Results
AFIP Wednesday Slide Conference - No. 14
December 15, 1999
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- Conference Moderator:
LTC Denzel Frost, Diplomate, ACVP
Chief, Research Services Branch
Armed Forces Institute of Pathology
Washington, DC 20306-6000
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- Case I - 27561-98 (AFIP 2680119)
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- Signalment: Five-month-old, female, Angus, bovine.
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- History: Acute onset of nervousness and ataxia progressing
to recumbency with opisthotonus.
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- Gross Pathology: Grossly visible lesions were limited
to the brain. There was a circumscribed area of malacia and discoloration
approximately 3 cm in diameter involving the cerebellum, pons,
and medulla.
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- Laboratory Results: Culture of the brain produced
Mortierella wolfii. Routine cultures of the lung, liver, and
kidney produced no significant bacteria. Fluorescent antibody
tests produced negative results for BVD virus.
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- Contributor's Diagnosis and Comments: Cerebellum:
Meningoencephalitis, necrotizing, chronic, focally extensive,
severe, with vasculitis, thrombosis, and hyphae, Angus, bovine,
etiology Mortierella wolfii.
Mortierella wolfii is a common cause of mycotic abortion
in cattle in New Zealand and is reported as an infrequent cause
in Great Britain and the United States. Under natural conditions,
proposed routes of infection include skin wounds, the conjunctiva,
and the respiratory, alimentary, and reproductive systems. The
pathogenesis in some cases has been associated with the feeding
of improperly handled silage. Mycotic pneumonia is often seen
concurrently with or as a sequella to infection and placentitis
in the cow.
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- Mycotic lesions are rarely found in cows in tissues other
than the uterus and lungs, suggesting that cattle do not remain
permanently infected following abortion and that only gravid
cows develop lesions. Fetal lesions include focal encephalitis,
hepatitis, and splenitis. In both the fetuses and cows, the lesions
are characterized by necrosis, vasculitis, serofibrinous exudates,
and neutrophil infiltrates with intra-lesional hyphae. In tissue
sections the hyphae are nonseptate but may contain intra-hyphal
vacuoles that appear similar to septa. Hyphae vary in width from
about 2 to 12 mm and are often short and branched.
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- The case presented here had similar changes including severe
encephalitis with necrosis of the neuropil, nonseptate hyphae,
and infiltration by numerous neutrophils and mononuclear cells.
Blood vessels often exhibited necrotizing vasculitis with thrombosis.
This case is unusual in that it involved a 5-month-old calf.
In addition to encephalitis, this calf had pneumonia and necrotizing
splenitis with fungal hyphae. There was no history of silage
feeding.
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- AFIP Diagnosis: Cerebellum and brain stem: Meningoencephalitis,
subacute, focally extensive, severe, with necrotizing vasculitis,
infarction and fungal hyphae, Angus, bovine, etiology consistent
with a zygomycete.
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- Conference Note: Mortierella wolfii belongs in the
mucormycosis group of zygomycotic fungi. This family is characterized
by the presence of broad (3-25mm), non-septate or rarely septate
hyphae, with non-parallel walls, and right angle, nondichotomous
(unequal) branching. Although the H&E stained sections generally
demonstrated the diagnostic features of this fungus, strong GMS
positivity facilitated assessment of fungal morphology. Culture
is required for specific identification of zygomycotic fungi.
The primary differential discussed in conference was aspergillosis.
Histologic features of Aspergillus include thin (2-6mm), septate
hyphae with parallel walls and dichotomous (equal) branching.
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- Contributor: University of Kentucky Livestock Disease
Diagnostic Center, 1429 Newtown Pike, Lexington Kentucky 40511
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- References:
- 1. Cordes DO, Carter ME, Di Menna ME: Mycotic pneumonia and
placentitis caused by Mortierella wolfii. Vet Pathol 9:190-201,
1972
- 2. Done SH, Sharp MW, Lupson GR: Isolation of Mortierella
wolfii from bovine lung. Vet Rec 134:194, 1994
- 3. McCausland IP, Slee KJ, Hirst FS: Mycotic abortion in
cattle. Aust Vet J 64:129-132, 1987
- 4. Wohlgemuth K, Knudtson WU: Abortion associated with Mortierella
wolfii in cattle. JAVMA 171:437-439, 1977
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- Case II - 99RA415 (AFIP 2681364)
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- Signalment: Adult, female, white-tailed deer (Odocoileus
virginianus)
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- History: In March of 1999, an adult female white-tailed
deer in Maine was observed to be very pruritic and in poor condition.
The animal was destroyed humanely and necropsy was performed
by the state veterinarian. Tissues were submitted to the National
Veterinary Services Laboratory for surveillance for chronic wasting
disease.
