Farm animal abortion Flashcards
what is the difference between abortion and still birth?
What is a bovine abortion?
Abortion = birth before full term, of a dead or non-viable foetus
Stillbirth = birth at full term, of a dead or non-viable foetus
Bovine abortion = Expulsion of a foetus between the completion of differentiation (day 42) and the limit of foetal independent viability (day 265).
why do we investigate abortion?
- Economic impacts – calf, milk, AI, feed etc.
- Wider significance or an easily solved problem?
- Public Health – zoonoses e.g. Salmonellosis
- Neospora – nearby footpaths
- Poor nutrition
- Statutory Requirement – Brucellosis Order
- The legislation requires anyone in charge of bovine animals to report any abortion or premature calving (< 271 days after service or < 265 after implantation whether calf is dead or alive) within 24 hours.
- Suspicion of Brucella abortus must be reported to APHA in the same way as other notifiable diseases.
what are the general themes of approaching an abortion case?
- history - individual and herd, clinicla signs in dam
- foetus quality
- decide adn intervention figure
- sampling - serology, PM of foetus
- list differentials
- biosecurity and zoonosis
- control/treatment plan
why are diagnositc rates for abortion low?
- Non-infectious causes
- Cost
- Limited farm history & data
- Sample quality & quantity
- No placenta
- Bacterial contaminant overgrowth
- Autolysis
- Cattle – time to abort
- Laboratory test limitations – only so many things can be tested for!
- Sampling bias – some farmers sample every abortion, some only with a disaster!
what are the non-infectious causes of abortion in cattle?
common in cattle, but difficult to prove:
* Hereditary disorders/congenital defects
* Toxins e.g. ergot, nitrates, brassicae, mycotoxins, hemlock, heavy metals
* Trauma/physical factors
* Prostaglandins – endogenous (stress), inflammation, pyrexia; exogenous
* Nutritional deficiencies/toxicities – severe starvation, pregnancy toxaemia, vit. A, iodine, selenium, manganese
* Concurrent disease – liver fluke, pneumonia, Johne’s, lungworm etc.
what are the viral causes of abortion in cattle? which are notifiable?
BVD
IBR – BoHV-1
Schmallenberg virus
Bluetongue virus - notifiable
what are the bacterial/Rickettsia causes of abortion in cattle? Which are notifiable and zoonotic?
Brucellosis - notifiable and zoonotic
Leptospirosis - zoonotic
Salmonellosis - zoonotic
Bacillus licheniformis
Listeria spp. - zoonotic
Coxiella burnetti (Q Fever) - zoonotic
what are the fungal, protozoa and sporadic infectious cuases of abortion in cattle? which are notifiable and zoonotic?
Fungal – Aspergillus, Absidia, Rhizopus etc.
Protozoal
* Neospora caninum
* Trichomoniasis
*Sporadic causes *
* Trueperella pyogenes
* E. coli - zoonotic
* Histophilus somni
* TB - notifiable
what are the viral causes of abortion in sheep? which are notifiable?
Border disease
Bluetongue virus - notifiable
Schmallenberg virus
what are the bacterial/rickettsia causes of abortion in sheep? which are notifiable and zoonotic?
Campylobacter fetus fetus, Campylobacter jejuni - zoonotic
Listeria spp. - zoonotic
Salmonellosis - zoonotic
Leptospirosis - zoonotic
Brucellosis - notifiable
Coxiella burnetti (Q Fever) – Rickettsia - zoonotic
Tick Borne Fever - Anaplasma phagocytophilum
what are the protozoal causes of abortion in sheep? is this zoonotic or notifiable ?
toxoplasma gondii - zoonotic
How is neospora canium transmited to cattle and within cattle?
protozoal parasite:
* Canines are the definitive host but vertical transmission much more common
* Exogenous transmission = Canine ingestion of tissue cysts e.g. in placenta –>oocysts passed in faeces –> contaminate feed/water –> cow injests infectious dog faeces –> cysts primarily in neural tissue –> Vertical transmission withing cow from tachyzoites, via the placenta –> foetus
* Endogenous transmission = Previously/persistently infected cow has reactivation of tissue cysts
what are the clinical signs of neospora caninum in cattle?
what problems does this cause in a herd?
