion of the tunica media and adventitia at branching sites. The infiltrating cells were primarily CD3+CD4+ T cells, with some macrophages.  Focal accumulations of mononuclear cells in the arterial wall of healthy humans at predilection sites for atherosclerotic lesions.

A prospective, case control study evaluating the association between Clostridium difficile toxins in the colon of neonatal swine and gross and microscopic lesions.  J Vet Diagn Invest 19:52–59  2007). Clostridium difficile –suckling pigs with mesocolonic edema and typhlocolitis.

Brain lesions in pigs affected with PMWS postweaning multisystemic wasting syndrome. J Vet Diagn Invest 19:109–112 (2007). Cerebellar lymphohistiocytic vasculitis and fibrinoid degeneration combined with hemorrhages or with lymphohistiocytic meningitis in pigs with PMWS.

Association of myocarditis with high viral load of porcine circovirus

type 2 in several tissues in cases of fetal death and high mortality in

piglets. A case study. J Vet Diagn Invest 19:368–375 (2007).  High number of mummifications and stillbirths, a high neonatal mortality rate, and many piglets with congenital tremors or hind leg ataxia.   A high load of PCV2 DNA was observed in myocardium, liver, and spleen from mummified or stillborn piglets, lower in piglets with myocarditis, and even further lower in pigs without myocarditis.  Neither porcine parvovirus nor encepaholomyocarditis virus was detected.

Paramyxovirus infection in pigs with interstitial pneumonia and encephalitis in the United States. J Vet Diagn Invest 13:428–433 (2001). In the last few years, newly recognized paramyxoviruses have been associated with severe disease in several animal species, including swine, as well as in human beings. Recently, a paramyxovirus was isolated from a swine herd in the northcentral United States that experienced an epizootic of respiratory and central nervous system disease. Affected pigs had interstitial pneumonia with necrotizing bronchiolitis and encephalitis characterized by lymphocytic perivasculitis and diffuse gliosis.   Other pig respiratory viruses are PRRS, porcine respiratory coronavirus (PRCV), porcine circovirus (PCV) type 2, antigenically variant H1N1 strains of swine influenza virus (SIV), as well as H1N2 SIV in England and H3N2 SIV in the United States have been identified. Historically, only a few viruses had been associated with respiratory disease in swine, and, in field situations, only swine influenza virus (SIV) and pseudorabies virus (PRV) were detected with any frequency.  Cytomegalovirus, adenovirus, and enterovirus also have been reported to cause pneumonia in swine but are rarely encountered.

Fibroepithelial Hamartoma in a Domestic Pig.  Vet Pathol 44:411–413 (2007). Histologic examination revealed a moderate orthokeratotic hyperkeratosis with variable degrees of epithelial proliferation. The main body of the dysplasia consisted of collagenous fibers. In addition, some proliferating small blood vessels as well as focally gathered dilated apocrine glands were evident.

Porcine Circovirus Type 2-Associated Cerebellar Vasculitis in Postweaning Multisystemic Wasting Syndrome (PMWS)-Affected Pigs. Vet Pathol 44:621–634 (2007).  Acute hemorrhages and edema of cerebellar meninges and parenchyma due to a necrotizing vasculitis resulted in degeneration and necrosis of the gray and white matter. Few to numerous PCV2 DNA and antigenbearing endothelial cells were detected.  Detection of caspase 3 activity and DNA strand breaks showed numerous apoptotic endothelial cells in the vascular lesions observed.   Lesions in PDNS are characterized primarily by a cutaneous and subcutaneous necrotizing vasculitis and glomerulonephritis and are likely mediated by immune complex deposition.

Multiple Hepatic Peribiliary Cysts in a Young Pig. Vet Pathol 44:707–709 (2007). All lobes of the liver contained numerous cysts of varying size containing serous fluid in all lobes. Histopathologically, the cysts were located mainly around the large bile duct and in the connective tissue of the portal tracts.  The cysts were lined by a single layer of columnar, cuboidal, and flattened epithelial cells. Occasionally, goblet cells were observed. The epithelial cells were stained with periodic acid–Schiff/alcian blue and high-iron diamine/alcian blue, indicating the presence of neutral mucin, sialomucin, and sulfomucin.

