Bovine Abortion

Question 1

1. Causes of bovine abortion.

Answer 1

1. Infectious:
   - Sexually transmitted e.g. Campylobacter foetus, BHV-1, BVD, Mycoplasma and Ureaplasma, Leptospires, Tritrichomonas foetus, Histophilus somni, C. renale.
   - Non-sexually transmitted Salmonella Dublin, Bacillus licheniformis, Schmallenberg virus.
   Non-infectious.

Question 2

Classification of infectious agents.

Answer 2

• Primary:
  – Acting directly upon uterus, placenta, foetus.
• Secondary:
  – Causing systemic diseases which as a secondary effect adversely influence conception / pregnancy.

Question 3

How can infectious causes of infertility exert their effect?

Answer 3

• Stopping fertilisation.
• Early-embryonic death.
• Late-embryonic death.
• Pyometra.
• Mummification.
• Maceration.
• Abortion / premature birth.
• Stillbirth.
• Birth of a non-viable neonate.

Question 4

Define abortion.

Answer 4

• Production of one or more calves less than 271 days after service or AI.
• They are either dead or live for less than 24 hours.

Question 5

Frequency of abortion.

Answer 5

A level of sporadic abortion of 1-2% of pregnant cows is normal.
If it exceeds 3-5%, or a number of abortions occur in an apparent cluster then a thorough investigation is necessary.
Stillbirths and premature calvings must also be taken into consideration.

Question 6

Action to be taken following an abortion.

Answer 6

Under Brucellosis Orders, ALL births before 271 days constitute an abortion, whether the calf is born alive or dead, must be reported to DEFRA. Not all are currently investigated – risk based surveillance.
Aborting or aborted cow must be isolated together with the foetus or calf and placenta.
After investigation, placenta and foetus should be disposed of by incineration or deep burial.

Question 7

What is involved in systemic examination of abortion?

Answer 7

• History.
• General exam of cow.
• Exam of foetus and placenta (send all to lab OR collection of samples for the lab.
  – blood, milk, placenta, foetal stomach contents, foetal blood, brain, other internal organs.
• Interpretation of results.,

Question 8

1. Viral causes of bovine abortion.
2. Bacterial causes of bovine abortion.

Answer 8

1. BVD, BHV-1, Blue Tongue, Schmallenberg virus.
2. Leptospira hardjo, Salmonella, Bacillus licheniformis, Listeria monocytogenis, Campylobacter foetus venerealis, Mycoplasma, Coxiella burnetii (Q fever), Chlamydophila psittaci, Trueperella pyogenes, others incl, Mycobacterium TB, Parachlamydia.

Question 9

1. Fungal cause of bovine abortion?
2. Protozoal cause of bovine abortion?

Answer 9

1. Mycotic abortion.
2. Neospora caninum, Tritrichomonas foetus (not UK), Babesia.

Question 10

Reasons for failure to identify cause of abortion.

Answer 10

• Cause occurred much earlier.
• Foetus retained after death for some time – autolysis.
• Foetal membranes not available.
• Toxic and genetic factors not identified in specimens.
• Many cases unknown or physiological.
• Interpretation of tests can be difficult.

Question 11

Most common infectious causes of abortion in UK cattle.

Answer 11

Bacillus licheniformis.
Neospora caninum.
Trueperella pyogenes.
Schmallenberg virus.
Aspergillus fumigatus.
Bovine Viral Diarrhoea.
Listeria.
(Brucella abortus).

Question 12

6 main ways BHV-1 presents.

Answer 12

• Respiratory (IBR).
• Conjunctival (IBR).
• Abortion.
• IPVV/IBP.
• Encephalomyelitis.
• Enteritis.

Question 13

1. Effect of BHV-1 on pregnancy.
2. Prevention and control of BHV-1.

Answer 13

1. • Depends on time at which susceptible female acquires infection.
     - Venereal transmission.
     - May cause embryonic death and repeat breeding.
     - Abortions usually from 5 months onwards.
     - Infection late in pregnancy may cause stillbirths or non-viable calves.
2. • No long term effect on fertility
     - Eliminate carriers if they can be identified.
     - Killed vac available for pregnant stock but will not prevent abortion if female already infected (long incubation period).
     Marker vaccines.

Question 14

1. Aetiological agent of Infectious Pustular Vulvo-vaginitis.
2. Transmission of IPVV?
3. Effect of IPVV on fertility?
4. Clinical signs of IPVV.