- Abortion typically at 4-7 months but can cause resorptions, mummification, stillbirth, or may be born alive and persistently infected +/- congenital CNS disease
- Persistently infected calves grow to become persistently infected cows –> 40-50% abort in their first year, or results in vertical transmission
how is neospora caninum diagnosed and prevented?
Diagnosis
* Serology in cows
* Negative – rules out Neospora
* Positive – not diagnostic as not definitely the cause
* Antibody levels tend to be highest 10 to 4 weeks before calving
* PCR on foetal brain
* Histopathology +/- IHC on fixed brain
Prevention
* Infected dog faeces
* Remove access to placental material
* Test purchased cattle
* Avoid retaining breeding heifers born from seropositive cows
* Test and cull cows
what occurs if a cow is infected with BVD in pregnancy?
Abortion can occur at any point in gestation (usually 1st/2nd trimester)
* 0 - 30 days – infertility or early embryonic death
* 18-125 days – PI calves
* 80-150 days – congenital defects e.g. cerebellar hypoplasia, cataracts, hydrocephalus etc.
* > 150 days – the calf can launch an immune response and often survives
how is BVD diagnosed? what is the control?
PCR, antigen and antibody testing available
* PI calf – antigen positive, antibody negative
* PCR on aborted calf tissue (spleen often used)
* Antigen or antibody testing on blood (avoid antibody testing on post-colostral neonatal calves)
* Antigen/PCR testing on tissue in live animals e.g. ear tag
Control – routine herd testing, culling PIs, vaccination
what are the risk factors for leptospirosis in cattle?
what are the clinical signs?
how is it diagnosed?
how is it controlled?
- Higher risk if grazing with sheep
- Clinical signs – infertility, abortion usually >6 months, premature calves, milk drop
- Diagnosis
- PCR on foetal kidney, lung, or placenta
- Histopathology – foetal interstitial nephritis is pathognomonic
- Control and treatment
- Vaccination
- Avoid grazing with sheep
what is the main species of almonella in cattle?
what does salmonella cause in cattle?
how does it get on farm?
how is it diagnosed?
what is the the prevention?
- Primarily S. Dublin- ~80%
- Sporadic cause of abortion +/- dysentery and pyrexia in cows
- Introduction of carrier animals or contamination of feed/water
- Diagnosis – culture from foetal stomach contents
- Serology may be useful, but titres fall rapidly after abortions
- Faecal culture from the dam has low sensitivity
- Cows that abort shed for a very short period of time compared to enteric cases where there is intermittent or continuous shedding
- Prevention – vaccination, destroy contaminated bedding, isolate cows until vaginal discharge stops
what are the clinical signs of these species of salmonella in sheep?
S. abortusovis
S. montevideo
S. typhimurium
S. Dublin
- S. abortusovis – few clinical signs other than abortion in the last 6 weeks of gestation
- Lambs may be born alive but die within the first week of life
- S. montevideo – few clinical signs other than abortion, no diarrhoea in lambs
- S. typhimurium – pyrexia, anorexia, and profuse scour in ewes with foul smelling vaginal discharge
- May be fatal
- Lambs not aborted may be born stillbirth, or born alive and die soon after with evidence of scour
- Outbreaks often follow times of stress
- S. Dublin – clinical signs similar to S. typhimurium but usually not as severe
what is the diagnosis, treatment and prevention of salmonella in sheep?
Diagnosis – culture of foetal stomach contents
Treatment – treat ewes with a sensitive antibiotic if necessary
Prevention – vaccination, isolate aborted ewes, avoid stress etc.
what are the clinical signs of Campylobacter fetus subsp. venerealis in cattle?
how is it transmitted?
how is it diagnosed?
- Cause of infertility and embryonic death primarily, associated with a mucopurulent endometritis
- Occasionally abortion at 4-8 months
- Venereal transmission
- Cows – fertility returns after 4-8 months once the uterus recovers
- Bulls – may recover or be infected for life. The older the bull, the more likely to be persistently infected
- Diagnosis
- Culture from vaginal washes or preputial scrapings/washes – difficult to culture successfully
- Vaginal Mucous Agglutination Test – picks up ~50% of positive cows
- Serology – very poor humoral response to venereal infection so of little value
how is Campylobacter fetus subsp. fetus
transmitted in cattle?
what are the clinical signs?
how is it diagnosed?
