AFIP Wednesday Slide Conference - No. 29
May 5, 1999

Conference Moderator: LTC Dale G. Dunn
Department of Veterinary Pathology
Armed Forces Institute of Pathology
Washington DC 20306-6000
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Case I - Lilly Res. Lab. and/or C20190 (AFIP 2487654)

Signalment: 33-week-old, female, chicken.
History: This chicken was from a flock with decreased egg production and increased morbidity and mortality.
Gross Pathology: At necropsy, yolk follicles had abnormal appearance and consistency, and there were white foci on the kidney, liver, and heart.
Laboratory Results: None.
Contributor's Diagnosis and Comments: Myocarditis, multifocal, subacute, moderate, with sporozoan megaloschizonts.

Etiology: Leucocytozoon caulleryi
Microscopic examination revealed groups of large cysts characteristic of the megaloschizonts of Leucocytozoon caulleryi. They are enclosed by a well-defined membrane and contain numerous granular merozoites. A few of the mature cysts are empty with only the remains of the limiting membrane, presumably following rupture and release of merozoites. Ruptured cysts contain red blood cells, residual merozoites, and some inflammatory cells. Collapsed and degenerate schizonts are infiltrated by histiocytes, few heterophils, and multinucleated giant cells. Except for pressure atrophy, there is limited host response to intact schizonts.
Leucocytozoonosis is a malaria-like disease affecting many wild and domestic birds in Asia, Europe, and North America. Several species of Leucocytozoidae range from the semiarctic conditions of Canada and Sweden to the tropics of Indo-China. In domestic fowl, four species have been reported to cause economic losses: Leucocytozoon simondi, L. smithi, L. sabrezi, and L. (Akiba) caulleryi (Springer, 1991).
L. caulleryi infection of chickens is prevalent in several Asian countries (Morii et al., 1981) where it is transmitted by Culicoides sp. to the chicken host. Sporogony takes place in the insect vector and schizogony and gametogony occur in the chicken (Fallis and Desser, 1977; Pan, 1963). Exoerythrocytic schizogony with massive invasion of visceral organs and other tissues is responsible for the pathogenic effects of the parasite (Manuel, 1969).
In the Philippines, generally, 5 to 10% of the flock in most poultry farms are affected with a mortality rate of 1 to 3 per 500 birds. Petechial hemorrhages may occur in various tissues, with blood clots in the thoracic and abdominal cavities. Hemoptysis has been recorded in severely affected chickens. Young birds are more susceptible than adults to the parasitic infection. L. caulleryi invades and destroys red blood cells, resulting in anemia, leg weakness, greenish diarrhea, anorexia, weight loss, and decreased egg production.
AFIP Diagnosis: Heart: Myocarditis, granulomatous, multifocal, mild, with protozoal megaloschizonts, avian, chicken.
Conference Note: Leucocytozoonosis is a parasitic protozoan disease that almost exclusively affects birds. Leucocytozoon species are Apicomplexans of the family Plasmodiidae, and are closely related to Haemoproteus sp. and Plasmodium sp., based on similarities in life-cycle and ultrastructure. Each genus is characterized by developmental stages within an arthropod vector, and developmental stages within host vertebrate blood cells and tissue cells.
Several differences also exist among the three groups, which can be observed microscopically. Although gametocytes occur in host erythrocytes in all three, in Leucocytozoon sp., gametocytes may also be found in leukocytes. Plasmodium sp. and Haemoproteus sp. are characterized by the presence of pigment within erythrocytes containing developmental stages of the parasites; Leucocytozoon sp. do not induce "malarial" pigment formation in infected red blood cells. In Leucocytozoon sp. and Haemoproteus sp., schizogony takes place in tissue cells; with Plasmodium sp., both extraerythrocytic and intraerythrocytic schizogony occurs. Finally, megaloschizonts are frequently present in tissues in cases of leucocytozoonosis and with infection of some species of Haemoproteus, but are not characteristic of Plasmodium sp. Morphologically, megaloschizonts are large (100 to 200mm), multiloculated, and contain small (1mm), circular, basophilic merozoites.
