AFIP Wednesday Slide Conference - No. 18
26 January 2000
- Conference Moderator:
LTC Crystal M. Briscoe
US Army Medical Research Institute of Chemical Defense
Aberdeen Proving Ground, MD 21010-5425
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- Case I - PAI/WSC#1 (AFIP 2686445)
- Signalment: 24-month-old New Zealand white rabbit.
- Gross Pathology: 9.5x7x8 cm tan mass replacing right
Contributor's Diagnosis and Comments: Nephroblastoma (syn:
embryonal nephroma, Wilm's tumor)
- Although reported as rare in all species except the pig and
chicken, this tumor does occur with some regularity in rabbits.
This case is a classic presentation--a large tumor with no metastatic
lesions in a fairly young animal. Embryonal nephromas are second
in incidence only to uterine tumors in rabbits according to Benirschke
et al. in Pathology of Laboratory Animals.
- AFIP Diagnosis: Kidney: Nephroblastoma, New Zealand
white rabbit, lagomorph.
Conference Note: As mentioned by the contributor, nephroblastomas
occur commonly in pigs and chickens. Nephroblastomas are true
embryonal tumors that arise from primitive nephrogenic blastema.
They can be unilateral or bilateral, and are frequently very
large, often compressing adjacent tissue and filling the abdominal
cavity. Histologically nephroblastomas are composed of three
components: primitive glomeruli, abortive tubules, and loosely
arranged spindle cell stroma (blastema) which can differentiate
into neural tissue, fat, striated muscle, cartilage and bone.
With the exception of the dog where up to 50% of nephroblastomas
have been reported to metastasize, they are rarely malignant.
- In humans, nephroblastoma is referred to as Wilm's tumor
and is the most common primary renal tumor of childhood. Wilm's
tumor has been associated with a defect in chromosome 11 band
p13 at or near the Wilm's tumor locus. The risk for developing
Wilm's tumor is increased with three groups of congenital malformations
including WAGR syndrome, Denys-Drash syndrome, and Beckwith-Wiedemann
- Contributor: Pathology Associated International, 15
Wormans Mill Court, Frederick, MD 21701
- 1. Benirschke K, Garner FM, Jones TC: Pathology of Laboratory
Animals, Vol II, pp. 1171-1172. Springer-Verlag, New York, NY,
- 2. Kelly WR: The Liver and Biliary System. In: Pathology
of Domestic Animals. eds. Jubb KVR, Kennedy PC, Palmer N, 4th
ed., vol. 2, pp. 387-389. Academic Press, San Diego, , 1993
- 3. Schofield D, Cotran RS: Diseases of Childhood and Infancy.
In: Robbin's Pathologic Basis of Disease, eds. Cotran RS, Kumar
V, Collins T, 6th ed., pp. 487-489. WB Saunders Company, Philadelphia,
- Case II - NADC BCS 99-1 (AFIP 2673504)
- Signalment: Two 7-week-old, crossbred, female, porcine
Caesarian derived, colostrum deprived (CDCD)
- History: These pigs were experimentally inoculated
with porcine circovirus (type II) and porcine parvovirus. They
were euthanized and necropsied 32 days post inoculation. These
lesions were incidental findings.
- Gross Pathology: The aortic, right atrioventricular,
and left atrioventricular valves were markedly enlarged with
proliferative tissue on all leaflets. These masses were multiple,
large, raised, friable, white to yellow, and firmly attached
to the valve leaflets. The brain contained no grossly evident
lesions. The kidney contained multifocal red foci throughout
- Laboratory Results: Streptococcus sp. was cultured
from the heart valves and brain. White blood cell counts were
<10,000 cells/ml (normal: 10-20,000/ml) on the day of necropsy.
- Contributor's Diagnoses and Comments:
- 1) Brain: encephalitis, purulent, acute, moderate to severe,
- 2) Heart: endocarditis, valvular, proliferative, purulent,
subacute, severe, multifocal to coalescing, with intralesional
cocci and mineralization.
- Etiology: Streptococcus sp.
- This case represents a classic case of streptococcal infection
in nursery age swine. Streptococcus suis is found in the normal
flora of the tonsil and nasal cavity of swine. S. suis infections
are characterized by one or a combination of the following: septicemia,
bronchopneumonia, embolic pneumonia, endocarditis, polyarthritis,
meningitis, encephalitis, nephritis, ophthalmitis, and polyserositis.
We attribute the leukopenia in the face of this fulminating bacterial
infection to the effects of the porcine circovirus infection.