The Distribution and Density of Clostridium difficile Toxin Receptors on the Intestinal Mucosa of Neonatal Pigs. Vet Pathol 44:814–822 (2007).   The most important virulence  factors of C. difficile are 2 large exotoxins, toxin A (TcdA) and toxin B (TcdB). TcdA is a potent enterotoxin with effects on host tissues that are dependent upon receptor-mediated endocytosis of the intact toxin. TcdB is an effective cytotoxin, but it apparently does not bind receptors on intact mucosal epithelium. TcdB is much less toxic in vivo unless there is underlying damage to the mucosa, and it is not essential for the virulence of C. difficile.  The receptors for TcdA in the pig remain to be identified, but a-galactosyl does not seem to be significant to its binding.

Histopathological and Immunohistochemical Findings in the Lungs of Pigs Infected Experimentally with Mycoplasma hyopneumoniae Histopathological changes consisted of exudates in airways and alveolar lumina, peribronchial and peribronchiolar lymphoid hyperplasia, and enlargement of alveolar septa. These changes coincided with significant increases in the expression of cytokines (IL-1a, IL-1b, IL-8, TNF-a and INF-g) and lymphoid markers (CD4+, CD8+, muramidase, IgG+, IgA+).

Characterization of Interstitial Nephritis in Pigs with Naturally Occurring Postweaning Multisystemic Wasting Syndrome Vet Path 2008 Jan: types of tubulointerstitial inflammation seen were: lymphoplasmacytic, granulomatous and mixed. The epithelium of renal tubules was the consistently positive with in situhybridization. Unlike in lymphoid tissue, the amount of PCV-2 was not associated with severity of granulomatous inflammation, but did for lymphoplasmacytic inflam.

Metritis, Valvular Endocarditis, and Septicemia by Actinobacillus equuli in a Gilt in the United States.  Vet Pathol 45:495–499 (2008). Gross findings included metritis, splenomegaly, and valvular endocarditis. Bacterial endocarditis (in the mitral and  tricuspid  valves)  and  metritis  with  dissemination  to  multiple  organs  was  diagnosed  by  using histologic examination. Gram-negative coccobacillary organisms present in the valvular lesions were characterized as Actinobacillus equuli.

Porcine Circovirus 2 Inclusion Bodies in Pulmonary and Renal Epithelial Cells.  Vet Pathol 45:640–644 (2008). The most common lesions of PMWS are lymphohistiocytic to granulomatous lymphadenitis, interstitial pneumonia and interstitial nephritis, with intracytoplasmic amphophilic botryoid inclusion bodies in macrophages. Intracytoplasmic botryoid inclusion bodies were observed in bronchial, bronchial glandular, and renal tubular epithelium of several pigs from 4 different farms in Western and Eastern Canada

Reproduction of Postweaning Multisystemic Wasting Syndrome in Pigs by Prenatal Porcine Circovirus 2 Infection and Postnatal Porcine Parvovirus Infection or Immunostimulation.  Vet Pathol 45:842–848 (2008). Postweaning multisystemic wasting syndrome (PMWS) was reproduced in prenatally porcine circovirus 2 (PCV2)-infected pigs by either postnatal infection with porcine parvovirus (PPV) or by immunostimulation.  Prenatal infection (PCV-2) Plus Postnatal PArvo or immunostimulation or any Post natal PCV-2 infection. But not PCV-2 in utero with no subsequent infection or immunostimulation.

Naturally occurring sheep-associated malignant catarrhal fever in North American pigs.  J Vet Diagn Invest 21:250–253 (2009). typicallymphoproliferative vasculitis in multiple tissues of the affected pigs. Ovine herpesvirus 2 (OvHV-2) DNA was detected by polymerase chain reaction in the tissues of affected pigs in both cases. The amplified sequences were identical between the clinically affected pigs and the OvHV-2–infected sheep. Additional virological and bacteriological examination showed that the affected pigs were negative for agents that cause Aujeszky’s disease, classical swine fever, porcine enterovirus, and rabies.

Acquired Melanosis Caused by Acorn Ingestion in the Nero Siciliano Pig: Diffuse black discoloration of lymph node cortex and medulla and melanosis of fat. Acorns have high total phenolic compounds. Hypothesized that swine tyrosinase could act on phenolic substances found in acorns and increase the biosynthesis andthe anomalous storage of melanin.