Answer 14

1. BHV-1.
2. Venereally.
3. Can cause embryonic death (not abortion).
4. Vulval hyperaemia.
   Vesicles.
   Ulcers.
   Pain, straining, frequent urination, tail swishing, pyrexia, milk yield drop, vaginal discharge.

Question 15

1. What does IBP stand for and who does it affect?
2. Signs of IBP.
3. Treatment / prognosis.

Answer 15

1. Infectious Balanoposthitis affects males.
2. Preputial discharge.
   Similar lesions on penis and prepuce therefore libido decreased, but fertility normally unaffected.
3. Spontaneous recovery over 2-4 weeks.
   All breeding must cease until clinical signs resolve.

Question 16

1. Effects of Blue Tongue on bull and ram fertility.
2. Effect on cows?
3. Effect on foetus.
4. Outcome of infection?

Answer 16

1. Temporary infertility.
2. Reduced conception rates (infertility).
3. Virus can cross placenta and infect foetus.
4. Depends on stage of pregnancy:
   - abortion.
   - Foetal deformity.
   - Foetal mummification.
   - Birth of weak calves.
   - Birth of viraemic calves which may or may not develop BT.

Question 17

1. 2 strains of leptospirosis.
2. Clinical signs of leptospirosis in bovids.
   – Subclinical signs.
3. Symptoms of lepto in man.
4. Signs of lepto in sheep.

Answer 17

1. Hardjo and Bovis.
2. Abortion, milk drop, infertility.
   – Reduced milk yield, weak calves.
3. Flu-like (frontal headaches).
   May lead to meningitis.
   May become chronic and debilitating.
4. Isually no signs evident.
   Minor cause of abortion.
   Important source of infection for cattle.

Question 18

Risk factors of leptospirosis and the level of risk increase for each.

Answer 18

• Bought in cattle = X2.
• Use of a bull = X4.
• Grazing with sheep = X6.
• Access to water courses = X8

Question 19

1. Treatment of bought-in stock to reduce lepto.
2. Reducing risk of lepto through management factors.

Answer 19

1. Isolate, (poss. treat w/ abx) and vac.
   Keep in isolation until ~1 week after second vac.
2. • Prevent access to water courses.
     - Minimum 2 month gap between sheep grazing and cattle grazing pasture.
     - Minimum 2 month gap between slurry spreading and cattle grazing.
     - Use AI rather than hired or shared bull.
     - Operate closed herd.
     - BIOSECURITY!

Question 20

1. Advantages of vac against lepto.
2. Disadvantages of vac against lepto.
3. Timing of vac against lepto in cattle.

Answer 20

1. • Good ctrl of clinical disease in uninfected animals subsequently meeting infection.
     - Ideally used in combination w/ abx to remove renal infection.
2. • Will not affect disease established before vac.
     - If placenta already damaged, will not prevent abortion.
3. Ideally at turnout in the Spring (prior to time of significant exposure to infection).
   Ideally start at 5-6 months old to give protection and reduce risk of renal carrier in the herd.

Question 21

Recommended vac programme for vac against lepto.

Answer 21

Initial course = 2 x 2ml doses 4-6 weeks apart.
Annual booster vac given a max of 12 months after previous vac to protect against re-infection.
Early vac can stop infection before it starts as prevents calves from being infected and becoming carriers.

Question 22

1. How does Salmonella cause bovine abortion?
2. When is Salmonella most common in cattle? – when do most abortions occur?
3. Cycle of Salmonella infection in cattle.

Answer 22

1. Secondary to systemic infection.
2. Summer and autumn at pasture. – late pregnancy in the absence of systemic illness.
3. Transmission via excretion > contamination of environment > ingestion > and back around again.

Question 23

1. Diagnosis of Salmonella in cattle.
2. Control of Salmonella in cattle.

Answer 23

1. Presence of organism in cotyledons / foetal stomach contents. milk, discharges and faeces of dam.
   Serology rarely helpful.
2. • Isolate aborters for 5 weeks.
     - Dispose of products of abortion very carefully.
     - Decontaminate environment as much as poss.
     - Consider vac where S. Dublin is a persistent problem.
     - Under Zoonoses Regs Reportable (by lab).

