JPC SYSTEMIC PATHOLOGY

REPRODUCTIVE SYSTEM

January 2025

R-F01

 

Signalment (JPC# 1421031): Bovine fetus

 

HISTORY: None

 

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 µm 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 1-2µm 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 rare 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 µm 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. 

MORPHOLOGIC DIAGNOSIS: 1. Placenta, chorioallantois: Placentitis, necrotizing, subacute, diffuse, moderate, with necrotizing vasculitis, coccobacilli and fungal hyphae, breed unspecified, bovine.

2. Haired skin: Dermatitis, subacute, diffuse, moderate, with multifocal orthokeratotic hyperkeratosis and few superficial fungal hyphae.

ETIOLOGIC DIAGNOSIS: Mycotic placentitis and dermatitis

GENERAL DISCUSSION:

• Placental fungal infections are a major concern in certain geographic areas and sporadic in others.
• Aspergillus fumigatus is the most common cause of mycotic placentitis in cattle 
  1. Majority of cows recover sufficiently after abortion and can carry subsequent pregnancies.
• Absidia, Mucor, Rhizopus, Mortierella, Candida and Torulopsis are other common causes 

 

PATHOGENESIS: 

• Bovine – Usually hematogenous route to the placentomes suspected to be thru descending intra-uterine spread; however portal of entry is unknown, infection from rumen or respiratory tract is possible
• Lesions begin in the cotyledons and spread to the intercotyledonary placenta 
• Mare - Ascending infection
• Late term abortions - between the 6th and 8th month of gestation; frequently retention of placenta

 

TYPICAL GROSS FINDINGS:

• Placenta - often retained and has remarkable lesions (similar to brucellosis but more severe)
  1. Placental lesions are both cotyledonary and intercotyledonary
  2. Enlarged, yellow-brown, necrotic to hemorrhagic cotyledons with prominent margins (“cupping”) and thickened, yellow, leathery intercotyledonary areas covered in brown exudate.
  3. Fungal hyphae are often abundant in the lesions. 
• Amnion may be thick, white, or yellow w/ leathery areas. 
• Fetus
  1. Cutaneous lesions are multifocal to coalescing, irregular, elevated, alopecic, white to gray plaques resembling ichthyosis or ringworm
     • Not present in mild infections
  2. Most common on the periorbital area, head, shoulders, neck, back and sides
  3. Gastric contents almost always have fungi. 

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

• Placenta 
  1. Necrotizing placentitis with fungal hyphae, and vasculitis and thrombosis at base of cotyledons
  2. Endometrial lesions are less severe than those in the placenta
  3. Necrosis and desquamation of trophoblasts
  4. Chorioallantois contain large numbers of neutrophils, macrophages, and lymphocytes
• Amnion if affected has large number of neutrophils, macrophages, and lymphocytes
• Fetus
  1. Cutaneous lesions: Hyperkeratosis, acanthosis, dermatitis
  2. Infection is superficial involving just the epidermis, however invasion into hair follicles and dermis can occur
  3. Bronchopneumonia

 

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
• Immunohistochemistry
• ELISA 

DIFFERENTIAL DIAGNOSIS:

Both cotyledonary and intercotyledonary bovine placentitis: 

 

Late term abortion in cattle:

 

Fetal dermatitis with multifocal dermal plaques:

 

Amniotic fluid changes: thick, white, yellow

COMPARATIVE PATHOLOGY:

• Mare: Aspergillus fumigatus and Mucor sp. 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 subsp. fetus, Coxiella burnetti, Chlamydophila sp. and Toxoplasma gondii are much more common causes of abortion than are fungi
• Cervids: Brucellosis abortus, Listeria monocytogenes, Toxoplasma gondii causes abortion
• Non-domestic bovid species: Toxoplasma spp. most commonly found as cause of abortion in gazelles, Gerenuk, dik dik, and saiga
• Mustelids, seals: Brucella pinnipedialis, Toxoplasma gondii causes placentitis and abortion
• Primates: Listeria monocytogenes and Toxoplasma gondii causes placentitis and abortion.
• Cetaceans; bottlenose dolphis, harbor porpoise, striped dolphis: Brucella ceti, Brucella pinnepedialis, Toxoplasma gondii causes placentitis and abortions.
• Giraffe: Listeria monocytogenes causes placentitis and abortions. Asperguillis may be normal aural flora. 
• Mustelids: Toxoplasma gondii placentitis and abortions.
• Rats: Mycoplasma pulmonis
• Rabbits: Listeria monocytogenes

 

REFERENCES:

1. Abee CR, Mansfield K, Tardif S, Morris T. Nonhuman Primates in Biomedical Research: Volume 2: Diseases. 2nd ed. San Diego, CA: Elsevier; 2012: 112, 525. 
2. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: Wiley Blackwell; 2016: 134, 281.

3. Foster RA, Premanandan C. Female Reproductive System and Mammae In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:1296-1297. 

4. Colegrove KM, Burek-Huntington KA, Roe W, Siebert U. Pinnipediae. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:582. 
5. Howerth EW, Nemeth NM, Ryser-Degiorgis MP. Cervidae. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:164, 176.e6, 176.e11. 
6. Jones MEB, Gasper DJ, Mitchell E. Bovidae, Antilocapridae, Giraffidae, Tragulidae, Hippopotamidae. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:136-137, 140, 141e.9. 
7. Matz-Rensing K, Lowenstine LJ. New World and Old World Monkeys. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:338, 362.

8. 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.

9. St. Leger J, Raverty S, Mena A. Cetacea. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:556-557,563. 
10. Williams BH, Burek-Huntington KA, Miller M. Mustelids. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:300, 141.e13.

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