Contributor: Lilly Research Laboratories, PO Box 708, Greenfield, IN 46140.
1. Fallis AM, Desser SS: On the species of Leucocytozoon, Haemoproteus, and Hepatocystis. In: Parasitic Protozoa, Kreir JP, ed., vol. 3, pp. 239-266, Academic Press, New York, 1977.
2. Manuel MF: Further studies on Leucocytozoon caulleryi in domestic fowls in the Philippines. Avian Dis 13:280-287, 1969.
3. Morii T, et al.: Seroimmunological and parasitological surveys of Leucocytozoon caulleryi in chickens in several Asian countries. Int J Parasitol 11:187-190, 1981.
4. Pan IC: A new interpretation of the gametogony of Leucocytozoon caulleryi in chickens. Avian Dis 7:361-368, 1963.
5. Springer WT: Other blood and tissue protozoa. In: Diseases of Poultry, Calneck BW, et al., eds., 10th ed., pp. 900-907, Iowa State Univ. Press, Ames, IA, 1997.
6. Charlton BR, et al.: Blood-borne parasites. In: Avian Disease Manual, 4th ed., pp. 162-165, American Association of Avian Pathologists, University of Pennsylvania, New Bolton Center, PA, 1996.
7. Gardiner CH, et al.: Apicomplexa. In: An Atlas of Protozoal Parasites in Animal Tissues, 2nd ed., pp. 65-68, 73-76, AFIP, Washington DC, 1998.

Case II - R98-329a (AFIP 2652491)

two 2x2 gross color photo transparencies
Signalment: 22-year-old, female Bengal tiger (Panthera t. tigris).
History: This female tiger was kept in a local zoo over 15 years. In March 1996, a single round mass measuring 2x2x1 cm was found in the subcutis of the left abdomen. On palpation, this mass was soft, and the skin over the mass was freely movable. Needle aspiration revealed oily material with a few intact fat cells. She didn't show any signs of illness at that time. Six months later, the tumor mass was enlarged. She showed anorexia and was reluctant to walk and exercise. By October, the tumor had grown rapidly to 18x15x12 cm and had a tendency to bleed. Surgical removal was performed.
In April 1998, two ovoid masses from the previous surgical site measuring 18x18x15 cm and 7x5x5 cm in size, respectively, recurred. Both tumors were surgically removed. After four months, tumor masses rapidly recurred on the first surgical site and extended to the left subcutis and midline of abdomen. She died of weakness.

Gross Pathology: At necropsy, she was thin with a large round tumor growth over the left and midline sections of the abdomen. The tumor mass was 30x30x28 centimeters with skin ulceration. On cut surface, the tumor was white to gray, multilobulated, partially circumscribed, incompletely encapsulated, and soft. There was also a metastatic nodule about 1.5x1x1.5 cm on the ventral diaphragmatic lobe of the right lung.
Laboratory Results: None.
Contributor's Diagnosis and Comments: Liposarcoma, skin, with metastasis to the lung, Bengal tiger (Panthera t. tigris).
Microscopically, the skin mass is encapsulated, highly cellular, with scant fibrous stroma. It consists of tremendous round cells, some of which are polygonal, stellate, or elongated. The cytoplasm of the tumor cells contains variably-sized vacuoles suggestive of fat content. The nuclei are round to ovoid with a single large nucleolus. Mitotic figures are infrequently seen. Similar lesions are observed in the lung in which the mass compresses the surrounding lung tissue. Cryosections from the skin mass stained with osmium tetroxide revealed positive reaction for adipose cells. Immunocytochemistry of vimentin was strongly positive for the tumor cells. Ultrastructural examination with transmission electronic microscope showed variably-sized lipid droplets in cytoplasm of the tumor cells.

