Pig reproduction disease Flashcards
How should sows be managed postweaning to ensure prompt return to oestrus?
- After weaning, boar contact from day 1 is essential (for tight serving window) .
◦ LH pulsatility
◦ Must stop day before service - This should be intensive, for a short time, twice a day.
- Best if sows are brought to the boar.
- Apply back-pressure test (swelling of vulva, mounting behaviour)
- Continuous contact is NOT desirable, habituation
- Sows on ad-lib lactator diet - to promote them coming into oestrus, to decrease NEB
- Day length is important:
◦ 16 hours of light
◦ 200 Lux - Wean-to-Service Interval is usually 5 days
- Sows should be served 24 hours after onset of standing heat.
◦ Gilts 8-12hrs - Min two inseminations
◦ 24hr intervals (Sows)
◦ 12hr intervals (Gilts)
◦ Big herds (will have three servers, one at first standing heat (which is 25 hours before ideal serving time, will then server 2 more times) - Sows will usually need to be moved either <5 days after insemination, OR not until 35 days after insemination (otherwise will interfere with implantation)
When does ovulation occur in the pig?
Ovulation occurs 12 hours before the end of standing oestus in the pig
What is the average lactation length in the sow?
26 days
What BCS should sows be at weaning?
2-3 (outdoor can be 3-3.5)
What are the most important gilt reproductive targets?
- Puberty by 180 - 210 days of age
- Boar contact from d180 (vasectomised boar or different pen)
- Mated at 235 -255 days at 135 -150 kg live-weight line dependant
- Mated at 2nd or 3rd recorded heat period (not puberty heat)
- Total born within no less then 0.5 pig / litter, of the sow herd average
- Successfully re-breed within 6 days of weaning
How can you prevent seasonal infertility in sows?
In autumn
* Increase feed level 0.25-0.5 kg/sow/day
* Increase boar contact 30-60 min/day
* Avoid chilling
In summer
wallows are a good way to mitigate this as mud = natural sunscreen - but not a requirement on assurance schemes
What are the signs of infectious disease affecting fertility?
- Sows or boars off-feed
- Sows or boars pyrexic
◦ Rarely this easy with endemic disease - Abortions/mummified foetuses
- Irregular returns to heat
- Weak and premature pigs
- High incidence of mummies and/or stillbirths
- Often just one of the above signs and can be subtle
What are the most common infectious causes of reproductive failure in pigs?
Viruses
* Porcine reproductive and respiratory syndrome virus - PRRSv
* Swine Influenza
* Porcine parvovirus (PPV) and Porcine enterovirus - stillbirth, mummification, embryonic death, and infertility (SMEDI) (old disease, more common in backyard pigs)
What signs are associated to PRRSv? What are the 3 possible disease statuses? How can it be controlled? What replacement strategy should be used? How is it diagnosed?
- blue ear commonly
- Spread by movement of carrier pigs (airborne spread), infect piglets via the placenta
- Invades and kills macrophages- causes immunocompromise
Disease status
* Negative
◦ Biosecurity is key
◦ Check status maintained with serology
* Positive, stable
◦ Sows serologically positive but not shedding virus
◦ Piglets weaned virus –ve
◦ Achieved primarily with vaccination
* Positive, unstable
◦ Sows serologically positive and shedding virus
◦ Piglets weaned virus +ve – problems in feeding herd - then can spread
◦ Restabilisation can be difficult to achieve
Control
Risks with:
◦ Stock
◦ People
◦ Vehicles
◦ Airborne
Vaccination
Replacement strategy
* PRRS –ve:
◦ Buy –ve replacements
◦ Quarantine min 8wks and check with own sentinels after 5wks
◦ Strict biosecurity
◦ Home breed
* PRRS +ve
◦ Isolate and vaccinate replacements
◦ Vaccination
◦ Do not serve gilts until >6wks since infection/vaccination
Diagnosis
* PCR - Oral fluids, bloods, tissue
* Oral Fluid
◦ Sample lots of animals easily (should be)
◦ Rarely enough virus to sequence
◦ Contamination
* Bloods
◦ Ear pin prick in 30x piglets at weaning
◦ Aborted sows
◦ Care re live vaccine
◦ Sequencing
* Tissue
◦ Foetal thymus
◦ Spleen
◦ Lung
What signs are associated to swine influenza? How is it diagnosed? How is it controlled?
- Predominantly a respiratory disease but will cause sows to return by causing pyrexia
- Therefore it is usually included in the investigation of high pregnancy failure rates
- Can be introduced by infected people, carrier pigs, birds.
- Can also cause inappetence in farrowing house and disease in pre-weaned piglets
- Diagnosis: clinical signs, nasal swabs, serology
- Control: Biosecurity
What are the possible causes of SMEDI? What does it stand for? What does it cause?