Multifocal Granulomatous Hepatitis Caused by Actinobacillus pleuropneumoniae Serotype 2 in Slaughter Pigs APP occurs in all pigs of all ages characterized by necrotizing, hemorrhagic bronchopneumonia and serofibrinous pleuritis. Other rare manifestations of APP are meningitis, osteomyelitis, arthritis, endocarditis, otits media and granulomatous hepatitis. The granulomas have asteroid bodies formation (Bodies with splendore hoeppli material)

Reproductive Failure Experimentally Induced in Sows via Artificial Insemination with Semen Spiked with Porcine Circovirus Type 2.  Vet Pathol 46:707–716 (2009). All live-born piglets -PCV2 viremic at birth. Stillborn fetuses-congestive heart failure. Mummified fetuses – crown-rump length from 7 to 27 cm, indicating fetal death between 42 and 105 days of gestation. PCV2 antigen was detected in the myocardium by immunohistochemistry of 7/8 (88%) live-born piglets, 2/2 (100%) of the stillborn fetuses, and 25/25 (100%) of the mummified fetuses. In addition, 4/25 mummified fetuses had PCV2 antigen associated withsmooth muscle cells and fibroblasts. The results of this study indicate that intrauterine administration of PCV2 causes reproductive failure in naıve sows


Expression of Mx protein & interferon-α (IFN-α) in pigs experimentally infected with swine influenza virus. pp161-67. March 2006  NW

Mx protein and IFN-a antigen were expressed in the lung from pigs experimentally infected with swine influenza virus

Simultaneous detection of viral RNA, Mx protein, and IFN-a in the bronchial and bronchiolar epithelial cells and macrophages in lung

Probably, the cells infected virus produce Mx protein and IFN-a

Mx proteins mediate antiviral activity of IFN-a

Antiviral activity of IFN-α in swine influenza is mediated by all of the following:

2’5’oligoadenylate synthetase, Protein kinase R, Mx1 protein

Mx proteins inhibit synthesis of viral protein

Evidence of breed-dependent differences in susceptibility to porcine circovirus type-2(PCV2)-associated disease &  lesions. pp281-93. May 2006  AR

· Predisposition of Landrace pigs to PCV-2 induced disease and lesions (PMWS)

· Low levels of passively acquired antibodies are protective

Pathogenicity of Vietnamese enterotoxigenic Escherichia coli strains in colostrum-deprived 1-day-old piglets. pp150-160, Mar 2006  AR

· preweaning colibacillosis is major cause of death in Vietnam

o isolates belonging to serotype O8

o produced heat stabile and heat labile enterotoxins; did NOT produce any of the recognized fimbriae

o hemagglutination: unique mannose-resistant hemagglutination activity with guinea pig, sheep, human, & chicken red blood cells at 37°C, but not 18°C

o enterocyte brush border attachment – unidentified colonization factor

· inoculation into colostrum-deprived 1 day old piglets:

F- strain: acute watery diarrhea w/in 4 hrs; up to 20% weight loss

attached exclusively to ileum

EM demonstrated presence of fimbriae

Conclusion: new pathogenic ETEC fimbrial type in piggeries in Vietnam, with a unique hemagglutination property and attachment characteristics similar to ETEC bearing F5 fimbriae.

Brain Lesions Induced by Experimental Intranasal Infection of Japanese Encephalitis Virus in Piglets: J Comp Path 141 vol 2-3:JE experimentally induced in 3 week-old piglets by a single intranasal inoculation of Japanese encephalitis virus (JEV). The lesions consisted of glial cell aggregates and lymphocytic perivascular cuffing throughout the olfactory tract and pyriform cortex. JEV antigens were detected in the cytoplasm and neuronal processes of small nerve cells in the granule cell layer of the olfactory bulb, in the neuronal processes of the olfactory tract and in the cytoplasm of neurons in the pyriform cortex. JEV is one of 4 major encephalitic flaviviruses of public health importance, the other 3 being West Nile virus, St. Louis encephalitis virus in America, and Murray Valley encephalitis virus in Australasia