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- Gross Pathology: The animal was emaciated. Fat was
present on heart and around kidneys. The skin had bilateral alopecia
over large areas of the shoulders, lateral thorax, inguinal areas,
and flanks with hyperpigmentation in many areas. There were some
excoriations on neck and legs.
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- Laboratory Results: Histopathology of brain was negative
for lesions of chronic wasting disease.
Contributor's Diagnoses and Comments:
- 1) Skin: hair follicle and sebaceous gland parasitism, Demodex
odocoilei, severe.
- 2) Skin: dermatitis, pustular and ulcerative (some sections),
subacute, with acanthosis, orthokeratotic hyperkeratosis, hyperpigmentation,
and hair loss, mild to moderate.
Anagen follicles are abundant in the section, but intact hairs
are scarce. The mites that are present in the hair follicles
are consistent with previous records of demodicosis in white-tailed
deer. The mites are present in all developmental stages, not
only in the follicle lumen, but also in sebaceous gland ducts,
within sebaceous glands, and occasionally on the surface. Adults
and nymphs are recognized by 4 pairs of evenly spaced legs that
are segmented in adults. Larvae and protonymphs are also present.
This species has been reported to invade dermis and even venules,
but none were identified outside of follicles in this specimen.
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- The mites are thought to first occupy hair follicles with
intact hairs and then move into sebaceous glands to feed and
reproduce. Increasing numbers of mites cause distention of glands
and follicles eventually causing hair loss. Hairs typically are
in anagen at this stage. The exact cause of the hair loss is
not known, and a mite induced retardation of hair growth has
been proposed. Inflammation is present in some areas but is typically
weak even when the dermis is invaded. The superficial inflammation
in this case may be secondary to pruritus, excoriation, and bacteria.
The cause of this animal's debilitation is not known, but the
demodecosis is likely secondary.
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- Thanks to Dr. C. W. Ridky of the Maine Department of Agriculture,
Department of Inland Fisheries and Wildlife for submission of
the case and Dr. Tom Gidlewski of the National Veterinary Services
Laboratory, Department of Pathobiology, Ames, Iowa for the referral.
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- AFIP Diagnoses:
- 1. Haired skin: Epidermal hyperplasia, diffuse, moderate,
with superficial and follicular orthokeratotic hyperkeratosis,
follicular ectasia, minimal multifocal chronic dermatitis, and
numerous mites, white-tailed deer (Odocoileus virginianus), cervid.
2. Dermis, vessels: Vasculitis, necrotizing and fibrinous, multifocal,
with overlying subepidermal hemorrhage and focal ulceration.
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- Conference Note: The key features for identification
of mites in tissue section are chitinous exoskeleton, jointed
appendages, skeletal muscle, and a hemocoelom. Most animals are
parasitized by a Demodex species. They are generally considered
normal inhabitants of the hair follicle and sebaceous glands.
Factors predisposing to development of generalized demodicosis
are not fully understood; some of the more significant factors
include: immune status, breed and breeding line, age, length
of hair coat, nutritional status, stage of estrus cycle, parturition,
stress, endoparasitism and debilitating disease. Immunity is
thought to be the most significant. Both immunodeficiency and
immune-mediated injury to the skin may play roles in the disease.
The cause of the vasculitis that was present in some sections
was not evident, but conference participants considered the possibility
of epizootic hemorrhagic disease of deer.
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- Contributor: Department of Veterinary Pathology, Iowa
State University, Ames, Iowa 50011-1250
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- References:
- 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.173-174. Academic Press, San Diego,
CA, 1993
- 2. Desch CE and Nutting WB: Demodex odocoilei sp nov. from
the white-tailed deer, Odocoileus virginianus. Can J Zool 52:785-789.
1974.
- 3. Yager JA, Scott Danny: The Skin and Appendages. In: Pathology
of Domestic Animals, eds Jubb KVF, Kennedy PC, Palmer N, 4th
ed., vol. 1, pp. 686-690. Academic Press, San Diego, CA, 1993
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- Case III - 1968406 (AFIP 2679046)
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- Signalment: Adult, ovine, male, bighorn sheep, Ovis
canadenis
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- History: This adult ram was observed to be depressed
for 2 days, had watery diarrhea, and subsequently died. The animal
had been purchased and shipped in from Colorado to this mixed
herd in Michigan which consisted of bighorn sheep, mule deer
and elk.
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- Gross Pathology: On necropsy, this ram was in good
body condition. The mucosal linings throughout the abomasum,
small intestine and colon were diffusely congested and thickened.
No other gross lesions were noted.
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- Laboratory Results: Yersinia pseudotuberculosis was
isolated in high numbers from abomasum, small intestine and liver.