In our studies, we have found that the type II porcine circovirus
- AFIP Diagnoses:
- 1. Heart, valve: Valvulitis, fibrinosuppurative, chronic,
focally extensive, severe, with numerous cocci, domestic pig,
2. Brain: Meningoencephalitis, subacute, multifocal, moderate,
3. Heart: Myocarditis, subacute, multifocal, mild.
Conference Note: Numerous Streptococcus species have been reported
to infect domestic swine, but Streptococcus suis has classically
been recognized as the most common cause of streptococcal meningitis
and valvulitis. Two types of S. suis are recognized. Type
one infects young piglets (2-3 weeks of age) and causes septicemia,
synovitis and meningitis; type two is clinically and pathologically
similar, but generally produces a larger range of lesions, as
described in the contributor's comments.
- S. suis is a Gram positive, a hemolytic, coccus that
can be found singly, in pairs and in short chains. S. suis
is spread by aerosol or contact. The organisms multiply in the
tonsillar crypts. From there they enter the circulation and cause
septicemia, synovitis, meningitis and other localized infections.
S. suis has zoonotic potential.
- Contributor: National Animal Disease Center, 2300
Dayton Avenue, P.O. Box 70, Ames, IA 50010
- 1. Sanford SE: Gross and histopathological findings in unusual
lesions caused by Streptococcus suis in pigs: I. Cardiac lesions,
II. Central nervous system lesions. Can J Vet Res 51:481-485,
- 2. Sanford SE, Higgins R: Streptococcal Diseases. In: Diseases
of Swine, 7th ed., pp. 588-590. Iowa State University Press,
Ames, IA, 1992
- 3. Sanford SE, Tilker AME: S. suis associated diseases in
swine: observations of a 1-year study. J Am Vet Med Assn 181:673-676,
- 4. Taylor DJ: Pig Diseases, 6th ed., pp. 207-212. St. Edmundsbury
Press, Bury St Edmunds, UK, 1995
- Case III - W308/99 (AFIP 2694732)
- Signalment: mixed ages and sexes of quail.
- History: King and Brown quail were hatched and reared
in a suburban backyard amongst a variety of other aviary birds.
Signs of respiratory distress including ocular and nasal discharges,
swelling of the tissues around the eyes and labored, open-mouthed
breathing were first seen at 4 weeks of age. Affected birds lost
weight and died. Treatment provided by the owner (doxycycline
in drinking water plus chloromycetin eye ointment) provided temporary
remission of clinical signs but with relapse proceeding to death
on withdrawal of the medication. Of 115 King Quail hatched 61(53%)
died or required euthanasia and of 49 Brown Quail hatched 48
(98%) died or required euthanasia.
- Eight live quail were submitted for examination. One died
soon after submission, the other birds had evidence of respiratory
distress, high respiratory rate and marked respiratory effort,
swelling around the orbit, photophobia, serous rhinitis and conjunctivitis.
They were killed with halothane.
- Gross Pathology: There were no significant gross lesions
apart from swelling of the tissues around the eyes, serous discharges
from the eyes and nose and a slight excess of serous fluid in
the conjunctival sacs and nasal and infra-orbital sinuses. In
some birds there were small scabs or thickenings in the skin
of the face/beak suggesting dermatitis; otherwise the plumage
- Laboratory Results:
- There was a moderate growth of Pseudomonas aeruginosa
and Proteus mirabilis from swabs of the infra-orbital
sinus of each of 6 birds. Mycoplasma broths were overgrown with
- Contributor's Diagnoses and Comments:
- 1. Hyperplastic/dysplastic conjunctivitis, rhinitis and sinusitis
associated with respiratory cryptosporidiosis.
- 2. Secondary bacterial (Pseudomonas aeruginosa and
Proteus mirabilis) infection of sinuses, extension to
other tissues with production of acute necrotizing osteomyelitis
of facial/cranial bones and/or cellulitis in periorbital and
- 3. Mycotic stomatitis and dermatitis associated with Candida-like
- The circulated slides are cross-sections of the nasal cavity/infra-orbital
sinus and eyes of each of two of the affected quail. In both
there is extensive cryptosporidial infection of the conjunctival,
nasal and sinus epithelia with both hyperplasia and dysplasia
of the affected epithelia, including change from the normal ciliated
columnar mucus-secreting structure, loss of cilia and mucus secretory
function, disorientation of cells from their normal orderly position
and form and the formation of papillary proliferations. A variety
of different life cycle stages of Cryptosporidium is present
in/on the luminal surface of affected epithelial cells. There
is mild to moderate heterophilic and lymphoplasmacytic leukocyte
infiltration in the connective tissues underlying affected epithelia
and the development and/or hypertrophy of lymphoid follicles
in some places. Accumulations of mucoid cellular debris, exudate
and organisms are present within sinuses.
