JPC SYSTEMIC PATHOLOGY
Signalment (JPC# 1421031): Bovine fetus
HISTOPATHOLOGIC DESCRIPTION (Slide a): Chorioallantois: Diffusely there is loss of chorionic villar epithelium of the cotyledon and replacement by abundant eosinophilic cellular and karyorrhectic debris (necrosis) admixed with few lightly basophilic, 2-4 um wide, infrequently septate hyphae that have parallel walls and dichotomous, right angle branching as well as fibrin, basophilic granular mineral and moderate numbers of lymphocytes, plasma cells, macrophages, and fewer neutrophils. Multifocally within low to moderate numbers of sloughed trophoblasts and extracellularly in the necrotic debris there are colonies of 1-2um coccobacilli. The chorioallantoic stroma is expanded by similar inflammatory cells with hemorrhage, fibrin, edema and scattered necrotic debris and mineral. Multifocally within vessels there is disruption of the tunica intima and tunica media with replacement by cellular and karyorrhectic debris and rare fungal hyphae (necrotizing vasculitis). Multifocally within the cellular debris on the allantoic membrane of the intercotyledonary chorioallantois, as well as enmeshed within fibrin and debris along the margin of the parietal yolk sac, there are many fungal hyphae. The yolk sac stroma is infiltrated by neutrophils, lymphocytes and macrophages admixed with small amounts of necrotic debris.
Haired skin: There is multifocal mild epidermal hyperplasia, acanthosis, spongiosis and orthokeratotic hyperkeratosis admixed with few previously described fungal hyphae. Diffusely, the superficial dermis is infiltrated by moderate numbers of lymphocytes, plasma cells and fewer macrophages, and there is separation of dermal collagen by increased clear space (edema). There is a focal intra-corneal pustule composed of few degenerate neutrophils. The follicle subjacent to this pustule is hyperkeratotic and contains a small amount of amorphous eosinophilic cellular debris and few degenerate neutrophils (folliculitis).
Slide b (Periodic Acid Schiff): PAS positive fungal hyphae that are 2-4 um wide, infrequently septate, parallel walled, and having dichotomous, right angle branching present on the allantoic membrane, parietal yolk sac within chorioallantoic stroma and vessels, and within the stratum corneum of the skin.
- Placenta, chorioallantois: Placentitis, necrotizing, subacute, diffuse, moderate, with necrotizing vasculitis, coccobacilli and fungal hyphae, breed unspecified, bovine.
- Haired skin: Dermatitis, subacute, diffuse, moderate, with multifocal orthokeratotic hyperkeratosis and few superficial fungal hyphae.
ETIOLOGIC DIAGNOSIS: Mycotic placentitis and dermatitis
- Aspergillus fumigatus is the most common cause of mycotic placentitis in cattle
- Absidia, Mucor, Rhizopus, Mortierella, Candida and Torulopsis are other common causes
- In one prevalence study of cases diagnosed as mycotic abortions in the northern plains states the following prevalence was determined
- Aspergillus accounted for 71% of cases diagnosed as mycotic abortion with 62% of these cases being Aspergillus fumigatus.
- Zygomycetes (Absidia, Mucor, Rhizopus, Mortierella) accounted for 21% of the cases diagnosed as mycotic abortions
- Candida and Torulopsis accounted for 2% of cases diagnosed as mycotic abortion; Pseudallescheria boydii is also an uncommon cause of abortion
- Bovine – usually hematogenous route to the placentomes by extension from forestomach or respiratory infections; however portal of entry is unknown
- Late term abortions - between the 6th and 8th month of gestation
- Lesions begin in the cotyledons and spread to the intercotyledonary placenta
TYPICAL GROSS FINDINGS:
- Placenta - often retained
- Placental lesions are both cotyledonary and intercotyledonary
- Enlarged, yellow-brown, necrotic to hemorrhagic cotyledons with prominent margins and thickened, yellow, leathery intercotyledonary areas
- Cutaneous lesions are multifocal, irregular, elevated, alopecic, gray plaques resembling ichthyosis or ringworm
- Most common on the periorbital area, occiput, shoulders, back and sides
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Necrotizing placentitis with fungal hyphae, vasculitis and thrombosis
- Endometrial lesions are less severe than those in the placenta
- Cutaneous lesions: Hyperkeratosis, acanthosis, dermatitis
- Infection is superficial, however invasion into hair follicles and dermis can occur
ADDITIONAL DIAGNOSTIC TESTS:
- Periodic acid Schiff (PAS), Gridley"s, Grocott"s methenamine silver nitrate (GMS)
- Culture of placenta and fetal skin or fetal gastric contents
- Murine monoclonal and rabbit polyclonal antibodies in immunohistochemistry
- ELISA of antibodies in serology
Both cotyledonary and intercotyledonary bovine placentitis:
- Brucella abortus: Cotyledonary necrosis, intercotyledonary areas thickened and leathery; numerous bacteria in chorionic epithelium and trophoblasts
Late term abortion in cattle:
- Brucella abortus, Campylobacter fetus venerealis, Leptospira sp., Listeria monocytogenes, Epizootic bovine abortion (foothills abortion; Pajaroellobacter abortibovis), Salmonella sp., Sarcocystis cruzi
Fetal dermatitis with multifocal dermal plaques:
- Icthyosis fetalis or icthyosis congenita – an autosomal recessive molecular defect in many breeds of cattle that results in flat plates of hyperkeratosis; icthyosis fetalis is the more severe form compared to icthyosis congenital
Amniotic fluid changes: thick, white, yellow
- Ureaplasma diversum
- Mare: Aspergillus fumigatus and Mucor are the most common causes of equine mycotic abortion; infections are transcervical; grossly, there is brown inflammatory exudate that thickens the chorion adjacent to the cervical os (cervical star)
- Small ruminants: Campylobacter fetus fetus, Coxiella burnetti, Chlamydophila sp. and Toxoplasma gondii are much more common causes of abortion than are fungi
- Swine: Viral and bacterial abortions are common; mycotic abortions are rare
- Allison N. Theriogenology question of the month. How would you confirm a diagnosis of mycotic infection in an aborted fetus? J Am Vet Med Assoc. 2004;225(6):849-851.
- Antoniassi NA, Juffo GD, Santos AS, Pescador CA, Ferreiro L, Driemeier D. Geotrichum candidum as a possible cause of bovine abortion. J Vet Diagn Invest. 2013 Nov;25(6):795-797.
- Foster RA. Male reproductive system. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:1181-1182.
- Hughes K, Mueller K. Pathologic lesions of mycotic pneumonia in an alpaca following third compartment ulceration. J Vet Diag Invest. 2008;20(5): 672-675.
- Johnson CT, Lupson GR, Lawrence KE. The bovine placentome in bacterial and mycotic abortions. Vet Rec. 1994;134(11):263-266.
- Knudtson WU, Kirkbride CA. Fungi associated with bovine abortion in the northern plains states (USA). J Vet Diag Invest. 1992;4(2): 181-185.
- Schlafer DH, Foster RA. Female genital system. In: Maxie MG, ed. Jubb, Kennedy, and Palmers Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Saunders Elsevier; 2016:418-419.