Investigation into the pathology of shoulder ulcerations in sows.  Veterinary Record (2009) 165, 171-174. Stage 1- epidermal necrosis, thrombosis of dermal blood vessels, multiple colonies of bacteria.  Stage 2 Dermal necrosis, and multiple colonies of bacteria. Stage 3 – Subcutis necrosis, the periosteum of the tuber spina scapula was reactive and thickened.  Stage 4 – Exposed bone of the tuber spina scapula was covered with a thin layer of granulation tissue that was superficially necrotic.  tuber spina scapula was extremely deformed and had developed into a mushroom-like shape due to the formation of an excessive volume of osseous tissue (no osteitis or osteomyelitis). The initial lesions were due to thrombosis (failures of the blood supply) and secondary infection.  Similar to pressure sores in humans.

REVIEW PAPER: Host-Pathogen Interactions in the Kidney during Chronic Leptospirosis. Vet Pathol 46:792–799 (2009). During chronic infection, renal colonization and leptospiruria persist despite cellular  and  humoral  responses  by  the  host. Tubulointerstitial  nephritis is  the  most  common  lesion associated with chronic infection, and this may progress to fibrosis and subsequent renal failure. For  leptospires  to  disseminate  within  the  host, leptospiral  invasion  is  likely  mediated by  enzyme secretion,  hemolysins, sphingomyelinases.  Tubulointerstitial  nephritis  is  a  primary lesion during acute renal injury in leptospirosis, with characteristic lesions, such as interstitial edema and lymphocytic infiltrates. proteins called Len (leptospiral endostatin-like)  proteins,  some  of  which  were  shown  to bind complement regulatory proteins, e.g., plasma factor H.  Pathogenic   Leptospira   spp.   can   also   bind   the human  complement  regulator  C4BP,  which  can provide added resistance against host complement.5 LPS   from   Leptospira   is   atypical   in   that   it activates human cells throughTLR2 and not the conventional   TLR4   pathway.    Leptospiruria persists  despite  active  immune  processes,  such  as interstitial  nephritis  characterized  by lymphocyte infiltration,  anti-leptospiral  immunoglobulin  production, MHC II expression, and TLR activation.

Expression of Major Histocompatibility Complex Class II Antigens in Porcine Leptospiral Nephritis.  Vet Pathol 46:800–809 (2009). cytokine-stimulated  tubular  epithelial  cells  express  MHCII.  Leptospirosis in fattening pigs is characterized by several degrees of nephritis, from absence of lesions to severe  multifocal  tubulo-interstitial  inflammation. Nephritic lesions were classified histologically into perivascular lymphocytic (4 pigs), lymphofollicular (6 pigs), lymphohistiocytic (8 pigs), and neutrophilic (2  pigs)  pattern.  MHCII  expression  by  histiocytes  and  lymphocytes  was  observed  in  all  lesions. Prominent MHCII expression in regenerating tubular epithelium was observed in lymphofollicular and lymphohistiocytic  nephritis. MHCII contributes to the intensity of the inflammatory response.

Brain lesions induced by Experimental Intranasal infection of Japanese Encephalitis virus in piglets. Glial aggregates, lymphocyte cuffs, Olfactory bulb granular cell layer, and neurons of and pyriform cortex. JEV is flavivirus- WNV, St Louis Encephalitis, Murray Valley encephalitis in Australia.

Lymphocyte Apoptosis and Thrombocytopenia in Spleen during Classical Swine Fever: Role of Macrophages and Cytokines: Results showed a progressive depletion of splenic lymphoid structures and evidence of platelet aggregation processes. Lymphoid depletion was due to lymphocyte apoptosis, which could not be ascribed to the direct action of the virus on these cells; direct virus action could play only a secondary role in the death of these cells. Absence of severe tissue and endothelial damage, together with moderate procoagulant cytokine levels in the serum, suggest that hemorrhage in CSF is due to thrombocytopenia.Monocyte/macrophages were the main target cells for the CSF virus, TNF-{alpha} and, to a lesser extent, IL-1{alpha} and IL-6 appear to be the major cytokines involved in the pathogenesis of lymphocytopenia and thrombocytopenia.

