Heart tissue and fetal membranes are from a male, mixed-breed goat fetus with a crown to rump measurement of 28cm and weighing 911gA group of pregnant does at various stages of gestation were co-mingled with three, BVDV (Type 2) persistently infected heifers.
Examination of fetal tissues revealed no significant gross lesions.Â
Placenta: Creating a thin band along the superficial chorionic stroma, there are scattered necrotic cells admixed with abundant cellular debris.Â The overlying trophoblastic epithelium is often absent within the more affected regions.Â The vessels deep to the more affected areas are similarly peppered with nuclear debris, which occasionally obscures the endothelium and muscular layers of the vessel wall.Â In the deeper stroma, there is a mild, multifocal infiltrate of individually scattered mononuclear cells.Â
Heart: The heart exhibits a mild infiltrate of mononuclear inflammatory cells forming scattered infiltrates within the epicardium and forming perivascular cuffs within the myocardium.
1.Â Placenta: Marked, acute, multifocal to coalescing, necrotizing placentitis and vasculitis
2.Â Heart: Mild, multifocal, non-suppurative epicarditis and perivascular myocarditis
Tests performed on fetal tissues
- Bacterial cultures, negative
- Fluorescent Antibody
- BVDV, positive
- BVDV, positive
- Polymerase chain reaction (PCR)
- BVDV, positive (typed as Type 2)
- Chlamydia, negative
- Bluetongue virus (BTV), negative
- Chlamydia, negative
- Virus Isolation
- Negative on tissues from this case submission; however, BVDV was isolated from 2 other aborted fetuses with similar histological lesions in this study.
Bovine diarrhea virus
Based upon the histological lesions and ancillary testing (FA, IHC and PCR), the abortion syndrome in these goats is blamed on BVDV infection.Â
Although BVDV most commonly infects cattle, the virus can also be found in other domesticated and wild ruminants.1 It was hypothesized that these species may serve as a reservoir for the disease.1 Seroprevalence to BVDV has also been recognized in many other domesticated and wild ruminant species, the geography of which continues to expand.1,6,7,12
Experimental and natural intraspecies transmission of ruminant pestiviruses has been confirmed.8 This is also supported by the observation that higher seroprevalence rates of BVDV in goats occurs in regions/countries where goats are more likely to be co-mingled with cattle or wild ruminant species.7 Goats are thus infected by exposure to other persistently infected species.Â
The reproductive consequences of BVDV infection in cattle have been reviewed.5 BVDV disease in goats, reproductive failures or otherwise, have been less characterized.Â Experimental infection of adult goats with BVDV results in seroconversion with formation of neutralizing antibodies that persisted for up to 4 years.9 Infection of kids similarly showed development of neutralizing antibodies accompanied by an impaired growth rate, but otherwise, no significant clinical symptoms.10 Field outbreaks and experimental inoculation of BVDV in goats has produced reproductive failures.8 These have been characterized by barreness, abortions, stillbirths or births of weak kids and birth of kids exhibiting clinical signs similar to border disease accompanied by histological lesions in the CNS.8,11 Also, kids born to does experimentally infected with BVDV during gestation were highly contagious for goats and other susceptible ruminant species.10
BVDV should be considered as a cause of abortion in goats or perinatal deaths in goats with or without CNS disease.Â This is especially true in geographic regions where goats and cattle (persistently infected BVDV cattle) are in close proximity.
Placenta: Placentitis, necrotizing, multifocal, moderate, goat
(Capra hircus), caprine.
Diffuse autolysis obscured many histologic features and
complicated the assessment of necrosis in this case.Â Pathologic lesions of BVD
infection in fetal tissues are not considered characteristic and are rarely seen due
to fetal autolysis.13 Although the Bovine Viral Diarrhea Virus was not isolated
from this particular animal, a PCR, immunohistochemistry, and fluorescent
antibody were all positive, making diagnosis highly probable.Â Convincing
vasculitis was not present in the slides reviewed during the conference, but this is
possibly due to slide variation.
BVDV is a RNA virus of the Pestivirus genus in the family Flaviviridae.2 BVDV is known to naturally and subclinically infect pigs, sheep, goats, and several wild African ruminants.6 Other pestiviruses in animals include Porcine Pestivirus (classical swine fever virus/hog cholera virus) in swine, and Ovine Pestivirus (Border disease virus) in sheep.13
BVDV infection may result in three main disease syndromes: embryonal/fetal disease (transplacental infection), mucosal disease (infection in immunotolerant animal), or bovine viral diarrhea (infection in immunocompetent animal).13
Transplacental infections with BVDV13
|Cytopathic Strain of BVDV||Prior to 100 days of gestation||embryo and fetuses resorption or expulsion days to months following infection.|
|Â||100 -150 days of gestation||teratogenic effects on fetal organs that may result in microencephaly, cerebellar hypoplasia, hydraencephaly, hydrocephalus, microphthalmia, thymic aplasia, hypotrichosis, alopecia, brachygnathism, growth retardation, and pulmonary hypoplasia|
|Non-Cytopathic Strain of BVDV||Prior to 100-125 days of gestation||Immunotolerance results in birth of persistently infected calf|
|Â||After 150 days of gestation||Fetuses mount relatively normal immune response and are born with circulating antibodies|
Mucosal disease results when an immunotolerant cow is infected with a cytopathic strain of BVDV either from an exogenous source, or through a mutation of the endogenous non-cytopathic strain.13
Postnatal infection with BVDV in an immunocompetent animal predominantly result in enteritis primarily of the ileum and proximal colon.Â Multifocal erosions may occur in oral and esophageal areas.13
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