- Sections of one of the circulated cases also have evidence
of acute necrotizing osteomyelitis within the medullary cavities/air
spaces of facial and/or cranial bones. This is associated with
the presence of large colonies of gram negative bacilli, possibly
the P. aeruginosa and/or P. mirabilis cultured from the sinuses.
- Sections of the other circulated case have evidence of a
moderate to intense cellulitis including edema, fibrinous exudate
and mixed leukocyte infiltrations extending through the connective
tissues adjacent to affected conjunctivae and/or sinuses, possibly
also (though not definitely demonstrated) the result of extension
of the bacterial infection into these tissues. The nasal gland
has evidence of mild inflammation with the accumulation of degenerate
inflammatory debris within its ducts.
- Sections also have evidence of proliferation of Candida-like
fungal organisms in the superficial layers of oral mucosa and/or
in the squamous layers of the beak, facial skin and external
nares. Most affected birds had moderate to severe mycotic stomatitis,
esophagitis and/or ingluvitis probably in consequence of the
prolonged antibiotic treatments provided by the owner.
- Most affected birds also had cryptosporidial infection of
their trachea; some only mild infections, others with severe
infections resulting in hyperplasia/dysplasia of the affected
epithelium. The primary bronchi of some birds were also affected,
but none had evidence of significant pneumonia or air sac disease.
- Most of the quail also had cryptosporidial infections of
the epithelial lining of their bursa of Fabricius, one with severe
infection and hyperplasia/dysplasia of the affected epithelium,
prominent heterophil infiltration in and through the epithelium
and the accumulation of a cast of necrotic debris within the
lumen of the bursa. While some quail had mild coccidial gametocyte
parasitism of their intestinal mucosa none had evidence of cryptosporidial
infection of intestinal epithelia.
- Isolation of P. aeruginosa and P. mirabilis from the infra-orbital
sinus of each of six birds implies a significant finding yet
neither organism might have been expected as a primary pathogen
in this site. Demonstration of respiratory cryptosporidiosis
in each of the birds suggested it as the primary disease with
the bacteria as secondary pathogens especially in those birds
which developed cellulitis and/or osteomyelitis.
- Differential diagnosis of the clinical problem required elimination
of infections caused by Pasteurella sp., Haemophilus sp., Mycoplasma
sp. and related bacteria. Mycoplasma broths were overgrown by
bacteria thus precluding further exploration of their importance.
None of the other bacteria considered to be possible significant
pathogens were isolated in primary cultures. In the light of
the histopathological findings it seemed reasonable to discount
the possibility of their importance. Moreover microscopic examination
of tissues failed to demonstrate evidence of any significant
viral disease, particularly adenovirus which might have suggested
a diagnosis of "quail bronchitis". No investigative
service was available for further virological exploration of
these birds. There was no evidence of mycotic respiratory disease
in any of the quail.
- Some of the affected quail had relatively normal lymphoid
follicles in their bursa of Fabricius. In other birds the follicles
were small and had a thin cortex but medullae were well populated
with lymphocytes and there was only a minimum of interstitial
fibrous tissue. In a few birds bursal follicles were very small
to almost non-existent. It is unknown whether this implied any
degree of immunocompromization; impressions were that the change
represented an age-related atrophy of bursal follicles rather
than the effects of an immuno-suppressive agent. Similarly the
thymus of most birds, though small, was otherwise normal in structure
and that this also was considered an age-related atrophy. The
submitted specimens were from birds of different age and no "normal"
tissues of these species of quail were available for comparison.
The spleen of only some of the quail was available for microscopic
examination; those examined appeared to have the normal range
of lymphoid components and structure.
- Both respiratory and intestinal cryptosporidiosis have been
described in quail though definition of the specific organism(s)
involved would seem to require further work (Current, 1997).
Cryptosporidium baileyi is well recognized as the cause of cryptosporidial
infections of the respiratory tract and bursa of Fabricius of
domestic fowl and is associated with the development of lesions
similar to those occurring in these quail. Similar respiratory
and bursal cryptosporidiosis was reported in Coturnix coturnix
quail in South Australia (Tham et al. 1982) but without characterization
of the species involved. Intestinal cryptosporidiosis with clinical
signs of diarrhea and lesions of enteritis was reported in bobwhite
quail (Colinus virginianus) (Hoerr et al. 1985). There was no
evidence of infection of the respiratory tract and/or bursa of
Fabricius in those birds.