- Stillbirth
- Mummification
- Embryonic Death
- Infertility
- Is a syndrome with various (usually ubiquitous viral) causes:
◦ Parvovirus (PPV) (every commercial herd should be vaccinated against parvo)
◦ Teschoviruses (Sapelovirus, Teschen/ Talfan)
◦ Encephalomyocarditis Virus (EMCV)
◦ PCV2 - Porcine circovirus - Transplacental infection of fetuses occurs resulting in sequential fetal death.
- Abortion is rare; fetuses usually go to term as no prostaglandin trigger
What are the most common bacterial diseases causing reproductive problems in pigs?
- Leptospirosis
- Erysipelas
What signs are associated with leptospirosis? How is it diagnosed? How is it treated? How is it controlled?
- Main serovars causing disease in pig are L. pomona, L. tarassovi and L. bratislava/muenchen.
- Clinical signs: abortions/stillbirths, vaginal discharge
- Diagnosis: Difficult (chronic). Serology in returning sows. Foetal tissues (FAT).
- transmitted: rodents, boar prepuce
- Treatment: Antimicrobials (tetracyclines)
- Control: use of AI, hygiene in service areas, vaccination, rodent control
What are consequences of erysipelas? How is it diagosed? How is it treated? How is it controlled?
- E. rhusiopathiae – ubiquitous
- Excreted via saliva, faeces or urine
- Zoonotic potential (rare)
- Abortions, mummified foetuses, returns to service
- Diagnosis: difficult
- Tx: sensitive to penicillin
- Control: Vaccination
- Nearly all commercial herds vaccinating
How does endometritis affect sows? What is vulval discharge syndrome? How are they diagnosed? How are they controlled?
- Discharge at 14-21d post-service
- ‘Normal’ up to 2 days post-service
- Many different bacteria (opportunists)
- May cause reduced fertility
- Lots of risk factors related to management at service
- Diagnosis: observation and records
- Control: cull affected sows, service management
- Very uncommon in modern production
What are notifiable diseases causing procine reproductive failure?
- Brucella suis
- Aujezsky’s disease
- Classical Swine Fever
- African Swine Fever
What are possible reproductive problems in anoestrus?
- Rarely true Anoestrus usually increased W-S interval
- Usually related to sub-optimal nutriotion during lactation in young animals.
- Rarely failure to recognise oestrus (rule out)
- Main areas:
◦ Gilts: group management, health & nutrition, acclimatisation, boar contact, light, housing
◦ Sows: nutrition, environmental management
What are possible reproductive problems in ovulation?
- Low/variable litter size, decreased farrowing rate
- Main areas:
◦ Nutrition
◦ Hybrid vigour
◦ Good general health
◦ Ensure good feed intake during lactation
◦ Manage sows so they come into oestrus during the early fertile period (4-6d)
◦ Disease causing early embryonic death or foetal damage later on
What are possible reproductive problems during fertilisation?
- High rate of returns to service/variable litter size.
- Main areas:
◦ Accurate oestrus detection
◦ Served at correct time
◦ Nutrition
◦ Care with group changes after service
◦ Boar management if natural service – very rare
◦ Disease
What are the main things that can cause issues during implantation?
- Occurs d14-17 after ovulation
- Irregular returns (d25-35), small litter sizes.
- Main areas:
◦ Nutrition
◦ Boar contact for >28d post-service
◦ 16hrs light
◦ Stress 2-25d post-service
◦ General sow health
What are the main things that can cause foetal death or abortion?
- If embryos die <35d
◦ Resorption, return to service ~63d - If embryos present after 35d
◦ Mummification - Crown rump length will indicate age at death
- If large no. of piglets healthy then unlikely to be disease
- If small no. of pigs born healthy and large no. mummified then disease more likely
What are the main causes of stillbirth?
- Very frustrating to investigate.
- Usually related to sow factors:
◦ Fat sows, prolonged farrowing/dystocia
◦ Large litters, large piglets
◦ Fresh born dead is usually poor supervision around farrowing - Usually not infectious
What samples should we take in infectious causes?
- If sows are systemically ill:
◦ Serum (paired), nasal swabs, other tissues as appropriate
◦ Fetuses/fetal tissues often unrewarding - If sows are clinically ‘well’:
◦ Fetuses/fetal tissues, placenta
◦ Serology from sow may be helpful to rule out disease (seroconverted)
◦ Foetus usually better than sow samples due to vaccine complications
◦ However be prepared to be frustrated - Try to submit samples from 4-6 fetuses/litter from at least 3 litters. (Brain, Heart, Lung, Liver, Spleen, Kidney, Placenta, FSC, FF)