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- Contributor's Diagnosis and Comments: Small intestine:
moderate acute necrotizing enteritis with numerous microabscesses
and bacterial colonies.
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- The histologic appearance of the intestinal tract with necrosis,
suppurative infiltrates, and presence of bacterial colonies supports
a bacterial etiology in this case. The extremely prominent colonies
of small gram-negative bacilli, associated with microabscess
formation in the intestinal mucosa are highly suggestive of infection
with Yersinia spp.5 Isolation of high numbers of Y. pseudotuberculosis
confirmed the diagnosis in this case.
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- Cases of acute enterocolitis due to Yersinia spp. infection,
frequently associated with septicemia and high mortality, have
been reported frequently in sheep, goats, and farmed deer in
New Zealand and Australia.4,6 In addition, many different species
of mammals and over 50 species of birds, including both captive
and free-living, have been reported with Yersinia spp. infection
from throughout the world.3 In North America, outbreaks of yersiniosis
have been more sporadic than in Europe or Australia, 2,3 however,
several outbreaks of yersiniosis have been recently reported
in North American deer ranches, wildlife parks, and in free-ranging
wildlife.1,5,7 It is believed that wild birds and rodents serve
as reservoirs of infection for captive and wild mammals.3
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- AFIP Diagnosis: Small intestine: Enteritis, erosive,
subacute, diffuse, moderate, with microabcesses containing numerous
large colonies of bacteria, bighorn sheep (Ovis canadenis),
ovine.
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- Conference Note: Yersinia pseudotuberculos
is is a gram negative, facultative, nonmotile, psychrophilic
(able to replicate at 4° C), coccobacillus. It is difficult
to isolate on routine culture; cold enrichment and culture at
20° C are required for isolation. The organism is considered
to be commensal in many species; therefore, isolation of the
organism from deeper tissues, such as blood, urine, lymph nodes,
wounds or abscesses is more meaningful.
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- The genus Yersinia contains six species: Y. pestis,
Y. pseudotuberculosis, Y. enterocolitica, Y.
frederiksenii, Y. intermedia and Y. ruckerii
(fish). Y. pestis, the etiologic agent of human plague,
Y. pseudotuberculosis and Y. enterocolitica are
the major species of this genus; Y. pseudotuberculosis
and Y. enterocolitica are considered primarily enteric
pathogens. Y. frederiksenii, Y. intermedia tend
to cause skin and wound infections. Y. pseudotuberculosis
and Y. enterocolitica have little host specificity and
infect many avian and mammalian species; differentiation between
the two requires culture.
Infection generally occurs following orogastric inoculation,
in which the bacteria enter the lamina propria of the distal
ileum, cecum and colon with subsequent necrosis of Peyer's patches
and eventual mucosal ulceration; extension to mesenteric lymph
nodes and septicemia may also occur. If septicemia develops,
suppurative lesions may develop in various organs (e.g. liver,
spleen, lungs, meninges). Yersiniosis is frequently associated
with a triad of gross lesions; hepatosplenomegaly and distended
bowel. Infection is precipitated by changes in environmental
conditions, such as a decrease in temperature, poor nutrition
or overcrowding. Epizootics in domestic species are frequently
preceded by outbreaks in rodents or birds.
Contributor: Animal Health Diagnostic Laboratory, PO Box
30076, Lansing, MI 48909-7576
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- References:
- 1. Blake JE, McLean BD, Gunn A: Yersiniosis in free-ranging
muskoxen on Banks Island, Northwest Territories, Canada. J. Wildl
Dis 27:527-533, 1991
- 2. Hubbert WT: Yersiniosis in mammals and birds in the United
States: case reports and review. Am J Trop Med Hyg 21:458-463,
1972
- 3. Mair NS: Yersiniosis in wildlife and its public health
implications. J Wildl Dis 9:64-71, 1973
- 4. Philbey AW, Glastonbury JRW, Links IJ, Mathew LM: Yersinia
species isolated from sheep with enterocolitis. Aust Vet J 68:108-110,
1991
- 5. Sanford KJ: Outbreaks of yersiniosis caused by Yersinia
pseudotuberculosis in farmed cervids. J Vet Diagn Invest 7:78-81,
1995
- 6. Slee KJ, Skilbeck NW: Epidemiology of Yersinia pseudotuberculosis
and Y. enterocolitica infections in sheep in Australia. J Clin
Microbiol 30:712-715, 1992
- 7. Welsh RD, Ely RW, Holland RJ: Epizootic of Yersinia pseudotuberculosis
in a wildlife park. J Amer Vet Med Assoc 201:142-144, 1992
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- Case IV - 99-08 (AFIP 2679432)
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- Signalment: Owl monkey, Aotus vociferans, adult, female
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- History: This monkey was splenectomized and inoculated
with Plasmodium cynoniologi ten months prior to death. It developed
alopecia and thickened scaly skin on the tail. It also developed
a bloody nose and mucopurulent discharge over the left eye. The
monkey was treated with SMZ -TMP, and the eye im-proved but the
tail did not. The monkey went into respiratory arrest and died
during recovery from surgery to amputate the tail.
