AFIP Wednesday Slide Conference - No. 24
March 29, 2000
- Conference Moderator:
Dr. Corrie Brown, Diplomate, ACVP
Chairman, Department of Pathology
College of Veterinary Medicine
University of Georgia
Athens, Georgia 30602-7388
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- Case I - 99-6934C ( AFIP 2682159)
- Signalment: Six-day-old, 1.0 kg, white, male, cross-breed
- History: This pig was a member of a group of four
piglets submitted for necropsy from a farrowing operation where
piglets aged 5 to 14 days old, stopped growing, and developed
a mild to moderate diarrhea. Morbidity was high, but mortality
was relatively low. The herd had recently had problems with colibacillosis
in young pigs, but they had responded well to antibiotic therapy.
This group of pigs was not responding to antibiotic therapy and
many pigs were unthrifty or stunted.
- Gross Pathology: The piglet was presented alive and
in poor body condition with mild to moderate yellowish diarrhea.
Intestinal con-tents were bright yellow and watery. The spiral
colon had mild diffuse mesenteric edema. A moderate amount of
curdled milk was present in the stomach. No other significant
gross changes were observed in the carcass. Two other piglets
from this submission had similar lesions and the remaining pig
- Laboratory Results: CBC results indicated a high normal
WBC count (21.6 X 103), but other parameters were normal. No
viruses were detected on electron microscopic evaluation of feces.
Fluorescent antibody examinations of intestines were negative
for coronavirus and rotavirus; and lung was negative for PRRS.
Intestinal culture revealed low numbers of K88+ E. coli. Fecal
smears for coccidial oocysts were negative.
- Contributor's Diagnoses and Comments:
- 1. Small intestine, enteritis, necrotizing with intralesional
immature coccidia compatible with Isospora suis.
2. Small intestine, enteritis, with attaching bacilli.
- Sections of small intestine (jejunum and ileum) have mild
to moderate diffuse atrophy of villi with blunting and fusion
of remaining villi. Villus lacteals are moderately dilated. Rare
small crypt abscesses are present. There is erosion of the villus
tips with occasional necrotic epithelial cells. Adjacent intestinal
epithelial cells are often flattened or cuboidal. Moderate numbers
of coccidial meronts, banana-shaped merozoites, developing oocysts
and microgametocytes that are morphologically compatible with
Isospora suis are present in intestinal epithelium. Inflammatory
infiltrate in the intestine is minimal to mild and consists of
occasional small aggregates of neutrophils. Rare sections of
small intestine have occasional small clusters of small Gram
negative bacilli attached to villus epithelium resembling E.
coli. Sections of spiral colon had moderate diffuse submucosal
edema with dilation of lymphatics and overgrowth of mixed bacilli
within the lumen.
- Isospora suis is known for its short prepatent period
(5 days) and rapid sporulation (12 hrs). Isospora suis
replicates in the epithelium of the distal third of villi primarily
in the jejunum and ileum. The height of host cell infection is
at 4 - 5 days. Diarrhea often begins at 5 to 10 days of age and
many animals become unthrifty and/or stunted. Pigs usually become
infected at 1- 2 days of age, possibly due to ingestion of feces
from the dam or environmental contamination. The severity of
infection is directly related to the size of the inoculum. In
mildly affected individuals the immature coccidial forms of Isospora
suis are often low in number and require fresh tissues and
diligent evaluation to identify.
- AFIP Diagnosis: Small intestine: Enteritis, subacute,
diffuse, mild, with villar blunting and fusion, necrosis, and
numerous intraepithelial coccidia, cross-breed, porcine.
- Conference Note: Coccidians are obligatory intracellular
protozoa that parasitize the intestinal mucosa of all animal
species. The two genera of most concern in swine are Eimeria
and Isospora. Other coccidian genera include Toxoplasma, Sarcocystis,
Hammondia, Besnoitia, Cystoisospora, and Frankelia. The various
species of Eimeria and Isospora are species-specific and are
usually found in specific segments of intestine. The majority
infect villous and crypt epithelial cells, although some species
can be found in lacteal endothelial cells, the lamina propria
and regional lymph nodes. Synergism with other pathogens may
result in marked pathologic changes.