The benign tumors of fat cells (lipomas) are most common in dog; they are seen less frequently in horse and ox, and are rare in cat, sheep, and pig. The average age of occurrence in dogs is 9 years, and the incidence increases with age. The growths in dogs are most often in the subcutis of the lateral and ventral thorax, abdomen, and upper hindlimbs and forelimbs.
Liposarcomas are uncommon in domestic cats and undocumented in wild felids; when they do occur, they are usually seen in adult and old animals. Liposarcomas are poorly defined, firm, frequently ulcerated, and locally invasive tumors that are slow to spread to other organs. The lung is the most common site for metastasis. Therapy includes surgical excision, which is usually curative for lipomas and liposarcomas. This is the first report of liposarcoma of Bengal tiger in Taiwan zoos.
AFIP Diagnoses:
1. Fibrovascular tissue (subcutis per contributor): Liposarcoma, Bengal tiger (Panthera t. tigris), feline.
2. Lung: Liposarcoma, metastatic.
Conference Note: Expanding and effacing the lung and subcutis are infiltrative, lobulated, neoplastic masses separated by variably-thick bands of dense fibrous connective tissue. The neoplasms are composed of closely packed, variably-sized, spindled to polygonal cells arranged in irregular interlacing streams, bundles, and whorls, with occasional regimentation of nuclei. Neoplastic cells have variably-distinct cell borders and moderate to abundant amounts of vacuolated eosinophilic cytoplasm. Cells sometimes contain multiple, clear, discrete, vacuoles. In many cells, vacuoles coalesce to form a single, large, clear cytoplasmic vacuole that displaces the nucleus peripherally. Nuclei are irregularly round to elongate, finely stippled to vesiculate, and contain 1-3, variably-distinct nucleoli. There is moderate anisokaryosis, and scattered multinucleate cells.
Most participants favored the diagnosis of liposarcoma. However, the varied histomorphologic patterns prompted consideration of balloon cell melanoma, sebaceous carcinoma, and malignant peripheral nerve sheath tumor. Immunohistochemistry performed at the AFIP demonstrated that neoplastic cells were diffusely negative for cytokeratin and glial fibrillary acidic protein (GFAP), and diffusely positive for vimentin. The S-100 protein immunostain did not work properly, but argyrophilic melanin granules were not demonstrated by the Fontana-Masson method. Ultrastructural studies described by the contributor are consistent with liposarcoma.
According to the World Health Organization International Histological Classification of Tumors of Domestic Animals, tumors arising from adipose tissue are classified as either benign (lipoma and angiolipoma) or malignant (liposarcoma). An infiltrative variant of lipoma, composed of well-differentiated adipocytes that invade adjacent muscle and fascia, also occurs and is found most commonly in the deep subcutaneous regions of the trunk, gluteal region, and proximal limbs. Infiltrative lipomas are difficult to excise and commonly recur. Angiolipomas resemble typical lipomas but contain clusters of small, well-differentiated blood vessels. Liposarcomas are further classified according to histologic appearance as well-differentiated, pleomorphic, or myxoid. Because of the regional variation in histomorphology in this case, it was not sub-classified.
Recently, deep intermuscular lipomas located in the caudal thighs of dogs have been described. The histologically benign tumors do not invade the adjacent muscles or fascia, and are found between the semimembranosus and semitendinosus muscles of mature, medium-sized, female dogs.
Contributor: Pig Research Institute Taiwan, PO Box 23, Chunan, Miaoli, Taiwan 350.
1. Martin de las Mulas J, Espinosa de los Monteros A: Immunohistochemical distribution pattern of intermediate filament proteins in 50 feline neoplasms. Vet Pathol 32:692-701, 1995.
2. Saik JE, Diters RW, Wortman JA: Metastasis of a well-differentiated liposarcoma in a dog and a note on nomenclature of fatty tumours. J Comp Path 97:369-373, 1987.
3. Doster AR, Tomlinson MJ, Mahaffey EA, Jordan C: Canine liposarcoma. Vet Pathol 23:84-87, 1986.
4. Stephens LC, King GK, Jardine JH: Attempted transmission of a feline virus-associated liposarcoma to newborn kittens. Vet Pathol 21:614-616, 1984.