Melamine- and Cyanuric Acid–Associated Renal Failure in Pigs in Thailand. Vet Pathol 46:1156–1159 (2009). kidneys of all 5 pigs were yellowish and slightly swollen, with precipitation of crystalline material on the cut  surface.  Histologically, epithelial  degeneration  and  necrosis were  evident  in proximal  and  distal tubules and  collecting  ducts.  Round, yellow-brown  crystals with  radiating  striations  were  diffusely distributed through the lumen of proximal and distal tubules and collecting ducts. Blood urea nitrogen and creatinine levels were elevated. Melamine and analogs, including cyanuric acid, were detected by gas chromatography mass spectrometry.

Pro-inflammatory, Pleiotropic, and Anti-inflammatory TNF-a, IL-6,

and IL-10 in Experimental Porcine Intervertebral Disk Degeneration.  Vet Pathol 46:1292–1300 (2009). TNF-a and IL-10 are involved in the late reparatory phases of the experimental disk lesion. Use of an experimental model showed that strictly disk-directed manipulation and degeneration are also reflected in the contiguous vertebrae, including adjoining cartilage, bone, marrow, and ligaments.

Oral squamous cell carcinoma in a Vietnamese pot-bellied pig (Sus scrofa). J Vet Diagn Invest 21:905–909 (2009). chronic, intermittent nasal discharge and sneezing. The animal was diagnosed with severe periodontal disease (grade IV), an oronasal fistula, and multiple tooth root abscesses via dental examination and computed tomography of the skull. Eighteen months later, the animal was evaluated for lethargy, anorexia, and a firm, 12 cm 3 12 cm mass between the 2 rami of the mandible.  Skull radiographs indicated osteomyelitis of the mandible and soft-tissue swelling. On postmortem examination, the right mandibular area contained multiple, coalescing, irregular masses extending from the ramus rostrally to the mandibular canine teeth and ventrally within the intermandibular space, completely obliterating the normal anatomy. An open midshaft fracture was present on the right mandible. On histopathology, the masses were confirmed as locally invasive and destructive squamous cell carcinoma. No evidence of metastasis was noted in regional lymph nodes or in any of the distant sites evaluated.

Immunohistochemical Detection of Aetiological Agents of Proliferative and Necrotizing Pneumonia in Italian Pigs. J. Comp. Path. 2010, Vol. 142, 74e78. Proliferative and necrotizing pneumonia (PNP) is a form of interstitial pneumonia that occurs in weaning and  post-weaning  pigs.  PNP  is  characterized  by  hypertrophy  and  hyperplasia  of  type  II  pneumocytes and coagulative necrosis and granular debris within alveolar spaces. The principle aetiological agent of PNP in Italy therefore appears to be PRRSV (11 of 28 pigs). Coinfection with PRRSV and PCV2 (8 pigs) is characterized by more severe microscopical changes in affected lungs.

Vascular Lesions in Pigs Experimentally Infected With Porcine Circovirus Type 2 Serogroup B. Veterinary Pathology 47(1) 140-147.  The acute vasculitis was accompanied by marked pulmonary and mesenteric edema and pleural effusion-intracytoplasmic porcine circovirus type 2 (PCV2) nucleic acid in endothelial, smooth muscle–like, and inflammatory cells within and around affected arteries. The pigs with lymphohistiocytic and plasmacytic vasculitis had lesions of systemic PCVAD, including multisystemic lymphoplasmacytic and histiocytic or granulomatous inflammation.  The 2 pigs with acute vasculitis had no PCV2-specific antibodies (or a low titer of), whereas the pigs with lymphohistiocytic and plasmacytic vasculitis developed high antibody titers against this virus. These observations suggest that (1) acute vasculitis observed in the current studies is directly caused by PCV2b, (2) chronic vasculitis may in part be mediated by the subsequent immune response, and (3) host factors and viral strain may both contribute to vasculitis in

animals infected with PCV2b.

Systemic Toxoplasmosis and Concurrent Porcine Circovirus-2 Infection in a Pig. J. Comp. Path. 2010, Vol. 142, 228e234:  necrotizing inflammation of the lung, adrenal glands and lymph nodes, associated with lymphoid depletion, cytoplasmic basophilic botryoid inclusion bodies and protozoal microorganisms.

One Response to Porcine

  1. Karen Nouf says:

    Great post, bookmarked for future reference. One more regular visitor 🙂
    Thanks, keep us posting Karen.

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