- Isospora suis is a species specific coccidial pathogen
of very young swine that replicates in the villar tips of the
jejunum and ileum. Piglets have an age related susceptibility
to infection and disease. Very young pigs (1-2 days) are highly
susceptible to infection whereas 2-4 week old piglets are commonly
resistant. A very short life cycle (as little as 5 days) for
I. suis can lead to significant disease in piglets as young as
- Other pathogens causing diarrhea in very young pigs include
E. coli (colibacillosis; a hypersecretory disease with minimal
microscopic changes), rotavirus (most common cause of villar
tip destruction), coronavirus (transmissible gastroenteritis;
characterized by severe villous atrophy and epithelial cell necrosis),
Clostridium perfringens (usually older pigs, causes full
thickness hemorrhagic enteritis).
- No enterocyte-adherent bacilli were observed in the sections
examined at the conference.
- Contributor: Veterinary Diagnostic and Investigational
Laboratory, College of Veterinary, Medicine, University of Georgia,
PO Box 1389, Tifton, Georgia 31793.
- 1. Barker IK, Van Dreumel AA, Palmer N: The Alimentary System.
In: Pathology of Domestic Animals, eds. Jubb KVF, Kennedy PC,
Palmer N, 4th ed, vol. 2, pp. 304-306. Academic Press, San Diego,
- 2. Lindsay DS, Blagburn BL, Dubey JP: Coccidia and Other
Protozoa. In: Disease of Swine, eds. Straw BE, D'Allaira S, Mengeling
WL, Taylor DJ, 8th edition, pp.655-659. Iowa State University
Press, Ames, Iowa, 1999
- Case II - 19476 (AFIP 2684461)
- Signalment: Adult, female, white-tailed deer (Odocoileus
- History: In 1997, a game farm in Iowa purchased 3
adult male white-tailed deer from Minnesota and placed them in
a pen with 20 does. Over the course of 3 months, all of the bucks
died without clinical signs noted prior to deaths. Necropsies
were not performed on the first 2 due to autolysis. Samples of
the third revealed pulmonary congestion and multifocal hepatic
necrosis but no etiologic diagnosis. In April 1998, four months
after the last buck died, a pregnant doe from the same pen died
without history of illness and was submitted to the Iowa State
University Veterinary Diagnostic Laboratory. Two more adult deer
died, one in June and one in August, and were submitted for diagnosis.
Both had pulmonary edema and similar microscopic findings. No
further deaths have occurred. Elk in an adjacent but separate
enclosure were not affected.
- Gross Pathology: The doe was pregnant with two 4-5
kg fetuses. Body condition was excellent. Moderate hydrothorax
and severe diffuse bilateral pulmonary edema were present. Marked
distention of interlobular septa with fluid and abundant froth
in trachea and bronchi were noted. No other gross lesions were
- Laboratory Results: Bacterial cultures of lung, liver,
spleen, pleural fluid, and brain were negative. Immunohistochemistry
of lungs revealed adenoviral antigens in scattered endothelial
cells of lung, abomasal submucosa, and lymph node using polyclonal
antisera against bovine adenovirus type 5. Transmission electron
microscopy of lung from deparaffinized blocks revealed loosely
arranged 68-69 nm diameter icosahedral structures with electron-dense
cores consistent with adenoviral nucleocapsids.
- Contributor's Diagnoses and Comments:
- 1. Lung: Endothelial degeneration, hypertrophy, and necrosis,
acute, multifocal, with intranuclear inclusion bodies consistent
with adenovirus (adenovirus hemorrhagic disease)
- 2. Lung: interlobular edema and fibrin, acute, severe.
- The lesions in this case are consistent with the pulmonary
lesions previously described in both natural and experimental
cases in black-tailed deer. Adenovirus was isolated from the
last case submitted using white-tailed deer lung cell cultures
from a newborn. The virus was neutralized by antiserum to the
California black-tailed deer adenovirus isolate and had a virtually
identical restriction endonuclease pattern. Although recognized
by antisera to bovine adenovirus-5, hexon gene sequence data
indicate that the black-tailed deer adenovirus is closely related
to bovine adenovirus-3.