- Further submissions from the affected group of these quail
had similar clinical signs and lesions. Impression smears of
their tracheal mucosa, stained by the acid-fast method, contained
cryptosporidial oocysts suggestive of C. baileyi. DNA analysis,
courtesy of Dr. Una Morgan, Murdoch University, Perth, Western
Australia, was consistent with their identification as C. baileyi.
- AFIP Diagnosis:
- 1. Conjunctiva, nasal mucosa, and sinuses: Conjunctivitis,
sinusitis, and rhinitis, proliferative, subacute, multifocal,
moderate, with numerous superficial epithelial adherent protozoa,
king (Coturnix chinensis) and brown (Coturnix australis) quail,
avian, etiology consistent with Cryptosporidium sp.
2. Periorbital tissue: Cellulitis, subacute, focally extensive,
3. Turbinates: Osteomyelitis, heterophilic, multifocal, moderate,
4. Oral mucosa: Stomatitis, hyperkeratotic, multifocal, moderate,
with superficial crust containing yeast, hyphae, pseudohyphae,
and abundant cocci.
- Conference Note: Cryptosporidium species are coccidian
parasites that infect the microvillous borders of host epithelial
cells. In birds they infect the respiratory, intestinal and bursal
epithelium. Species of Cryptosporidium have also been reported
in a wide variety of vertebrate hosts, including reptiles, amphibians,
fish, and mammals (including humans). C. parvum infects only
mammals, C. baileyi and C. meleagridis infect only birds, and
C. serpentis infects only reptiles.
- Cryptosporidium spp. are apicomplexan protozoans in the Order
Eucoccidiorida, Family Cryptosporidiidae. Transmission is direct.
Sporulated oocysts are excreted in the feces. Ingested or inhaled
sporozoites invade epithelial cells, disrupting the apical microvillous
border in an intracellular but extracytoplasmic location. Asexual
replication results in formation of first, second and third generation
meronts (merogony). Merozoites then form microgamonts and macrogamonts
(gametogony), which fuse (fertilization) forming an oocyst. Formation
of sporulated oocysts (sporogony) occurs within the host epithelial
- Contributor: School of Veterinary Science, University
of Melbourne, Veterinary Clinical Centre, Werribee Victoria 3030,
- 1. Gardiner CH, Fayer R, Dubey JP: An Atlas of Protozoan
Parasites in Animal Tissues. 2nd ed., pp. 37-40. Armed Forces
Institute of Pathology, Washington, DC, 1998
- 2. Current WL: Cryptosporidiosis. In: Diseases of Poultry,
ed. Calnek BW, 10th ed., pp. 883-890. Mosby-Wolfe, London, 1997
- 3. Hoerr FJ, Current WL, Haynes TB: Fatal Cryptosporidiosis
in Quail. Avian Dis 30:421-425, 1986
- 4. Tham VL, Kniesberg S, Dixon BR: Cryptosporidiosis in Quails.
Avian Pathol 11:619-626, 1982
- Case IV - 96-2874 (AFIP2592869)
- Signalment: Adult male mixed breed dog.
- History: This dog was one of five received by University
Animal Care for use in an experimental protocol. Routine physical
exam and screening exams were performed. Babesia canis
and Babesia gibsonii parasites were seen on blood smears.
The dogs were administered di-(p-amidinophenyl) triazene (Berenil®)
at a dosage of either 7mg/kg IM one time or 3.5mg/kg IM SID on
two consecutive days to clear the infection. Twenty-four to 48
hours post injection, the dogs developed clinical signs, which
included head tilt, ataxia, vomiting, fever, diarrhea, intention
tremors, opisthotonous and seizures. A neurologic examination
of the dog from which slides for this conference were obtained
revealed exaggerated extensor radialis and patellar reflexes
on the right side, normal pupillary reflexes, absent proprioceptive
reflexes in all four limbs, and exaggerated hopping reflex to
the side in all four limbs. The dogs were euthanized and necropsies
- Gross Pathology: Foci of hemorrhage and malacia were
observed in the cerebellum and medulla in the location of the
cerebellar and vestibular nuclei.
- Laboratory Results: A complete blood count, serum
chemistry panel and urinalysis were unremarkable. Liquid chromatography-mass
spectrometry revealed a three-fold, higher level of di-(p-amidinophenyl)
triazene in the lot of Berenil® administered to these animals
when compared to an older lot which had been used previously
without incident. No evidence of product degradation was apparent
in either lot. Quantitation of the drug concentration was not
possible due to our inability to obtain a standard.
Contributor's Diagnosis and Comments: Necrosis, hemorrhagic,
subacute, multifocal, severe, vestibular and cerebellar roof
Etiology: di-(p-amidinophenyl) triazene toxicity.