- Found in the intestinal tract faeco-oral transmission
- Placental lesions – necrosis, intercotyledonary thickening and oedema, yellow-brown cotyledons
- Placental culture is difficult due to other contaminants overgrowing
- Foetal stomach contents – Campylobacter enrichment cultures
how is Campylobacter fetus fetus and C. jejuni transmited to sheep?
what are the clinical signs?
Campylobacter fetus fetus – from carrier sheep;
C. jejuni from wildlife vectors
Faeco-oral transmission –> ewe to ewe transmission
Clinical signs – infection –> abortion 7-25 days later, followed by strong immunity
* Abortion in the last 6 weeks of gestation and weak lambs born alive.
* May see diarrhoea as well as abortions.
* Up to 25% of ewes may abort in naïve flocks.
* Very few clinical signs in ewes other than abortion initially, though metritis may develop
* Aborted material is infectious
* Venereal spread not a feature (as in cattle – Campylobacter fetus venerealis)
how is campylobacter diagnosed in sheep?
how is it prevented?
Placenta may have intercotyledonary oedema and cotyledonary necrosis
Foetal livers may have multifocal areas of grey necrotic foci – pathognomonic
Culture – foetal stomach contents (or placenta, or liver)
prevention:
Some people will mix aborted ewes with lambed ewes to generate immunity
how is toxoplasma gondii transmited to sheep?
what does it cause in sheep?
infection is through ingestion of oocysts shed in cat faeces. - Cats are definitive host – sheep (and other mammals) are intermediate hosts.
Oocysts may survive for up to 2 years on pasture, feed, or bedding.
Causes infertility, mummification, stillbirth and abortion depending on stage of gestation and infective dose.
< 60 days –> foetal resorption –> high barren rate if ram has been removed
Mid-gestation –> abortion or mummification
> 120 days –> stillbirth, weak lambs, or normal lambs
how is toxoplasma gondii diagnosed and controlled?
Diagnosis – ‘frosted strawberry’ cotyledons
* Intercotyledonary areas unaffected (c.f. C. abortus)
* PCR – placenta
* Foetal serology – foetal fluid
* Maternal serology – antibodies can remain elevated for years (paired?)
Control – retain aborted ewes, keep old neutered cats on farm, and vaccinate!
what does chlamydia abortus (EAE) cause in sheep?
how is it diagnosed and controlled?
> 80% of outbreaks are from the purchase of infected ewes
* Ewes infected early in pregnancy may abort this year. If non-pregnant or in late gestation (~>100d), they lie dormant until the next pregnancy (will then abort).
* Results in late-term placentitis and abortion typically in the last 3 weeks of gestation.
* Some ewes become carriers and may excrete organism in their faeces.
Diagnosis
* Ewes are not ill
* Intercotyledonary areas are thickened, leathery, and oedematous
* Necrosis of foetal cotyledons
* May get birth of weak lambs
* Smears from intercotyledonary areas are stained with a modified ZN stain –> intracellular cocci seen
* Serology – maternal or foetal fluids
Control – retain ewes, biosecurity, vaccinate, antibiosis (prophylactic use of Oxytetracycline, to maintain the placenta until the end of pregnancy)
what infectious causes of abortion in sheep can be vaccinated against?
Chlamydia abortus (EAE), Toxoplasmosis, Campylobacter (import), Salmonella abortusovis
what virus is spread to foetuses by culicoides midges?
what are the clinical signs?
if you see these clinical signs what do you need to do and why|?
Schmallenberg virus
May see pyrexia, diarrhoea, anorexia, milk drop
Abortion and stillbirth, with congenital defects
* Arthrogryposis most common defect
* Neurological defects – hydrancephaly, hydrocephalus, cerebellar hypoplasia, porencephaly
if you see fluid filled cavities in foetuses then could be BVD or bluetounge virus and therefore need to report to APHA