5. Thomson MJ, Withrow SJ, Dernell WS, Powers BE: Intermuscular lipomas of the thigh region in dogs: 11 cases. J Amer Anim Hosp Assoc 35:165-167, 1999.
6. Hendrick MJ, et al.: Histological classification of mesenchymal tumors of skin and soft tissues of domestic animals. In: World Health Organization International Classification of Tumors of Domestic Animals, Schulman FYS, ed., 2nd series, volume 2, Armed Forces Institute of Pathology, Washington D.C., 1998.

Case III - 4 (AFIP 2663390)

Signalment: Third trimester fetus, Hereford, female, bovine.
History: This abnormally small (approximately 35 to 40 lb), third trimester, aborted fetus was submitted to the California Veterinary Diagnostic Laboratory Service. The fetus had multiple enlarged lymph nodes, and the presumptive diagnosis was epizootic bovine abortion.
Gross Pathology: The conjunctiva and ventral surface of the tongue contained numerous petechiae that multifocally coalesced to form broad regions of hemorrhage across the conjunctiva and the distal portion of the tongue. The tongue was markedly edematous, and adherent strands of fibrin multifocally covered hemorrhagic regions. The subcuticular tissues and skeletal muscle also contained widespread petechiae. All of the peripheral and internal lymph nodes and the spleen were markedly enlarged, and the spleen was dark and firm. Approximately 500 ml of thin, amber colored fluid containing thin strands of fibrin was present in the abdominal cavity. The capsular surface of the liver was irregular and slightly nodular. The lungs were not inflated.
Laboratory Results: IgG levels in this third trimester fetus were notably elevated (39mg/dl). Blood samples were negative (BAPA) for Brucella and toxicologic screening for abnormal levels of nitrates was negative. Microbiologic aerobic bacterial cultures of samples collected from the abomasum, liver, and lung resulted in no growth; Campylobacter cultures of samples collected from the abomasum and liver were negative; darkfield examinations of samples from the abomasum were negative for Campylobacter-like organisms; fluorescent antibody examination of the kidney was negative for Leptospira-like organisms; and Brucella microaerophilic cultures of samples from the abomasum and lung were negative.
Contributor's Diagnoses and Comments:
1. Thymus: Severe chronic cortical atrophy and severe histiocytic and lymphoplasmacytic thymitis with focal hemorrhage and fibrin exudate.
2. Lymph node: Severe chronic histiocytic and lymphocytic lymphadenitis and perinodal steatitis.
3. Spleen: Severe chronic lymphofollicular hyperplasia with moderate multifocal necrosis.
The spleen contained numerous, coalescing foci of lymphofollicular hyperplasia and necrosis. Lymph nodes were enlarged, and the architecture was effaced by inflammation that extended into the adjacent perinodal adipose tissue and consisted predominantly of sheets of macrophages and lymphocytes. Atrophy of the cortical regions of the thymus was severe. In addition, both the lobules and interlobular septa were infiltrated and often somewhat expanded by severe histiocytic and lymphoplasmacytic inflammation along with mild to moderate, multifocal hemorrhage and fibrin exudation. Additional histologic findings included severe histiocytic and lymphoplasmacytic periportal inflammation in the liver, moderate multifocal nonsuppurative interstitial inflammation in the kidney, mild multifocal nonsuppurative inflammation in both the meninges and parenchyma of the brain, intra-alveolar meconium, interlobular edema and lymphohistiocytic inflammation in the lungs, and multifocal lymphocytic inflammation in the epicardium and endocardium.
Epizootic bovine abortion (EBA) is an infectious disease that causes late term (usually third trimester) abortion of fresh fetuses or the birth of weak calves. This is a vector borne disease whose distribution is associated with that of the argasid tick, Ornithodoros coriaceus. Since its original description in the foothills of the Sierra Nevadas from which the common name for the disease "foothill abortion" is derived, it has since been reported along the coastal range of California and in Nevada, Oregon, and northern New Mexico. The disease generally causes greatest losses in naive cows that are introduced into tick-infested areas during pregnancy.