Question 24

1. Where do Bacillus spp. thrive?
2. How does infection occur?
3. Clinical signs of Bacillus licheniformis?

Answer 24

1. Mouldy hay, feed, straw. and silage.
2. Ingestion and then haematogenous spread.
3. • Usually abort in late pregnancy.
     - Usually sporadic but occasional small outbreaks.

Question 25

1. Diagnosis of Bacillus licheniformis?
2. Control of Bacillus licheniformis?

Answer 25

1. Gross appearance of placenta (similar to mycotic abortion).
   Isolation of Bacillus from placenta, foetal stomach and vaginal discharge.
2. Difficult; the organism is ubiquitous.
   Improve ventilation.
   Avoid contaminated and poor quality feed and bedding.

Question 26

1. How does infection with listeria occur in cattle?
2. When seen mainly?
3. What disease is listeria associated with?

Answer 26

1. Principally by ingestion.
   Related to ingestion of high pH silage produced from 2nd and 3rd cuts.
2. Winter, sporadically.
3. Repro disease and meningo-encephalitis but these rarely occur simultaneously.

Question 27

1. Transmission of Campylobacter?
2. Clinical signs?
3. Who in the herd are affected?
4. First sign of Campylobacter problem in in the herd?

Answer 27

1. Venereal.
2. Male – none –> asymptomatic carrier.
   Females:
   – Mucopurulent vaginal discharge.
   – Repeat breeder due to early embryonic death.
   – Abortion at 4-7 months of gestation.
3. All – following intro via:
   - infected bull or
   - infected females who then infect bull (rare).
4. Large number of returns to oestrus following service with this bull. Only later may abortions be seen.

Question 28

Diagnosis of Campylobacter in females?

Answer 28

• Isolate organism from vaginal discharge or products of abortion.
• Vaginal microscopic agglutination.
  – Collect mucus in luteal phase of cycle and examine for antibodies. Titre of 1:50 is significant.
• PCR – commercially available.
• Serology useless.

Question 29

Diagnosis of Campylobacter in males.

Answer 29

• Bacteriological examination of semen.
• Florescent antibody test on preputial washings/scrapings.
• Virgin heifer test – ethical?
• PCR ?

Question 30

Control of campylobacter?

Answer 30

Based on the fact that:
- Transmission = venereal.
- Untreated bulls remain permanently infected.
- Cows overcome the infection and develop immunity over 3-6 months.

– Specific treatment of females not required.
– Use A.I.
– To avoid infected females infecting or reinfecting a male, allow 2 normal pregnancies by A.I. before resuming natural breeding.

Question 31

Treatment of Campylobacter in the bull.

Answer 31

Antibiotic systemically for several days and by penile and preputial irrigation.
4 consecutive fluorescent antibody tests should be negative before bull re-used on clean stock.
Vacs available in other countries.

Question 32

1. Mycoplasmosis organisms associated w/ bovine repro problems.
2. What disease entities are associated with such spp.?

Answer 32

1. M. bovigenitalium.
   M. bovis.
   Ureaplasma spp.
   Acholeplasma laidlawii.
2. • Granular vulvovaginitis.
     - Abortion and premature birth.
     - Venereal transmission.
     NB. not all infected animals develop clinical disease.

Question 33

1. How is Q fever (Coxiella burnetii) transmitted?
2. Diagnosis of Q fever.

Answer 33

1. Airborne, ticks, contaminated needles etc.
2. Demonstration of organism in stained smears of cotyledons and foetal stomach contents.
   Serology.

Question 34

1. Clinical signs of Chlamydia psittaci.
2. Diagnosis of Chlamydia psittaci.

Answer 34

1. Early embryonic death.
   Abortion in late pregnany w/ or w/o systemic disease (conjunctivitis, ocular and nasal mucopurulent discharge, pyrexia, milk yield decrease).
2. Isolation of organism from ocular discharge in affected animals and cotyledonary smears.
   Serology of dam and foetal pleural fluids.

Question 35

1. Brucella abortus.
2. How does infection occur?
3. How can it present in herds?
4. Diagnosis?
5. Control of Brucellosis.

Answer 35

1. Notifiable and zoonotic, now eradicated from UK.
2. Venereal possible. Most usually by ingestion.
3. Abortion storms.
4. All abortion / premature calvings must be reported.
   Blood, milk and vaginal swabs taken if requested by DEFRA.
5. Majority of dairy cows checked routinely via the monthly bulk milk test.

