As Red Dane has recently diversified to include a pork and sheep business in our family, Kikaboni, we thought we’d share a series of blogs on the most common pig diseases in Zimbabwe, and how you can prevent, diagnose and treat them! The second blog in the series is on Porcine Parvovirus (PPV).
Subclinical PPV is prevalent in the majority of swine herds worldwide. At one time, before the development of effective vaccinations, it was the second most responsible disease for reproductive failure in pigs. The virus can infect and kill embryos and foetuses and may arise every 3 to 6 years in herds that have not been properly vaccinated The virus enters pigs orally or by venereal routes and then transfers to the blood by entering the reproductive system and crossing the placenta after 10 to 14 days after infection. It may be found on boar sperm from 5 to 9 days after infection[i]. Boars will not be clinically affected by the PVV virus; however, they can potentially infect the females that they inseminate.
PPV outbreaks usually last about 3 to 4 months but the blanket impact is much worse: it can drastically reduce litter sizes by 3 to 4 piglets, so it is highly recommended that the correct preventative measures are taken. The PPV virus is very resilient and can live for at least 4 months outside a host.
Prevention
The following practices will help you to prevent PPV in your herd:
- Gilts should be vaccinated before their first service twice between 24 and 30 weeks of age. They should be provided with booster vaccinations again before farrowing.
- Sows should be booster vaccinated before each farrowing
Clinical symptoms depend on the stage of pregnancy at which the gilt or sow is infected. The sow or gilt herself will not display any signs of illness at any time because the infection is only in the uterus and the unborn piglets. So if the signs below are demonstrated without any apparent illness in the gilt or sow, then it is likely that PPV is the cause.
- Infection in the uterus at serving time can kill all embryos.
- Infection soon after serving time can partially or entirely terminate early embryos. If only partial, there may be an abnormal return to service just a small litter. Generally, a very small litter will be delivered if the embryos are destroyed between 14 and 30-35 days after implantation.
- If infection occurs after day 35, i.e. after the foetal structure has developed, then foetuses will die (still births) or be mummified.
- Mummified foetuses are the best indication that PVV, rather than another disease such as Aujeszky’s Disease or PRRS, is affecting unborn piglets. Abortions are not a common result of PPV.
Treatment
Once a wave of PPV has manifested in the herd, there is no way to halt its progress. The only way to control it is by effective vaccination and immunisation before serving the gilts and sows.
[i] Parvovirus [Internet]. Pig Progress 2019 [Cited 2019 October 3]; Available from: https://www.pigprogress.net/Health/Health-Tool/diseases/Parvovirus/ [ii] Parvovirus [Internet]. Iowa State University College of Veterinary Medicine, 2019 [Cited 2019 October 3]; Available from: https://vetmed.iastate.edu/vdpam/FSVD/swine/index-diseases/parvovirus [iii] Porcine Parvovirus [Internet]. NADIS Animal Health Skills, 2019 [Cited 2019 October 3]; Available from: https://www.nadis.org.uk/disease-a-z/pigs/porcine-parvovirus/