- The deer from the Iowa herd had all been purchased since
1995 from Minnesota, Michigan, Ohio, and Wisconsin. This is likely
the first case of deer adenovirus hemorrhagic disease diagnosed
in the eastern US, and the first in white-tailed deer. In contrast
to the cases in black-tailed deer where fawns are primarily affected,
the white-tailed deer deaths occurred in adults. No intestinal
lesions were found in the white-tailed deer in contrast to the
intestinal hemorrhage often noted in the black-tailed. Virus
was identified in abdominal viscera of the white-tailed deer.
- Pulmonary edema is also present in both bluetongue and epizootic
hemorrhagic disease; these are the predominant differential diagnoses
for adenovirus hemorrhagic disease.
- AFIP Diagnosis: Lung: Vasculitis, multifocal, moderate,
with endothelial intranuclear inclusion bodies, edema, and fibrin
white tailed deer (Odocoileus virginianus), cervid.
- Conference Note: Additional information on adenoviral
epizootics in black-tailed and mule deer can be found in 1998-99
Wednesday Slide Conference, 13 Jan 99, Case II (http://www.afip.org/vetpath/WSC/wsc
- The causative agent of adenovirus hemorrhagic disease (AHD)
belongs to the genus Mastadenovirus of the family Adenoviridae.
Adenoviruses are non-encapsulated, icosahedral, double-stranded
DNA viruses that range from 70-90 nm in diameter. Adenoviruses
have a longer replication cycle than other viruses and are therefore
more likely to develop large, dense intranuclear inclusions consisting
of massive numbers of virions. Ultrastructurally, adenoviruses
are arranged in a characteristic paracrystalline array. There
are two antigenically distinct genera of adenoviruses, namely
Mastadenovirus (mammals) and Aviadenovirus (birds). Adenoviruses
are generally host specific, although some may infect animals
closely related to the definitive host. For example, sheep can
be infected with some serotypes of bovine adenovirus.
Generally, transmission is fecal-oral or direct contact via oro-nasal
secretions. Adenoviruses are primarily epitheliotropic (respiratory
and enteric) and less frequently endotheliotropic. Mammalian
adenoviral infections are usually subclinical. Exceptions are
infectious canine hepatitis (CAV-1) and infections in immunosuppressed
and stressed animals. Marked cytomegaly with large basophilic
inclusions are often noted in avian and ovine adenoviral diseases.
Although conference participants all favored AHD, the following
differential diagnosis was discussed: epizootic hemorrhagic disease,
bluetongue, heartwater and malignant catarrhal fever. Diagnosis
depends on detection of adenovirus in endothelial intranuclear
- Contributor: Department of Veterinary Pathology, Iowa
State University, College of Veterinary Medicine, Ames, Iowa
- 1. Lapointe J-M, Hedges JF, Woods LW: The adenovirus that
causes hemorrhagic disease of black-tailed deer is closely related
to bovine adenovirus-3. Arch Virol 144:393-396, 1999
- 2. Woods LW, Hanley RS, Chiu PH, Lehmkuhl HD, Nordhausen
RW, Stillian MH, Swift PK: Lesions and the transmission of experimental
adenovirus hemorrhagic disease in black-tailed deer fawns. Vet
Pathol 36:100-110, 1999
- 3. Woods LW, Hanley RS, Chiu PH, Lehmkuhl HD, Nordhausen
RW, Stillian MH, Swift PK: Experimental adenovirus hemorrhagic
disease in yearling black-tailed deer. J Wildl Dis 33:801-811,
- 4. Woods LW, Swift PK, Barr BC, Horzinek MC, Nordhausen RW,
Stillian MH, Patton JF, Oliver MN, Johnes KR, MacLachlan NJ:
Systemic adenovirus infection associated with high mortality
in mule deer (Odocoileus hemionus) in California. Vet Pathol
- Case III - 01713 (AFIP 2677997)
- Signalment: Two tooth (1.5 - 2 years), Awassi, male,
sheep, Ovis aires.
