Latest pig circovirus disease treatment options

Due to the association of circovirus with a number of common pig health conditions, it is important to manage the overall health status of the herd. Circovirus is almost always found in combination with other pathogens and mortality can be very high.

Piglets should be vaccinated about the same time as weaning, when they are most likely to first come into contact with the virus. | Boehringer Ingelheim Animal Health
Piglets should be vaccinated about the same time as weaning, when they are most likely to first come into contact with the virus. | Boehringer Ingelheim Animal Health

Due to the association of circovirus with a number of common pig health conditions, it is important to manage the overall health status of the herd. Circovirus is almost always found in combination with other pathogens, and mortality can be very high. 

“Antibiotics are used to treat secondary infections, and anti-inflammatories may also be used with some success,” said Brad Leuwerke from the Swine Vet Center in the U.S. “But we don’t have good mitigation strategies for circovirus in pigs.” Otherwise, in severe cases, the advice is to remove sick animals to a hospital pen for care. Vaccination or preventative treatments for porcine reproductive and respiratory syndrome (PRRS) and mycoplasma may help to reduce disease pressure within the herd. 

Control strategies

Improving the health status of the herd in general is important, and a thorough biosecurity program should be employed. “Before PCV2 vaccine became available ‘Madec’s 20-point plan’ was used as a reference,” said Dr. Grosse Liesner, global technical manager of swine vaccines at Boehringer Ingelheim Animal Health. “It includes measures to improve biosecurity, reduce virus transmission and improve pigs' ability to cope with infection. It is well-established that stressors will aggravate the outcome of PCV2 infections.”

effects of PCV2 vaccination

A meta-analysis of 10 studies showed a significant and consistent improvement in average daily gain (ADG) when piglets were vaccinated at weaning.

Nutritional supplements have also been used to help prevent the loss of performance associated with circovirus. It is thought that by adding powerful natural antioxidants and other botanical extracts to the diets of piglets they are better able to fight the virus. Similarly, by supporting the pigs’ immune system, they may be less susceptible to secondary infections and their recovery quicker.

Commercial vaccines started to be available in the U.S. by early 2006, and they worked very well. “Performance of pigs improved greatly, if you were able to vaccinate,” Liesner said. “However, supply was limited, and it wasn’t until 2008 that it finally stabilized and the disease started to come under control.”

 Vaccination

There are several commercially available vaccines for circovirus. The specific vaccination program will differ depending on the vaccine used. Some only need one dose, while others require one or more booster doses. Strategies also differ between the breeding and growing herds. One-dose products are generally given to piglets just prior to weaning. For a two-dose program, the first should be given at weaning and the second three to four weeks later. “The aim is to create immunity in piglets before they come into contact with the field virus,” Leuwerke underlined. “If this is successful, then it will protect them for at least the following six months.”

Health and circovirus status will also influence decisions on how and when to vaccinate. “In rare cases a further vaccination of older pigs may be suggested,” Leuwerke said. He advised that if piglets were already suffering from post-weaning multisystemic wasting syndrome (PMWS) when they were due to be vaccinated, producers should go ahead. “In these cases, achieving good immunity will be difficult so a booster should be given once the animals have recovered. It would also be important to put the sow herd under surveillance to assess immune stability.

Read more: Understanding circovirus diseases in piglets and sows

“All incoming replacement gilts should be vaccinated one to two months before entering the herd,” continued Leuwerke. “If this is done, then the sows won’t need to be vaccinated again.” He went on to advise that if there has been a break-down in this routine, then a one-off mass vaccination of the breeding population should be carried out. Producers may be alerted to a problem by reduced conception rates or weak born piglets. It may also influence the pattern of disease in piglets, where symptoms of PMWS are seen much earlier. “Recent studies have shown that PCV2 may be impacting reproductive performance of older sows,” re-enforced Grosse Liesner. “Therefore, mass vaccination of the sow herd can have positive effects.”

Unlike some other viruses, immunity to circovirus will not pass from the sow to the piglets and give full protection until slaughter. It is therefore essential to have effective strategies to ensure immunity in both the breeding and the growing herd, to reduce the amount of virus circulating. “If producers are seeing problems in growing pigs they should evaluate the effectiveness of their vaccination strategy in both gilts and piglets,” stressed Leuwerke. “Ensuring that the right dose is given at the right time is the best way to control the disease.” 

Impact on pig production

There are numerous papers showing that vaccinating piglets has performance benefits including improved average daily weight gain, better uniformity, reduced mortality, improved feed conversion and reduced antibiotic use. Researchers have reported a return on investment (ROI) for PCV2 vaccines of between 6:1 and 8:1 in commercial situations. Even under experimental conditions, where the pigs were free of other diseases, the ROI was 3:1. These results show that under sub-clinical conditions the virus can be hiding performance losses. Vaccination, however, doesn’t prevent pig’s exposure to PCV2; the virus can still be found in herds with optimal protection. Stress reduction through proper housing, nutrition and biosecurity are essential for herd health.

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