Infectious factor | Abortion rate | Abortion timing | Recurrence of abortion | Foetal lesions | Samples |
|---|---|---|---|---|---|
Bacterial | |||||
Brucella abortus Brucellosis Bang’s disease Zoonosis | Up to 80% of unvaccinated animals infected in 1st or 2nd trimester | 6-9 months Abortion or stillbirth 2 wk to 5 mo after infection | Majority abort only once | Placenta: retained, cotyledons necrotic, red-yellow,; area between thickened Calf: normal or autolytic with bronchopneumonia | placenta, foetus, or uterine discharge Diagnosis: maternal serology, IFAT for Abs in placenta, bacteria isolation |
Campylobacter fetus venerealis Vibriosis | >10% | 5-8 months | Uncommon, convalescent cows resistant to infection | Placenta: mild placentitis, hemorrhagic cotyledons and an edematous intercotyledonary area. Foetus: fresh or autolysed; mild fibrinous pleuritis, peritonitis, bronchopneumonia. | Placenta, foetal abomasal contents, vaginal flushing Diagnosis: microscopic detection, isolation |
C fetus fetus C jejuni | Sporadic | 4-9 months | Uncommon, convalescent cows resistant to infection | See above | See above |
Leptospira interrogans, serovarsgrippotyphosa, pomona, hardjo, canicola, icterohaemorrhagiae Zoonosis | 5-40% | Last trimester Abortion 2-5 weeks after infection | Immunity to the serotype causing abortion but sensitive to other types | Placenta: diffuse placentitis with avascular, light tan cotyledons and edematous, yellowish intercotyledonary areas Foetus: autolysed | Placenta, foetus Diagnosis: IFAT foe Abs or PCR testing forLeptospira |
Arcanobacterium (Actinomyces) pyogenes | Sporadic | Any stage | Not known | Placenta: endometritis and diffuse placentitis, reddish brown to brown colour. Foetus: autolysed, fibrinous pericarditis, pleuritis, or peritonitis | Placenta, foetus Identification in bacterial culture from placenta or abomasal contents |
Listeria monocytogenes Zoonosis | Usually sporadic but can reach 50% | Last trimester | May recur | Dam: fever, inappetance Placenta: retained Foetus: autolysed Fibrinous polyserositis and white necrotic foci in the liver and/or cotyledons | Placenta, foetus Identification in bacterial culture from placenta or abomasal contents |
Fungal | |||||
Aspergillus sp (60-80% Mucor sp, Absidia, orRhizopus sp | Usually sporadic but can reach 5-10% | 4 months to term most common in winter | May recur | Placenta: severe, necrotising placentitis Cotyledons enlarged, necrotic, intercotyledonary area is thickened and leathery. Foetus: autolysed~30% have gray ringworm-like skin lesions principally involving the head and shoulders | Foetus, placenta Diagnosis: isolation from the stomach contents, placenta, and skin lesions. |
Protozoan | |||||
Tritrichomonas (Trichomonas) foetus Trichomoniasis | Sporadic | first half of gestation | Animal gains immunity but probably not life-long | Placenta: retained, mild placentitis with hemorrhagic cotyledons and thickened intercotyledonary areas covered with flocculent exudates Foetus: no specific lesions | Placenta, foetus, vaginal/uterine discharge Diagnosis: detection in abomasal contents, placental fluids, and uterine discharges |
Neospora caninum Neosporosis | High in first gestation and when infection enters the naïve herd Up to 30% first outbreak Enzootic: 5-10% | Any stage, but most often 5-6 months | Decreases with parity but always possible | Placenta, foetus: no specific gross lesions, autolysed Microscopic: focal encephalitis with necrosis and nonsuppurative inflammation, hepatitis in | Placenta, foetus (brain, heart, liver, body fluids), serum samples from the dam Diagnosis: detection of antigen in brain histology samples Immunochemistry in tissue samples Abs - PCR, ELISA |
Viral | |||||
Bovine Viral Diarrhoea Virus BVD-MD | Usually low | Complex pathology Abortion usually up to 4 months | Uncommon, immunity develops | Placenta: retained, no specific lesions Foetus: no specific lesions, autolysed, mummified | Placenta, foetus (preferred -spleen), dam and herdmates serum Diagnosis: isolation, immunologic staining, PCR, or detection of precolostral antibodies in aborted calves |
Bovine Herpesvirus type I (BHV I) Infectious Bovine rhinotracheitis virus (IBRV) IBR IBR-IPV | 5-60% in non vaccinated herds | Possibly any stage but most common from 4 months to term | Uncommon, immunity develops | In the majority of cases there are no gross lesions in the placenta or foetus Placenta: necrotizing vasculitis Foetus: autolysed, foci of necrosis in the liver | Placenta, foetus, serum samples from the dam Diagnosis: Immunochemistry in samples from kidney and adrenal glands, blood serology, PCR |
Blue tongue virus Blue tongue | Usually low | Variable | Unlikely | No specific Foetus: autolysed | Placenta, foetus, serum samples from the dam Diagnosis: virus isolation |
Epizootic Bovine Abortion Foothill Abortion etiologic agent has not been definitively determined, vector – tickOrnithodoros coriaceus | Can reach 75% Limited mainly to California in the US | Usually in the last trimester | Unlikely | Placenta: No specific Foetus: hepatomegaly, splenomegaly, and generalized lymphomegaly. Microscopically - marked lymphoid hyperplasia in the spleen and lymph nodes and granulomatous inflammation in most organs. | Anamnesis Diagnosis: elevated foetal Ig-G |
Factors not typical for cattle or rarely occurring | |||||
Chlamydophila abortus (Chlamydia psittaciserotype 1) enzootic abortion of ewes Zoonosis | Sporadic | Near the end of the last trimester | Unlikely | Placenta: placentitis, thickening and yellow-brown exudate adhered to the cotyledons and intercotyledonary areas. Foetus: fresh, minimal autolysis, pneumonia, hepatitis | Placenta, foetus Diagnosis: identification in stained smears of the placenta or by ELISA, fluorescent antibody staining, PCR, or isolation in embryonated chicken eggs or cell culture. |
Ureaplasma diversum | Usually sporadic, but outbreaks possible | Third trimester | Possible | Placenta: retained, intercotyledonary areas thickened, nonsuppurative placentitis Foetus: no gross lesions, pneumonia | Placenta, foetus Diagnosis: isolation from the placenta, lungs, and/or abomasal contents |
Salmonella spp | Usually sporadic but can take form of an abortion storm | Any stage | Possible | Cows: clinically ill Placenta and foetus: autolysed and emphysematous. | Placenta, foetus Diagnosis: isolation from the abomasal contents other tissues. |
Other infectious factors that potentially can cause abortion in cattle: Parainfluenza 3 Virus (PI3V), Mycoplasma spp , Histophilus somni (Haemophilus somnus), Staphylococcus spp, Streptococcus spp, Pasteurella spp, E.coli, Toxoplasma gondii | |||||