Though first thought to be caused by chlamydia and then possibly by a virus, the disease is now thought to be associated with a Borrelia-like organism. Borrelia coriaceae, a newly identified organism, was implicated in the recent literature. However, numerous attempts to identify it, or the previously implicated organisms within tissue lesions, have not been successful. Some investigators have postulated that the disease is immune-mediated due to the rather characteristic appearance of the histologic lesions and the presence of IgG and IgM in late stage vascular lesions. This too remains to be proven. Diagnostically, while the gross lesions and presence of elevated fetal IgG levels may be suggestive of EBA, necropsy and routine histologic examination of tissue samples remain the most reliable methods by which to diagnose this disease.
Clinical findings in naturally occurring disease include palpable lymphadenopathy and may include petechial hemorrhage of the conjunctiva, oral mucus membranes and tracheal mucosa. Fetal IgG levels are often elevated, and while trace to moderate levels can be seen, elevations of up to 800 mg/dl are not uncommon. At postmortem examination, gross changes are characterized by marked enlargement of the lymph nodes, markedly enlarged nodular liver, marked ascites, and splenomegaly. Histologic changes can be seen by 30-50 days, are severe by 90 days, and the unique and diagnostic (though not pathognomonic) changes that characterize the disease are generally present by 100 days post-infection.
Early stages of the disease can be subtle, and are localized within the monocyte phagocytic system. They are characterized by a transition in the nodal and splenic lymphocytes from small cells with dark nuclei to slightly larger cells with less darkly staining nuclei, with lymphoid hyperplasia and early germinal follicle formation in the cortex and paracortical regions of the nodes, and with nodal sinus histiocytosis. Additional changes include histiocytic expansion of the pulmonary interstitium and the periportal regions throughout the liver. As the disease progresses, histiocytic inflammation within the liver and lungs becomes more severe, and inflammation can be found in many organs, including the brain.
The most characteristic lesions are found late in the disease, and are most pronounced and severe in the thymus. In contrast to enlargement of other lymphoid tissues, the thymus at this point is often smaller than normal due to severe cortical atrophy. The thymic cortex, medulla and septa contain numerous macrophages. Widespread vasculitis of large and small arteries and veins, and focal necrosis in the lymph nodes and spleen, though less common, have also been reported in late stages of the disease.
AFIP Diagnoses:
1. Thymus: Thymitis, granulomatous, diffuse, moderate, with lymphoid hypocellularity, and multifocal necrosis, edema, and hemorrhage, Hereford, bovine.
2. Lymph node: Lymphadenitis, granulomatous, diffuse, moderate, with lymphoid hypocellularity, multifocal necrosis, and perinodal steatitis.
3. Spleen: Necrosis, multifocal and coalescing, severe, with fibrin exudate and hemorrhage.
Conference Note: The history, signalment, laboratory results, necropsy findings, histopathological features of the submitted tissues, and the contributors' descriptions of the remaining affected organs are consistent with reported cases of epizootic bovine abortion (EBA; foothill abortion).

Conference participants identified most of the histopathological features described by the contributor within the submitted lymphoid organs. However, attendees did not observe lymphofollicular hyperplasia in the examined sections of spleen. Rather, a decrease in lymphoid tissue, with necrosis and accumulation of cellular debris, fibrin and hemorrhage was noted. Attendees also observed rare multinucleated cells within the thymic medulla and lymph node. Based only on histological findings, most participants initially favored a viral etiology and included bovine morbillivirus (rinderpest), bovine pestivirus (bovine viral diarrhea), and bovine herpesvirus-1 (infectious bovine rhinotracheitis/infectious pustular vulvovaginitis) in the differential diagnosis. Given the additional background information, conference attendees agreed with the contributors' assessment of this case.
Contributor: California Veterinary Diagnostic Laboratory System, School of Veterinary Medicine, PO Box 1770, Davis, CA 95617-1770.
