Lecture 79: Reproductive pathology- Female Reproduction: Bacterial and Viral Diseases

Brucellosis - causative agent

Brucella spp.; gram-negative coccobacilli; intracellular; chronic infection with persistent/recurrent bacteremia.

Brucellosis - transmission in cattle

Ingestion of aborted fetus, placenta, or uterine discharge; alimentary route most common.

Brucellosis - species affected

Cattle, sheep (B. ovis), dogs (B. canis); zoonotic risk via milk and discharge.

Brucellosis - pathogenesis

Systemic infection → bacteremia → localization in genital tract and placenta → placentitis → abortion.

Brucellosis - placental lesions

Dirty yellow, slimy exudate with gray-yellow floccules between chorion and endometrium; not pathognomonic.

Brucellosis - fetal lesions

Autolysis, edema, blood-tinged subcutis; pneumonia common in late-term abortions.

Brucellosis - diagnosis

Culture, immunofluorescence, immunohistochemistry; organism shed in colostrum and milk.

Brucella ovis - sheep lesions

Placental edema (2-5 cm thick), plaque-like intercotyledonary thickening, firm pale cotyledons.

Brucella canis - transmission

Ingestion of vaginal discharge, venereal via semen; semen remains infectious for months.

Brucella canis - clinical signs

Abortion after 30-50 days gestation; epididymitis, testicular degeneration, scrotal ulceration in males.

Brucella canis - fetal lesions

Pneumonia, endocarditis, hepatitis; live fetuses often die shortly after birth.

Campylobacter fetus venerealis - cattle

True venereal disease; causes infertility, repeat breeding, prolonged interestrus; abortion ~4-6 months.

Campylobacter fetus fetus - sheep

Oral transmission; causes late abortion, weak lambs; hepatic "target" lesions diagnostic.

Campylobacter jejuni - sheep and cattle

Common intestinal inhabitant; causes abortion in sheep, less often cattle; fecal-oral transmission.

Campylobacter - placental lesions

Enlarged, pale cotyledons with brown exudate; intercotyledonary edema; fetal liver with target lesions.

Listeriosis - causative agent

Listeria monocytogenes; gram-positive rod; survives in soil, feces, silage; zoonotic.

Listeriosis - transmission

Ingestion of contaminated silage, feces, urine, placenta, vaginal discharge.

Listeriosis - species affected

Cattle and sheep; abortion in last trimester; sporadic or outbreaks.

Listeriosis - placental lesions

Severe necrotic cotyledon tips with purulent exudate; red-brown intercotyledonary placentitis.

Listeriosis - fetal lesions

Pinpoint yellow foci in liver; bacteria within necrotic hepatic lesions.

Listeriosis - diagnosis

Refrigerate samples; culture on enriched/selective media; autolysis may hinder recovery.

Leptospira - cattle serovars

Hardjo (hardjo-bovis, hardjoprajitno), Pomona; spread via urine, placenta, semen, in utero.

Leptospira - cattle abortion timing

Last trimester; follows acute infection by 1-6 weeks (Pomona) or 4-12 weeks (Hardjo).

Leptospira - fetal/placental lesions

Nonspecific; icterus, hepatic necrosis, petechiae; diagnosis via PCR, culture, immunohistochemistry.

Leptospira - swine abortion

Occurs late gestation; stillbirths, mummified fetuses, weak piglets; placental edema, icterus, hepatic necrosis.

Leptospira - horses

Foals aborted in last trimester; icterus, mottled liver, petechiae; fetal antibody detectable by MAT.

Ureaplasma diversum - cattle

Colonizes mucosae, semen, embryo fluids; causes vulvitis, abortion, weak calves, retained membranes.

Ureaplasma - placental lesions

Amnion thickened with fibrosis, necrosis, hemorrhage, fibrin, mineralization, meconium staining.

Ureaplasma - fetal lesions

Meconium staining, firm lungs, poor aeration; diagnosis via culture or DNA detection.

Salmonella - species affected

Cattle, sheep, horses; ubiquitous serotypes (e.g., Typhimurium, Dublin, Abortusovis).

Salmonella - transmission

Contaminated feed, water, bedding, equipment; stress precipitates abortion.

Salmonella - pathogenesis

Intestinal colonization → bacteremia → placental infection → destruction of fetal villi → abortion.

Salmonella - placental lesions

Thickened chorioallantois, amber fluid, gray-red chorion, yellow exudate, adherent caruncles.

Salmonella - fetal lesions

Autolysis common; diagnosis via culture from placenta, stomach contents, vaginal discharge.

Chlamydophila abortus - sheep/goats

Causes enzootic abortion; zoonotic; infects placenta and fetus via trophoblasts.

Chlamydophila - transmission

Exposure to abortion products, vaginal fluids, semen; oral, conjunctival, reproductive mucosae.

Chlamydophila - abortion timing

Early infection → abortion in same pregnancy; late infection → abortion in next pregnancy.

Chlamydophila - placental lesions

Firm, matted cotyledons with dirty-red exudate; leathery intercotyledonary thickening with edema.

Chlamydophila - fetal lesions

Usually well preserved; few gross lesions; diagnosis via organism detection in fetal/placental tissue.