- Gross Pathology: Necropsy revealed a moderately enlarged
heart.
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- Contributor's Diagnoses and Comments:
- 1) Liver, vacuolar degeneration (lipidosis), mild-moderate.
- 2) Kidney, membranoproliferative glomerulopathy, multifocal,
severe, with multifocal tubular degeneration, mild.
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- It has been recognized for many years that renal disease
occurs in association with malarial infection. In recent years,
P. falciparum infections have been reported to produce circulating
immune complexes, which deposit in the glomeruli. The occurrence
of renal disease in Aotus monkeys infected with P. malaria and
P. falciparum and clinical courses are similar to those of humans.
In P. falciparum infection, large immune complexes tend to be
taken up by the mesangium rather than passed through the basement
membrane. Because of this activity, the mesangium may expand.
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- Histologically, there is glomerular hypercellularity, infiltration
by polymorphonuclear leukocytes, mild thickening of the glomerular
basement membrane, and glomerular mesangial expansion. There
may also be mild tubular degeneration. Glomerulopathies and interstitial
nephritis are common causes of death in Aotus monkeys. Differential
diagnosis for glomerular disease includes Herpesvirus saimiri,
Pasteurella pseudotuberculosis, and rheumatoid arthritis.
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- AFIP Diagnosis:
- 1. Kidney: Glomerulopathy, global, diffuse, moderate, with
mesangial proliferation, synechia and obsolescence, owl monkey
(Aotus vociferans), non-human primate.
2. Kidney: Nephritis, tubulointerstitial, chronic-active, multifocal,
moderate.
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- Conference Note: Malarial parasites of animals belong
to the genera Plasmodium, Hepatocystis, Hemoproteus and Leucocytozoon;
the genus Plasmodium is the cause of malaria in man, and also
parasitizes a number of non-human primates, rodents, birds (most
often canaries, cockatoos, pigeons and penguins) and reptiles.
The 4 species of Plasmodium that infect man are P. falciparum
(highest morbidity and mortality), P. vivax, P. ovale and P.
malariae. The main species in rats and mice are P. berghei and
P. vinckei. The rodent species are endemic in South Africa, and
have been extensively studied as animal models. Malaria occurs
in all major families of lizards and occasionally in snakes,
but not in crocodiles, turtles or tuataras.
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- Mammalian malarias of the genus Plasmodium are transmitted
by mosquito hosts of various species of Anopheles. Avian malarial
parasites are mainly transmitted by mosquitoes of the genera
Aedes and Culex. The owl monkey is not a natural host of any
of the plasmodia, but is of great research interest because it
can be experimentally infected with the three human malarial
parasites, and most importantly, P. falciparum. The common glomerulonephritis
and interstitial nephritis of owl monkeys complicates its use
in studies of Plasmodium-associated renal disease.
Contributor: Emory University, Division of Animal Resources,
G70 Rollins Research Center, 1510 Clifton Road, Atlanta, GA.
30322
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- References:
1. Aikawa M, Broderson JR, Igarashi I, Jacobs G, Pappaioanou
M, Collins WE, Campbell CC: Atlas of renal disease in Aotus monkeys
with experimental plasmodial infec-tion, pp. 1, 10-11, 86-89.
American Institute of Biological Sciences, 1988
- 2. Benirschke, Garner & Jones: Pathology of Laboratory
Animals, Vols 1 & 2, pp. 1001-1008, 1610-1613. Springer-Verlag.
1978
- 3. Cotran RS, Kumar V, Collins T: Pathologic Basis of Disease,
6th ed., pp. 943-968. Saunders, Philadelphia, PA. 1999
- 4. Michael AF: The glomerular mesangium. Kid. Int., 7:141-154,
1980
- 5. Nagatake N: Renal pathology in Owl monkeys vaccinated
with Plasmodium falciparum asexual blood-stage synthetic peptide
antigens. Am. J. Trop. Med. Hug., 47(5):614-20, 1992
- 6. Samuelson J: Infectious Diseases. In: Pathologic Basis
of Disease, eds. Cotran RS, Kumar V, Collins T, 6th ed., pp.
389-390. Saunders, Philadelphia, PA, 1999
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- 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
Internet: estep@afip.osd.mil
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- * 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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