1. Kennedy PC, et al.: Epizootic bovine abortion: Histogenesis of the fetal lesions. Amer J Vet Res 44:1040-1048, 1983.
2. Kimsey PB, et al.: Studies on the pathogenesis of epizootic bovine abortion. Amer J Vet Res 44:1266-1271, 1983.
3. Kennedy PC, Miller RB: The female genital system. In: Pathology of Domestic Animals, Jubb KVF, Kennedy PC, Palmer N, eds., 4th ed., vol. 3, pp. 440-443, Academic Press, San Diego, CA, 1993.
4. Osebold JW, Osburn BI, Spezialetti R, Bushnell RB, Stott JL: Histopathologic changes in bovine fetuses after repeated reintroduction of a spirochete-like agent into pregnant heifers: Association with epizootic bovine abortion. Amer J Vet Res 48:627-633, 1987.
5. LeFebvre RB, Perng GC: Genetic and antigenic characterization of Borrelia coriaceae, putative agent of epizootic bovine abortion. J Clin Microbiol 27:389-393, 1989.
6. Zingg BC, LeFebvre RB: Polymerase chain reaction for detection of Borrelia coriaceae, putative agent of epizootic bovine abortion. Amer J Vet Res 55:1509-1515, 1994.
7. BonDurant RH, Anderson ML: Epizootic bovine abortion. In: Current Therapy in Large Animal Theriogenology, Youngquist RS, ed., pp. 386-389, WB Saunders, Philadelphia, PA, 1997.

Case IV - B1272 (AFIP 2505594)

Signalment: Belgian Blue fetal calf, eight months of gestation, sex unrecorded.
History: The cotyledon is from the placenta of the third Belgian Blue embryo transfer recipient to abort from a group of thirteen cows implanted with embryos from the same superovulated donor cow. Abortions occurred between 7½ and 8½ months of pregnancy.
Gross Pathology: No gross lesions were identified in the normal-sized fetus. The placenta had numerous, irregularly-shaped, umbilicated brown plaques varying from 5-25 mm in diameter on the amniotic surface. The chorioallantoic membrane was extensively thickened, discolored red-brown, and edematous, and the margins of some cotyledons had firm, brown areas of necrotic tissue.
Laboratory Results: Bacillus licheniformis was isolated in pure culture from fetal stomach contents and placental tissue.
Contributor's Diagnosis and Comments: Acute fibrino-necrotic suppurative placentitis with necrotizing vasculitis, Bacillus licheniformis.
The chorioallantoic thickening is mainly the result of edema with contribution from leukocytic infiltration. There is necrotizing and suppurative vasculitis with thrombus formation. Infarcted tissue was present in many areas of the placenta, but although there is widespread chorionic necrosis in the section, it is not clear that it is an infarctive process. Clumps of filamentous bacilli (Gram reactive) are present throughout the tissue. No lesions of significance were identified in the histological examination of the lung, liver, or kidney of the fetus.
Bacillus licheniformis is usually a cause of sporadic abortions in New Zealand. The route and the time of infection are unclear in this case, but the high prevalence of infections in the embryo transfer group raises the possibility that the embryos/washings may have been contaminated at the time of their collection.
AFIP Diagnosis: Allantochorion (cotyledon): Placentitis, necro-suppurative, acute, diffuse, moderate, with multifocal necrotizing vasculitis, fibrin thrombi, and numerous extracellular bacilli, Belgian Blue, bovine.
Conference Note: In addition to the microscopic features noted by the contributor, participants also observed small amounts of golden-brown, granular to globular pigment (meconium), and few scattered fungi and anisotropic crystals. Participants were unsure of the origin or clinicopathological significance of the latter two observations; contamination of the tissue sample was suspected. Participants noted that the cotyledon was more severely affected by the inflammatory process than the intercotyledonary tissue.