- History: Imran Awassi wearily stretched his neck above
the dusty wall of his new prison encampment and cast a rheumy
eye out over the other assembled flock. He was no longer blasé
about his situation and days of travelling had taken their toll.
All around him his new friends stood with heads hanging, some
grinding their teeth. Others had mild diarrhoea. More than he
could count had collapsed and been taken from the room by blue-overalled
men who sweated profusely and appeared agitated. In the last
few hours his toes had begun to throb and his paunch ached. He
baa-leated to no-one in particular.
- The above sheep was one of 250 Awassi, Merino and cross-bred
sheep which died in a group of 30,000 sheep held in a quarantine
feedlot in New Zealand prior to loading and shipment to Middle
- Gross Pathology: The outstanding gross lesion in the
sheep was rumen distension with fermenting, acidic-smelling content
in which undigested meal/concentrate was present. The carcass
was dehydrated and all viscera congested. There was patchy reddening
of rumen epithelium especially affecting the ventral surface.
In these areas the papillae were uneven and erosions and ulcers,
often with irregular and ill-defined margins, had formed. The
submucosa was edematous (as in the present sample), and the reaction
extended transmurally with haemorrhage, congestion, and serosal
thickening and localised peritonitis with unorganised omental
- Laboratory Results: Ruminal pH 4.1, motile protozoa
were not identifiable in rumen fluid.
- Contributor's Diagnoses and Comments:
- 1. Rumen: Rumenitis, acute, diffuse, severe with intraepithelial
and submucosal microabscessation and degeneration of superficial
- 2. Rumen: Rumenitis, necrotizing with intralesional fungal
- 3. Rumen: Vasculitis, necrotizing with thrombosis and intralesional
- 4. Rumen: Peritonitis, steatitis, granulomatous
- Etiology: Ruminal acidosis with secondary mycosis
consistent with zygomycosis.
- Ruminal acidosis most commonly occurs as a consequence of
ingestion of excessive quantities of fermentable carbohydrate,
resulting in the explosive proliferation of lactic acid producing
organisms. In the first instance this is mainly Streptococci
sp. As the acidity of the rumen increases (pH less than 4.5)
the normal ruminal microflora is destroyed and other lactobacilli
proliferate and produce further excesses of lactic acid. This
results in acidosis and hemoconcentration with hypovolemic shock,
the later the result of osmotic imbalance in the rumen. Both
factors contribute to the death of the animal.
- In the present outbreak, the most severely affected sheep
were from the Awassi groups, in fact those which had been preconditioned
longest to concentrate feeding. This group ate the ration greedily,
whereas others in less or non-affected groups refused it. The
carbohydrate in this ration was assayed at 28.1 gm/l00 gm dry
matter which is considerably in excess of the recommended level.
Whether or not Awassi sheep are more susceptible to acidosis
than the other breeds represented in the feedlot is unreported.
- Secondary fungal infections, in this case probably a mucoraceous
Zygomycetes, are common opportunistic invaders of the ruminal
wall in this condition.
- AFIP Diagnosis: Rumen: Rumenitis, necrosuppurative,
transmural, diffuse, moderate, with necrotizing vasculitis, myriad
bacteria, and numerous fungal hyphae, Awassi sheep, ovine.
Conference Note: The general gross appearance of "grain
overload" is a distended rumen filled with fermenting, undigested
grain which gives off an acidic smell and has a fluid-like consistency.
- The contributor described the pathogenesis, but this was
expanded on during conference: increased carbohydrates lead to
increased dissociated volatile fatty acids (propionic, butyric
and acetic) -> decreased pH 5.5-5.0 -> increased Streptococci
-> decreased pH, due to lactic acid production; both D and
L isomers, of which the D isomer is poorly metabolized and accumulates
in systemic circulation -> death of streptococci and proliferation
of lactobacilli<5.0 -> further decrease of pH due to larger
amounts of lactic acid production -> ruminal atony and cessation
of salivary secretion + increased ruminal organic acids (not
lactic acid) -> osmotic fluid shift -> movement of fluid
from blood into rumen -> hemoconcentration, severe dehydration,
elevations in serum protein, inorganic phosphorous, lactate,
pyruvate, and liver enzymes, anuria, circulatory collapse, and
diarrhea) -> systemic acidosis + vesicular degeneration of
surface stratified squamous epithelium accompanied by granulocytic
infiltrates into the epithelium and vesicles -> invasion by
fungi and Fusobacterium -> liver abscesses and possible systemic
disease, to include polioencephalomalacia due to proliferation
of thiaminase-producing bacteria.