Coxiella burnetii - species affected

Sheep, goats, cattle; causes Q fever in humans; persists in environment and animals.

Coxiella - transmission

Inhalation of contaminated dust; oral transmission in heavily contaminated pastures.

Coxiella - abortion timing

Late gestation; fetus may be autolysed or well preserved; weak neonates may be born.

Coxiella - placental lesions

Thickened, leathery placenta; mineralization; off-white exudate in intercotyledonary region.

Equine ascending placentitis

Caused by bacteria or fungi; thickened cervical star with tan-white chorionic exudate.

Contagious equine metritis - agent

Taylorella equigenitalis; gram-negative coccobacillus; venereal transmission.

Contagious equine metritis - clinical signs

Temporary infertility, mucopurulent discharge (2-3 weeks); mares may carry organism for months.

Abortion diagnosis - sample strategy

Collect dam, placenta, fetus, and herd samples; include serum, swabs, tissues for culture and histology.

Abortion diagnosis - histology samples

Endometrium, placenta, brain, eyelid, thyroid, thymus, lung, heart, liver, spleen, kidney, adrenal, intestine.

Abortion diagnosis - fetal culture samples

Placenta, stomach contents, lung, kidney; fix or chill tissues properly for transport.

Abortion - fetal outcomes

Resorption, mummification, abortion, stillbirth; depends on gestational age and species.

Fetal infection - species differences

Bacterial/mycotic infections common in cattle and horses; cattle = hematogenous; horses = transcervical.

Abortion - noninfectious maternal causes

Hemoconcentration, anemia, fever, endotoxemia, respiratory disease; may indirectly affect fetus.

Abortion - diagnostic rate

Varies 5-90% depending on species and region; full history and sampling critical.

Abortion - sample strategy

Examine dam, placenta, fetus, and herd; collect serum, swabs, tissues for culture and histology.

Abortion - fetal culture samples

Placenta, stomach contents, lung, kidney; transport chilled or fixed, not frozen.

Abortion - histology samples

Endometrium, placenta, brain, eyelid, thyroid, thymus, lung, heart, liver, spleen, kidney, adrenal, intestine.

Equine ascending placentitis - cause

Bacterial or fungal infection ascending through cervix; non-contagious.

Equine ascending placentitis - lesions

Thickened cervical star, tan-white chorionic exudate; sample leading edge for culture and histology.

Contagious equine metritis - stallions

Transmit organism via coitus; asymptomatic carriers; reservoir for infection.

Chlamydophila abortus - incubation

50-90 days; early infection → abortion same pregnancy; late infection → abortion next pregnancy.

Chlamydophila abortus - epidemiology

Naïve or newly introduced animals most vulnerable; enzootic form causes ~5% yearly abortion rate.

Chlamydophila abortus - zoonotic risk

Can cause abortion in pregnant women exposed to infected sheep/goats.

Coxiella burnetii - zoonotic risk

Causes Q fever in humans; transmitted via inhalation of contaminated dust.

Coxiella burnetii - placental lesions

Thickened, leathery placenta; mineralization; copious off-white intercotyledonary exudate.

Coxiella burnetii - cotyledon lesion

Early lesion = white outer ring with central flecks; may resemble other bacterial placentitis.

Salmonella - stress triggers

Transport, diet change, spoiled feed; disrupt flora → increased bacterial growth → abortion.

Salmonella - abortion timing

Late gestation; sporadic or epizootic; may follow clinical illness or occur without signs.

Salmonella - fetal/placental lesions

Autolysed fetus; thickened chorioallantois; amber fluid; gray-red chorion; yellow exudate on cotyledons.

Ureaplasma diversum - transmission

Breeding, semen, embryo transfer fluids; survives freezing; colonizes mucosae and fluids.

Ureaplasma diversum - abortion timing

Last trimester; may cause premature delivery, weak or dead calves; retained membranes common.

Ureaplasma diversum - diagnosis

Culture or DNA detection from placenta, stomach contents, or lung; lesions not pathognomonic.

Leptospira - swine transmission

Urine contamination; enters via mucosa or skin breaks; poor effluent management spreads infection.

Leptospira - swine fetal lesions

Icterus, hepatic necrosis, peritoneal fluid/fibrin, multisystem inflammation; most severe in live but sick piglets.

Leptospira - equine fetal lesions

Icterus, yellow mottled liver, hepatomegaly, petechiae; diagnosis via fetal antibody or PCR.

Campylobacter - fetal liver lesions

Target-like tan foci with white rim and depressed center; diagnostic in sheep abortions.

Campylobacter fetus venerealis - bulls

Carried in preputial cavity; permanent carriers ≥4 years old; transmit via coitus.

Campylobacter fetus venerealis - cows

Temporary infertility, repeat breeding, prolonged interestrus; immunity develops over time.

Listeria - silage risk

High pH silage (6-7.8) supports growth; dies at pH <5.5; aerobic surface layers most dangerous.

Listeria - abortion timing

Last trimester; incubation 5-12 days; sporadic or up to 50% abortion rate in outbreaks.

Listeria - fetal liver lesions

Pinpoint yellow necrotic foci; bacteria present within lesions; diagnostic.