Several bacteria were initially considered by attendees as potential causes of this lesion, including Arcanobacter (Actinomyces) pyogenes, Listeria monocytogenes, Campylobacter sp., coliforms, Brucella sp., and Yersinia pseudotuberculosis. Tissue Gram stains performed at the AFIP demonstrated moderate numbers of large, Gram-positive, pleomorphic bacilli occurring singly and in aggregates near inflamed and necrotic areas of the cotyledon. These findings and the contributor's culture results were considered to be consistent with B. licheniformis infection.
Abortions in cattle, sheep, and swine have been associated with bacteria of the genus Bacillus worldwide, with an incidence of 1-10%. The highest incidence rates have been reported from Europe. Most Bacillus sp., including Bacillus licheniformis, are considered opportunistic pathogens, and primarily cause disease in immunosuppressed or debilitated hosts, or as a sequela to trauma or surgery. Opportunistic infections with B. licheniformis are rare in humans. Bovine infections, however, are more common, and most occur in pregnant cows that develop placentitis with subsequent abortion.
The ability of Bacillus sp. to infect the pregnant uterus has been studied primarily for B. cereus, although sporadic cases of bovine abortion have been associated with B. licheniformis. A recent retrospective study of bovine abortion associated with B. licheniformis described several common clinicopathological features including: abortions were found to predominantly occur during the winter months and in late pregnancy; the most common lesions were necrotizing placentitis and multifocal suppurative bronchopneumonia in the fetus; bacteria were demonstrated immunohistochemically in association with tissue lesions and intracellularly in trophoblasts; and bacteria were isolated from the placenta, lungs and abomasal contents. The findings suggested that B. licheniformis abortions were of hematogenous origin, with subsequent transplacental spread to the fetus.
More recently, several pregnant cows were inoculated intravenously with B. licheniformis during late gestation to study the abortifacient potential and fetoplacental tropism of the organism. The organism was found to have tropism for the bovine placentome. Inflammatory lesions were restricted to the cotyledon, with few lesions in the caruncle. Bacteria were found extracellularly and intracellularly within trophoblasts and neutrophils. Bronchopneumonia and enteritis were observed in several fetuses as a result of aspiration and ingestion of contaminated amniotic fluid, causing abortion or premature delivery. In other cases, the infection remained localized in the placenta, and normal calves were delivered at term. Infection of extrauterine maternal tissues was only observed in the lungs of cows euthanized within two days of inoculation, indicating that bacteria are rapidly eliminated from extrauterine tissues in the dam. The high number of bacteria required to establish experimental infection and induce abortion suggests that factors other than exposure to the bacteria are present in field cases of abortion.
Contributor: New Zealand Registry of Animal Pathology, Batchelar Animal Health Laboratory, PO Box 536, Palmerston North, New Zealand.
1. Mitchell G, Barton MG: Bovine abortion associated with Bacillus licheniformis. Aust Vet J 63:160-161, 1986.
2. Mason RW, Munday BL: Abortion in sheep and cattle associated with Bacillus spp. Aust Vet J 44:297-298, 1968.
3. Smith ID, Frost RJ: The pathogenicity of pregnant ewes of an organism of the genus Bacillus. Aust Vet J 44:17-19, 1968.
4. Agerholm JS, Krogh HV, Jensen HE: A retrospective study of bovine abortions associated with Bacillus licheniformis. Zentralbl Veterinarmed 42:225-234, 1995.
5. Agerholm JS, et al.: A preliminary study on the pathogenicity of Bacillus licheniformis bacteria in immunodepressed mice. APMIS 105:48-54, 1997.
6. Agerholm JS, et al.: Experimental infection of pregnant cows with Bacillus licheniformis bacteria. Vet Pathol 36:191-201, 1999.
Course Coordinator:
Ed Stevens, DVM
Captain, United States Army
Registry of Veterinary Pathology*
Department of Veterinary Pathology
Armed Forces Institute of Pathology
(202)782-2615; DSN: 662-2615
* The American Veterinary Medical Association and the American College of Veterinary Pathologists are co-sponsors of the Registry of Veterinary Pathology. The C.L. Davis Foundation also provides substantial support for the Re
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