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
- 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
- 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
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.
- 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,
- 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
- 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
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
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
- 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,
- 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,
- 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
- 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
- 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
- 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
- Contributor: New Zealand Registry of Animal Pathology,
Batchelar Animal Health Laboratory, PO Box 536, Palmerston North,
- 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
- 6. Agerholm JS, et al.: Experimental infection of pregnant
cows with Bacillus licheniformis bacteria. Vet Pathol 36:191-201,
- 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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