Question 36

1. What is Trueperella pyogenes associated with?
2. Disease in the dam?

Answer 36

1. Suppurative lesions in foetus and placenta.
2. No systemic disease.

Question 37

Other microorganisms that sporadically cause abortion.

Answer 37

Histophilus somni.
Coliforms.
Yersinia paratuberculosis.
Nocardia asteroides.
Pseudomonas.
Streptococci and Staphylococci.

Question 38

What is mycotic abortion related to?

Answer 38

• Heavy rainfall during haymaking and straw bailing.
• Storage in conditions of high temperature and humidity.
• Use of affected material in conditions of poor ventilation / overcrowding.

Question 39

1. Commonest agents causing mycotic abortion in UK.
2. Routes of infection?
3. At what point of pregnancy does mycotic abortion usually occur? – What happens to the placenta?

Answer 39

1. • Aspergillus.
     - Absidia.
     - Mucor.
2. Ingestion (major) / Inhalation&raquo_space; blood stream&raquo_space; uterus&raquo_space; placentitis & endometritis&raquo_space; foetal infection.
3. 7 months gestation. – Usually retained.

Question 40

1. What are the 3 identified parasite stages of Neospora caninum?
2. Transmission type of N. caninum?
3. Treatment of N. caninum?

Answer 40

1. Tachyzoites, bradyzoites and oocytes.
2. Vertical transmission v efficient (>95%) w/ low levels of horizontal transmission.
3. No drug treatment is effective against N. caninum in cattle.
   No vac available in UK.

Question 41

Diagnosis of Neospora abortion.

Answer 41

• Abortion usually mid-term (3-8mths).
• Mummification may occur.
• Histopathology of foetal tissues shows non-suppurative encephalomyelitis, also myocarditis.
• Parasites in CNS or heart confirmed by immunoperoxidase.
• Serology on cow at abortion usually shows titre >1/1280.
• Titres fall rapidly after abortion, so samples collected at times other than abortion may not be meaningful.

Question 42

Neosporosis in new-born calves.

Answer 42

Majority of infected cattle will give birth to congenitally infected calves.
New-born congenitally infected calves typically have a very high antibody response.
Calves should be tested either before colostrum intake, or after having colostrum from their dam (as uninfected calves may give false positives if fed colostrum or milk from infected cows).
New-born calves should be tested to allow selection of uninfected replacement heifers, and to check the infection status of their dams.

Question 43

Clinical signs of neosporosis in cattle.

Answer 43

Infertility:
- abortion, early foetal death, mummified foetuses, stillbirths.
Neuromuscular disease in neonatal calves.
Reduced milk production.

Question 44

Neosporosis control options.

Answer 44

Cull infected cattle or do not breed for replacements.
Select seronegative heifer replacements.
Restrict access of dogs (and other animals) to feed and water sources.
Improve hygiene at calving and abortion including careful disposal of all placentae, even those from ‘normal’ calvings.

Question 45

1. What type of parasite is Trichomonas?
2. Where does it reside?
3. Transmission?
4. Clinical signs?

Answer 45

1. Flagellate protozoan parasite.
2. Bovine prepuce, vagina and uterus.
3. Venereal.
4. Herd infertility:
   – males –> balanoposthitis w/ slight catarrhal discharge.
   – Females –> repeat breeders w/ vaginal discharge, pyometra w/ acyclicity, abortion usually at 2-4mths.

Question 46

1. Trichomoniasis diagnosis.
2. Treatment and control of trichomoniasis.

Answer 46

1. Identification of organism in vaginal discharge, penile and preputial scrapings.
2. Females acquire resistance.
   Untreated bulls will remain carriers.
   Use A.I.

Question 47

Miscellaneous non-infectious causes of abortion.

Answer 47

• Genetic factors or teratogens.
• Twin pregnancy.
• Trauma / stress.
• Insemination / intra-uterine infusion.
• High fever and endotoxins.
• Nutritional deficiency.
• Hypothyroidism (goitrogens).
• Drug induced: PGF2a, corticosteroids, oestrogen, xylazine.
• Exotoxins (poisonous plants), mycotoxins, nitrates.
• Shock / fright.

Question 48

1. Schmallenberg virus first seen?
2. Vectors?
3. Spread through the UK?
4. Vac?

Answer 48

2. Insects.
3. Spread North through UK and now reached Scotland.
4. Bovilis SBV (MSD) – cattle 2 doses, sheep 1 dose.