- Contributor: New Zealand Registry of Animal Pathology,
Pathology Section, IVABS Massey University, Palmerston North,
- 1. Barker IK, Van Dreumel AA: The Alimentary System. In:
Pathology of Domestic Animals, eds. Jubb KVF, Kennedy PC, Palmer
N, 4th ed. vol. 1, pp. 47-50. Academic Press, Inc, San Diego
- 2. Bruere AN, West DM. Metabolic diseases. In: The Sheep:
health, disease and production, eds. Bruere AN, West DM, pp.191-192.
Foundation for Veterinary Continuing Education of the New Zealand
Veterinary Association, Massey University, Palmerston North,
New Zealand, 1993
- 3. Slyter LL, Rumsey TS: The effect of coliform bacteria,
feed deprivation, and pH on ruminal D-lactic acid production
by steer on continuous-culture microbial populations changed
from forage to concentrates. J Anim Sci 69:3055-3066, 1991
- Case IV- H86-0130 (AFIP 2505039)
- Signalment: 15-month-old female Bali cattle (Bos javanicus)
- History: This Bali cow was experimentally infected
with Jembrana disease virus (JDV) approximately 15 days prior
to euthanasia and necropsy. Clinical signs of fever, malaise,
anorexia, depression, and lymphadenopathy began developing at
5 days post inoculation.
- Gross Pathology: Severe lymphadenopathy and splenomegaly,
several ecchymotic hemorrhages on serosal surfaces particularly
epicardium, pulmonary consolidation, and pale foci in most parenchymatous
organs including liver, myocardium, kidneys and adrenals.
- Laboratory Results: Hematological changes included
severe lymphopenia and thrombocytopenia, and moderate neutropenia.
- Contributor's Diagnoses and Comments:
- 1. Lung: pulmonary vascular lymphocytosis and monocytosis,
atypical, multifocal, subacute, moderate, with mild arteriolar
2. Lymph node: atypical lymphoid hyperplasia (not on all sections).
3. Kidney: interstitial vascular and perivascular lymphocytosis
and monocytosis, atypical, multifocal, subacute, moderate, with
glomerular hypercellularity, segmentation and occasional synechiae
(not on all sections).
4. Liver: portal and sinusoidal lymphocytosis and monocytosis,
atypical, multifocal, subacute, moderate (not on all sections).
- Jembrana disease was first recognized in 1964 in Bali and
is now endemic throughout parts of Indonesia. It is an acute,
severe disease of Bali cattle (Bos javanicus) with a short incubation
period of 5-12 days. Fever, lymphadenopathy and lymphopenia are
the major clinical changes (Soesanto et al, 1990; Soeharsono
et al., 1990). Pathological changes reflect an intense lymphoproliferative
disorder (Dharma, et al., 1991). There is marked enlargement
of lymph nodes and spleen, which feature proliferating lymphoblastoid
cells in parafollicular areas, and follicular atrophy. A proliferative
lymphoid and mononuclear infiltrate is also found in many other
tissues, but the central nervous system is spared.
- Many cases show unusual intravascular lesions in the lungs
as observed in this case, which contain proliferative, immature
blastic cells, that have been identified as macrophages by electron
microscopy (Budiarso & Rikihisa, 1992). Severe cases often
show pleomorphic, basophilic, intracytoplasmic inclusions, in
the proliferative mononuclear cell population, although the nature
of these inclusions is unclear and repeated attempts to demonstrate
viral antigen within them have been unsuccessful. Very high titres
of virus (up to 10 to the 8th ID50/ml) are found in the plasma
during the febrile stage of the disease and a persistent viremia
can be demonstrated for at least 25 months. Surviving animals
show regression of lesions commencing about five weeks post-infection.