- Di-(p-amidinophenyl) triazene is one of a group of drugs
known as diamidines. These were developed specifically for their
antitrypanosomal activity. Some were also found to be effective
against Babesia sp. and, outside of the United States, are widely
used for treatment of this infection in dogs. The drug is not
available in the United States but can (and was in this case)
be purchased from pharmacies in Mexico.
- Reports of toxicity following therapeutic use of di-(p-amidinophenyl)
triazene have occurred sporadically in the literature and one
experimental replication study has been published. Typically,
the history is that of repeated therapeutic doses followed in
a few days by the acute onset of CNS signs. At the recommended
dosage rate of 3.5 mg/kg for elimination of Babesia canis,
serious side effects are not expected. However, there have been
undocumented reports of dogs treated at this dosage that have
developed clinical signs, died and had characteristic necropsy
lesions. The dosage of 7mg/kg was utilized for treatment of our
dogs based on recommendations in a current pharmacology text
for the elimination of Babesia gibsonii. It is recommended
that the dosage never exceed 7mg/kg, single dose, administered
IM. Dosage over 10mg/kg will result in CNS injury. There is,
apparently, marked individual variability in sensitivity to the
drug among dogs. The results of the LC-Mass Spec analysis suggest
that the lot used to treat our dogs contained a higher concentration
of the drug than represented on the label.
- Clinical signs of toxicity include behavioral changes, nystagmus,
ataxia, extensor rigidity, opisthotonus, coma and death. Hemorrhagic
gastroenteritis, hepatic failure and muscle degeneration have
also been reported. Necropsy lesions are foci of hemorrhage and
malacia affecting white and gray matter in the cerebellum, medulla
oblongata, midbrain and thalamus. The vestibular nuclei and cerebellar
roof nuclei are the most commonly involved areas. Less frequently
affected areas include the olfactory lobes, basal ganglia, thalamus,
midbrain and cerebellar peduncles and cortex (uvula). The histologic
lesions are multifocal hemorrhage, necrosis, edema and rarefaction
followed by an influx of neutrophils and Wallerian degeneration.
The mechanism of toxicity is not well defined. The drug has a
histamine-like action which leads to increased vascular permeability
and may have some relevance to the lesions in the CNS.
- AFIP Diagnosis: Cerebellum and brainstem, cerebellar
nuclei: Necrosis and hemorrhage, bilaterally symmetrical, extensive,
with neutrophilic inflammation, fibrinoid vasculitis, and perivascular
edema, mixed breed, canine.
Conference Note: The differential diagnosis for necrosis
and hemorrhage of cerebellar nuclei includes thiamin defiency,
nigropallidal encephalomalacia in horses, focal symmetrical spinal
poliomalacia of sheep and goats, nicotinamide antagonists, polioencephalomalacia
of ruminants, Aspergillus clavatus mycotoxicosis, and
rickettsial infection. In very few of these conditions is the
pathogenesis well understood. A common pathway seems to be shared
by many of these diseases, whereby ischemia, hypoxia or a direct
toxic effect results in lactic acid production and/or tissue
damage with release of vasoactive amines, leading to vasodilatation,
edema, and inflammation.
- CNS edema results from 4 mechanisms:
- 1. increased vascular permeability, resulting in increased
extracellular fluid (vasogenic type);
- 2. increased intracellular fluid with intact vascular permeability
- 3. increased hydrostatic pressure (hydrostatic type);
- 4. abnormal osmotic gradient between tissues and blood (osmotic
- CNS cells and tissue structures, in decreasing order of susceptibility
to ischemia are neurons, oligodendroglia, astrocytes, microglia,
and blood vessels. Neuronal susceptibility to ischemia varies
by location within the CNS.
- Contributor: Arizona Veterinary Diagnostic Laboratory,
University of Arizona, Tucson, Arizona 85705
- 1. Jubb KVF, Huxtable CR: The Nervous System. In: Pathology
of Domestic Animals, eds. KVF Jubb, PC Kennedy, N Palmer, 4th
ed., vol. 1, pp. 338-350. Academic Press, San Diego, CA, 1993
- 2. Carlton WJ, McGavin MD: Thompson's Special Veterinary
Pathology, 2nd ed., pp. 338-350. Mosby Yearbook, Inc., St Louis,
- 3. Moore DJ: Therapeutic implications of Babesia canis infection
in dogs. J South African Vet Assoc 50:346-352, 1979
- 4. Naude TW, Basson PA, Pienaar JG: Experimental diamidine
poisoning due to commonly used babecides. Onderstepoort J Vet
- 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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