Mortality is usually about 17% and relates to hemorrhages and
multiple organ systems, although the precise cause of death remains
- The etiological agent, Jembrana disease virus (JDV), has
been recently identified as a lentivirus, closely related to
bovine immunodeficiency virus (BIV), by nucleotide sequence analysis
(Chadwick et al., 1995a,b). Lentiviruses are usually associated
with chronic progressive diseases such as granulomatous encephalitis,
pneumonia, arthritis, mastitis, etc. (CAEV, Visna virus) or AIDS
(HIV, SIV and FIV). Except for the acute phase of EIAV infection,
it is most unusual for a lentivirus to induce an acute disease
with a short incubation period. It is precedent however, by the
emergence of a strain of SIV from sooty mangabey monkeys (SIV-SMMPBj14),
that is acutely pathogenic in macaques (Fultz, 1994), and produces
lymphoproliferative changes that are remarkably similar to those
observed with Jembrana disease.
- AFIP Diagnoses:
- 1. Lung; kidney: Atypical lymphohistiocytic infiltrates,
perivascular, intravascular and multifocal, with vasculitis,
Bali cow (Bos javanicus), bovine.
2. Lymph node: Atypical lymphohistiocytic hyperplasia, diffuse.
3. Liver: Atypical lymphohistiocytic infiltrates, portal and
sinusoidal, diffuse, moderate, with biliary hyperplasia and portal
Conference Note: Without the knowledge that the tissues
were from a Bos javanicus, it would be very difficult to determine
the etiology from this slide. Conference participants considered
a wide variety of possible etiologies from malignant catarrhal
fever (MCF) (Alcelaphine herpesvirus 1), to lymphoma, to theileriosis
(East Coast fever). Most favored MCF. The primary histologic
features that differentiate MCF from Jembrana disease (JD) are:
JD consistently produces a distinct alveolar pneumonia, mesangial
glomerulonephritis, and choroid plexus infiltration, but spares
the remaining CNS; JD can produce granular intracytoplasmic inclusions;
and JD does not cause the generalized mural vasculitis that is
commonly reported in MCF.
- Contributor: Murdoch University, School of Veterinary
Studies, Murdoch, WA 6150, Australia.
- 1. Budiarso IT, Rikihisa Y: Vascular lesions in lungs of
Bali cattle with Jembrana disease. Vet Pathol 29:210-215, 1992
- 2. Chadwick BJ, Coelen RJ, Sammels LM, Kertayadnya G, Wilcox
GE: Genomic sequence analysis identifies Jembrana disease virus
as a new bovine lentivirus. J Gen Virol 76:189-192, 1995
- 3. Chadwick BJ, Coelen RJ, Sammels LM, Kertayadnya G, Wilcox
GE: Nucleotide sequence analysis of Jembrana disease virus: a
associated with an acute disease syndrome. J Gen Virol 76:189-192,
- 4. Dharma DMN, Budiantono A, Campbell RSF, Ladds PW: Studies
on experimental Jembrana disease in Bali cattle. J Comp Pathol
- 5. Fultz PN: SIV-SMMPBj14: an atypical lentivirus. Cur Top
Microb Immuno 188:65-76, 1994
- 6. Murphy FA, Gibbs EBJ, Horzinek MC, Studdert MJ: Veterinary
Virology, 3rd ed., p. 389. Academic Press, San Diego, CA, 1999
- 7. Soeharsono S, Hartaningsih N, Soetrisno M, Kertayadnya
G, Wilcox GE: Studies of experimental Jembrana disease in Bali
cattle. I. Transmission and persistence of the infectious agent
in ruminants and pigs, and resistance of recovered cattle to
reinfection. J Comp Pathol 103:49-59, 1990
- 8. Soesanto M, Soeharsono S, Budiantono N, Sulistyana K,
Tenaya M, Wilcox GE: Studies on experimental Jembrana disease
in Bali cattle.
Clinical signs and haematological changes. J Comp Pathol 103:61-71,
- J Scot Estep, DVM
Captain, VC, USA
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 Registry.
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